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School of Surgery

First metatarsophalangeal joint range of motion: influence of ankle joint position and gastrocsoleus muscle stretching.

Ian Graham North

BSc (Podiatry)

Post Grad Dip (Podiatry)

This thesis is presented for the degree of Master of Medical Science within the

School of Surgery, at The University of Western Australia, 2008.

i

ABSTRACT

First metatarsophalangeal joint (MTPJ1) motion is an important factor in normal

weight transference during walking. Disruptions to normal range can influence

joints both proximal and distal to the MTPJ1, potentially leading to pain and

dysfunction. Whilst the MTPJ1 has been investigated significantly, the

numerous methodologies described to quantify range of motion can be

questioned and makes comparisons difficult. Range of MTPJ1 motion is

commonly assessed in a clinical setting to determine pathology as well as to

make decisions on appropriate intervention. The anatomical and biomechanical

influence of tendo Achilles load and MTPJ1 motion has been well described;

however few studies measuring MTPJ1 range control for Achilles load or

describe ankle joint positioning. Further to this the effects of reducing tendo

Achilles stiffness on MTPJ1 extensions has yet to be investigated. The purpose

of this study was to describe a technique to quantify passive MTPJ1 extension

and to determine the influence of ankle joint position on joint range. Secondly

the effect of calf muscle stretching on MTPJ1 range was also investigated. The

information gathered will assist both research and clinical protocols for

quantifying MTPJ1 range, and provide a greater understanding of the anatomic

and biomechanical relationship between tendo Achilles load and MTPJ1

extension.

In order to fulfil the purposes of the study it was necessary to establish a

reliable methodology to quantify non weight bearing MTPJ1 extension.

Reliability testing was undertaken in three parts. First the appropriate number of

load un-load cycles was determined to produce statistically stable measures of

joint range. It was determined that beyond six load un-load cycles there was no

statistical significant difference in degrees of motion at the MTPJ1 representing

satisfactory joint conditioning. The second part of the reliability testing

determined the same day test re-test intra-rater reliability which was deemed to

be high (ICC 3, 1 0.89-0.99) across all derived variables. Test re-test intra-rater

reliability across one week was similarly good to high for all derived variables

(ICC 3, 1 0.76-0.98) with the exception of derived variable ankle joint dorsi flexion

at 10 Newtons (ICC 3, 1 0.23) which was low due to the actual low values in

degrees of motion.

ii

The influence of ankle joint position on MTPJ1 extension was investigated using

37 subjects [21 females and 16 males] with a mean age of 28 years.

Measurement of MTPJ1 extension was made in degrees at 10 and 30 Newton’s

across three ankle joint positions, namely ankle joint neutral, ankle joint dorsi

flexed and ankle joint plantar flexed. Data were analysed using paired t-tests.

The results indicated a statistical difference between MTPJ1 across each ankle

joint position, with a 90% and 70% reduction in the mean MTPJ1 range

between ankle joint plantar flexed to ankle joint dorsi flexed for 10 and 30

Newtons respectively.

Comparisons were made between left and right feet which indicated a trend

towards increased MTPJ1 range on the right limb with statistical significant

reached for variables ankle joint dorsi flexed at 10 Newton’s and ankle joint

neutral, ankle joint dorsi flexed and ankle joint plantar flexed at 30 Newtons.

Females appeared to display greater MTPJ1 range compared to males. There

was a statistical difference for variables ankle joint neutral and ankle joint

plantar flexion at 10 and 30 Newtons.

The study also investigated the immediate effect of a one minute calf muscle

stretch on MTPJ1 extension and ankle joint range as well the effect of the same

calf stretch performed twice daily over one week. Eleven subjects [7 males and

4 females] with a mean age of 29 years participated in this study. One limb was

randomly assigned as the stretch leg with the contralateral limb acting as the

control. The results demonstrated a statistically significant increase in joint

range immediately following a one minute stretch for variables ankle joint range

of motion as well as MTPJ1 extension for ankle joint plantar flexed at 10

Newton’s and ankle joint neutral and plantar flexed at 30 Newtons. No

significant differences were noted in ankle or MTPJ1 range of motion in either

the control group on immediate re-testing, or in both groups after a one week

stretch program.

The findings of this study support those documented in the literature pertaining

to the ankle joint position, tendo Achilles load and plantar fascial stiffness to

MTPJ1 range of motion. Increased stiffness at the MTPJ1 was noted dependant

iii

on ankle joint position from ankle joint plantar flexion through to ankle joint

dorsiflexion. This appears most likely due to increases in tendo Achilles load

and subsequent forces transmitted to the plantar aponeurosis. The present

study also demonstrated a trend towards increased joint extensibility and limb

dominance. The study also supports previous literature into gender differences

and joint extensibility, with a positive trend towards increased MTPJ1 range

evident in the female subjects tested. The study also demonstrated the

immediate effect of calf muscle stretching on ankle and MTPJ1 range of motion.

It remains however unclear as to the exact mechanisms involved in producing

increased joint range be it reflex inhibition or actual changes to the viscoelastic

properties of the soft tissues. Despite this, no changes were evident following a

one week stretching program, which supports previous literature describing a

short lag time before soft tissues revert to baseline length properties following a

single stretch session.

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ACKNOWLEDGEMENTS

I would like to express my appreciation to:

My supervisors, Professor Kevin Singer, Head of the Centre for Musculoskeletal

Studies (CMS) UWA, and Associate Professor Alan Bryant, Head of Podiatric

Medicine UWA for their commitment to my work from an academic view point as

well as the personal after hours work in helping me through this research

process. I would also like to thank Associate Professor Gary Allison School of

Physiotherapy, Curtin University for providing some equipment and guidance

through the initial period of this research. Also, a special thank you to Ray Smith

CMS UWA for his technical advice and computer programming skills used

throughout the work.

My family and friends for their ongoing support and constant asking of “how’s

your study going”, for which I found great motivation.

All the participants who volunteered their time for the study, including my

colleagues at Willetton Physiotherapy and Podiatry clinic who I used extensively

during the pilot stages.

Finally and most importantly, my partner Kaye Hosking and our children Riley

and Brianna, who have supported me wholeheartedly throughout this project.

Without such great support I would never have completed this thesis.

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DECLARATION OF ORIGINALITY

This thesis is presented for the degree of Master of Medical Science of The

University of Western Australia. Studies were undertaken between February

2006 and July 2008, through the Centre for Musculoskeletal Studies, School of

Surgery.

The pilot studies and final research study were developed in association with

my thesis supervisors, who were involved in editing this thesis. I have

performed all the experimental work and analyses of results independently.

I declare that all material presented in this thesis is original, apart from the work

from other sources which has been acknowledged within the text. Review of the

relevant literature to the thesis has been included up to July 2008.

Ian Graham North July 2008

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TABLE OF CONTENTS

PAGE

ABSTRACT i

ACKNOWLEDGEMENTS iv

DECLARATION OF ORIGINALITY v

TABLE OF CONTENTS vi

LIST OF TABLES xi

LIST OF FIGURES xiv

LIST OF ABBREVIATIONS xvi

DEFINITION OF TERMS xvii

CHAPTER ONE

DEVELOPMENT OF THE PROBLEM 1.0 Introduction 1

1.1 Statement of the problem and purpose of the study 1

1.1.1 Pilot Study: Weight bearing MTPJ1 extension 3

1.2 Significance of study 5

1.3 Research questions 5

1.4 Summary 6

CHAPTER TWO

REVIEW OF THE LITERATURE

2.0 INTRODUCTION 7

2.1 First Metatarsophalangeal Joint Anatomy 7

2.2 First Metatarsophalangeal ROM 9

2.3 Plantar Fascia and Windlass Mechanics. 11

2.4 MTPJ1- Pathology 12

2.4.1 Hallux rigidus 12

2.4.2 Functional hallux limitus 13

2.4.3 Plantar Fasciitis 13

2.4.4 Diabetes Mellitus and Limited Joint Mobility 14

2.5 Ankle Joint Position and MTPJ1. 15

2.6 Effects of Muscle Stretching 17

vii

2.7 Symmetry and Laterality 19

2.8 Assessment of foot type 20

2.9 Summary 21

CHAPTER THREE

METHODOLOGY 3.0 Introduction 22

3.1 Pilot Studies 22

3.2 Non-weight bearing Instrument methodology 22

Part One: Instrument development 24

3.3 Series I: Number of joint cycles 24

3.3.1 Description 24

3.3.2 Sample 25

3.3.3 Data 25

3.3.4 Derived Variables 25

3.3.5 Results 26

3.3.6 Summary 27

3.4 Series II- Test re-test reliability (same day) 28


3.4.2 Sample 28

3.4.3 Data 28

3.4.4 Derived variables 28

3.4.5 Results 29

3.4.6 Summary 29

3.5 Series III- Test retest reliability (one week) 29


3.5.2 Sample 30

3.5.3 Data 30

3.5.4 Derived variables 30

3.5.5 Results 30

3.5.6 Summary 31

Part Two: Normal series 31

3.6 Study design and subjects 31

3.6.1 Recruitment 31

3.7 Data collection procedures 32

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3.7.1 Inclusion criteria 32

3.7.2 Exclusion criteria 32

3.7.3 Ethical Considerations 32

3.7.4 Data collection 33

3.7.5 Procedures 33

3.7.5.1 Foot Posture Index (FPI-6) 33

3.7.5.2 Ankle Joint Range of Motion 33

3.7.5.3 MTPJ1 ROM 35

3.7.5.4 Data processing 35

3.7.5.5 Analysis of Data 35

Part Three: Stretching series 36

3.8 Study design and subjects 36

3.8.1 Recruitment 37

3.9 Data collection procedures 37

3.9.1 Inclusion criteria 37

3.9.2 Exclusion criteria 37

3.9.3 Ethical Considerations 37

3.9.4 Data collection 37

3.9.5 Procedures 38

3.9.5.1 Foot Posture Index 38

3.9.5.2 Ankle Joint Range of Motion 38

3.9.5.3 MTPJ1 38

3.9.5.4 Calf muscle stretching 38

CHAPTER FOUR

RESULTS 4.0 Introduction 40

4.1 Demographics 40

4.2 Normality 41

4.3 Laterality 41

4.4 Gender differences 42

4.5 Ankle joint position and MTPJ1 ROM 43

4.6 Foot posture 46

4.7 Calf MTU stretching and MTPJ1 ROM 49

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CHAPTER FIVE

DISCUSSION 5.0 Introduction 54

5.1 Research questions 54

5.1.1 Reliability of methodology 54

5.1.2 Ankle joint position and MTPJ1 ROM 56

5.1.3 Gender differences in ROM 57

5.1.4 Laterality 58

5.1.5 Foot posture and MTPJ1 ROM 59

5.1.6 Calf MTU stretching and MTPJ1 ROM 60

5.1.7 Limitations and recommendations for further

study 62

CHAPTER SIX

CONCLUSIONS 6.0 Introduction 65

6.1 Conclusions 65

REFERENCES 67

APPENDIX 1

Development of measurement tool: Weight bearing test set up 88

APPENDIX 2 Raw data MTPJ1 Cycles 96

APPENDIX 3 Summary of Analysis of Variance Analyses: MTPJ1 cycles. 99

APPENDIX 4 MTPJ1 ROM test retest raw data 103

APPENDIX 5

MTPJ1 ROM: test retest over one week raw data 104

APPENDIX 6

Information Sheet 105

APPENDIX 7

Consent Form for Participants 107

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APPENDIX 8

MTPJ1 ROM Data Recording Sheet 109

APPENDIX 9

Foot Posture Index (FPI-6) – Collection Form 110

APPENDIX 10

Ankle joint ROM pilot study: WBLT 111

APPENDIX 11

Stretch instructions and participation diary 116

APPENDIX 12

MTPJ1 ROM Raw Data: (part two) 117

APPENDIX 13

Raw data: Stretch and control cohorts; baseline, re-test (same day) and

retest (one week) 123

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LIST OF TABLES TABLE: PAGE

Table 3.1: Least Significance Difference (Scheffé) between the mean

of the groups of cycles 2,3,4; 7,8,9 and 12,13,14. 26

Table 3.2: Intraobserver ICC values,95% Confidence Limits, and

SEM for MTPJ1 motion for each force and ankle position

measured on the same day. 29

Table 3.3: Intraobserver ICC values,95% Confidence Limits, and

SEM for MTPJ1 motion for each force and ankle position

measured across time (one week). 31

Table 4.1: Demographic data including ankle joint range and foot

posture for Part two of the study investigating ankle joint

position and MTPJ1 ROM. 41

Table 4.2: Demographic data foot posture for Part three of the study

investigating calf MTU stretching and MTPJ1 ROM across

ankle joint positions. 41

Table 4.3: Results of paired t-tests comparing left and right feet for

derived variables WBLT and ankle joint position across

loads 10 and 30 Newtons. 42

Table 4.4: Mean, standard deviation (SD), T values, p values, 95%

lower and upper confidence intervals (CI), and mean

difference for dependent variables between male and

female subjects from paired t tests. (21 female – 16 male) 43

Table 4.5: The mean, standard deviation (SD), minimum, maximum

and range of dependent variables for part two of the study

investigating ankle joint position on MTPJ1 ROM. (all

measurements are in degrees). 44

Table 4.6: Paired t-test results between dependant variables; MTPJ1

ROM and ankle joint position and force (Newton’s)

demonstrating a highly significant change in MTPJ1

extension between ankle joint positions. 44

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Table 4.7: Mean and standard deviation of ankle joint (WBLT) and

MTPJ1 ROM across ankle joint positions and loads;

according to foot type as determined by the FPI-6. 47

Table 4.8: Paired t-test analyses between foot types (FPI-6) for

derived variables for ankle joint ROM (WBLT) and MTPJ1

ROM. 48

Table 4.9: The mean and standard deviation (SD) of dependent

variables and paired t-tests for the stretch group in part

three of the study investigating the effect of a one minute

calf MTU stretch on MTPJ1 and ankle joint ROM

measured on the same day.(all measures are in degrees) 50


variables and paired t-tests for the stretch group in part



measured at one week.(all measures are in degrees) 51


variables and paired t-tests for the control group in part



measured on the same day.(all measures are in degrees) 52


variables and paired t-tests for the control group in part



measured at one week.(all measures are in degrees) 52

Table 4.13: T values, p values, 95% confidence intervals (CI), and

mean difference for dependent variables; ankle joint

position at 10N, between stretch and control groups at

base line, repeat test (same day) and repeat test (one

week). 53

xiii

Table 4.14: T values, p values, 95% confidence intervals (CI), and

mean difference for dependent variables; ankle joint

position at 30N, between stretch and control groups at

base line, repeat test (same day) and repeat test (one

week). 53

xiv

LIST OF FIGURES FIGURE: PAGE

Figure 1.1: Outline of research steps summarising the development of

research questions, methodology and sections of

investigation. 4

Figure 2.1: Anatomy of the first metatarsophalangeal joint. 8

Figure 2.2: Initiation of the windlass mechanism via tightening of the

plantar aponeurosis accompanied with MTPJ1 extension. 12

Figure 3.1: MTPJ1passive extension using a force transducer

perpendicular to the axis and a potentiometer to

simultaneously record force/angle data. 23

Figure 3.2: Mean and 95% Confidence Intervals for MTPJ1 extension

through 15 cycles for loads 10N and 30N across three

ankle joint positions measured in degrees. 26

Figure 3.3: Mean difference and 95% confidence intervals for cycles

7,8,9. Derived variables 10 and 30N across the three

ankle joint positions. 27

Figure 3.4: Weight Bearing Lunge Test (WBLT) using a digital

inclinometer to measure angle from vertical. 34

Figure 3.5: Design and flow of participation through part III of the

study investigating the effect of calf MTU stretching on

MTPJ1 ROM. 36

Figure 3.6: Static calf MTU stretch. Subjects maintained full knee

extension whilst moving the hips anteriorly until a non

painful stretch was felt. Subjects were instructed to hold

the stretch for 30 seconds. 39

Figure 3.7: Cyclic calf MTU stretch, where subjects lunged their knee

forward and back to resistance. Subjects were instructed

to move at approximately one cycle per second for 30

repetitions. 39

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Figure 4.1: Box plot of MTPJ1 extension for ankle joint positions

neutral (AJN); dorsi flexed (AJDF) and plantar flexed

(AJPF) at 10N force (A) and 30N force (B). 45

Figure 4.2: Representation of variables obtained from force-angle

data of a single participant (subject 8). (A) The

displacement (angle) at force 10 and 30 Newtons for each

ankle joint position: AJDF (Ankle joint dorsi flexed); AJN

(Ankle joint neutral); AJPF (Ankle joint plantar flexed) (B)

The MTPJ1 passive stiffness defined as the ratio of

change in force to change in displacement determined

using a linear best fit model. 46

Figure 4.3: Comparison of mean MTPJ1 extension for ankle joint

positions, neutral, dorsi flexed and plantar flexed

(AJN;AJDF; AJPF) at 10 Newton’s (A) and 30 Newton’s

(B) of force by foot type determined by FPI-6. 49

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LIST OF ABBREVIATIONS

AJDF: Ankle joint dorsi flexed

AJN: Ankle joint neutral

AJPF: Ankle joint plantar flexed

BMI: Body mass index

FnHL: Functional hallux limitus

FPI: Foot posture index

HL: Hallux limitus

MTPJ1: First metatarsophalangeal joint

MTU: Musculoskeletal unit

N: Newton

Nm: Newton meter

ROM: Range of motion

WBLT: Weight bearing lunge test

xvii

DEFINITION OF TERMS

‘Body mass index’ (BMI): Refers to the body weight (kg) divided by the square

of the barefoot height (m).

‘Dorsiflexion’: Flexion or bending of the foot or ankle towards the extensor

aspect of the limb in the sagittal plane.(1)

‘First metatarsophalangeal joint’ (MTPJ1): Articulation of the first metatarsal and

proximal phalanx including the sesamoidal complex.(2)

‘Functional hallux limitus’ (FnHL): Refers to a reduced range of motion at the

MTPJ1 during weight bearing with normal range available during non weight

bearing examination.(3)

‘Foot Posture Index’ (FPI-6): A six criterion assessment tool used to quantify

static foot posture in a clinical setting.(4,5)

‘Hallux’: Refers to the big toe as a whole, incorporating the proximal and distal

phalanges.(2)

‘Hallux limitus’ (HL): Refers to a reduced or limited range of motion, particularly

extension, at the MTPJ1 due to progressive joint degeneration.(6)

‘Laterality’: The relationship and preferential use of one side in voluntary motor

acts.(1)

‘Passive range of motion’: Motion occurring around a joint not produced by

active efforts.(1)

‘Plantar flexion’: Flexion or bending of the foot or ankle towards the flexor

aspect of the limb in the sagittal plane.(1)

‘Stiffness’: Term used to describe the deformation of properties under the

influence of external force. (7)

xviii

‘Viscoelastic’: Describes a materials response to stress. If it returns to its

original pre stress geometrical shape it is said to be elastic, if it does not it is

said to be viscous. Tendons for example are sensitive to different strain rates

and our viscoelastic.(8,9)

‘Weight bearing lunge test’ (WBLT): Reliable method of quantifying ankle joint

range of motion particularly Soleus muscle length.(10)

‘Windlass mechanism’: Term used to describe the effect of the plantar fascia

being wound around the MTPJ1 during extension resulting in arch height

increase and inversion of the rear foot.(11)

1

CHAPTER ONE DEVELOPMENT OF THE PROBLEM

1.0 Introduction

First metatarsophalangeal joint (MTPJ1) motion is well recognised in its

importance to normal foot function and weight transference throughout the gait

cycle.(3,12-14) Dysfunction to the mechanics of the MTPJ1 can lead to

pathologies both proximal and distal to the joint.(15-17) Interventions aimed at

improving MTPJ1 function such as manipulation or mobilisation, orthotic therapy

and surgery are common practice, however further investigation is required to

quantify the mechanics of the MTPJ1 to determine clinical outcomes of such

interventions. Measurement of MTPJ1 range is non-standardised and is

reflected in the literature by way of large variances in quoted normal range

values.(18, 19) Few studies report on ankle joint position when measuring MTPJ1

ROM. Also lacking within the literature is information regarding the load

deformation characteristics of the MTPJ1 in normal subjects.

The functional and anatomical association between the calf muscle tendinous

unit (MTU), the plantar aponeurosis and MTPJ1 ROM has been described.(20-27)

To the author’s knowledge, clinical intervention by way of gastrocsoleus

stretching on MTPJ1 function has not been investigated to date. Recognition of

the effect of ankle joint position and calf MTU stiffness on MTPJ1 ROM will

provide further direction to specific clinical interventions and protocols to

enhance joint function.

Chapter One introduces the rationale behind the present investigation,

highlighting the nature of the problem, purposes and significance of the study,

assumptions, limitations, and relevant terminology. The research hypotheses

are outlined and a summary of the chapter is provided.

1.1 Statement of the problem and purpose of the study

Measurement of MTPJ1 ROM is commonly performed by clinicians to

determine pathology as well as to assess interventions. Controversy exists

within the literature as to a standard, reliable and valid method of measuring

MTPJ1 and what a normal value for MTPJ1 ROM should represent. Historically,

2

non weight bearing measures are taken using goniometers, however little

attention has focussed on joint displacement under load or the joint ‘stiffness’.

The viscoelastic nature of the joint means there is an amount of joint creep due

to stretch and relaxation of the soft tissue structures through the load un-load

cycles. To date no study has quantified the preconditioning aspects of the

MTPJ1 in terms of the number of joint displacement cycles required to minimise

this creep effect to produce reliable measures of range of motion.

Understanding joint stiffness may hold greater clinical relevance than actual

peak joint ranges as static measures of joint range are poorly correlated to

dynamic range.(28)

The anatomical and functional relationship between the Achilles tendon, plantar

fascia and first metatarsophalangeal joint has been outlined within the

literature.(21,25,89,90) Similarly the effect of gastrocsoleus stretching and ankle

joint ROM has been extensively investigated. Radford et al (29),in a systematic

review of the effect of gastrocsoleus stretching and ankle joint ROM, reported a

statistical improvement in ROM, however the actual increase in range was

relatively small. The clinical significance of these findings remains unclear. Calf

MTU stretching is a common clinical tool used in such pathologies as plantar

fasciitis and those with Type 2 diabetes where limited joint mobility can lead to

gait changes.(30, 31) Improved clinical outcomes are common, despite a relatively

small increase in ankle joint range produced by stretching. The elastic series

effect of increasing gastrocsoleus muscle length or reducing tendo Achilles

stiffness on MTPJ1 ROM has not been investigated. Such improvements in

ankle ROM may represent a concomitant improvement in MTPJ1 function and

therefore favourable gait changes throughout propulsion.

In light of these problems the present investigation contains four main purposes:

i. To develop a methodology to quantify MTPJ1 passive extension ROM and

investigate the reliability of this method in non weight bearing, using

asymptomatic normal subjects.

ii. To determine the effect of joint creep on MTPJ1 passive extension using

the developed methodology and to quantify the effect of joint conditioning

when measuring MTPJ1 passive extension.

3

iii. To examine the effect of ankle joint position on MTPJ1 passive extension

ROM. Three ankle joint positions will be tested namely; ankle joint plantar

flexion (AJPF), ankle joint dorsi flexion (AJDF) and ankle joint neutral

(AJN). Ankle joint neutral is described as the foot being ninety degrees to

the long axis of the tibia, with AJPF and AJDF measured ten degrees

respectively from this neutral position.

iv. To determine the short and medium term effects of a specific calf MTU

stretch on MTPJ1 passive extension ROM. To satisfy this purpose subjects

without MTPJ1 pathology will be measured before, immediately after a calf

MTU stretch and again after a one week home stretching regime.

1.1.1 Pilot Study: Weight bearing MTPJ1 extension

The preliminary focus for this investigation was to examine the influence of foot

orthoses and their various design parameters on MTPJ1 ROM. To achieve this,

a weight bearing methodology was required. Appendix 1 outlines this initial work

and testing regime for weight bearing measurement of MTPJ1 extension.

Test re-test reliability was performed together with the influence of foot orthoses

on MTPJ1 extension. A large degree of measurement error was noted in the

methodology which deemed it unsuitable for detecting any significant

intervention effect from the influence of foot orthoses.

It was hypothesised that the influence of postural sway, in particular the

recruitment of lower limb muscles had a large impact on the stiffness though the

MTPJ1 during testing. Hallux extension cycles during weight bearing appeared

to shift the body’s centre of mass anteriorly and posteriorly thus muscle

recruitment was necessary for maintenance of equilibrium, however myogenic

activity was not investigated. A degree of within trial and between trial errors

seen in this methodology appeared to be influenced by compensatory postural

muscle activation due to anteroposterior perturbations during testing.(32) This

highlighted the intricate inter relationship between Achilles tendon load and

MTPJ1 extension.

4

This experience formed the basis for the thesis with further work quantifying the

effect of ankle joint position, or tendo Achilles load, and MTPJ1 extension,

together with the subsequent effect of interventions used to reduce tendo

Achilles and calf MTU stiffness, on MTPJ1 extension ROM. Figure 1.1 outlines

the progression of the research towards answering the specific research

questions.

Figure 1.1: Outline of research steps summarising the development of research questions, methodology and sections of investigation.

Non weight bearing assessment of MTPJ1 extension: Reliability testing. • Influence of joint conditioning • Same day reliability • Reliability over time

Non weight bearing MTPJ1 ROM and the effects of ankle joint position in healthy asymptomatic adults. [N=73 feet]

The immediate and longer term effects of calf MTU stretching on ankle joint and MTPJ1 ROM, in healthy asymptomatic adults.

Case control study design [N=11 feet]

Weight bearing assessment of MTPJ1 ROM and the effects of foot orthoses design parameters on joint extensibility.

• development of technique • calibration of instrumentation • customisation of computer software

Technique deemed unreliable due to muscle

activation throughout perbutations.

5

1.2 Significance of study

It is hoped the findings of this study will contribute to a greater understanding of

MTPJ1 function and its inter relationship with ankle joint position and tendo

Achilles loading. The presented results of MTPJ1 ROM demonstrate greater

validity as the methodology presented incorporates known values of joint pre

conditioning as well as exact moments acting across the joint, something

lacking in previous studies. The clinical intervention of calf MTU stretching,

which is commonly advocated in many clinical presentations, has been shown

to improve ankle joint range. Whilst these values appear clinically small,

changes to MTPJ1 extension may provide insight into improved clinical

outcomes, potentially due to gait improvements throughout propulsion.

A number of assumptions were made within this study. Firstly the study

assumes that there is a direct inter relationship between tendo Achilles load and

passive MTPJ1 ROM. Additionally, whilst efforts were made to produce true

passive movements no control for intra subject muscle influences were made.

1.3 Research questions

Results of pilot work and review of the literature resulted in the following

research questions to be investigated:

i. Is the developed methodology for measuring MTPJ1 ROM and stiffness

reliable compared to established clinical protocols?

ii. How many joint pre-conditioning trials are required to provide stable

measures of MTPJ1 extension?

iii. Does ankle joint position significantly affect MTPJ1 passive extension and

stiffness in asymptomatic normal subjects?

iv. Are there gender differences with MTPJ1 ROM or stiffness in

asymptomatic normal subjects?

v. Are there symmetrical or limb dominance differences with MTPJ1 ROM or

stiffness in asymptomatic normal subjects?

vi. Does foot posture influence MTPJ1 ROM?

vii. Does static and cyclic calf MTU stretches improve MTPJ1 range of motion

and stiffness in asymptomatic normal subjects?

6

1.4 Summary

The purpose of this investigation was to provide information on the effects of

ankle joint position and MTPJ1 passive extension in the population studied,

together with the effects of short term musculotendinous stretching to putatively

improve MTPJ1 range. The above research questions will be answered using

the developed methodology which incorporates simultaneous angle and force

data as the MTPJ1 is passively extended across three ankle joint positions. The

findings of this thesis will be discussed in relation to information concerning the

clinical influence of calf MTU load and MTPJ1 function. Limitations and

recommendations for further work will also be presented.

7

CHAPTER TWO REVIEW OF THE LITERATURE

2.0 Introduction

The following chapter provides a synopsis of the relevant literature, searched

through data bases such as PubMed and Google scholar up until July 2008,

which relates to the first metatarsophalangeal joint and areas pertinent to the

present investigation. Anatomy of the MTPJ1 is presented together with

descriptions of normal and abnormal function. Methodologies used to quantify

MTPJ1 ROM are outlined as well as a description of assessment tools

described in the literature to quantify foot shapes and postures. Pathologies

affecting MTPJ1 ROM both intrinsically and extrinsically are discussed as they

relate to this investigation. Secondly the inter relationship between the calf

MTU, plantar aponeurosis and MTPJ1 function is presented. Finally, review of

the phenomenon of laterality and its relevance to the present investigation is

outlined. Gender differences in joint extensibility are also discussed as are the

effects of stretching on the mechanical properties of the musculotendinous unit

and joint range of motion.

2.1 First Metatarsophalangeal Joint Anatomy

The first metatarsophalangeal joint consists of the articulations of the head of

the first metatarsal and the proximal phalanx of the hallux. The sesamoidal

complex, made up of two sesamoid bones, is located in grooves beneath the

plantar aspect of the first metatarsal head. They assist in the movement of the

joint by allowing the metatarsal head to glide posteriorly during plantar flexion.

MTPJ1 is a synovial, modified hinge joint with primarily sagittal plane motion

available i.e. plantar flexion and dorsi flexion. Small amounts of motion are seen

in the transverse plane (adduction and adduction) with no normal available

motion seen in the frontal plane (inversion and eversion).(12)

Fig 2.1 illustrates the complex array of ligamentous structures supporting the

first metatarsophalangeal joint. This includes on the medial aspect of the joint

the tibial collateral, tibial sesamoid and plantar tibial sesamoid ligaments. These

intra-articular ligaments are mirrored on the lateral side by the fibular collateral,

fibular sesamoid and plantar fibular sesamoidal ligaments. Supporting these

8

structures are an intersesamoidal ligament, the joint capsule and the deep

plantar transverse ligaments.(2)

Soft tissue structures surrounding the joint include the extensor hallucis longus

tendon located dorso lateral to the midline of the joint, the extensor hallucis

brevis lateral to this tendon and a small tendinous slip from extensor hallucis

longus medially, referred to as extensor hallucis capsularis. Located plantar to

the MTPJ1 is the tendon of flexor hallucis longus, which courses between the

sesamoid bones to insert into the plantar aspect of the distal phalanx. The

tendon of flexor hallucis brevis muscle connects plantarly into the sesamoid

bones and becomes continuous with the plantar sesamoidal ligaments to insert

into the plantar aspect of the proximal phalanx of the hallux. The intrinsic

musculature includes the abductor hallucis and adductor hallucis muscles,

which respectively approach medially and laterally to the joint attaching into the

medial and lateral sesamoid bones.(2) The plantar aponeurosis lies superficial to

the muscles of the plantar foot, with the distal slip blending with the flexor

hallucis and brevis tendons, terminating at the distal and proximal hallux

phalanx respectively.

Figure 2.1: Anatomy of the first metatarsophalangeal joint (Adapted from Hetherington, 1994) (33)

9

2.2 First Metatarsophalangeal ROM

Motion of MTPJ1 has been extensively investigated using both live subjects and

cadaver specimens. Studies have examined MTPJ1 function both statically and

dynamically as well as during passive and active motion. Various techniques

reported include weight bearing and non weight bearing protocols and there are

marked differences in terms of equipment sophistications. Due to variations in

quantifying MTPJ1 motion there is a reciprocal variation in reported normal

ranges of joint motion.(18,34) These differences are further extended by a lack of

agreement within the literature as to reference or starting positions to measure

angulations. For example, using the plantar plane of the foot as opposed to the

toe referenced to the shaft of the first metatarsal will produce lower figures,

given the declination of the first metatarsal.(34,35)

It is generally accepted that for normal walking around 60-75 degrees of hallux

extension is required at the terminal propulsive phase of gait.(12,35) However

others have noted less MTPJ1 extension is required during gait in normal

subjects.(28,36,37) Reports within the literature for clinical dorsiflexion range of

motion values for the MTPJ1 vary between 65 and 110 degrees.(18,34,35,38,39)

Non weight bearing techniques have been shown to demonstrate good

reliability however these may lack clinical relevance.(40) Measuring the dynamic

range of motion of MTPJ1 is technically more difficult and has limitations within

a clinical setting.

Traditionally a standard goniometer is used to quantify MTPJ1 ROM. The

reliability of measuring MTPJ1 ROM using a goniometer has shown moderate

to high intra-rater reliability.(35,41,42) Buell et al (34) in a radiographic study

compared clinical measures to lateral radiographs for MTPJ1 ROM in twenty

feet and report a good correlation between goniometer measurements and

radiographic angles for MTPJ1 ROM. However their methodology for clinical

evaluation of joint range relied on skin markings and assisted dorsiflexion did

not control for ankle joint positioning or torque applied across the joint.

Fluoroscopy has been used to determine range of motion dynamically however

this is limited by ignoring out of plane motion and malalignment of anatomical

segments that can cause distortion of angular data.(43,44)

10

Umberger et al (45) developed a reliable and valid method of measuring three-

dimensional motion of MTPJ1 dynamically. Nawoczenski et al (28) used an

electromagnetic goniometer which demonstrated a strong correlation between

static active range of motion to that of dynamic range.

The methodologies used to quantify static MTPJ1 range of motion have often

ignored the effect or otherwise of force and velocity used during testing. These

aspects potentially have a large influence on joint range due to the viscoelastic

nature of the biological tissues being tested. Few studies have described or

measured the effect of joint creep, symmetry, laterality or the concept of

circadian variation. Measuring the force required to move a joint through its

range appears more clinically relevant than end range or peak joint angles as

studies demonstrate less than peak values are needed for normal gait.(28, 36, 37)

Joint stiffness, describing angular resistance to an external force, has had little

attention paid to it with regards to MTPJ1 mechanics. Paton (46) attempted to

estimate the moment applied to the hallux during weight bearing extension by

comparing the force used during testing against a spring balance. Given the

known distance of the applied force to the determined joint axis an estimated

dorsiflexion moment of 1.76Nm was established. Unfortunately the amount of

force necessary to dorsi flex the hallux during weight bearing incrementally

increases with angular change and it is unclear whether this moment value is at

the initiation of hallux extension or at peak ROM. Birke et al (17) investigated the

torque range of motion and stiffness of MTPJ1 in diabetics and non diabetics.

Using an electro goniometer, strain gauge and microcomputer they were able to

develop a stress strain curve for normal subjects and for those with hallux and

plantar ulceration. Measurements were taken at an angle corresponding to a

particular force demonstrating a reduction in range of motion between those

with hallux ulceration versus normal subjects. Goldsmith et al (47) measured

force versus displacement of the first metatarsophalangeal joint and ankle joint

in controls and diabetics subjects and found a statistically non significant trend

towards an increase in flexibility following a home-based stretching programme.

Perez et al (48) used a three dimensional tracking system to measure angle

along with a pulley system tensioned at 40 Newtons of force to measure MTPJ1

dorsiflexion range in cadaver specimens to assess the effect of hallux motion

following first tarsometatarsal arthrodesis. The system controlled for physiologic

11

axial load through the tibia to simulate weight bearing as well as extrinsic

tendon loads. Whilst the methodology appears useful the clinical relevance of

their results should be viewed cautiously as only five specimens were tested.

2.3 Plantar Fascia and Windlass Mechanics.

The plantar fascia or aponeurosis is a deep fibrous layer on the sole of the foot

attached proximally, primarily at the medial calcaneal tubercle and extending

distally to attach to the bases of the phalanges, especially the hallux. Its

function is to attenuate shock and retain elastic energy through its viscoelastic

properties as well as provide structural support to the medial column of the foot,

particularly during mid stance and propulsion phases of gait.(49-51) With heel rise

the first metatarsophalangeal joint is extended resulting in the distal plantar

fascia being wound around the metatarsal head, in effect shortening the

distance between the hallux and the heel due to the medial longitudinal arch

rising. The term ‘windlass mechanism’ describes this phenomenon. It provides

support to the foot by creating a supination moment across the sub talar joint

and externally rotating the lower leg. This supportive mechanism is crucial

during the propulsive phase of gait and for normal function.

Disruptions to normal windlass mechanics have been described. Medial

longitudinal arch collapse, early heel rise as well as knee and lower back

pathologies have been associated with dysfunctional windlass mechanics. (13,16)

MTPJ1 motion appears critical for normal windlass mechanics and

abnormalities to the plantar fascia are said to impede MTPJ1 range of motion.

Thickening of the proximal plantar fascia has been demonstrated in diabetic feet

and appears associated with reduced MTPJ1 ROM and increased plantar

pressures throughout gait.(31,52,53) Allen and Gross (54) compared hallux

extension and muscle strength in normal subjects and those presenting with

plantar fasciitis. They found a significant decrease in flexor muscle strength,

however no significant difference in MTPJ1 extension. Their methodology used

a semi weight bearing technique and did not control for the amount of force

used to measure the MTPJ1 ROM.

12

Figure 2.2: Initiation of the windlass mechanism via tightening of the plantar

aponeurosis accompanied with MTPJ1 extension (Adapted from Baxter, 1995) (55)

2.4 MTPJ1- Pathology

2.4.1 Hallux rigidus

Hallux rigidus is a progressive degenerative disorder of the first

metatarsophalangeal joint, characterised by reduced range of motion. In most

cases there is some available motion; hence the term hallux limitus is

sometimes used. The progressive nature of the condition sees early cyclic

articular deterioration leading to ultimate ankylosis and virtual absence of

motion. Suggested etiologies for hallux rigidus include, trauma, footwear, ankle

joint equinus, elevated first ray position along with gout, psoriatic or rheumatoid

arthritis.(6) The condition is relatively common with hallux rigidus being the most

common site for osteoarthritis in the foot and the second most common foot

deformity after hallux valgus.(56) The incidence of hallux rigidus is reported as

1/40 in adults over the age of 50 years.(57) Clinical findings typically include

reduced passive motion and localised pain around the 1st MPJ. Several

classification systems have been proposed describing each stage of

degeneration.(58,59)

13

2.4.2 Functional hallux limitus

The term functional hallux limitus describes the situation where there is a

reduced range of hallux extension during weight bearing, particularly terminal

stance phase of gait, whereas normal available range is present in non-weight

bearing examination.(3,16) Little or no structural joint degeneration is evident.

Normal MTPJ1 ROM is critical during the propulsive phase of gait when the

body’s centre of mass is moving forward. Restriction in this normal motion can

lead to compensations to proximal foot and lower limb joints, namely midtarsal

joint pronation.(13,60) Shoe and orthoses with specific design parameters have

been used in the management of functional hallux limitus.(14,61,62)

2.4.3 Plantar Fasciitis

Plantar fasciitis is a common cause of foot pain and discomfort with estimates of

the condition affecting around ten percent of the United States population over

the course of a lifetime.(67) It is described as a degenerative, inflammatory

process primarily affecting the proximal attachment of the plantar

aponeurosis.(54,63-67) Others however consider the condition to be non-

inflammatory but more degenerative in nature with histological findings lacking

inflammatory cells.(68,69) Typical clinical presentation includes pain palpable over

the plantar medial tubercle extending through the medial longitudinal arch, heel

pain on first rising and often post static dyskinesia.

Multifactorial in nature, it is believed to be due to excessive strain of the plantar

fascia during heel rise and propulsive phase of gait. It appears more prevalent

in females than males and is correlated to restricted ankle joint range of motion

and increased body weight.(67)

Disruptions to the plantar fascia are easily demonstrated by high resolution

ultrasound imaging, with thickening of the proximal plantar fascia considered

diagnostic. Normal plantar fascia thickness is reported as ranging between 2.0-

5.9mm, with fasciitis cases ranging from 3.9 - 9.1mm in thickness.(64,70,71)

An array of management strategies are presented within the literature including;

rest, anti-inflammatory modalities, stretching of the plantar fascia and

gastrocsoleus complex, footwear modification, orthoses to control foot

14

mechanics particularly compressive and tensile loads, extracorporeal shock

wave therapy and surgical trans-section in recalcitrant cases.(63,67)

2.4.4 Diabetes Mellitus and Limited Joint Mobility

Diabetes mellitus is a progressive endocrine disorder which is common in

western societies and impacts enormously both economically and individually.

Foot complications, such as ulceration and amputation, associated with

diabetes are a significant factor to this burden. There are several ways diabetes

affects the foot and lower limb including changes to vascular supply and

disruption to peripheral nerve function. Also recognized within the literature are

the changes to soft tissues and the subsequent effects to joint mobility.(72)

Many studies have demonstrated that diabetics have limited joint mobility when

compared to controls.(73-77) It is postulated that this phenomenon is a result of

nonenzymatic glycosolation of collagen from chronic hyperglycemia, the result

being stiffening of joint ligaments and surrounding structures.(78-80)

Investigation of diabetic and non diabetics populations have demonstrated

thickening of both the plantar aponeurosis and Tendo Achilles.(31,52,81,82) It is

thought that this thickening of the plantar aponeurosis would concomitantly

result in contracture which in turn may lead to an accentuated arch height via

the windlass mechanism and lead to a more rigid foot. The literature

demonstrates a significant reduction in ankle joint range of motion and MTPJ1

range of motion in diabetic subjects due to increased stiffness of these

structures.(31,73,83) Limited joint mobility and subsequent gait changes evident in

this population can relate to higher magnitudes of plantar pressures which can

be independent of body weight.(53)

Turner et al (84) compared passive ROM with dynamic motion of the ankle and

MTPJ1 and demonstrated an increase in joint stiffness in diabetics with passive

motion however no significant differences in ROM were seen during dynamic

testing. It is hypothesized that diabetics adopt varying gait strategies to

modulate their forward progression such as shortening their stride length.(30)

These changes pose a significant risk factor for foot ulceration. Diabetics with

restricted MTPJ1 ROM have been shown to be more likely to suffer a

15

breakdown on the hallux, most likely due to disruption of normal weight

transference throughout propulsion and a subsequent increase in plantar

vertical and shear stress.(17,53,74,79,84-86)

Intervention to reduce the stiffness of the ankle and MTPJ1 seems prudent in

reducing plantar pressures and improving gait. Goldsmith et al (47) ,by way of a

one month unsupervised home stretching protocol demonstrated a reduction in

peak plantar pressures in diabetic subjects compared with non diabetics.

Interestingly this trend was greater in the dominant limb as compared to the non

dominant limb. Garcia and Lund (87) describe the use of a motorised phlebo-

pump, which passively dorsi flexes the ankle thirty times per minute via motor

driven paddles. In a series of case studies it was suggested daily use of this

device to dorsi flex the ankle improved perfusion to the leg and foot thus

improving healing times for diabetic ulcers. The authors’ failed to report the

effects of this cyclic mobilization on the ankle joint and tendo Achilles stiffness

or on subsequent gait and loading patterns, as this may have also contributed

to improved tissue healing conditions. Vascular improvement via active and

passive mobilization of the MTPJ1 have also been reported by Elsner (88), who

describe a ‘toe-ankle pump’ for venous blood flow via the close anatomical

relationship between the MTPJ1 joint capsule and venous system. A significant

increase in venous flow was reported following five minutes of active movement

of the MTPJ1, which may also have clinical relevance in diabetic populations

with limitations to MTPJ1 range.

2.5 Ankle Joint Position and MTPJ1.

Ankle joint position has been shown to affect MTPJ1 mechanics. Anatomically

the gastrocsoleus muscle complex and tendo Achilles demonstrate connectivity

to the plantar fascia. Using cadaver models and 3D reconstruction, Milz, et al (25) demonstrated via histological sections of the Achilles tendon that as the

Achilles tendon is loaded, forces are directed towards the plantar fascia via

highly orientated trabeculae in the calcaneum. Snow et al (89) similarly using

cadaver specimens described connectivity between the tendo Achilles and

plantar fascia in neonatal, adult and foetal feet with the continuation of fibres

diminishing with age to superficial periosteal fibres from tendon to fascia.

Sarrafian (20) demonstrated that as the tibia is flexed forward over the ankle joint

16

the plantar aponeurosis is loaded resulting in MTPJ1 ROM limitation. Similarly

Carlson et al (21) measured an incremental increase in plantar fascial strain with

increased tendo Achilles load and increased MTPJ1 extension in cadaver

specimens using an extensometer. Regression analyses revealed a greater

strain on the plantar fascia with toe extension than increased tendo Achilles

load.

Cheung et al (90), describe the influence of tendo Achilles load on plantar fascia

tension using finite element analyses. The results demonstrate that as tendo

Achilles load is increased greater force is transferred through the plantar fascia,

with almost a third of this transmitted through the first ray. Erdemir et al (23)

,using a cadaver model also described a positive correlation between plantar

fascial tension and Achilles tendon load in simulated stance phase of gait.

Demonstrated in these studies was a distal shift in ground reaction force as

Achilles load was increased as well as a reduction in arch height of the foot,

similar to the results described by Thordarson et al (91). Deformation of the arch

height results in increased plantar fascia tension, as seen in normal weight

bearing. However Cheung et al (90) report a two times greater straining effect on

the plantar fascia than bodyweight alone. So whilst arch deformation increases

plantar fascia tension, the load through the tendo Achilles appears to be of

greater influence. This is supported by Flanigan et al (92), who reported a

significant increase in stretch through the plantar fascia with ankle joint

dorsiflexion in non weight bearing cadaver specimens.

Despite the fact that ankle joint position influences plantar fascial stiffness, it is

surprising that several studies measuring MTPJ1 ROM do not report or control

for ankle joint position.(12,19,34,41,42)

Ankle joint and muscle stiffness has been shown to influence first ray (1st

metatarsal-cuneiform joint) function. Johnson and Christensen (24) ,described

increased Achilles loads on first ray function in cadaver specimens and reported

decreased peroneus longus muscle activity and greater medial column

collapse. MTPJ1 extension has also been shown to be limited if the first

metatarsal is dorsi flexed, due to increased tensile stress on the plantar

fascia.(19)

17

With medial longitudinal arch collapse, an increase in dorsiflexion moment

acting on the first metatarsal is seen due to higher ground reaction forces during

stance. This causes blocking of the MTPJ1, so therefore foot postures,

particularly pes planus or a valgus heel position, appear to negatively influence

MTPJ1 ROM.(93) The association between pes planus and restricted MTPJ1

extension is further demonstrated in subjects with Rheumatoid arthritis where

disruption to the flexor hallucis longus tendon is present.(94) Grebing and

Coughlin (95) also report on the effect of ankle joint position and first ray mobility

and demonstrated a decrease in mobility with ankle joint dorsiflexion.

The effect of ankle joint position and MTPJ1 mechanics is yet to be quantified

and seems important to determine so that clinical and research protocols can

be established. Subtle changes to the osseous alignment and viscoelastic

series of the lower leg and foot is likely to significantly influence MTPJ1

mechanics and hence the influence of calf MTU stretching requires further

investigation.

2.6 Effects of Muscle Stretching

Limitations to joint range of motions impacts negatively on the efficiency of body

movements. The passive extensibility of muscle is integral to joint range of

motion and joint stability. Muscle stretching has been investigated extensively to

assist clinicians make decisions about the effectiveness of such intervention on

pain relief, function and injury risk. Variables most often investigated include

passive extensibility, passive stiffness, muscle power output and joint range of

motion / muscle length. There remains some confusion as to the exact effects of

short and long term muscle stretching and the mechanisms behind myogenic

changes, nor is there an agreed protocol for length of stretching regimes for

clinical and research scenarios.(96)

Duration of stretch is a key area of investigation. The stress relaxation of a

muscle appears relatively rapid with almost half of the stretch effect returned to

baseline after two minutes.(97) Others report muscle stiffness returning to

baseline after one hour.(98) However increases in joint range of motion have

been detected following individual stretching programs spanning several

weeks.(99-101) It has been hypothesised that stretching over longer periods

18

changes the ‘stretch tolerance’ rather than other passive properties and

viscoelasticity of muscle.(98) This seems to result from either an analgesic effect

of stretching or from increases in muscle strength over time due to a muscle

hypertrophy.

In a literature review of the effects of stretching Shrier (96),found that a single

static stretch of 15–30 seconds duration was sufficient for most people to

increase joint range of motion. Longer hold times may produce greater gains (102) with the most important myogenic changes found early in the stretch

cycle.(103,104)

Controversy exists regarding the effectiveness of muscle stretching and injury

prevention. Restriction in ankle joint motion has been suggested to increase the

incidence of injury (63,105,106) and systematic review of the literature found a small

but statistically significant increase in ankle joint range of motion with

stretching.(29) Other studies suggest the use of stretching has no role in

decreasing the risk of injury (107,108) and indeed can cause detrimental effects to

performance, particularly muscle power output.(109,110)

Recent studies have described the benefits of a tissue specific stretch for

plantar fasciitis and has shown this technique to be superior to traditional calf

stretching in terms of pain and function associated with chronic heel pain.(111,112)

The technique involves the ankle and metatarsophalangeal joints being dorsi

flexed for thirty seconds. Cadaver testing has confirmed that greater stretch to

the plantar fascia is achieved with ankle joint dorsiflexion and MTPJ1

extension.(92)

There are several stretching techniques described in the literature and include

static weight bearing and non weight bearing, ballistic stretches and PNF

stretches.(113) Differences in the viscoelastic response and properties of muscle

tendinous units have been demonstrated between static and cyclic

stretches.(114-116) Investigation into the elastic properties of the calf muscle

tendon unit revealed both ballistic and static stretches result in increased range

of motion. However static stretches seem to reduce muscle passive resistive

torque whilst ballistic stretches appear to reduce tendo Achilles stiffness.(114)

Herbert et al(117) described changes to muscle and tendon length during passive

19

ankle joint dorsiflexion, attributing 27% of the overall length change to changes

in muscle length with the majority of extensibility due to the Achilles tendon or

other structures.

There also appears to be a strong gender relationship with muscle extensibility

and joint ranges of motion, particularly in the lower limb. Investigations into knee

and ankle range of motion and flexor muscle stiffness have suggested male

muscle shows greater resistance to length changes which therefore may

contribute to greater joint stability.(118-120) It remains unclear whether males

respond more favourably to stretching than females.

2.7 Symmetry and Laterality

Few studies have reported on symmetry and laterality of foot joint motions.

Studies involving the foot are often encouraged to test one side under the

assumption that symmetry exists, simplifying data collection. It has been

suggested that choosing to include both left and right side measurements may

inadvertently improve sample power and hence reduce statistical integrity.(121)

Whilst others argue relevant clinical information such as laterality could be lost

without testing both limbs.(122,123)

Debate remains as to the prevalence of asymmetry during gait and whether or

not such asymmetry can be attributed to laterality.(124) Maupas et al (125)

demonstrated asymmetric knee joint movement in normal subjects using

electrogoniometry, however laterality was found to be independent of the

asymmetry. Sadeghi (126),who investigated symmetry of gait in twenty healthy

males, suggested that global gait symmetry exists during gait when looking at

left and right sagittal plane movements of the entire lower limb. However local

asymmetry existed between segments of the lower limb according to specific

functional tasks or stage of gait. The suggestion made was that these local

asymmetries are compensatory in nature to produce an overall global

symmetry.

Symmetry and laterality behaviour of MTPJ1 during passive non-weight bearing

extension is yet to be defined in healthy adults.

20

2.8 Assessment of foot type

Foot morphology has often been associated with musculoskeletal injury.(127)

Overuse injuries have been reported in supinated (128,129) and pronated (130,131)

feet and often ortho mechanical intervention such as foot orthoses are

prescribed.(132) Other prospective studies have found no association between

foot morphology, static measures and increased injury risk.(133) It is

hypothesised that different foot types will behave differently to ortho mechanical

intervention, for example foot orthoses or taping, hence investigating the effects

of such intervention requires classification of foot types.(134) Categorisation of

the foot for research purposes is fundamentally difficult as the foot is a complex

multi-segmented body part.

Traditionally foot ink prints have been used to characterise the foot and medial

longitudinal arch across the pronation to supination continuum. The Chippaux-

Smirak and Staheli Arch Index are two such examples. Both require large

changes in foot posture to produce changes in the index scores, questioning

their validity.(135) Recent work by Urry and Wearing (136) has shown the use of

force plates to determine foot morphology to be less accurate than ink foot

impressions. These measures used to determine foot posture do not meet

acceptable validity and reliability rigour. Skin movement artefact and goniometer

measurement error are typically cited as contributing large sources or error

when catergorising foot types.(137)

The Foot Posture Index (FPI-6) developed by Redmond (138) is an observation

tool to quantify foot posture variation. It has the distinct advantage of not relying

on two dimensional measurements or the validity of the sub talar neutral

position. The FPI-6 allows clinicians to quantify foot posture in a relaxed stance

position without manipulation of the foot whilst being able to distinguish multi-

segment and multi-planar positions of the foot. The FPI-6 replaced the FPI-8

which had eight individual criteria. During validity testing it was shown that two

of the original eight criteria were problematic, thus the instrument was modified

to comprise six criteria measured on a five point scale (-2 to +2). These include:

1) talar head palpation, 2) supra and infra malleolar curves, 3) inversion and

eversion of the calcaneus, 4) talonavicular prominence, 5) congruence of the

medial longitudinal arch, and 6) abduction and adduction of the forefoot on the

21

rear foot. (5,139) Reliability testing has been described for both the original FP1-8

and FPI-6 instruments with high intra-rater reliability values reported; ICC’s 0.72

and 0.86 by Evans et al (140) and greater than 0.90 by Cornwall et al (4). Inter

rater reliability however is reported as being moderate with ICC values ranging

between 0.52 and 0.65.(4,140)

Classifying foot types will provide important information to the proposed thesis.

Patterns of MTPJ1 motion as they relate to foot morphology can be examined.

The FPI-6 is a valid, clinically useful tool to classify foot postures along the

pronation–supination continuum.

2.9 Summary

The literature reviewed has described normal and abnormal function of the

MTPJ1 and the relationship to the gait cycle, together with associated

pathologies.

Highlighted within the literature is a lack of standardised methodology to

quantify MTPJ1 ROM both clinically and in research settings. This lack of

agreement with measuring MTPJ1 ROM accounts for the wide variance in

reported normal range values described. The importance of a known force

being applied to the hallux during testing and the influence of ankle joint position

to quantify MTPJ1 ROM has been largely ignored.

The presented literature supports the functional and anatomical interaction

between the calf MTU and MTPJ1 ROM via the plantar aponeurosis. Stretching

protocols have been described with most demonstrating a small increase in

ankle joint ROM. Various stretch techniques, such as static and cyclic, are also

described and it appears that each may have an influence on the elastic series

of the lower limb.

The influence of ankle joint position on MTPJ1 ROM and the magnitude of

change remain unclear. Similarly the effect of commonly utilised calf MTU

stretching on MTPJ1 mechanics is yet to be reported.

22

CHAPTER THREE METHODOLOGY

3.0 Introduction

The purpose of this study was to investigate the resistance properties of the

MTPJ1 and the influence of ankle joint position and calf MTU extensibility in

asymptomatic normal subjects. This chapter provides detailed description of the

methodologies used to answer the proposed research questions. Reference is

made to pilot work which was used to develop the methodology, particularly the

reliability of the testing regime. A summary of the study design, subject

demographics and recruitment protocols are described. A thorough description

of the procedures used throughout the study is given together with an outline of

data collection and analyses.

3.1 Pilot Studies

Pilot work investigated the suitability of using a weight bearing set up to

measure passive MTPJ1 extensibility (Appendix 1). The influence of postural

sway was evident which resulted in the large variations of the data for MTPJ1

extension. Whilst the ICC3, 1 was acceptable, 0.81, the typical error in degrees

was 6.9 when testing five asymptomatic adult subjects. The initial aim of

developing this weight bearing methodology was to test the influence of foot

orthoses and different design parameters on MTPJ1 extension. Initial trials

revealed the ‘effect’ size was close to the measurement error and significant

‘noise’ in the measurement set up was evident. This work lead to the question

of examining ankle joint position and more particular the effects of tendo

Achilles load on MTPJ1 passive extension. To explore this further a non weight

bearing methodology was devised and tested.

3.2 Non-weight bearing Instrument methodology

The non weight bearing test procedure required subjects to lie supine with full

knee extension on a height adjustable motorised clinical plinth. The subject’s

test foot was then placed into position onto a custom built device (Fig 3.1). The

wooden rig consisted of several parts including a base plate 50cm by 40 cm, an

internal section consisting of two vertical arms, a cross plate connecting the two

arms and another connecting plate with a hinged extension measuring 5cm

23

across and 7cm long located in the middle of this plate. The hinged extension

had a small piece attached perpendicular to it so the force transducer could

maintain the force perpendicular to the hinge and therefore orthogonal to the

joint axis throughout testing. The distance from the hinge was 7cm which

represented the known lever arm so torque values (Nm) could be calculated.

The hinged plate cross section was able to be moved up and down along the

length of the upright vertical arms to accommodate various foot sizes and these

arms were able to be moved and locked by metal pins at ten degree intervals

either side of vertical to accommodate various ankle joint positions.

Attached internally to the hinge was a metal extension running laterally which

was connected to a custom built battery operated (9V) potentiometer. Prior to

testing each subject a calibration was performed with voltage recorded at 0 and

45 degrees as measured from a standard goniometer.

Figure 3.1: MTPJ1passive extension using a force transducer perpendicular to the axis and a potentiometer to simultaneously record force/angle data.

24

During testing the MTPJ1 axis was visually aligned with the hinged platform.

The test foot was then strapped into position with Velcro® fasteners across the

distal lower leg.

Subjects were instructed to relax whilst a hand held force transducer (McMesin®

AGF), moved the MTPJ1 through its range of extension motion and back to the

starting position. The transducer was held perpendicular to the hinged platform

with the guidance of the backing plate. Simultaneous force and angle data was

collected via the electrical potentiometer and force transducer sampling at

100Hz. Both instruments were connected to a portable laptop computer via a

data acquisition board (National Instruments® BNC 2110) and DAQ Card

(National Instruments® -6024E). Samples were then transferred to Labview®

software (v.7) with raw data passed through a fourth order Butterworth low pass

filter.

Each toe was moved through its extension range of motion fifteen times across

three ankle joint positions, namely; ankle joint neutral (vertical), ankle joint

plantar flexion (10 degrees) and ankle joint dorsiflexion (10 degrees). Full knee

extension was maintained throughout testing. A Latin Least Squares method

was adopted to ensure the order of testing ankle joint position was randomly

assigned for each participant, which was repeated for both feet.

A series of three experiments followed to refine the testing and determine the

suitability of this methodology to quantify MTPJ1 extension across ankle joint

positions and to assess the influence of stretching on joint motion.

Part One: Instrument development

3.3 Series I: Number of joint cycles

3.3.1 Description

The aim of the first series of testing was to determine the appropriate number of

joint excursions necessary to produce stable values for MTPJ1 extension range.

The viscoelastic nature of joints and surrounding structures means one can

expect a degree of ‘conditioning’ the joint must go through before values

stabilise. To date this has not been quantified for the MTPJ1. Further to this a

degree of familiarisation would be expected with subjects being tested and

25

hence this test series allowed testing protocol refinement. Unnecessary data

analyses and handling would be significantly reduced by exploring the

conditioning characteristics of MTPJ1 extension load un-load cycles.

3.3.2 Sample

Six consenting asymptomatic adults were recruited from the private practice of

the investigator for this initial series of testing. The sample included five females

and one male with an average age of 34 years (range 22-47 years). All subjects

were screened for pathology or significant medical history that would deem

them unsuitable for the study in accordance to inclusion and exclusion criteria

as outlined in section 3.7.1 and 3.7.2.

3.3.3 Data

Angle data were calibrated using a standard goniometer to the voltage across

0-45 degrees. Test data for force and angle was reduced using a custom

designed computer program within Labview® software (v.7). From there the

data were transferred to another custom designed spreadsheet (Microsoft

Excel®) where instantaneous force and angle data were represented at 0.5

degree intervals.

Raw data for this initial series is presented in Appendix 2. Further analysis was

performed using Statview® (SAS Institute Inc) statistical software. A repeated

ANOVA was performed and post-hoc comparisons (Scheffé analysis) for

clusters determined between joint cycles. Comparisons were made between the

means of joint clusters between cycles 2,3,4 and 7,8,9 and 12,13,14 that is, the

middle three cycles of each block of five joint extensions.

3.3.4 Derived Variables

Both feet of each subject were tested using the technique described in 3.2. The

MTPJ1 was moved through extension fifteen times across the three ankle joint

positions. The derived variables chosen for further analyses were joint angle at

10 and 30N of force for each ankle joint position and cycle.

26

3.3.5 Results

The ANOVA assessment for load un-load characteristics of the MTPJ1 across

fifteen cycles is presented in Appendix 3. Figure 3.2 and Table 3.1 illustrate the

significant increase in the means of cycles 2,3,4 compared with cycles 7,8,9 as

well as between cycles 2,3,4 and cycles 12,13,14. The results further

demonstrate that there was no significant difference between cycles 7,8,9 and

12,13,14. The results support the hypothesis that there is a degree of joint

conditioning and familiarisation within the testing process and that this variation

is mostly taken up within the first six joint cycles.

Figure 3.2: Mean and 95% Confidence Intervals for MTPJ1 extension through

15 cycles for loads 10N and 30N across three ankle joint positions measured in

degrees.

Table 3.1: Least Significance Difference (Scheffé) between the mean of the groups of cycles 2,3,4; 7,8,9 and 12,13,14.

Cycles (Mean) Mean Diff Crit. Diff p Value Ave[2,3,4] [7,8,9] -2.164 0.834 <.0001

Ave [2,3,4] [12,13,14] -2.525 0.834 <.0001

Ave [7,8,9] [12,13,14] -0.361 0.834 0.5641

p<0.05

-10

0

10

20

30

40

50

60

70

T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 T15

PF, 30NPF, 10Nneutral, 30Nneutral, 10NDF, 30NDF, 10N

27

Examination of the ANOVA for clusters table (Appendix 3) suggests a

significant difference between cycle clusters and ankle position p=0.0031. A

further two way ANOVA was performed to investigate the real difference. This

again demonstrated no significant differences between cycles 7,8,9 and

12,13,14.

Further analysis of the cycles 7,8,9 were performed via a three way ANOVA

(ankle position, load and cycles). The results show there was no systematic

difference between cycles 7,8,9. p=0.9. See Figure 3.3.

The typical error was also determined for cycles 7,8,9 and was found to be 2.3

degrees, which represents the largest variation between these three cycles.

Figure 3.3: Mean difference and 95% confidence intervals for cycles 7,8,9. Derived variables 10 and 30N across the three ankle joint positions. The 95% Confidence Intervals reach 0 and therefore no systematic difference is evident.

3.3.6 Summary

This part of the project successfully determined the number of cycles required

during testing to confidently produce stable results. A minimum of ten cycles

were required with derived variables taken from the mean of cycles 7,8,9 for

further analysis.

-5 -4 -3 -2 -1 0 1 2 3 4

Diff T7-9


28

3.4 Series II- Test re-test reliability (same day)

3.4.1 Description

The second series of preliminary testing was aimed at determining the same

day reliability of measuring MTPJ1 extension using the method previously

described. It was important to determine the repeatability of the measurement

technique, particularly aspects such as the visual alignment of the joint axis and

positioning of the foot. The following series outlines the design and investigative

methodology.

Subjects were tested as previously described in 3.2 and following this initial test

were then removed from the device and plinth. Subjects were then immediately

returned to the plinth, with both feet individually realigned for repeat testing.

Testing sequence for both feet followed a randomised Latin least square

method with the same testing sequence applied for re testing.

3.4.2 Sample

Six asymptomatic adults were recruited from the private practice of the

investigator for this series of testing. The sample included five females and one

male with an average age of 33 years, [range 20 - 47 years]. All subjects were

screened for pathology or significant medical history that would deem them

unsuitable for the study in accordance to inclusion and exclusion criteria as

outlined in section 3.7.1 and 3.7.2.

3.4.3 Data

Data was collected and reduced as described in 3.3.3. Raw data is presented in

Appendix 4. Further analyses were performed using Intraclass Correlation

Coefficients; model 3,1,(141) Standard Error Means (SEM) and 95% Confidence

Limits.

3.4.4 Derived variables

There were a total of six derived variables which included MTPJ1 angle at 10N

and 30N of force for each ankle joint position, namely ankle joint neutral, plantar

flexed and dorsi flexed, with the mean of cycles 7,8,9 used for further analyses.

30

3.5.2 Sample

Six asymptomatic adults were recruited from the private practice of the

investigator for this series of testing. The sample included five females and one

male with an average age of 41 years, [range 22 – 55 years]. All subjects were

screened for pathology or significant medical history that would deem them

unsuitable for the study in accordance to inclusion and exclusion criteria as

outlined in section 3.7.1 and 3.7.2.

3.5.3 Data

Data collection and reduction was performed as described in 3.3.3. Raw data is

presented in Appendix 5. Further analyses were performed using Intraclass

Correlation Coefficients; model 3,1, Standard Error Means (SEM) and 95%

Confidence Limits.

3.5.4 Derived variables

There were a total of six derived variables which included MTPJ1 angle at 10

and 30N of force for each ankle joint position, namely ankle joint neutral, plantar

flexed and dorsi flexed, with the mean of cycles 7,8,9 used for further analyses.

3.5.5 Results

Table 3.3 demonstrates the ICC 3, 1, SEM and 95 % Confidence Limits for the

test re-test reliability across one week. Reliability was good to high (ICC 3,1 0.76-

0.98) for all but one derived variable. Reliability for variable dorsiflexion at 10N

was poor (ICC 3,1 0.23). This is most likely due to the low actual values obtained

from this measure. The instrumentation used to detect change was arguably not

sensitive enough to detect change across time for variable AJDF10N, with

several subjects yielding no angular change at 10N force. Hence a small

between subject variance compared to a proportionately large ‘total variance’

resulted in a low ICC statistic.

29

3.4.5 Results

Table 3.2 demonstrates the ICC 3, 1, SEM and 95 % Confidence Limits for all six

derived variables for the same day test re-test reliability. Intra-class correlation

co-efficient values were high across all derived variables for the test re-test set

up. (>0.89). SEM’s were less than 2.7 degrees across all derived variables.

Table 3.2: Intraobserver ICC values,95% Confidence Limits, and SEM for MTPJ1 motion for each force and ankle position measured on the same day.

Variable ICC3,1 Lower Limit Upper Limit

SEM (degrees)

AJDF 10N 0.89 0.708 0.963 1.08 AJN 10N 0.95 0.864 0.984 2.60 AJPF 10N 0.98 0.953 0.995 1.66 AJDF 30N 0.97 0.917 0.99 1.51 AJN 30 N 0.98 0.926 0.991 2.58 AJPF 30N 0.99 0.981 0.998 1.18

AJDF: ankle joint dorsi flexed; AJN: ankle joint neutral; AJPF: ankle joint plantar flexed;

ICC: Intra-class correlation co-efficient model 3, 1; SEM: standard error mean

3.4.6 Summary

Same day test re-test reliability for measuring MTPJ1 extension was acceptably

high across all derived variables within the sample tested.

3.5 Series III- Test retest reliability (one week)

3.5.1 Description

The final series in the preliminary testing of the methodology was to determine

the reliability of measuring MTPJ1 extension over time. That is; could one

expect to yield similar joint displacement values over time thus rendering the

equipment and technique suitable to further assess interventions across time?

Subjects were tested on both feet as described in 3.2 with measurements

repeated after seven days. Testing sequence for both feet followed a

randomised Latin least square method with the same testing sequence re

applied after one week.

31

Table 3.3: Intraobserver ICC values,95% Confidence Limits, and SEM for MTPJ1 motion for each force and ankle position measured across time (one week).

Variable ICC3,1 Lower limit Upper limit SEM (degrees)

AJDF 10N 0.23 -0.300 0.657 0.97 AJN 10N 0.92 0.772 0.972 3.52 AJPF 10 N 0.93 0.814 0.977 5.08

AJDF 30N 0.76 0.421 0.913 3.64 AJN 30N 0.98 0.939 0.993 3.03 AJPF 30N 0.97 0.917 0.990 3.71

AJDF: ankle joint dorsi flexed; AJN: ankle joint neutral; AJPF: ankle joint plantar flexed;

ICC: Intraclass correlation co-efficient model 3, 1; SEM: standard error mean

3.5.6 Summary

Test re-test reliability across one week was acceptably high for five of the

derived variables. Variable, ankle joint dorsiflexion at 10N of force was

unreliable and hence these results should be viewed with caution. The actual

degree changes are small due to the low forces and higher stiffness of the

elastic series of the lower leg.

Part Two: Normal series

3.6 Study design and subjects

A prospective observational study design was used to determine the influence

of ankle joint position on MTPJ1 extension, as well as to assess the influence of

gender and laterality and foot posture in a normal asymptomatic population.

Demographic characteristics of the sample were collected including age,

gender, height, weight and body mass index (BMI), along with self determined

limb dominance indicated by the preferred kicking limb.

3.6.1 Recruitment

Convenience sampling was used to obtain subjects for this study. Subjects

were recruited from the author’s private podiatry clinics in the Perth metropolitan

area as well as students within the Podiatric Medicine Unit and Centre for

Musculoskeletal Studies, University of Western Australia. All subjects

underwent a screening process performed by the author to determine eligibility

32

for the study based on inclusion and exclusion criteria. Subjects were provided

with an information sheet (Appendix 6) and were required to complete a

consent form (Appendix 7), enabling participation in the study.

3.7 Data collection procedures

3.7.1 Inclusion criteria

Subjects were required to meet the following criteria:

• Have read and understood the information sheet

• Have read, understood and completed informed consent document

• Have reached skeletal maturity and be a minimum age of 18 years and less

than 60 years.

3.7.2 Exclusion criteria

Subjects were excluded from the study if they

• Have a history of lower limb surgery, trauma, gait abnormalities, neurological

disorders that directly affect the lower limb or any systemic disease such as

sero-negative or sero-positive pathology.

• Have a clinical diagnosis of Hallux Limitus/Rigidus or Functional Hallux

Limitus.

• Have a medical diagnosis of hyper mobility joint syndromes such as Ehlers

Danlos or Marfan’s syndrome

3.7.3 Ethical Considerations

The study was subjected and granted ethics approval by the Human Research

Ethics Committee of the University of Western Australia. All participating

subjects were required to read understand and sign a freedom of consent form

prior to entering the study (Appendix 6). This document along with the subject

information sheet (Appendix 7) outlined the purpose of the study, associated

know risks and addressed confidentiality issues. No invasive procedures were

performed on subjects.

Confidentiality of subjects was maintained by using alphanumerical coding,

known only to the author and primary supervisor. Individual data collection

forms were used throughout data collection with an appropriate alphanumerical

33

code applied. All data was saved, using Microsoft Excel® spreadsheets to the

author’s computer hard drive with password protection.

3.7.4 Data collection

All data was collected by the author, and systematically recorded according to

the procedures outlined below. Subjects were asked to volunteer for the study

following an introduction regarding the subject matter and procedures to be

undertaken. Subjects were issued with information and consent documentation.

Refusal without prejudice was highlighted and opportunity was given for further

information regarding procedures and purpose of study.

Individual participants were tested on one occasion. Following signing of the

consent form, subjects were screened to ensure they satisfied the inclusion

criteria. Demographic data was also collected at this time. All data handling was

performed by the author. This included completing the subject data collection

form (Appendix 8), reducing derived variables from computer programs and

saving collated data to Microsoft Excel® spreadsheets. Random cross checking

of raw data to spreadsheet entries was performed to identify any processing

errors. Outlier values of greater than two standard deviations of the respective

mean values were similarly checked.

3.7.5 Procedures

3.7.5.1 Foot Posture Index (FPI-6)

Each subject was assessed by the author to determine their foot posture of both

feet via the FPI-6.(5) Subjects were asked to stand, unshod, in their self

determined relaxed stance position with their head facing forward whilst

focussing on a random object during the assessment. A visual assessment of

foot posture was made by the investigator with data collected on the FPI-6 data

collection sheet (Appendix 9).

3.7.5.2 Ankle Joint Range of Motion

Ankle joint range of motion was quantified using the Weight Bearing Lunge Test

(WBLT).(10) A pilot study was performed to determine the intra-rater reliability,

comparing two methods of quantifying the WBLT. (Appendix 10) A same day

test re-test study design was used to compare two landmarks measuring angle

from the vertical during a WBLT. Ten asymptomatic subjects were tested using

34

both techniques with ICC’s3, 1 statistics reported as: 0.94 and 0.90 respectively,

and typical errors in degrees of 1.3 and 1.4 respectively. Measurement of angle

from the vertical derived from the anterior tibial border (Method A) was chosen

for testing throughout this study as it appears to anatomically represent the

longitudinal axis of the tibial more favourably.

For testing ankle joint range, subjects were given verbal instruction as to how to

perform the WBLT. An illustration was also provided on the wall in front of the

participants to visually demonstrate how the test was to be performed, (Fig 3.4).

Subjects were asked to place their foot perpendicular to the wall and lunge their

knee towards the wall so that the knee was lightly touching the wall. The foot

was then moved away from the wall until maximum ankle joint dorsiflexion was

achieved without lifting of the heel. Subjects were encouraged to hold onto the

wall during the lunge to maintain balance. A digital inclinometer (Smart Tool®-

digital angle finder) was used to measure tibial angle from the vertical as

described by Bennell et al (10) Each limb was measured three times with the

mean recorded for further analysis. Subjects tested their right limb followed by

their left limb across all test sessions.

Figure 3.4: Weight Bearing Lunge Test (WBLT) using a digital inclinometer to measure angle from vertical. Method A represents the chosen method, with the inclinometer positioned just distal to the tibial tuberosity.

35

3.7.5.3 MTPJ1 ROM

First metatarsophalangeal joint extension was performed using the method

described previously in 3.2. Each foot of the participant was measured and a

randomised Latin Least square ordering sequence was used for ankle joint

position which was replicated for both feet. Prior to testing of each participant

calibration of the instrumentation was performed with potentiometer voltage

determined for angles 0 and 45 degrees as determined by a standard

goniometer.

3.7.5.4 Data processing

Data was processed using Labview® software (v.7) sampling at 100Hz with raw

data filtered using a fourth order Butterworth low pass.

Data was then transferred to a custom computer spreadsheet (Microsoft Excel®)

where values were taken for force versus angle series across all derived

variables. Derived variables for cycles 7, 8 and 9 were recorded. The mean of

cycles 7, 8, 9 was used for further analyses as determined by previous reliability

work outlined in section 3.3.

3.7.5.5 Analysis of Data

All data was recorded on computer spreadsheets (Microsoft Excel®) and then

transferred to a statistical software package (Statview®, SAS Institute Inc) for

further analyses. For the purpose of data analysis the mean of MTPJ1

extension cycles 7, 8 and 9 were used. In all tests of statistical significance an

alpha level of p<0.05 was adopted.

Data analysis was undertaken using number of feet rather than number of

subjects. This direction was chosen namely to avoid excluding any possibly

symmetrical anomalies as well as not introducing potential bias by averaging

the sum of left and right feet. It is however noted that pooling the left and right

feet may increase the risk of both Type I and Type II statistical errors by

essentially doubling the sample size. Statistical significance is more likely to be

reached due to increased sample size as the confidence limits become smaller. (121, 122)

36

Part Three: Stretching series

3.8 Study design and subjects

A prospective observational case control study design was used to determine

the influence of calf MTU stretching on ankle joint range of dorsiflexion and

MTPJ1 extension. Both short term effects and those over time were

investigated. Demographic characteristics of the sample were collected

including age, gender, height, weight and body mass index (BMI).

Fig 3.5 provides a flow chart of the study design where participants in this study

were randomly assigned a control leg with the contralateral leg being the test

leg. This was subjected to stretch conditions as described below. Measures of

ankle joint range and MTPJ1 extension were made prior to stretch and

immediately after with the test repeated following a one week home stretching

program.

Figure 3.5: Design and flow of participation through part III of the study investigating the effect of calf MTU stretching on MTPJ1 ROM. Subjects randomly assigned a control and test leg. Both feet and ankles tested for ROM [WBLT and MTPJ1] at baseline and repeated after experimental limb stretch. WBLT and MTPJ1 ROM for both limbs re-tested following a one week calf MTU stretching program on the experimental limb only.

Repeat measures of ankle (WBLT) and MTPJ1 ROM

Repeat Measures of ankle joint (WBLT) and MTPJ1 ROM

No stretch

Calf MTU stretch twice daily

No stretch

Subjects assessed for eligibility (n=11) 22 limbs.

Ineligible (1 limb)

Ankle joint (WBLT) and MTPJ1 ROM measured. Randomised (n=21 lower limbs)

Experimental Group (Stretch) Control Group (No stretch) (n=11) (n=10)

Week

0

1

37

3.8.1 Recruitment

Convenience sampling was used to obtain volunteer subjects for this study.

Subjects were invited to participate from a student cohort within the Centre for

Musculoskeletal Studies; University of Western Australia. All subjects

underwent a screening process performed by the author to determine eligibility

for the study based on inclusion and exclusion criteria. Subjects were provided

with an information sheet (Appendix 6) and were required to complete a

consent form (Appendix 7), enabling participation in the study.

3.9 Data collection procedures

Data collection procedures followed those described in section 3.4.4. Data was

recorded on a specifically designed collection form. (Appendix 8)

3.9.1 Inclusion criteria

The inclusion criteria for this study were common to those outlined in section

3.7.1.

3.9.2 Exclusion criteria

The exclusion criteria for this study were common to those outlined in section

3.7.2.

3.9.3 Ethical Considerations

The ethical considerations have been described in section 3.7.3. All

participating subjects were required to read understand and sign a consent form

prior to entering the study (Appendix 6) An information sheet (Appendix 7)

outlined the purpose of this study together with associated know risks and

addressed confidentiality issues.

3.9.4 Data collection

Data collection procedures followed that as described in section 3.7.5.4.

38

3.9.5 Procedures

3.9.5.1 Foot Posture Index

Subjects underwent assessment of foot posture via the Foot Posture Index-6 as

described in section 3.7.5.1.

3.9.5.2 Ankle Joint Range of Motion

Subjects were required to perform a WBLT on both legs as described in section

3.7.5.2.

3.9.5.3 MTPJ1

MTPJ1 extension was performed using the method described previously in 3.2.

Each foot of the participant was measured and a randomised Latin Least

square ordering sequence was used for ankle joint position, replicated for both

feet. Prior to testing each participant, calibration of the instrumentation was

performed with potentiometer voltage determined for angles 0 and 45 degrees

measured against a standard goniometer.

3.9.5.4 Calf muscle stretching

Subjects participating in the stretching part of the investigation were instructed

to perform a specific calf muscle stretch. Based on previous literature a

combined cyclic and static stretch design was derived whereby the subjects

wedged their randomly assigned foot against a wall or door frame keeping the

knee fully extended. The hips were then moved anteriorly and held until a firm;

non painful stretch was felt in the calf muscle, (Fig 3.6).

Subjects were instructed to hold this stretch for 30 seconds. This was followed

by 30 seconds of steady rhythmic lunges, which involved the same foot

maintaining the stretch position while subjects gently bended the knee towards

the wall to resistance and re straightening in a cyclic fashion with one flex /

extend cycle occurring approximately every second, i.e. 30 up and downs, (Fig

3.7).

Measurement of ankle joint range, via the weight bearing lunge test and passive

MTPJ1 extension, was performed pre stretch and immediately after the stretch

39

on both limbs with the contralateral limb acting as a control. Subjects were also

asked to perform this stretch twice daily for one week where MTPJ1 extension

and ankle joint range was re tested. A participation diary including instructions

regarding stretch protocol was issued for completion during the week to assess

compliance (Appendix 11).

Figure 3.6: Static calf MTU stretch. Subjects maintained full knee extension whilst moving the hips anteriorly until a non painful stretch was felt. Subjects were instructed to hold the stretch for 30 seconds.

Figure 3.7: Cyclic calf MTU stretch, where subjects lunged their knee forward and back to resistance. Subjects were instructed to move at approximately one cycle per second for 30 repetitions.

40

CHAPTER FOUR RESULTS

4.0 Introduction

This study investigated the influence of ankle joint position on MTPJ1 ROM in

an asymptomatic normal population. The association between ankle joint

position and MTPJ1 ROM was further assessed by investigating the effects of

calf muscle stretching on hallux extension properties, immediately and after a

one week home stretching program. Six dependent variables were assessed,

namely; AJN, AJPF and AJDF for both 10N and 30N of force. This section

provides a summary of the results obtained from statistical analyses.

Demographic data pertinent to both study groups are presented together with

descriptive data for each dependant variable. Results of analyses are presented

regarding differences in laterality, gender and foot posture across all dependent

variables. Group differences for the stretch control cohorts are also presented

following analyses.

4.1 Demographics

Demographic data of the sample population for parts two and three of the study

are presented in Table 4.1 and 4.2. Raw data sets are presented in Appendix

12 and 13. Descriptive statistics for each dependent variable for part two of the

study are presented in Table 4.3. Figure 4.1 and Figure 4.2 represents

differences in MTPJ1 ROM based on ankle joint position.

The investigation into the influence of ankle joint position on MTPJ1 ROM

consisted of 37 subjects (73 feet) who satisfied inclusion criteria. Throughout

the study one foot did not meet inclusion criteria. The stretching section of the

study consisted of 11 subjects (11 feet for the stretch group and 10 feet for the

control group).

41

Table 4.1: Demographic data including ankle joint range and foot posture for Part two of the study investigating ankle joint position and MTPJ1 ROM.

N No. of feet (L/R)

Gender M,F

Age (yrs) (SD)

[Range]

BMI (SD)

WBLT (degrees) L/R (SD)

FPI-6 L/R (SD)

37

73

(37/36)

16,21

28 (10)

[18-55]

22.5

(2.7)

46.7/ 45.8

(7.4)/(7.1)

3.05/3.69

(3.26)/(3.49)

N: number of subjects; No: number of feet; L: left, R: right; M: male, F: female; WBLT: weight

bearing lunge test; FPI-6: foot posture index.

Table 4.2: Demographic data foot posture for Part three of the study investigating calf MTU stretching and MTPJ1 ROM across ankle joint positions.

N No. of feet (S / C)

Gender M,F

Age (yrs) (SD)

[Range]

BMI (SD) FPI-6 L,R (SD)

11 21 (11 / 10)

7/4 29 (3.5) [26-36]

22.8 (2.7) 2.12 2.73 (2.88) (3.19)

N: number of subjects; No: number of feet; S: stretch group, C: control group; L: left, R: right

M: male, F: female; FPI-6: foot posture index.

4.2 Normality

The entire sample of 37 participants (73 feet) were assessed for normality

across dependent variables WBLT, ankle joint positions dorsi flexed, neutral

and plantar flexed for loads 10 and 30 Newton’s. Histograms were produced for

each dependent variable for assessment of normality [via skewness and

kurtosis]. All variables were deemed normally distributed with variable AJDF at

10 Newton’s of force demonstrating a negative skew.

4.3 Laterality

Table 4.3 demonstrates comparisons between left and right feet for all

dependent variables. The right foot demonstrated a significant increase in

MTPJ1 range for dependant variables AJDF10N (t= -2.789 p=0.008), AJN30N

(t= -2.711 p=0.01), AJDF30N (t=-3.066 p=0.004) and AJPF30N (t= -2.695

p=0.01) for the 37 subjects tested.

42

Table 4.3: Results of paired t-tests comparing left and right feet for derived variables WBLT and ankle joint position across loads 10 and 30 Newtons.

Dependent variable

Mean (SD) L R

T value

p value

95% lower

CI

95% upper

CI

Mean Difference

WBLT

46.71 45.79 (7.49) (7.19)

1.12 0.27 -0.63 2.16 0.77

AJN10N

19.33 20.49 (11.42) (11.48)

-0.67 0.51 -3.04 1.54 -0.75

AJDF 10N

2.32 4.44 (3.09) (5.91)

-2.79 0.008* -3.54 -0.56 -2.05

AJPF10N

36.13 37.96 (15.23) (13.79)

-1.45 0.16 -4.01 0.67 -1.67

AJN 30N

40.49 43.82 (15.27) (16.18)

-2.71 0.01* -5.38 -0.77 -3.08

AJDF30N

15.64 18.60 (12.39) (13.03)

-3.07 0.004* -4.50 -0.92 -2.71

AJPF 30N

56.92 60.04 (15.38) (14.55)

-2.69 0.011* -5.13 -0.72 -2.93

L: left foot; R: right foot; WBLT: weight bearing lunge test; AJN: ankle joint Neutral; AJDF: ankle

joint dorsi flexed; AJPF: ankle joint plantar flexed; N: Newton’s; “*”: statistical significance p

<0.05.

4.4 Gender differences

Table 4.4 outlines the differences between males and females with respect to

MTPJ1 ROM across each ankle joint position together with comparisons of

ankle joint range as tested with the WBLT. A paired t-test revealed significant

differences between males and females for dependent variables WBLT (t= -

2.102 p=0.04), AJN 10N (t= 2.347 p= 0.02), AJPF 10N (t= 3.936 p=0.00), AJN

30N (t= 2.111 p=0.04) and AJPF 30N (t= 3.229 p= 0.00).

43

Table 4.4: Mean, standard deviation (SD), T values, p values, 95% lower and upper confidence intervals (CI), and mean difference for dependent variables between male and female subjects from paired t tests. (21 female : 16 male)

Dependent variable

Mean (SD) M F

T value

p value

95% lower

CI

95% upper

CI

Mean Difference

WBLT

47.79 45.13 (5.03) (8.46)

-2.102 0.044* -6.71 -0.10 -3.40

AJN10N

15.8 22.9 (10.46) (11.2)

2.347 0.026* 0.94 13.61 7.28

AJDF 10N

2.71 3.86 (4.4) (5.04)

0.828 0.41 -1.56 3.68 1.06

AJPF10N

29.81 42.72 (13.15) (13.28)

3.936 0.001* 7.17 22.65 14.91

AJN 30N

36.53 46.26 (17.25) (13.12)

2.111 0.043* 0.29 17.38 8.84

AJDF30N

14.27 19.19 (11.38) (13.35)

0.901 0.37 -3.59 9.27 2.84

AJPF 30N

51.13 63.88 (16.91) (10.61)

3.229 0.003* 4.75 21.09 12.92

M: male; F: female; WBLT: weight bearing lunge test; AJN: ankle joint Neutral; AJDF: ankle joint

dorsi flexed; AJPF: ankle joint plantar flexed; N: Newton’s; “*”: statistical significance p <0.05.

4.5 Ankle joint position and MTPJ1 ROM

Table 4.5 outlines the mean, standard deviation and range for derived variables;

ankle joint range (WBLT), and MTPJ1 extension for force 10 and 30 Newton’s

across ankle joint positions, neutral, dorsi flexed and plantar flexed. Table 4.6

demonstrates comparisons between ankle joint position and MTPJ1 extension

for force 10 and 30 Newton’s. Paired t-tests reveal a significant difference in

MTPJ1 extension according to ankle joint position (p<0.0001). Figure 4.1

graphically represents the differences in MTPJ1 extension according to ankle

joint position. A significant reduction in MTPJ1 extension is evident as the ankle

joint position moves from plantar flexion through neutral to dorsiflexion for both

10 and 30 Newton’s of force. Figure 4.3 represents a force displacement curve

from a single subject as well as the stiffness curve with stiffness defined as the

ratio of change in force to change in displacement determined using a linear

best fit model. The force displacement curve demonstrates a right shift with

ankle joint positions neutral and plantar flexed highlighting the increased MTPJ1

ROM, whilst the stiffness curves demonstrates a more linear shape with ankle

joint dorsi flexed in keeping with greater stiffness and reduced ROM.

44

Table 4.5: The mean, standard deviation (SD), minimum, maximum and range of dependent variables for part two of the study investigating ankle joint position on MTPJ1 ROM. (measurements in degrees).

Dependent Variable Mean (SD) Min-Max [Range]

WBLT 46.26 (7.28) 22.90 – 62.30 [39.40]

AJN 10N 19.88 (11.38) 0.00 - 45.70 [45.70]

AJDF 10N 3.36 (4.78) 0.00 - 20.50 [20.50]

AJPF10N 37.03 (14.47) 4.00 - 72.20 [68.20]

AJN 30N 42.13 (15.71) 1.83 - 79.83 [78.00]

AJDF30N 17.10 (12.71) 0.00 - 53.33 [53.33]

AJPF 30N 58.46 (14.96) 17.33 - 79.67 [62.34]

Min: minimum; Max: maximum; WBLT: weight bearing lunge test; AJN, ankle joint neutral;

AJDF, ankle joint dorsi flexed; AJPF ankle joint plantar flexed; N, Newton’s (number of subjects

= 37, number of feet = 73, 37 left and 36 right)

Table 4.6: Paired t-test results between dependant variables; MTPJ1 ROM and ankle joint position and force (Newton’s) demonstrating a highly significant change in MTPJ1 extension between ankle joint positions.

Dependant

Variable T value p value 95% CI

(lower) 95% CI (upper)

Mean Difference

10 N

AJN & AJDF 15.09 <0.0001* 14.34 18.70 16.52AJN & AJPF -17.51 <0.0001* -19.10 -15.19 -17.14AJDF & AJPF -21.99 <0.0001* -36.72 -30.61 -33.6630 N AJN & AJDF 22.25 <0.0001* 22.78 27.27 25.03AJN & AJPF -19.39 <0.0001* -18.01 -14.65 -16.33AJDF & AJPF -28.18 <0.0001* -44.28 -38.43 -41.35

AJN: ankle joint neutral; AJDF: ankle joint dorsi flexed; AJPF: ankle joint plantar flexed; N:

Newton’s; CI: confidence intervals; “*”: statistical significance p <0.05.

45

-10

0

10

20

30

40

50

60

70

80

AJN10N AJDF10N AJPF10N

-10

0

10

20

30

40

50

60

70

80

90

AJN30N AJDF30N AJPF30N

Figure 4.1: Box plot of MTPJ1 extension for ankle joint positions neutral (AJN); dorsi flexed (AJDF) and plantar flexed (AJPF) at 10N force (A) and 30N force (B).

A

B

46

Angle (degrees)

AJPFAJNAJDF

Angle (degrees)

AJPFAJNAJDF

Figure 4.2: Representation of variables obtained from force-angle data of a single participant (subject 8). (A) The displacement (angle) at force 10 and 30 Newtons for each ankle joint position: AJDF (Ankle joint dorsi flexed); AJN (Ankle joint neutral); AJPF (Ankle joint plantar flexed) (B) The MTPJ1 passive stiffness defined as the ratio of change in force to change in displacement determined using a linear best fit model.

4.6 Foot posture

Analysis of the sample group (73 feet) was made based on foot posture

presentation. The FPI-6 instrument was used to determine foot type for each

subject. These were further catergorised into supinated (FPI-6 < 0), normal

(FPI-6 0- 5) and pronated (FPI-6 >6) feet. Table 4.7 outlines the mean and

standard deviation for MTPJ1 ROM across each foot type, ankle joint position

and MTPJ1 load. Table 4.8 describes the statistical comparison, via paired t-

tests of foot types and MTPJ1 ROM across all derived variables. Figure 4.3

represents graphically MTPJ1 extension for each foot type across loads 10 and

A

B

Forc

e (N

) 10

30

Forc

e (N

)

47

30 Newton’s of force. Significant differences were found between supinated and

neutral feet for derived variables AJPF 10N (t=-2.55, p=0.05); AJN 30N (t=-2.86,

p=0.04); AJDF30N (t=-1.23, p=0.03) and AJPF 30N (t= -3.53, p=0.02). A

significant difference was also found between neutral and pronated feet for

AJPF 10 N (t=2.70, p=0.01).

Table 4.7: Mean and standard deviation of ankle joint (WBLT) and MTPJ1 ROM across ankle joint positions and loads; according to foot type as determined by the FPI-6.

Foot Type (FPI-6)* Supinated Neutral Pronated

No of Feet (M,F) 6 (2,2) 50 (9,14) 17 (6,4)

WBLT 36.11 (11.13) 47.19 (6.37) 47.09 (5.81)

AJN 10N 14.06 (4.60) 20.98 (11.70) 18.72 (11.82)

AJDF 10N 0.11(0.20) 3.65 (4.82) 3.67 (5.22)

AJPF10N 33.42 (6.38) 39.79 (15.19) 30.18 (12.00)

AJN 30N 33.75 (3.51) 43.94 (15.76) 39.75 (17.40)

AJDF30N 8.61 (4.93) 18.65 (13.44) 15.55 (11.36)

AJPF 30N 54.05 (6.10) 60.82 (14.23) 53.08 (17.87)

M, Male; F, Female; WBLT, Weight bearing Lunge Test; AJN, ankle joint neutral; AJDF, ankle

joint dorsi flexed; AJPF ankle joint plantar flexed; N, Newton’s *Foot Posture Index;FPI-6;

Supinated: (-1 to -12), Normal: (0 to +5): Pronated (+6 to +12)

48

Table 4.8: Paired t-test analyses between foot types (FPI-6) for derived variables for ankle joint ROM (WBLT) and MTPJ1 ROM.

AJN, ankle joint neutral; AJDF, ankle joint dorsi flexed; AJPF ankle joint plantar flexed; N,

Newton’s: S, supinated: N, normal: P, pronated: “*”: statistical significance p <0.05.

Variable Foot type

Mean Difference T value p value 95% CI

(lower) 95% CI (upper)

WBLT S & N -7.95 -1.54 0.18 -21.17 5.27 S & P -7.65 -1.47 0.20 -20.99 5.69 N & P -2.89 -1.89 0.07 -6.12 0.35

10N AJN S & N -15.45 -2.43 0.06 -31.76 0.86

S & P 1.95 0.44 0.68 -9.36 13.25 N & P 4.08 0.80 0.44 -6.71 14.87

AJDF S & N -4.01 -1.86 0.12 -9.54 1.52 S & P -0.67 -1.20 0.28 -2.09 0.75 N & P -0.68 -0.37 0.72 -4.61 3.25

AJPF S & N -19.76 -2.55 0.05* -39.70 0.18 S & P 8.22 2.10 0.09 -1.86 18.31 N & P 15.62 2.70 0.01* 3.35 27.90

30N AJN S & N -16.12 -2.86 0.04* -30.63 -1.61

S & P 6.39 1.28 0.26 -6.42 19.20 N & P 4.29 0.63 0.54 -10.16 18.74

AJDF S & N -6.39 -1.23 0.03* -19.79 7.01 S & P 2.75 1.02 0.35 -4.15 9.65 N & P -2.07 -0.47 0.64 -11.42 7.27

AJPF S & N -15.37 -3.53 0.02* -26.55 -4.19 S & P 8.47 1.54 0.18 -5.69 22.64 N & P 10.30 1.55 0.14 -3.80 24.41

49

Figure 4.3: Comparison of mean MTPJ1 extension for ankle joint positions, neutral, dorsi flexed and plantar flexed (AJN;AJDF; AJPF) at 10 Newton’s (A) and 30 Newton’s (B) of force by foot type determined by FPI-6. Statistical difference p<0.05 [ ]

4.7 Calf MTU stretching and MTPJ1 ROM

Within group paired t-tests were performed for the control and stretch cohorts

for dependent variables WBLT, and MTPJ1 ROM across each ankle joint

position and force 10 and 30 Newton’s. Tables 4.9 and 4.10 compare ankle and

MTPJ1 ROM immediately following a one minute calf MTU stretch and again

after a one week home stretch program. Participants were required to complete

a participation diary indicating when stretching was performed at home.

(Appendix 11) A participation rate of 88% was achieved for the calf MTU

stretching over one week performed twice daily. Tables 4.11 and 4.12 outline

0

5

10

15

20

25

30

35

40

45

AJN AJDF AJPF

Mean value (degrees)

SupinatedNeutralPronated

A

0

10

20

30

40

50

60

70

AJN AJDF AJPF

Mean value (degrees)

SupinatedNeutralPronated

B

50

comparisons to baseline for the control group on the same day repeat test, and

again after one week.

Tables 4.13 and 4.14 demonstrate across group paired t-tests comparing

stretch and control cohorts for variables ankle joint neutral, dorsi flexed and

plantar flexed for forces 10 and 30 Newton’s respectively.

Table 4.9: The mean and standard deviation (SD) of dependent variables and paired t-tests for the stretch group in part three of the study investigating the effect of a one minute calf MTU stretch on MTPJ1 and ankle joint ROM measured on the same day.(all measures are in degrees)

Dependant

Variable Baseline

Mean (SD)

Retest (same day) Mean (SD)

T value p value 95% Upper and

Lower CI

Mean difference

WBLT 49.17 (5.51)

52.46 (4.67)

-3.446 0.006* (-5.42 : -1.16)

-3.29

AJN10N 13.89 (9.77)

16.70 (16.77)

-0.999 0.34 (-9.05 : 3.45)

-2.80

AJDF10N 2.89 (3.91)

4.79 (6.72)

-1.440 0.18 (-4.94: 1.06)

-1.94

AJPF10N 29.85 (13.80)

34.06 (15.81)

-2.477 0.03* (-8.00 : -0.42)

-4.21

AJN30N 40.21 (19.38)

45.45 (18.75)

-2.546 0.03* (-9.83 : -0.65)

-5.24

AJDF30N 19.88 (16.93)

23.32 (15.76)

-2.691 0.02* (-6.23 : -0.59)

-3.44

AJPF30N 54.38 (18.02)

55.42 (17.80)

-0.709 0.49 (-4.33 : 2.24)

-1.04

WBLT: weight bearing lunge test; AJN, ankle joint neutral; AJDF, ankle joint dorsi flexed; AJPF

ankle joint plantar flexed; N, Newton’s (number of subjects = 11, number of feet = 11, 5 left and

6 right); “*”: statistical significance p <0.05.

51

Table 4.10: The mean and standard deviation (SD) of dependent variables and paired t-tests for the stretch group in part three of the study investigating the effect of a one minute calf MTU stretch on MTPJ1 and ankle joint ROM measured at one week.(all measures are in degrees)

Dependant

Variable Baseline

Mean (SD)

Retest (one

week) Mean (SD)

T value p value 95% Upper

and Lower CI

Mean difference

WBLT 49.17 (5.51)

50.86 (6.56)

-1.643 0.13 (-3.98 : 0.60)

-1.69

AJN10N 13.89 (9.77)

18.182 (12.59)

-1.117 0.29 (-12.84 : 4.26)

-4.29

AJDF10N 2.89 (3.91)

4.39 (4.68)

-0.992 0.34 (-5.02 : 1.93)

-1.54

AJPF10N 29.85 (13.80)

30.89 (14.84)

-0.268 0.79 (-9.73 : 7.64)

-1.04

AJN30N 40.21 (19.38)

45.18 (15.64)

-1.588 0.14 (-11.94: 2.00)

-4.97

AJDF30N 19.88 (16.93)

19.48 (13.57)

0.153 0.88 (-5.36 : 6.12)

0.39

AJPF30N 54.38 (18.02)

53.74 (18.57)

0.402 0.69 (-2.88 : 4.16)

0.64

WBLT: weight bearing lunge test; AJN, ankle joint neutral; AJDF, ankle joint dorsi flexed; AJPF

ankle joint plantar flexed; N, Newton’s (number of subjects = 11, number of feet = 11, 5 left and

6 right)

52

Table 4.11: The mean and standard deviation (SD) of dependent variables and paired t-tests for the control group in part three of the study investigating the effect of a one minute calf MTU stretch on MTPJ1 and ankle joint ROM measured on the same day.(all measures are in degrees)

Dependant Variable

Baseline Mean (SD)

Retest (same day) Mean (SD)

T value p value 95% Upper and

Lower CI

Mean difference

WBLT 48.78 (4.28)

48.69 (5.81)

0.087 0.93 (-2.26 : 2.44)

0.09

AJN10N 16.8 (11.66)

17.167 (14.18)

-0.178 0.86 (-5.01 : 4.28)

-0.37

AJDF10N 1.417 (1.61)

1.8 (2.17)

-0.517 0.62 (-2.06 : 1.29)

-0.38

AJPF10N 30.3 (11.58)

29.05 (12.68)

0.314 0.76 (-7.75 : 10.25)

1.25

AJN30N 40.9 (15.04)

42.83 (18.45)

-0.955 0.36 (-6.51 : 2.65)

-1.93

AJDF30N 19.3 (12.03)

18.467 (11.19)

0.594 0.57 (-2.34 : 4.01)

0.83

AJPF30N 53.52 (14.81)

53.15 (17.56)

0.141 0.89 (-5.54 : 6.27)

0.37

WBLT: weight bearing lunge test; AJN, ankle joint neutral; AJDF, ankle joint dorsi flexed; AJPF ankle joint plantar flexed; N, Newton’s (number of subjects = 10, number of feet = 10, 6 left and 4 right)

Table 4.12: The mean and standard deviation (SD) of dependent variables and paired t-tests for the control group in part three of the study investigating the effect of a one minute calf MTU stretch on MTPJ1 and ankle joint ROM measured at one week.(all measures are in degrees)

Dependant Variable

Baseline Mean (SD)

Retest (one week) Mean (SD)

T value

p value

95% Upper

and Lower CI

Mean difference

WBLT 48.78 (4.28)

48.24 (5.91)

0.357 0.73 (-2.88 : 3.96)

0.54

AJN10N 16.8 (11.66)

14.3 (10.72)

1.052 0.32 (-2.88 : 7.88)

2.50

AJDF10N 1.417 (1.61)

3.117 (3.52)

-1.512 0.16 (-4.24 : 0.84)

-1.70

AJPF10N 30.3 (11.58)

31.55 (13.42)

-0.279 0.79 (-11.38 : 8.88)

-1.25

AJN30N 40.9 (15.04)

42.567 (10.68)

-0.504 0.63 (-9.15 : 5.82)

-1.67

AJDF30N 19.3 (12.03)

20.1 (11.01)

-0.352 0.73 (-5.94 : 4.34)

-0.80

AJPF30N 53.52 (14.81)

56.48 (13.18)

-0.637 0.54 (-13.50 : 7.56)

-2.97

WBLT: weight bearing lunge test; AJN, ankle joint neutral; AJDF, ankle joint dorsi flexed; AJPF, ankle joint plantar flexed; N, Newton’s (number of subjects = 10, number of feet = 10, 6 left and 4 right)

53

Table 4.13: T values, p values, 95% confidence intervals (CI), and mean difference for dependent variables; ankle joint position at 10N, between stretch and control groups at base line, repeat test (same day) and repeat test (one week).

Dependant Variables

T value

p value

95% Lower CI

95% Upper CI

Mean Difference

AJDF10N Baseline Retest (same day) Retest (one week)

1.028 1.231 0.387

0.33 0.25 0.71

-1.72 -1.99 -3.23

4.59 6.76 4.56

1.43 2.38 0.67

AJN10N Baseline Retest (same day) Retest (one week)

-1.983 -0.338 0.418

0.08 0.74 0.68

-9.81

-12.69 -10.07

0.64 9.39

14.64

-4.58 -1.65 2.28

AJPF10N Baseline Retest (same day) Retest (one week)

-0.303 0.965

-0.453

0.77 0.36

0.66

-9.89 -6.00

-13.68

7.56

14.94 9.11

-1.17 4.47

-2.28

AJDF: ankle joint dorsi flexed; AJN: ankle joint neutral; AJPF: ankle joint plantar flexed; N:

Newton’s.

Table 4.14: T values, p values, 95% confidence intervals (CI), and mean difference for dependent variables; ankle joint position at 30N, between stretch and control groups at base line, repeat test (same day) and repeat test (one week).

Dependant Variables

T value p value 95% Lower CI

95% Upper CI

Mean Difference

AJDF30N Baseline Retest (same day) Retest (one week)

0.839 2.636 0.855

0.42 0.03* 0.42

-3.25 0.80

-1.56

7.08

10.49 3.46

1.92 5.65 0.95

AJN30N Baseline Retest (same day) Retest (one week)

0.079 1.834 1.792

0.93850.09990.1068

-5.51 -0.80 -1.02

5.90 7.67 8.75

0.20 3.43 3.87

AJPF30N Baseline Retest (same day) Retest (one week)

0.434 1.064

-0.287

0.67430.31480.7807

-5.54 -2.48

-10.52

8.18 6.88 8.15

1.32 2.20

-1.18

AJDF: ankle joint dorsi flexed; AJN: ankle joint neutral; AJPF: ankle joint plantar flexed; N:

Newton’s; (*) statistical significance p<0.05.

54

CHAPTER FIVE DISCUSSION

5.0 Introduction

The present study was undertaken to determine the extensibility characteristics

of the MTPJ1 and its relationship to tendo Achilles load explored through

differing ankle joint positions. Further to this the immediate and longer term

effect of calf MTU stretching on MTPJ1 extension was also determined in a

sample of healthy asymptomatic subjects.

Review of the literature identified considerable variability in the methodology

used to determine MTPJ1 extension and, subsequently, normal range values

were similarly diverse. The research questions for this investigation derived

from findings of pilot work measuring MTPJ1 extension during quiet standing.

The initial results demonstrated a large influence on range of MTPJ1 motion by

associated postural muscle control used to maintain equilibrium from

perbutations throughout the load un-load cycles. The literature supports the

close interaction between tendo Achilles load and MTPJ1 extension through its

relationship to the plantar aponeurosis. The effect on MTPJ1 has yet to be

quantified. The influence of ankle joint position on measurement of MTPJ1

extension appears important for both clinical and research settings. Further to

this, the effect of commonly prescribed calf MTU stretching on MTPJ1 extension

remained unknown.

The chapter begins with a discussion of the study results including the reliability

testing for the methodology with reference made to individual research

questions. Statistical testing of dependent variables is further discussed in this

chapter with comparisons made to previous literature findings. Limitations and

recommendations for future studies are also presented.

5.1 Research questions

5.1.1 Reliability of methodology

i. The developed methodology for measuring MTPJ1 ROM and stiffness is

reliable compared to established clinical protocols.

55

ii. How many joint pre conditioning trials were required to provide stable

measures of MTPJ1 extension?

Reliability testing of the methodology for measuring MTPJ1 extension was

developed in three parts, as presented in sections 3.3, 3.4 and 3.5 of Chapter 3.

It is known that a joint, including surrounding soft tissues, displays viscoelastic

properties. Therefore some degree of creep and stress relaxation is

expected.(104) Results of section 3.3 confirmed that a degree of conditioning was

present when measuring MTPJ1 ROM. Analysis demonstrated that statistical

differences in joint range were evident during the initial load un-load cycles and

that beyond the sixth cycle no further statistical change was noted. This is

supported in the literature by Taylor et al(104) who reported a 16.6% decrease in

tension in rat tendons loaded and unloaded to 10% of resting length over ten

cycles. Taylor et al(104) also demonstrated a statistically significant difference in

the first four load unload cycles with no statistical difference noted beyond the

seventh peak tension cycle. Maganaris(103) also described tendon conditioning

noting that no further tendon elongation occurred after the first five load un-load

cycles in the gastrocnemius tendon in healthy men.

To yield more reliable results when measuring MTPJ1 extension, a degree of

conditioning appears necessary, a factor which is either not controlled for or

partially controlled for in many studies reporting MTPJ1 range.(34,35,41,42,46,142)

This study has shown improved stability of MTPJ1 measures following six load

un-load cycles. This can be attributed, in part, to neutralizing the mechanical

properties of the surrounding soft tissues as well as a degree of familiarity to the

testing procedure from the participants. Consequently previous data not citing

joint preconditioning should be viewed with caution and both research and

clinical protocols can be adapted from the results of this study.

Further reliability testing investigated the intra-rater reliability determined for the

same day testing as well as over time, i.e. one week. Results of section 3.4 and

3.5 confirm that the methodology used in this investigation for quantifying

MTPJ1 ROM was reliable. Specifically, the intra-rater reliability for the same day

test re-test was high (ICC 3,1 : 0.89-0.99) across all dependent variables. The

typical error ranged between 1.1 - 2.6 degrees, indicating test retest intra-rater

56

reliability would produce values to within 3 degrees on 95% of occasions when

measured on the same day.

Reliability of measurement of the MTPJ1 was further explored with intra-rater

test retest reliability determined over one week. All dependent variables

demonstrated good to high ICC’s (ICC 3,1 : 0.76 – 0.98) with the exception of

derived variable MTPJ1 extension range at 10 Newton’s of force in ankle joint

position dorsi flexion (ICC3,1 : 0.234). This poor reliability statistic was attributed

to the actual low values recorded at this level of force. Caution should further be

adopted when interpreting results for variable AJDF at 10N force as the

standard deviation was greater than the mean value. It would appear that in

AJDF, 10 Newton’s of force is insufficient to produce meaningful joint angle

changes. The typical error across all derived variables ranged from 0.97 – 5.08

degrees. This indicates test retest intra-rater reliability would produce values to

within 5.5 degrees on 95% of occasions when re measured following one week.

The methodology used in this study is unique; hence comparisons to previous

work are limited. However traditional methods of quantifying MTPJ1 ROM have

demonstrated high ICC’s. Hopson et al (35) examined four methods of measuring

static MTPJ1 extension and reported high intra-rater reliability with ICC’s

ranging between 0.91 and 0.98, with a standard error of the mean between 0.80

and 1.44 degrees across each measurement technique. Similarly Hogan and

Kidd(42) reported intra-rater reliability of measuring weight bearing MTPJ1

extension across two weeks as 0.87 and 0.98 for the left and right foot

respectively, with a standard error mean of 4.8 degrees.

Whilst these studies report good reliability of using a standard goniometer for

measuring MTPJ1 ROM, neither controlled for load applied to the hallux during

testing and the measurement tool was restricted to measures of at least one

degree increments.

5.1.2 Ankle joint position and MTPJ1 ROM

iii. Does ankle joint position significantly affect MTPJ1 passive extension and

stiffness in healthy asymptomatic subjects?

57

The present study investigated the above question by determining MTPJ1

extension across three ankle joint positions: dorsi flexed, neutral and plantar

flexed, and two loads: 10 and 30 Newtons of force. The results of this study

demonstrated a reduction of 84% and 60% in MTPJ1 extension between ankle

joint neutral and ankle joint dorsi flexed positions for loads 10 and 30 Newtons

respectively (p<0.0001). Similarly a reduction in range of 46% and 28% was

found between ankle joint plantar flexed and ankle joint neutral positions for

loads 10 and 30 Newtons respectively (p<0.0001).

The results are consistent with work by Flanigan et al (92) who demonstrated a

7.3% increase in tensile stretch of the plantar fascia with the ankle joint in fifteen

degrees dorsi flexion. Increased tension of the plantar fascia will produce a

plantar flexion moment across the MTPJ1, thus increasing the stiffness

characteristics of the joint.(143) The anatomical and functional interrelationship

between the tendo Achilles and plantar fascia has been described and the

results of this study are consistent with this phenomenon.(20-23,25-27,49,89,91,95)

Increased tendo Achilles load has been shown to transmit tensile load through

the plantar fascia with around one third of fascial stress transmitted to the first

ray.(90)

Ankle joint position therefore has important implications to both research and

clinical assessment of non weight bearing MTPJ1 ROM. Few studies describe

the position of the ankle joint when reporting joint range values, and hence

comparisons of normal range must be viewed with caution. Clinicians should

also be aware of the implications of MTPJ1 range across different ankle joint

positions when decision making or assessing outcomes from intervention.

5.1.3 Gender differences in ROM

iv. Were there gender differences with MTPJ1 ROM or stiffness in healthy

asymptomatic subjects?

The results of this study demonstrated increases in the means for MTPJ1

extension range for females across all derived variables. Statistical significance

was reached for ankle joint neutral at 10 Newton’s force (t=2.35, p= 0.02), ankle

joint plantar flexion at 10 Newton’s force (t=3.94, p=0.0005), ankle joint neutral

58

at 30 Newton’s force (t=2.11, p=0.04) and ankle joint plantar flexion at 30

Newton’s force (t= 3.23, p=0.003). Females demonstrated an increase in the

mean MTPJ1 extension across all variables from 20% for AJPF30N up to 31%

for AJN10N. The mean difference increase in MTPJ1 extension across all ankle

joint positions and loads was 7.97 degrees.

These results support previous reported findings of increased musculoskeletal

stiffness in males compared to females where these differences are attributable

to varied tendon mechanics and muscle architecture between the genders. (118-

120,144)

Whilst greater than the overall error level of the instrumentation, the clinical

relevance of this gender difference in a clinical setting remains unclear. Mobility

of joints through the medial column of the foot has been attributed to a greater

risk of hallux valgus development and studies similarly report a greater

incidence of hallux valgus in a female population.(145,146) Whilst

acknowledgement is made to other contributing factors, joint mobility

differences between the genders is supported within this thesis and may pose a

greater risk of pathology involving the MTPJ1.

The present study did, however, demonstrate a statistically significant increase

in ankle joint range of motion for males using the WBLT (t=-2.10, p= 0.04).

Males demonstrated a 6% increase in ankle joint range compared to females.

The WBLT relies on a self perceived maximum range and one may hypothesise

that males may demonstrate a higher perceived stretch tolerance. The mean

difference between males and females for ankle joint range was 3.4 degrees.

Given the available range afforded at the ankle joint the difference appear

clinically small.

5.1.4 Laterality

v. Were there symmetrical or limb dominance differences with MTPJ1 ROM

or stiffness in healthy asymptomatic subjects?

The results of this study demonstrate asymmetry across the entire sample for

non weight bearing MTPJ1 extension range. A significant difference was noted

59

between left and right feet for dependent variables ankle joint dorsi flexion at 10

Newton’s of force (t= -2.79, p=0.008), ankle joint neutral at 30 Newton’s force

(t=-2.71, p=0.01), ankle joint dorsi flexed at 30 Newton’s force (t=-3.07, p=

0.004), and ankle joint plantar flexed at 30 Newton’s force (t= -2.69, p= 0.01).

The results demonstrated an average increase of around 8% in MTPJ1

extension for the right side with the exception of variable AJDF10N which

showed much greater magnitude of difference. However this result can be

viewed cautiously as the angular change of the MTPJ1 was small. The average

mean difference for MTPJ1 extension across all variables was 2.19 degrees

which, given the associated instrumentation error, the clinical relevance of these

findings should be viewed cautiously.

The phenomenon of limb dominance has not been reported for MTPJ1 ROM.

Studies have described asymmetries in joint movement and limb segments

throughout gait, however the influence of limb dominance remains unclear.(124-

126,147) The sample population used in this present study, with the exception of

one subject, was right limb dominant. Whilst speculative, these results support

the hypothesis that limb dominance relates to asymmetrical joint range of

motion in the foot, notably MTPJ1. It must however be noted that the limb

dominance for MTPJ1 ROM was across all derived variables with statistical

significance reached for four of the six variables. One could speculate that there

may have been some influence in the methodological technique to produce

such a trend. Further investigation using a larger sample of equal left and right

sided dominant participants would provide greater insight into this phenomenon

within the joints of the foot.

5.1.5 Foot posture and MTPJ1 ROM

vi. Does foot posture influence MTPJ1 passive non weight bearing extension?

The current study revealed a slight trend towards a pronated foot type across

the sample of 73 feet, with FPI-6 values of 3.05 and 3.69 for the left and right

feet respectively. Whilst a neutral foot is commonly thought to be a ‘normal’ foot

type, several studies using the FPI instrument have described the ‘normal’ or

average foot to be mildly to moderately pronated, similar to the findings of this

study.(5,128,129,148) Assessing foot type for research purposes is common as it

60

has been hypothesised that foot morphology may predispose to certain

pathologies. Studies have however described increased risk of lower limb injury

with pronated,(130,131) as well as supinated foot types.(128,129) Another prospective

study found no association between foot type and lower limb injury.(133)

Differences in dynamic and static functions of the foot have been described

between foot types with the pronated foot often associated with joint mobility

and the cavus foot with rigidity.(128,149-152)

The present study demonstrated a significant increase in MTPJ1 ROM between

the supinated and neutral foot types across all ankle joint position under 30N of

force and for AJPF under 10N of force. However a reduced MTPJ1 ROM was

evident between the neutral foot type and the pronated foot type with statistical

significance reached for AJPF under 10N of force. No significant differences

were noted between the supinated and pronated foot types. Assuming that the

pronated foot type displays a larger degree of joint mobility then it may be

plausible that during non weight bearing testing of MTPJ1 ROM that recruitment

of muscle activity was present in this group to provide stability throughout the

load un-load cycles thus reducing toe extension. This again is speculative as

there were no controls for myogenic activity.

The study also demonstrated that supinated foot types had a reduced tendo

Achilles length as determined via the WBLT. Although not statistically significant

the reduced ankle joint dorsiflexion angle in the supinated group supports the

work by Burns and Crosbie (149), who demonstrated a strong positive correlation

between tendo Achilles length and foot type.

5.1.6 Calf MTU stretching and MTPJ1 ROM

vii. Does static and cyclic calf MTU stretches improve MTPJ1 range of motion

and stiffness in healthy asymptomatic subjects?

This study investigated the immediate and longer term effects of a one minute

hybrid, static and cyclic stretch of the calf MTU on ankle and MTPJ1 ROM. A

combined static and cyclic stretch regime was chosen as they each have been

shown to produce different modifications to the viscoelastic properties of the calf

MTU.(114)

61

The results demonstrated an increase in the mean ROM across all variables

immediately following calf MTU stretching, with statistical significant achieved

for ankle joint range via the WBLT (t= -3.45, p= 0.006), AJPF10N (t=-2.48, p=

0.03), AJN30N (t= -2.55, p= 0.03) and AJDF30N (t= -2.69, p= 0.02). The control

group demonstrated no statistical difference between baseline testing and

repeat testing, both immediately and after one week, with the stretch group

demonstrating no statistical differences in ROM following a one week stretch

program.

Increases in ankle joint ROM following stretching have been documented with

small statistically significant increases in range noted.(29) The lasting effects and

mechanisms involved in achieving greater joint ROM remain unclear. Folpp et al (153) describe an increase in the stretch tolerance of soft tissues following

stretching however others describe changes to the mechanical properties of the

musculoskeletal unit.(103,154-156) As the WBLT is a self regulated test, a change

in the stretch tolerance could explain the increased ankle joint range

demonstrated. However the testing of the MTPJ1 ROM was not self regulated

and would perhaps demonstrate true changes in the viscoelastic series of the

lower leg and foot.

The present study investigated both the immediate effect on ankle joint and

MTPJ1 ROM of a one minute calf MTU stretch and the effect after the stretch

was performed twice daily for one week. The acute effects of gastrocnemius

stretching on ankle joint ROM have been described, with Morse et al(157)

reporting a 17% (4.6 degree) increase in ankle ROM following a series of one

minute calf MTU stretches. The longer term effect of muscle stretching has also

been outlined with de Weijer et al(158) describing the effect of static stretching on

hamstring length over a twenty four hour period. Whilst increases in hamstring

length were maintained at twenty four hours, by 15 minutes post stretch the

hamstring length had already decreased. Duong et al(97) also describe the initial

rapid recovery of the calf MTU following acute stretch. They described a 23%

decrease in ankle joint torque following a five minute stretch with a 43%

recovery of torque within 2 minutes of stretch release. Whilst the present study

did not quantify the creep or stress relaxation of the MTPJ1 over time following

stretching, it would appear the study supports previous findings where an

62

immediate increase in ankle and MTPJ1 range was noted but returned to

baseline following one week. One could speculate that the effect on ankle joint

and MTPJ1 ROM of stretching, be it changes to stretch tolerance or the

viscoelastic properties of the soft tissues declines rapidly following stretching.

However greater changes may be demonstrated with increased stretch times.

Whilst this study reports increases in ankle joint and MTPJ1 ROM immediately

following stretching, these values appear clinically small. The present study

demonstrated a mean increase in ankle joint range of 3.3 degrees and

increases in MTPJ1 extension ranged between 1.0 and 5.2 degrees across all

dependent variables following calf MTU stretching. Radford et al(29) found a

similar small increase in ankle joint range following a systematic review of the

effects of calf MTU stretching. Consistent with this study they found a weighted

mean difference of 2.07 degrees increase for ankle joint dorsi flexion following

calf stretches of less than 15 minutes duration. The clinical relevance of such a

relatively small increase in joint range remains unclear; however concomitant

changes in ranges to associated neighbouring joints could be one possible

explanation for positive outcomes seen clinically.(111,112) The influence of these

small improvements to joint extensibility on gait efficiency is an area of further

interest. Whilst speculative, stretching in the elderly, who are more susceptible

to falls, may have a positive affect on postural stability similar to the benefit of

foot mobilization in this subgroup.(159)

Analyses of the data between the stretch and control groups reports no

statistical difference across all derived variables with the exception of AJDF30N

(t=2.64, p=0.03). This demonstrated a significant increase in MTPJ1 ROM

between the stretch and control groups measured on the same day following a

one minute stretch. The small sample size in both groups may account for this.

Given the within subject changes noted with calf MTU stretching a larger study

may be warranted to explore group differences further.

5.1.7 Limitations and recommendations for further study

Limitations were identified within the study and are discussed below, together

with recommendations for further investigation informed by this series of

studies.

63

Comparisons of non weight bearing MTPJ1 ROM between this study and those

reported within the literature is difficult due to the methodology used. Unique in

its design, the methodology used in this study demonstrates the advantage of

controlling for ankle joint position, torque applied to the joint and the viscoelastic

nature of the joint. A longitudinal study with a larger sample size would be

recommended to report normative data for non weight bearing MTPJ1

extension. A study cohort could be further divided into age decades which could

then be used to assess the effect of ageing on passive MTPJ1 ROM and

development of pathology.

Another recommendation for further studies is to include a larger sample of left

sided dominant subjects. Whilst this study found a significant trend towards

increased ROM on the dominant side, a lack of left sided dominant participants

renders any conclusion in terms of asymmetry purely speculative. Additional

measures of leg length and foot length differences would also be encouraged.

A limitation of this study is the lack of a clinically defined foot pathology group.

The present study describes a phenomenon between ankle joint position, tendo

Achilles load and MTPJ1 ROM in healthy asymptomatic adults. Therefore

conclusions to ‘pathology’ subgroups cannot be made. The presented

methodology demonstrates good reliability for quantifying MTPJ1 ROM so

future investigations comparing pathological groups and age matched controls

can be made. Of further interest are the effects of calf MTU stretching and

MTPJ1 ROM in such pathological groups. One might intuitively expect to see a

greater response to calf MTU stretches with those displaying limited joint

mobility, than the normal, asymptomatic participants used in this current study.

A suggested group for further investigation are individuals diagnosed with Type

2 diabetes, where correlations would be assessed between, glycosolated

haemoglobin levels, ankle and MTPJ1 joint extensibility and plantar pressures.

Pre and post evaluations on joint extensibility and plantar pressures could be

made following a similar stretching protocol described in this thesis. This could

be combined with an age matched control group not instructed to perform calf

MTU stretches. Elevated plantar pressures and disruptions to pressure time

integrals can have detrimental effects on diabetic feet by way of tissue

64

breakdown, particularly those with neuropathic changes and MTPJ1 ROM has

been described as a good predictor of elevated pressures.(53,74,79,160)

Improvements in gait efficiency led by improved joint extensibility seems an

important preventative strategy in this population and worthy of further

investigation.

A further limitation of this study is the pseudo passive movement reported. No

control for muscle activity was utilized and therefore a true passive extension of

the MTPJ1 was unknown. A recommendation for further investigation into true

passive MTPJ1 ROM would be to use electromyography to detect active

participant assistance during testing. Similarly the velocity or acceleration used

during testing MTPJ1 cycles, whilst steady, was neither controlled for nor

quantified. The rate of load displacement, which can affect the mechanical

properties of soft tissues, could be controlled for by using a motorized rig

programmed to move at a set velocity.

A recommendation for further investigations would be the assessment of the

effect of calf MTU stretching on MTPJ1 and ankle joint ROM during dynamic

gait. A motion analysis system could be used to collect kinematic data during

gait cycles. Correlation to plantar pressures would be of interest in specific

groups such as diabetics, athletes or the elderly who represent a greater risk for

falls. Force plates or in-shoe pressure systems could be used to provide before

and after changes to peak pressures and pressure-time integrals following calf

MTU stretches. The time course changes could be followed and appear worthy

of further investigation.

65

CHAPTER SIX CONCLUSIONS

6.0 Introduction

This chapter presents the conclusions of the study, grouped according to the

original research questions (i-vi).

6.1 Conclusions

From this study the following conclusions, limited to this cohort, may be drawn:

Reliability:

i. Measurement of non weight bearing MTPJ1 range of extension was

reliable for both the same day testing and across one week. [ICC3,1: >0.89;

SEM <2.6 degrees and ICC3,1: >0.76; SEM <5.1 degrees respectively].

ii. Reliable quantification of non weight bearing MTPJ1 extension requires at

least 6 load un-load cycles to reduce the variability in measures as a result

of joint conditioning. Baseline data was achieved by using the mean value

of load un-load cycles between 7-9.

Ankle joint position and MTPJ1 ROM:

iii. Ankle joint position significantly effects non weight bearing MTPJ1 ROM.

Range of MTPJ1 extension significantly reduced from ankle joint plantar

flexion, ankle joint neutral to ankle joint dorsi flexion under both load

conditions of 10 and 30 Newton’s of force.

Gender differences and MTPJ1 ROM:

iv. Female subjects demonstrated a greater range of non weight bearing

MTPJ1 ROM for derived variables AJN10N, AJPF10N, AJN30N and

AJPF30N. Males demonstrated a greater ankle joint range of motion.

Symmetry and limb dominance on MTPJ1 ROM:

v. Right sided dominance was associated with increased non weight bearing

MTPJ1 ROM.

66

Foot posture and MTPJ1 ROM:

vi. Neutral foot types had a greater MTPJ1 ROM compared to supinated foot

types for derived variables AJPF10N, AJN30N, AJDF30N and AJPF30N.

There were no statistical differences in ankle joint ROM based on foot

type.

Effects of calf MTU stretching on MTPJ1 ROM:

vii A one minute static and ballistic calf muscle stretch significantly improves

ankle joint range of motion immediately following stretch as well as MTPJ1

range for variables AJPF10N, AJN30N and AJDF 30N. A one week home

stretching protocol did not increase ankle or MTPJ1 range of motion.

67

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APPENDIX 1 Development of measurement tool: Weight bearing test set up

1.0 Description

The basis for the thesis originated from initial trials to develop a weight bearing

test to quantify passive MTPJ1 extension during quiet standing. Initial focus was

to determine the influence of foot orthoses on MTPJ1 ROM and stiffness, and

whether certain foot orthoses design parameters would influence MTPJ1

mechanics. To achieve this, a weight-bearing model was required and

produced. The result utilised a hand held force transducer (McMesin® AGF),

and battery operated (9V) potentiometer attached to a hinged wooden platform

which supported the subject’s body weight. A fifty centimetre adjustable backing

plate extended vertically and was positioned to rest on the subjects calves in an

attempt to reduce postural sway.

Visual alignment of the MTPJ1 axis was made with the hallux resting on the

anterior platform. The force transducer was maintained orthogonal to the

platform whilst the hallux was moved through its extension ROM and back to

neutral at a relatively constant velocity. Simultaneous angle and force data was

captured via a data acquisition board (National Instruments® BNC 2110) and

DAQ Card (National Instruments® -6024E) to a laptop computer. See Fig1. Data

was processed using Labview® software Version 7 sampling at 100Hz with raw

data filtered using a fourth order Butterworth low pass.

89

Figure 1: Weight-bearing set up to measure MTPJ1 ROM extension and the influence of foot orthoses and different design parameters.

1.1 Calibration

Calibration of the potentiometer was performed using a standard goniometer

with recordings of voltage output taken twice at ten degree increments, (0-90

degrees). Linear regression analyses of the data showed a line of best fit

relationship between angle and voltage R2=0.998, and R2=0.9972. See Fig 2.

y = -38.388x + 328.4

R2 = 0.9972

y = -39.143x + 327.03

R2 = 0.998

0102030405060708090

100

5 6 7 8 9

Figure 2: Linear regression model detailing relationship between angle and voltage output measured on two occasions. x axis (voltage); y axis (angle in degrees)

Angle

Force DAQ Board

Force Transducer Potentiometer

90

Further testing to determine the voltage change between angles was

determined. A relatively constant offset (0.204 V) was noted across angles 0-90

degrees. The change in the battery charge was consistent across these angles

with around 0.5% change equating to 0.3 degrees over around 70 degree

range. See Fig 3.

y = -0.0048x + 0.204

R2 = 0.6024

0

0.05

0.1

0.15

0.2

0.25

1 2 3 4 5 6 7 8 9 10

Figure 3: Changes in potentiometer voltage outputs across each angle. (1=0degrees and 10=90 degrees.)

The results demonstrated the voltage output had around 2% drift over 100

degrees; therefore an offset was required to be determined prior to each testing

session. To do these two recordings of battery output were determined at

known angles as measured by the standard goniometer. The chosen angles

were zero and 45 degrees which could be subtracted to determine the angle

data for subsequent trials. Calibration was performed prior to testing each

subject.

1.2 Reliability

Initially five asymptomatic female volunteers participated in the trial which

measured MTPJ1 extension in weight bearing as described above. A total of 35

joint cycles were performed in seven blocks of five joint extensions with the

variable; MTPJ1 angle at 30 N of force derived. Data reduction saw the mean of

the three middle cycles for each block determined with further analyses made

on the mean of blocks 2, 3 and 4. A same day test re-test design was utilised

as summarised in Table 1. Reliability analysis was performed using an

Intraclass Correlation Coefficient statistic ICC model (3,1) .(141)

91

Table 1: Weight bearing MTPJ1 extension at 30N force/degrees measured in five asymptomatic adults. Same day test re-test with the mean of blocks 2,3,4 recorded and standard deviation (SD) and range across subjects.

Subject

Test1

Test2

Mean Difference

Left Foot 1 25.28 33.17 7.89

2 37.89 35.67 -2.22 3 56.83 50.50 -6.33 4 46.28 64.83 18.55 5 59.06 55.50 -3.56

Right Foot 1 32.78 28.00 -4.78 2 28.33 14.00 -14.33 3 58.00 64.67 6.67 4 53.67 55.67 2 5 67.11 56.00 -11.11

Mean, (SD), [Range]

46.52 (14.6) [25.28 - 67.11]

45.80 (17.1) [14 - 64.83]

The results demonstrated a large degree of variation with in some subjects

across trials and blocks, as evident in the mean test re-test values. Across all

subjects the mean difference between trials one and two performed on the

same day was 7.74 degrees (SD 9.8).

Reliability analysis between trial one and two demonstrated an ICC 3, 1 of 0.811,

with 95% Confidence Limit (0.370-0.954) and Typical error in degrees of 6.91.

1.3 Intervention

Subsequent pilot testing involved subject’s weight bearing on standard, non-

moulded, high density Ethyl Vinyl Acetate foot orthoses (ICB Medical

Orthotics®, ICB Medical Distributors P/L, Kirrawee). Two orthotic designs were

tested, one with no modification and the second with a first metatarsal cut out.

The latter is suggested to improve MTPJ1 extension by allowing first metatarsal

plantar flexion. Subjects were tested using the methodology described above

with the derived variable MTPJ1 angle at 30N force recorded with the mean of

blocks 2,3 and 4 used for further analyses. Table 2 summarises these results.

92

Table 2: Weight bearing MTPJ1 extension; degrees at 30N force, quiet standing versus a standard orthotic versus an orthotic with a first metatarsal cut out. Mean of blocks 2,3,4 represented and standard deviation (SD) across subjects.

Subject Baseline Standard Orthotic

Orthotic Cut Out

Left Foot 1 25.28 26.67 29.67 2 37.89 43 28.17 3 56.83 46.5 53.33 4 46.28 44.67 54.67 5 59.06 54.33 45 Right Foot 1 32.78 34 24.67 2 28.33 11.33 16.83 3 58 53.67 57.33 4 53.67 40.83 62.83 5 67.11 55.83 62.5

Mean, (SD), [Range]

46.52 (14.59)

[25.28 - 67.11]

41.08 (13.91)

[11.33 - 55.83]

43.5 (17.13)

[16.83 - 62.83]

Table 2 demonstrates inconsistencies between standing, standing on a

standard orthoses and standing on an orthoses hypothesised to increase

MTPJ1 ROM. Whilst the between subject variability is to be expected there was

no obvious direction with the intervention. Some subjects demonstrated a

decrease in MTPJ1 ROM with the orthotic conditions whilst others

demonstrated improvements. The mean difference between the standard

orthotic condition and modified orthotic condition compared to quiet standing

was 5.4 degrees (SD 7.2) and 3.0 degrees (SD 8.2) respectively.

What was demonstrated was the “effect size”, if any, was comparable with the

measurement error derived from the previous same day test re-test data and

not in keeping with the working hypotheses that orthoses improve MTPJ1

mechanics.

1.4 Foot Type

Individual response to the orthotic conditions could in part be contributed to

specific foot types i.e. pronation-supination continuum. Two subjects were

chosen to voluntarily participate in testing based on their individual foot posture

as determined by the Foot Posture Index (FPI-6). Comparisons were made

between a pronated foot type (Foot Posture Index: [9]) and a supinated foot

93

type (Foot Posture Index: [-3]). Subjects were tested whilst weight bearing as

previously described in quiet standing as well as standing on a standard

prefabricated orthotic device (ICB Medical Orthotics®, ICB Medical Distributors

P/L, Kirrawee).

Further to this the effect of Low Dye taping of the foot was tested to see if

changes to MTPJ1 mechanics could be detected. The Low Dye taping

technique is a commonly used therapy to assess the effects of supporting the

medial longitudinal arch of the foot. It has been shown to be effective in the

short term management of plantar fasciitis.(161)

The variables derived were MTPJ1 extension range in degrees at 30N of force.

The mean of blocks 2,3 and 4 were used for further analysis. Table 3 provides a

summary.

Table 3: Effects of foot posture on MTPJ1 weight bearing extension. Range of motion in degrees at 30N force with the mean of block 2,3,4 recorded; Subject 1 : Supinated foot FPI-6 [-3], and Subject 2 pronated foot FPI-6 [9].

Subject Baseline Standard Orthotic

Taping

Left Foot 1 33.88 19.83 32.05 2 50.38 55.66 43.5 Right Foot 1 22.16 13.55 29.56

2 52.05 62.33 58.33 The comparison of foot type and the effects of orthoses and taping revealed an

interesting phenomenon. It showed the supinated foot type actually had a

significant reduction in hallux ROM with the orthotic condition, whereas the

pronated foot type demonstrated a slight increase in MTPJ1 ROM. Foot posture

has been shown to correlate weakly to the location of the subtalar joint axis

(r2~0.30) and resistance to supinate the foot.(162) Therefore it can be

hypothesised that the supinated foot type tested may have had a more lateral

orientation of the subtalar joint axis although this was not assessed. In essence

the foot orthotic in this foot type was creating an increased supination moment

across the subtalar joint resulting in increased lateral instability. To compensate

this and maintain forefoot ground contact, greater muscle recruitment may have

been responsible for limiting hallux extension particularly the long plantar

94

flexors, peroneus longus, flexor hallucis longus, flexor digitorum longus. This

was not tested or controlled for.

Muscle recruitment of the lower leg muscles has been described in the literature

during quiet standing.(163-166) As the centre of gravity passes anterior to the

ankle joint axis recruitment of the plantar flexors, particularly the gastrocsoleus

muscle complex is required to maintain equilibrium. Conversely as the centre of

gravity passes posteriorly to the ankle joint the anterior leg muscles, namely

tibialis anterior is recruited to maintain equilibrium. The relationship between

gastrocsoleus muscle stiffness and MTPJ1 ROM has been described.(20,21,90)

From the above pilot work it was hypothesised that moving the hallux through

its ROM with a hand held force transducer in relaxed stance produced small

posterior – anterior acceleration to the centre of mass. It is plausible that these

perturbations produce compensatory postural muscle activation, influencing

hallux ROM and partially accounting for the error between trials.

1.5 Postural sway

To explore this hypothesis further a single subject design investigated the effect

of postural sway on forces required to dorsi flex the hallux and stiffness

(instantaneous angle divided by force) at 20 degrees extension. The subject

was measured in four postural positions, namely standard (quiet stance), self

selected maximum backward, maximum forward and maximum lateral. Whilst

the subject maintained these postural positions the hallux was moved to 20

degrees extension and the derived variables Force (N) and stiffness were

recorded. Table 4 provides a summary.

Table 4: Posture position and effect on MTPJ1. Force (N) and stiffness with the hallux at 20 degrees extension if four postural positions during quiet standing (baseline), maximum forward, maximum backwards and maximum lateral.

Posture Baseline Backward Forward Lateral

Force (N) Left Foot 18.71 18.38 34.47 15.97 Right Foot 25.01 23.1 36.1 23.22 Stiffness* Left Foot 0.25 0.31 0.59 0.11 Right Foot 0.39 0.36 0.71 0.37

*stiffness: defined as the as the ratio of change in force to change in displacement determined using a linear best fit model.

95

These data reveal large increases in force required to dorsi flex the hallux with a

forward postural position together with increased joint stiffness, most likely due

to increased tension in the gastrocsoleus muscle complex, tendo Achilles and

plantar aponeurosis. Muscle recruitment appeared evident to maintain the body

from falling forward with marked effects on MTPJ1 stiffness.

1.6 Development of research question

The above pilot work led to the further investigation of the inter relationship of

the posterior leg muscle group and particularly the correlation between the

Tendo Achilles, plantar aponeurosis and MTPJ1 mechanics.

As the weight bearing model was deemed unreliable and not sensitive enough

to detect meaningful change, a non weight-bearing device was derived. The

custom designed non weight bearing set up allowed testing of MTPJ1 extension

across ankle joint positions to represent varying loads through the Achilles

tendo and plantar aponeurosis. Reliability testing of this device is presented in

full within the main body of the thesis as to the effects of calf muscle tendon

stretching on MTPJ1 extension.

Further insight into the perturbation effects of measuring hallux ROM in weight-

bearing is an area for further investigation and could be achieved by collecting

centre of pressure (COP) data via a force platform concomitantly with hallux

ROM and electromyography activity.

96

APP

END

IX 2

R

aw d

ata

MTP

J1 C

ycle

s

Sx

Sex

Age

W

BLT

L

Mea

n W

BLT

R

Mea

n B

MI

Sequ

ence

1

M

47

47.7

45

.7

46.6

46

.67

43.7

43

.7

44.7

44

.03

24.2

AB

C

2 F

47

33.4

35

.2

35.4

34

.67

36.9

36

.7

36.7

36

.77

24.9

BA

C

3 F

29

45.4

47

45

.1

45.8

3 40

.3

37.8

38

.2

38.7

7 19

.8

CBA

4

F 26

54

.3

51

52.6

52

.63

48.9

47

.7

47.7

48

.10

24.2

AC

B

5

F 22

44

.8

44.1

47

.1

45.3

3 43

.8

44.4

43

.9

44.0

3 18

.8

BCA

6 F

34

22.6

22

.7

23.4

22

.90

23.1

23

.1

23

23.0

7 24

.7

CAB

A

JN: R

OM

at 1

0N

Sx

C

ycle

1

2 3

4 5

6 7

8 9

10

11

12

13

14

15

1L

18

.5

23.5

24

24

24

23

23

23

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23

21.5

23

25

22

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24

24.5

1R

20

28.5

34

37

38

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32.5

37

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37

34.5

34

33

33

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35

38.5

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.5

2L

22

17

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26

26.5

28

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24

28

28.5

28

29

29

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37

29.5

32

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32.5

2R

23

19

18

23.5

25

26

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24.5

23

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21.5

23

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32

31

25.5

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22.5

3L

29

35

38

35.5

35

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37.5

44

39

37

35

36

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42

37

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38

3R

36

39

40

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39

39

45.5

44

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44

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38

43.5

39

38

39

4L

7.5

11.5

14

11

11

10

14

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10

10.5

11

11

12

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10.5

12

11

4R

8.5

21.5

17

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18

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22

5L

7 15

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18

17

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23

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8 9

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12

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8

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19

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15.5

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24

23

24.5

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23

28

25

30

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24

AJN

: RO

M a

t 30N

Sx

Cyc

le

1 2

3 4

5 6

7 8

9 10

11

12

13

14

15

1L

34.5

39

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39

39.5

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41

39

40

40

42

41

44

42

42

42

1R

41

49

51

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53

52

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53.5

53

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54

52

51.5

52

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53

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2L

53.5

56

56

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56.5

57

56

60

59

58

57

60

60

60

60

58

2R

59.5

60

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61.5

61

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58

60

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56

57

60

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59

3L

56.5

62

61

61

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63

64

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63

63

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63

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97

3R

66

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69

69

69

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70.5

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70

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70

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28

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35

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40

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52

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54

56

55

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5L

26

31

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36

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36

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5R

22

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27

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36

34

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35.5

39

39

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44

44

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34.5

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44

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45

AJD

F: R

OM

at 1

0N

Sx

C

ycle

1

2 3

4 5

6 7

8 9

10

11

12

13

14

15

1L

0

0 0

0 0

1 1

1 0

0 1

1 0

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1R

0

1.5

1.5

2 2

1.5

3 2

3 3.

5 3

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4 6

6.5

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2.

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4 8.

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5 9

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5 8.

5 8.

5 10

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5 11

4L

1 0

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2 1

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1.5

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0 1.

5 6R

1.5

1 0

0 1

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0 0

AJD

F: R

OM

at 3

0N

Sx

C

ycle

1

2 3

4 5

6 7

8 9

10

11

12

13

14

15

1L

3

5 5

5 6

5.5

7 6

6 8

8.5

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8.5

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6.5

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12

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12.5

13

12

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13

13.5

14

14

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2L

16

.5

25.5

27

.5

27.5

30

.5

30

26.5

31

.5

32

31.5

30

.5

32.5

32

.5

30.5

30

2R

17.5

20

.5

19.5

19

19

.5

22.5

20

20

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21.5

23

20

20

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19

19.5

22

.5

3L

23

.5

30.5

29

28

.5

28.5

30

28

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30

31.5

28

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32

29.5

32

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31

30

3R

27

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26

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29

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28

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33

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33

32

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31

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4L

10

7.

5 6

6 5.

5 5.

5 6.

5 6

7 8

6.5

5.5

7.5

4.5

7 4R

6.5

5.5

6 7.

5 8.

5 10

8

8 7

9 10

7.

5 8.

5 7.

5 8.

5 5L

8 8

7 7.

5 6

5.5

4.5

4.5

5 5

4.5

5 4.

5 4.

5 5

98

5R

10

.5

9 8

7 7

5.5

5.5

5.5

5.5

5.5

6 5.

5 7.

5 8.

5 7.

5 6L

5 5.

5 4.

5 4.

5 4.

5 5.

5 5

6 6

7.5

8 8

8.5

8.5

8 6R

6.5

5.5

4.5

5.5

7 5

7 9

7 6.

5 7.

5 8

5.5

8.5

7

A

JPF:

RO

M a

t 10N

Sx

Cyc

le

1 2

3 4

5 6

7 8

9 10

11

12

13

14

15

1L

32.5

43

45

45

47

.5

46.5

45

.5

49

46

45.5

50

50

44

.5

54

52.5

1R

42

53

54.5

49

54

55

56

53

.5

53

46.5

56

57

55

.5

53

53

2L

45

.5

41

36

48.5

46

.5

49.5

45

.5

47.5

49

.5

49

46.5

42

50

49

.5

46

2R

35

.5

49

48.5

43

37

48

.5

49

49.5

49

52

47

32

.5

39

39

49

3L

57

.5

65.5

59

.5

65.5

72

67

73

.5

69.5

72

73

.5

72.5

69

70

.5

69

72.5

3R

59.5

64

69

67

.5

67.5

70

73

75

68

.5

71.5

75

74

76

74

74

.5

4L

35

.5

40.5

30

.5

35

45.5

50

.5

42.5

48

.5

51

43.5

42

60

50

.5

46

43.5

4R

20.5

30

35

.5

33

36

38

39

38.5

33

.5

37.5

37

39

.5

33.5

36

.5

50

5L

32

.5

38.5

43

43

44

39

.5

48.5

43

.5

43

45

44.5

42

44

45

47

5R

32

43

44

50.5

47

.5

50

54.5

47

51

.5

53.5

53

44

54

46

.5

52.5

6L

36.5

41

.5

48

45.5

45

.5

48

48.5

52

.5

48.5

47

.5

47.5

46

47

50

47

.5

6R

23

13

.5

20.5

23

.5

34

36.5

25

26

24

.5

24.5

24

.5

25

27.5

26

19

A

JPF:

RO

M a

t 30N

Sx

Cyc

le

1 2

3 4

5 6

7 8

9 10

11

12

13

14

15

1L

61

69

70

70

70.5

68

69

.5

69

71.5

70

.5

71

71

72

69

71

1R

69

.5

71.5

73

73

73

.5

74.5

74

72

72

73

.5

74.5

74

73

.5

73.5

73

2L

67.5

67

64

68

.5

66.5

67

.5

67

68.5

68

69

68

.5

68.5

68

68

69

.5

2R

64

.5

70.5

69

.5

67.5

70

.5

69

68.5

70

.5

69

70.5

69

66

.5

70

68

69.5

3L

79

78

80

80

77

79

78

79.5

78

78

78

80

76

.5

77

79

3R

80

77

.5

79

78.5

79

.5

80

78.5

79

76

.5

77.5

79

78

.5

79.5

78

.5

79

4L

69

71

.5

70.5

73

73

74

.5

73.5

71

.5

73.5

75

.5

76.5

78

73

76

76

.5

4R

66

75

78

.5

79.5

79

79

78

.5

78.5

78

79

77

77

79

.5

78.5

77

.5

5L

53

.5

59

59.5

59

.5

57.5

58

59

.5

60

60

59.5

58

.5

59.5

60

62

.5

63

5R

55

61

.5

62

63.5

64

.5

63

66.5

65

64

68

.5

68.5

63

70

66

68

6L

56

60.5

59

61

.5

59.5

61

62

64

65

64

.5

63.5

65

65

65

.5

66

6R

39

.5

35.5

45

43

.5

47

50.5

47

47

.5

49

48

49.5

45

.5

47

49.5

46

99

-2.164 .834 <.0001 S-2.525 .834 <.0001 S-.361 .834 .5641

Mean Diff. Crit. Diff. P-ValueAve 23&4, ave T789Ave 23&4, Ave T12-14ave T789, Ave T12-14

Scheffe for ClustersEffect: Category for ClustersSignificance Level: 5 %

APPENDIX 3 Summary of Analysis of Variance Analyses: MTPJ1 cycles.

In the assessment below the ANOVA reports a significant increase between the

means of cycles (T2,3,4) and (T7,8,9). Also of note is that there was not a

significant difference between the mean of cycles T7,8,9 and T12,13,14. Also

demonstrated is a significant interaction between Ankle joint position and cycles

(clusters) (p=0.0031) indicating the effect of the clusters is different depending

on ankle joint position. A further two way ANOVA is presented below to declare

where the difference lies.

1 18416.807 18416.807 55.921 <.0001 55.921 1.0002 89326.030 44663.015 135.616 <.0001 271.231 1.0002 1507.255 753.628 2.288 .1094 4.577 .437

66 21736.115 329.3352 268.627 134.313 32.902 <.0001 65.804 1.0002 16.598 8.299 2.033 .1350 4.066 .4004 68.568 17.142 4.199 .0031 16.797 .9254 36.112 9.028 2.212 .0711 8.846 .632

132 538.855 4.082

DF Sum of Squares Mean Square F-Value P-Value Lambda Pow erLoadVarAnkleLoad * VarAnkleSubject(Group)Category for ClustersCategory for Clusters * LoadCategory for Clusters * VarAnkleCategory for Clusters * Load * VarAnkleCategory for Clusters * Subject(Group)

ANOVA Table for Clusters

12 2.639 3.594 1.03812 2.861 4.028 1.16312 2.861 3.966 1.14512 21.986 9.723 2.80712 25.125 10.734 3.09912 25.708 9.996 2.88612 44.597 12.806 3.69712 49.736 12.839 3.70612 48.931 13.441 3.88012 13.167 9.844 2.84212 13.944 10.635 3.07012 14.806 10.875 3.13912 45.917 14.673 4.23612 48.306 13.094 3.78012 49.264 13.176 3.80412 67.347 10.621 3.06612 68.667 8.857 2.55712 69.236 9.006 2.600

Count Mean Std. Dev. Std. Err.10N, DF, Ave 23&410N, DF, ave T78910N, DF, Ave T12-1410N, neutral, Ave 23&410N, neutral, ave T78910N, neutral, Ave T12-1410N, PF, Ave 23&410N, PF, ave T78910N, PF, Ave T12-1430N, DF, Ave 23&430N, DF, ave T78930N, DF, Ave T12-1430N, neutral, Ave 23&430N, neutral, ave T78930N, neutral, Ave T12-1430N, PF, Ave 23&430N, PF, ave T78930N, PF, Ave T12-14

Means Table for ClustersEffect: Category for Clusters * Load * VarAnkle

100

Two way ANOVA split by ankle joint position:

The assessment below compares the influence of ankle joint position, namely

ankle joint dorsiflexion and ankle joint plantar flexion on the derived variables

from cycles 2,3,4; 7,8,9 and 12,13,14. The two way ANOVA demonstrates a

significant difference between cycles 2,3,4 and 12,13,14 for ankle joint

dorsiflexion, whilst ankle joint plantar flexion demonstrates a significant

difference between cycles 2,3,4 and 7,8,9 as well as between cycles 2,3,4 and

12,13,14. Importantly for both ankle joint positions there was no significant

difference between cycles 7,8,9 and 12,13,14, supporting the theory that joint

conditioning is mostly achieved after 6 cycles.

1 2251.951 2251.951 12.219 .0020 12.219 .93222 4054.506 184.2962 10.410 5.205 4.578 .0156 9.156 .7512 6.114 3.057 2.689 .0791 5.377 .495

44 50.031 1.137

DF Sum of Squares Mean Square F-Value P-Value Lambda Pow erLoadSubject(Group)Category for ClustersCategory for Clusters * LoadCategory for Clusters * Subject(Group)

ANOVA Table for ClustersSplit By: VarAnkleCell: DF

-.500 .780 .2777-.931 .780 .0157 S-.431 .780 .3840

Mean Diff. Crit. Diff . P-ValueAve 23&4, ave T789Ave 23&4, Ave T12-14ave T789, Ave T12-14

Scheffe for ClustersEffect: Category for ClustersSignificance Level: 5 %Split By: VarAnkleCell: DF

1 7684.556 7684.556 20.291 .0002 20.291 .99522 8331.796 378.7182 160.964 80.482 13.197 <.0001 26.394 .9982 44.908 22.454 3.682 .0332 7.364 .644

44 268.332 6.098

DF Sum of Squares Mean Square F-Value P-Value Lambda Pow erLoadSubject(Group)Category for ClustersCategory for Clusters * LoadCategory for Clusters * Subject(Group)

ANOVA Table for ClustersSplit By: VarAnkleCell: PF

-3.229 1.806 .0002 S-3.111 1.806 .0004 S

.118 1.806 .9864

Mean Diff. Crit. Diff. P-ValueAve 23&4, ave T789Ave 23&4, Ave T12-14ave T789, Ave T12-14

Scheffe for ClustersEffect: Category for ClustersSignificance Level: 5 %Split By: VarAnkleCell: PF

101

Three factor repeated measures ANOVA:

The following ANOVA is an assessment of the effect of cycles 7,8,9 against

ankle joint position and loads, namely 10 and 30 N. Of note is that the trials

have no systematic effect on the values, main effect p= 0.95.

1 16977.894 16977.894 51.505 <.0001 51.505 1.0002 93305.322 46652.661 141.527 <.0001 283.054 1.0002 1355.905 677.953 2.057 .1360 4.113 .396

66 21756.097 329.6382 .447 .223 .055 .9461 .111 .0582 1.572 .786 .195 .8231 .390 .0794 37.241 9.310 2.310 .0612 9.238 .6554 5.796 1.449 .359 .8371 1.438 .129

132 532.111 4.031

DF Sum of Squares Mean Square F-Value P-Value Lambda Pow erLoadVarAnkleLoad * VarAnkleSubject(Group)Category for T789Category for T789 * LoadCategory for T789 * VarAnkleCategory for T789 * Load * VarAnkleCategory for T789 * Subject(Group)

ANOVA Table for T789

12 2.458 3.158 .91212 2.500 3.529 1.01912 3.625 5.511 1.59112 25.583 11.016 3.18012 25.208 11.518 3.32512 24.583 10.029 2.89512 50.042 13.436 3.87912 50.000 12.767 3.68612 49.167 12.867 3.71412 13.250 9.666 2.79012 13.958 10.524 3.03812 14.625 11.804 3.40712 49.083 13.247 3.82412 47.875 13.094 3.78012 47.958 13.471 3.88912 68.542 9.235 2.66612 68.750 9.054 2.61412 68.708 8.398 2.424

Count Mean Std. Dev. Std. Err.10N, DF, T710N, DF, T810N, DF, T910N, neutral, T710N, neutral, T810N, neutral, T910N, PF, T710N, PF, T810N, PF, T930N, DF, T730N, DF, T830N, DF, T930N, neutral, T730N, neutral, T830N, neutral, T930N, PF, T730N, PF, T830N, PF, T9

Means Table for T789Effect: Category for T789 * Load * VarAnkle

-17.731 4.933 <.0001 SMean Diff . Crit. Diff . P-Value

10N, 30N

Scheffe for T789Effect: LoadSignificance Level: 5 %

-28.313 7.578 <.0001 S-50.799 7.578 <.0001 S-22.486 7.578 <.0001 S

Mean Diff. Crit. Diff. P-ValueDF, neutralDF, PFneutral, PF

Scheffe for T789Effect: VarAnkleSignificance Level: 5 %

.111 .828 .9464

.049 .828 .9895-.063 .828 .9827

Mean Diff . Crit. Diff. P-ValueT7, T8T7, T9T8, T9

Scheffe for T789Effect: Category for T789Significance Level: 5 %

Analysis of cycles 7,8,9:

The following assessment demonstrates the mean and 95% confidence limits

for cycles 7,8,9 for derived variables ankle joint neutral, dorsiflexion and plantar

flexion across loads 10 and 30 Newtons. The fact that the 95% confidence limits

includes zero demonstrates there is no systematic difference between trials

7,8,9.

102

-5 -4 -3 -2 -1 0 1 2 3 4

Diff T7-9


Cell Point ChartSplit By: VarAnkle, LoadError Bars: 95% Confidence Interval

Typical error is determined as the standard deviation of the difference scores

divided by the square root of the sample (i.e. 3) minus one. The typical error of

the difference between cycles 7,8,9 equals 3.297 / 1.4142 = 2.3 degrees, which

is relatively small given the fact that the variables are derived from the average

of cycles 7,8,9. 2.3 degrees represents the largest difference between cycles

7,8,9.

-.049 3.297 .389 72 -14.500 8.500 01.167 2.666 .770 12 -1.000 8.000 01.375 2.423 .699 12 -1.000 6.500 0

-1.000 2.788 .805 12 -7.000 3.000 0-1.125 4.811 1.389 12 -14.500 4.500 0-.875 4.052 1.170 12 -5.500 8.500 0.167 1.723 .497 12 -2.500 3.000 0

Mean Std. Dev. Std. Error Count Minimum Maximum # MissingDiff T7-9, TotalDiff T7-9, DF, 10NDiff T7-9, DF, 30NDiff T7-9, neutral, 10NDiff T7-9, neutral, 30NDiff T7-9, PF, 10NDiff T7-9, PF, 30N

Descriptive StatisticsSplit By: VarAnkle, Load

10

3

APP

END

IX 4

M

TPJ1

RO

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10

4

APP

END

IX 5

M

TPJ1

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7.5

9 7

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40

41.5

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11.5

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(Sx)

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(DF)

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join

t pla

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ed.

105

APPENDIX 6 Information Sheet

Study Title First metatarsophalangeal joint function: Influence of talocrural position and calf musculoskeletal unit stretching.

Investigator Ian G North BSc(Pod), Post.Grad.Dip(Pod).

Supervisors Professor Kevin Singer, Centre for Musculoskeletal Studies UWA Associate Professor Alan Bryant, Podiatric Medicine Unit UWA

1 Purpose of research You have been invited to participate in the above project investigating the joint range of motion and stiffness occurring at the 1st metatarsophalangeal joint (big toe). You have been asked to participate in this study as you are deemed to have no pathology affecting the big toe joint. The study protocol and design has received approval from the Human Research Ethics Committee of the University of Western Australia. This research will investigate the range of motion and relative stiffness of the first metatarsophalangeal joint (big toe) in different ankle joint positions. The data collected includes information about foot structures, joint angle and force data for the big toe joint. The big toe’s range of motion is extremely important to normal foot function and as such this investigation will look at values for normal toes across various ankle joint positions. Information from this study will help in understanding the mechanics of big toe joint function and extend to improve treatment methods and clinical assessments.

2 Methods The investigator (Ian North) will determine your basic foot type and structure following a brief visual examination of your bare feet whilst standing in a relaxed position. You will also be asked a series of general questions, such as ‘have you had any foot surgery?’ Your ankle joint range of motion will be tested, using a reliable technique called a lunge test. This involves facing a wall, ‘lunging’ your knee towards the wall to touch whilst moving your foot away from the wall as far as you can before the heel rises. The angle of the leg will then be measured. Following this, you will be asked to lie on your back on a height adjustable clinic plinth. Your feet will be positioned on a purpose built wooden platform with the assistance of the investigator. Your big toe will then be moved through its range of motion several times by the investigator using a hand held force transducer. Each big toe will be put through fifteen range of motion cycles in three different ankle joint positions.

106

The big toe joint will be moved to its normal end range of motion; no discomfort should be felt by you throughout the investigation. There are no known risks associated with this testing methodology. All data should be gathered within ten minutes, thus posing minimal inconvenience to you. Stretching Group: If selected to participate in the stretching section of the study, you will be assigned to perform one static lower limb stretch throughout the duration of one week. The stretch involves the calf muscles (behind the lower leg) and Achilles tendon. This particular stretch is routinely advocated in clinical practice for a range of pathologies however the effect on range of motion and MTPJ1 stiffness is yet to be determined. The investigator will demonstrate the stretch and will give you written instructions to have at home as a reminder. The stretching programme consists of a one minute stretch performed twice per day, on a randomly assigned leg only. You will be required to complete a diary (provided) to record your daily stretching activity. The investigator will measure your ankle and big toe range of motion, as described above, on day 1 as well as after one week of stretching, day 7.

3 Benefits Whilst there may be limited direct personal benefits from being involved in the study, data collected will provide greater insight into the mechanics of the big toe joint and will be used to determine better treatment options to improve big toe joint function. Thus your participation has the potential to benefit the wider community.

4 Confidentiality Information obtained from the study will be recorded and the data derived from this information will be used for teaching purposes and to produce publications in scientific or medical journals. All personal information gathered will be subject to the University’s confidentiality and privacy rules and regulations.

5 Request for further information You may ask for more information about the study now or at a later date as the study progresses.

6 Refusal or withdrawal of participation You may withdraw from the study at any time without prejudicing your continuing podiatric care. Your participation in this study does not prejudice any right you may have to compensation under statute or common law.

The Human Research Ethics Committee at the University of Western Australia requires that all participants are informed that, if they have any complaint regarding the manner, in which a research project is conducted, it may be given to the researcher or, alternatively to the Secretary, Human Research Ethics Committee, Registrar’s Office, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 (telephone number 6488-3703). All study participants will be provided with a copy of the Information Sheet and Consent Form for their personal records.

107

APPENDIX 7 Consent Form for Participants

Title of Project First Metatarsophalangeal Joint Function: Influence of talocrural position and calf musculoskeletal unit stretching.

Investigator Ian G North BSc(Pod), Post.Grad.Dip(Pod). Supervisors Professor Kevin Singer, Centre for Musculoskeletal Studies

UWA Associate Professor Alan Bryant, Podiatric Medicine Unit

UWA

1 Purpose of research

I have been informed that this research will investigate the range of motion and relative stiffness of the first metatarsophalangeal joint (big toe). The big toe joint is extremely important for normal walking and information gathered through this research will prove valuable in terms of understanding and management of disorders effecting first metatarsophalangeal joint function. The data collected includes information about foot structures, joint angle and force data. You have been invited to participate in this study because your big toe joints are deemed normal. Such an investigation will give clinicians greater insight into foot function and effective treatment strategies.

2 Procedure

I understand that my feet will be physically examined by an experienced podiatrist and I will be asked a series of questions by the investigator. I understand that I will be required to lie on my back on a height adjustable clinic plinth with my feet placed on a wooden platform. The investigator will then move my big toe forwards and backwards several times on each foot and in three different ankle positions whilst I remain relaxed to test the big toe joint range of motion.

3 Benefits

I understand that there are no direct benefits from being involved in the study.

4 Confidentiality

I understand that the information obtained from the study will be recorded and data derived from this information will be used for teaching purposes and to produce publications in scientific or medical journals. All personal information gathered will be subject to the University’s confidentiality and privacy rules and regulations.

5 Request for further information

108

I understand that I may ask for more information about the study now or at a later date as the study progresses.

6 Refusal or withdrawal of participation

I understand that I may withdraw from the study at any time without prejudice to my health service continuing care. I _________________________________ have read the information provided and any questions I have asked have been answered to my satisfaction. I agree to participate in this study, realising that I may withdraw at any time without reason and without prejudice to my future podiatric treatment. I understand that all information provided is treated as strictly confidential and will not be released by the investigator unless required to by law. I have been advised as to what data is being collected, what the purpose is and what will be done with data upon completion of the research. I agree that research data gathered for the study may be published provided my name or other identifying information is not used. Participant (signature):_______________________ Date: _____________

109

APPENDIX 8 MTPJ1 ROM Data Recording Sheet

Subject ID #: ________________________________________________ Date: __________________________

Age: _________________________ Weight (kg): ________________ Height (cm): ____________________

Sex: Male Female Dominance: Left Right

WBLT (L) WBLT (R) Cal

Left Right

Neutral

Plantar

Dorsi

Subject ID #: ________________________________________________ Date: __________________________




Left Right

Neutral

Plantar

Dorsi

Subject ID #: ________________________________________________ Date: __________________________




Left Right

Neutral

Plantar

Dorsi

11

0

APP

END

IX 9

Fo

ot P

ostu

re In

dex

(FPI

-6) –

Col

lect

ion

Form

111

APPENDIX 10 Ankle joint ROM pilot study: WBLT

Ankle Joint ROM (Lunge Test)

1.0 Description

Restricted ankle joint dorsiflexion has been implicated as a contributing factor in

several foot and lower limb pathologies, including plantar fasciitis. (63,167,168)

Clinical investigation of ankle joint range of motion is routinely performed and

like all quantitative tests reliability is paramount. The Weight Bearing Lunge

Test (WBLT) has been described and has been shown to be reliable.(10) The

technique to perform the lunge test appears standard across studies. However

there are measurement variations with some authors choosing to measure the

vertical angle from the anterior tibial crest (10,169,170) as opposed to the vertical

angle from the Achilles tendon.(149,171) Also described is the method of

measuring the distance from the wall to the toes whilst in the lunge position. (106,

170-172) There appears to be a preference in the literature to use the method

measuring the toe distance from the wall however, this doesn’t allow for

subjects height or indeed length of tibia. Therefore quantifying tibial angle may

give a more valid description of ankle range of motion. To date there is a lack of

normative data and accordingly values that may be deemed pathological.

2.0 Research Question

A pilot study was undertaken to investigate and compare the intra-rater

reliability of quantifying the weight-bearing lunge test using a digital

inclinometer. Two measurement techniques were compared to determine the

most reliable method for future aspects to this thesis.

3.0 Method

Ten asymptomatic adult subjects (6 female, 4 male) volunteered to participate

in measuring their ankle joint range of motion via the WBLT. All subjects had an

absence of lower limb pathology and significant orthopaedic, systemic or

neurological anomalies were excluded. Demographic data was collected

including age, gender and body mass index (BMI).

112

Subjects performed a WBLT, as described by Bennell et al (10) which involves

the subject placing their foot perpendicular to the wall and lunging their knee

towards the wall. The foot is then moved away from the wall until maximum

ankle joint dorsiflexion is achieved without lifting of the heel. Subjects are

encouraged to hold onto the wall during the lunge to maintain balance.

The subject’s left leg was tested. Each subject received instructions from the

investigator as to how to perform the task and this was supervised during

testing. Measurement of tibial angle was recorded using a digital inclinometer

with an accuracy of 0.1o (Smart Tool®-digital angle finder, M-D Building

Products, Oklahoma City). Calibration of the inclinometer was performed prior

to each test occasion according to manufacturer instructions.

Two standardised methods were tested for reliability comparison. Method A

measured the tibial angle in degrees (0.1o) taken from the anterior tibial border

just inferior to the tibial tuberosity. Method B was taken along the length of the

tendo-Achilles inferior to the musculotendinous junction. Recorded angles were

taken from the vertical. See Figure 1.

Three measures were recorded at each session for each method with the mean

taken for comparisons. The procedure was repeated after approximately one

hour with test re-test analysis made.

113

Figure 1: Weight-bearing Lunge Test (WBLT). Technique A; Anterior Tibial border; Method B; Achilles Tendon. Measurement taken is angle from vertical in degrees.

4.0 Results

Subject demographic data was recorded and is summarised in Table 1. WBLT

angle data for the left leg was recorded using the two methods described above

with the mean and standard deviation values in degrees shown in Table 2.

Reliability analysis was performed using Intraclass correlation co-efficients

(model 3,1) (141) and typical error and 95% confidence intervals are reported in

Table 3.

Table 1: Subject demographic data for WBLT mean and standard deviation (SD).

n: number of subjects; M: male; F: female; cm’s: centimetres; Kg’s: kilograms; BMI: body mass

index.

Subjects (n)

Gender (M,F)

Age (years) (SD)

Height (cm's) (SD)

Weight (kg's) (SD) BMI (SD)

10 4,6 38 (12.19) 173.1 (9.63)

69.55 (14.97)

23.07 (3.77)

114

Table 2: Subject data for weight bearing lunge test representing the mean and standard deviation (SD) in degrees from vertical of trial 1 and 2 for both measurement techniques

Method

A Method

B

Subject (n)

Test1 Test2 Test1 Test2

1 35.66 35.26 22.9 23.06 2 45.8 43.17 36.1 32.3 3 48.27 47.7 36.4 35.74 4 42.1 42.1 28.44 29.94 5 45.34 44.04 30.47 30.74 6 41.47 43.3 29.6 31.9 7 47.2 49.4 34.47 37.84 8 45.17 42.77 29 28.17 9 56.87 53.6 38.5 37.84

10 49.1 46.9 29.04 30.97 Mean (S.D)

45.7 (5.6)

44.8 (4.9)

31.5 (4.8)

31.9 (4.5)

Table 3: Intra-rater reliability (ICC 3,1), 95% confidence intervals (CI), typical error and confidence variance (CV) for weight bearing lunge test comparing two measurement techniques.

Method A Method B ICC (3,1) 0.938 0.903 95% CI (0.752-0.985) (0.634-0.977) Typical Error (degrees) 1.31 1.44 Typical Error CV(%) 2.8 4.4

5.0 Discussion

Results indicate excellent same day intra-rater reliability of the WBLT to quantify

ankle joint dorsiflexion for both measurement methods A and B with ICC’s (3,1),

0.938 and 0.903 respectively. Both methods of measurement are relatively easy

and efficient. The WBLT is functional in nature as it requires weight bearing

loading through the foot and ankle during testing.

Whilst both methods are reliable there were significant differences in actual

values between method types, due mainly to the anatomy of the lower limb.

Further investigation into the validity of both measurement techniques could be

performed via fluoroscopy. However one could intuitively surmise that Method

A, given its proximity to the tibial shaft, would produce more valid results.

115

For this reason, plus the marginally higher ICC and lower correlation variance,

Method A was chosen for quantifying ankle joint dorsiflexion for future aspects

of this project.

116

APPENDIX 11 Stretch instructions and participation diary

Stretch Protocol: You are asked to perform a calf muscle tendon stretch on your randomly assigned leg _____________. The technique is to place (wedge) the foot against a wall or door frame keeping the knee fully extended. Then the hips are moved anteriorly and held until a firm, non painful stretch is felt in the calf muscle. See fig 1a and 1b. Feel free to do this whilst wearing shoes if its more comfortable. Then you are instructed to hold this stretch for 30 seconds followed by 30 seconds of steady rhythmic lunges. These involves the foot being maintained in the stretch position with you gently bending the knee to resistance and re straightening in a cyclic fashion with one flex / extend cycle approximately every second. i.e. 30 up and downs. You are asked to perform this stretch twice (2x) daily for one week where MTPJ1 extension and ankle joint range will be re tested. Please indicate with a tick on the participation diary below as you perform a stretch.

Subject ID:______________________

MON TUES WED THURS FRI SAT SUN

AM

PM

* Please mark in box to indicate when stretch is performed.

11

7

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3

APP

END

IX 1

3 R

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Documents

School of Surgery First metatarsophalangeal joint range of ...€¦ · the effect of calf muscle stretching on MTPJ1 range was also investigated. The information gathered will assist