Scapular Positioning in Overhead Athletes With and Without Shoulder

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Scapular positioning in overhead athletes with and without shoulderpain: a case–control study

F. Struyf 1,2, J. Nijs1,2, J. De Graeve1, S. Mottram3, R. Meeusen2

1Division of Musculoskeletal Physiotherapy, Department of Health Sciences, Artesis University College Antwerp, Antwerp, Belgium,2Department of Human Physiology, Faculty of Physical Education and Physiotherapy, Vrije Universiteit Brussel, Brussels, Belgium,3Kinetic Control International, Ludlow, UK Corresponding author: Filip Struyf, PT, Campus HIKE, Dept G, Artesis University College Antwerp, Van Aertselaerstraat 31,2170 Merksem, Belgium. Tel: 132 36 418 265, E-mail: [email protected]

Accepted for publication 27 January 2010

Abnormalities of scapular positioning are considered im-portant risk factors for developing shoulder disorders. Thisstudy analyses the scapular positioning pattern in a group of overhead athletes with and without shoulder pain. In a multi-center blinded case–control study, 36 shoulder pain athletes(19 men, 17 women), were compared with 36 unimpairedathletes free of shoulder pain, matched for gender, age, handdominance and body mass index. The blinded assessorperformed visual observation, the measurement of the dis-

tance between the acromion and the table, inclinometry andthe kinetic medial rotation test for dynamic scapular controlin random order. Athletes with shoulder pain demonstratescapular asymmetry in the sagittal plane, observed visuallyas anterior tilting on the painful side. Athletes with shoulderpain show a lack of scapular motor control on their painfulside in contrast to their pain-free side. No scapular position-ing or motor control differences were found in athletes withor without shoulder pain.

Narrowing of the subacromial space might increasethe risk for developing shoulder pain, and be a factorin shoulder impingement syndrome. Abnormal scap-ular positioning has previously been related to this

excessive narrowing of the acromiohumeral distance(Brossmann et al., 1996; He ´ bert et al., 2002).Changes in scapular positioning are considered im-portant risk factors for developing shoulder disor-ders such as shoulder impingement syndrome,shoulder instability as well as post-operativeshoulder complaints, neck pain and cervicogenicheadache (Host, 1995; Paletta et al., 1997; Schmitt& Snyder-Mackler, 1999; Ludewig & Cook, 2000;He ´ bert et al., 2002; Lewis et al., 2002; Van Wilgenet al., 2003; Endo et al., 2004; Van Wilgen, 2004;Cools et al., 2005; Von Eisenhart-Rothe et al., 2005;McClure et al., 2006). In addition, a recent studysuggests that reducing the scapular mobility (non-specific) directly reduces the acromiohumeral dis-tance and therefore increases the risk for subacromialimpingement (Atalar et al., 2009).

Normally, humeral elevation is accompanied byscapular upward rotation and posterior tilting, gle-nohumeral external rotation, clavicular retraction,elevation and posterior axial rotation (Ludewig &Cook, 2000; McClure et al., 2001; Borsa et al., 2003;Ebaugh et al., 2006; Ludewig et al., 2009). Contro-versy exists on the pattern of internal or external

scapular rotation during humeral elevation (McClureet al., 2001; Ebaugh et al., 2006; Ludewig et al.,2009). In addition, scapular upward rotation appearsto be greater in the scapular plane than in the sagittal

plane (Borsa et al., 2003). In contrast to pain-freeshoulders, patients with various shoulder disordersdemonstrate altered scapular positioning patterns(Lukasiewicz et al., 1999; Ludewig & Cook, 2000;He ´ bert et al., 2002; Borstad & Ludewig, 2005;McClure et al., 2006; Ludewig et al., 2009). Excessivescapular internal rotation, a decrease in scapularupward rotation and a decrease of posterior scapulartilting are closely associated with shoulder impinge-ment syndrome (Solem-Bertoft et al., 1993; Ludewig& Cook, 2000; He ´ bert et al., 2002; Endo et al., 2004;Lukasiewicz et al., 2009). However, some studiesmention more upward rotation in patients withshoulder pain (Von Eisenhart-Rothe et al., 2005;McClure et al., 2006).

While the complex kinematic behavior of thescapula and shoulder has been studied extensively(McKenna et al., 2004), these full three-dimensionalmotion tracking systems are costly and not readilyavailable for clinical practice. Additionally, the ques-tion remains whether there are clinical tools that areable to demonstrate the same findings. Thereforethere is a need for valid and reliable measures thathave strong clinical utility. A literature review con-

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cluded that clinical assessment strategies for scapularpositioning are available but require further study of their clinimetric properties (Nijs et al., 2007).

Researchers have suggested that shortening of thepectoralis minor, a decrease in activity of the serratusanterior muscle and an increase of activity of theupper trapezius muscle may affect scapular position-ing in terms of winging, anteriorly tilting and a

reduced scapular upward rotation. (Ludewig &Cook, 2000; Borstad & Ludewig, 2005; Cools et al.,2003) It has also been shown that subjects with shortpectoralis minor muscle length demonstrate similarscapular kinematics as subjects with shoulder impin-gement syndrome (Lukasiewicz et al., 1999; Ludewig& Cook, 2000; Borstad & Ludewig, 2005; Smithet al., 2006).

Likewise, muscle imbalance results in an abnormalforce contribution around the shoulder, which couldlead to pain and pathology (Comerford & Mottram,2001). It is noted clinically that patients presentingwith upper extremity dysfunction, frequently demon-strate poor scapular control (Mottram, 1997; Mor-rissey et al., 2008). Consequently, abnormal scapularmovement and muscle function has been shown to berelated to shoulder impingement syndrome (Luka-siewicz et al., 1999; Ludewig & Cook, 2000). Noprevious study examined the ability of a muscularmotor control test in discriminating people with orwithout shoulder pain. In addition, the kinetic med-ial rotation test (KMRT) aims at observing move-ment faults at the scapula and glenohumeral jointassociated with glenohumeral medial rotation(Comerford & Mottram, 2001; Mottram, 2003).

This test has been developed by observation of patients together with research results relatingshoulder girdle movement (Comerford & Mottram,2001; Morrissey et al., 2008).

The specific purpose for this study was to analyzethe scapular positioning pattern: scapular upwardrotation, forward shoulder posture, tilting, wingingand scapular motor control in a group of athleteswith shoulder pain relative to a group of athleteswithout symptoms. Second, inter-individual differ-ences are subject to this research.

Materials and methodsStudy design

Scapular positioning and dynamic scapular control wereassessed in a case–control study in 153 voluntary overheadathletes (Fig. 1). Before assessment, a variety of sportsassociations agreed to participate in the study. Subsequently,athletes that were present at training, were asked to participatein the study. All athletes agreed to participate and filled in awritten informed consent. The assessor was blinded for thepresence of shoulder disorders among the participants. Aftermeasuring the athlete’s weight and height, the clinical assess-ment was performed in random order: observation of forward

tilt and winging, measurement of forward shoulder posture(the acromial distance), the measurement of scapular upwardrotation (inclinometry) and the assessment of scapulardynamic control (the KMRT). Scapular positioning of bothshoulders was assessed. After the assessment protocol, thestudy participants with shoulder pain were asked to fill inthe shoulder disability questionnaire (SDQ). Finally, theywere interviewed to collect relevant demographic information(age, gender and hand dominance). Height and weight weremeasured using a measurement tape and a digital scale(Exacta, Nassau, Germany). The study protocol was reviewedand approved by the local medical ethics committee.

Before the study, the assessor (holder of a bachelor degreein physiotherapy) underwent a 4-h training session. The

training session was used to instruct the assessor in performingan accurate measurement of scapular positioning and scapulardynamic control including pilot testing on healthy athletes.The assessor was trained by two highly experienced phy-siotherapists. All participants received an information leafletand provided written informed consent. The male athleteswere tested with their trunk bare. Female athletes wore asports bra or a halter-top so that the scapula remained visibleand shoulder movements were not hampered by clothing.Previous study concluded that palpation was a valid methodto find the location of the scapula, so all reference points usedduring the inclinometry and acromial distance were palpated(Karduna et al., 2001; Lewis et al., 2002).

Athlete recruitment

Seventy-two athletes (38 men, 34 women), 18–60 years of age[mean standard deviation (SD), 33 11 years] wereincluded in this study. Thirty-six shoulder pain athletes (19men, 17 women) were compared with 36 unimpaired athletesfree of shoulder pain, matched for gender, age, hand dom-inance and body mass index. Among the 36 athletes withshoulder pain, 35 painful shoulders were on the dominant side.The mean shoulder disability score (SDQ) was 35.8 13.5.No significant differences were noted in height, age, weight,hand dominance or duration of overhead activities betweenboth groups. Table 1 shows the descriptive characteristics of the athletes.

117 athletes without

shoulder pain

36 athletes with shoulder

pain

36 athletes matched for

age, gender, hand

dominance and Body

Mass Index.

Blinded clinical

assessment

Shoulder pain?YES NO

153 athletes voluntary

rectruited

Fig. 1. Flow chart of the study design; case vs control.

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A total number of 306 shoulders were examined from 153overhead athletes who were recruited from a variety of sportsassociations.

Because of possible differences in scapular positioningbetween adults and children, study participants had to be atleast 18 years of age to be included in the study (Dayanidhiet al., 2005; Struyf F, Nijs J, Horsten S, Mottram S, Meeusen R,unpublished observation). In addition, athletes had to parti-cipate in an overhead sport at least once a week and had to beable to perform at least 1401 of humeral abduction in thecoronal plane. This range of shoulder abduction was measuredby use of an inclinometer, using a standardized and reliable

protocol (Green et al., 1998). Sufficient reliability of themeasurement of scapular upward rotation (by means of twoinclinometers) was only attained for subjects performing 1401of humeral abduction or more (Watson et al., 2005). Theexclusion criteria for all athletes were a history of injury orsurgery to the shoulder complex, upper thorax, upper backand humerus in the past year.

Outcome measures

Visual observation for tilting and winging

Firstly, the scapular was observed to identify the restingposition. Secondly, observation of scapular positioning during

humeral movement was noted to assess the kinematicalrhythm between glenohumeral abduction and scapular up-ward rotation.

The observations were performed with the athlete standingand instructed to stay relaxed. Because high-heeled shoes caninfluence posture and consequently scapular positioning, weasked the athletes to stand barefoot. Only artificial lightingfrom above was used, in order to reduce the altering effect of natural light on the body. The scapula was observed in restingposture and during active unloaded movement. The athletewas observed from dorsal (frontal plane) and lateral (sagittalplane). During scapular observation at rest, we observed allparticipants bilaterally in three positions: static with botharms relaxed (thumbs facing forward), hands placed on

ipsilateral hips (thumbs facing backward) and arms in 901 of humeral abduction in the frontal plane (thumbs facing up).Scapular positioning was deemed impaired when (1) theinferior angle of the scapula becomes prominent dorsally(the axis of rotation is in the horizontal plane – tilting);(2) the entire medial border of the scapula becomes prominentdorsally (the axis of rotation is vertically and in the frontalplane – winging). If one (or more) of the criteria listed positive,we judged scapular positioning as impaired (score5 1), if noneof the criteria satisfy, we judged scapular positioning asnormal (score5 0). Next, the athlete performed active move-ment (unloaded) in standing posture. We asked them to

perform bilateral shoulder abduction (0–1801) in the frontalplane. The same criteria as above were used.

Forward shoulder posture (acromial distance)

The acromial distance is the measurement of the acromion tothe table in supine, intended to measure forward shoulderposture.

The measurement of the distance between the posteriorborder of the acromion and the table was performed in supine.In this position, the assessor measured the distance betweenthe most posterior aspect of the posterior border of theacromion and the table bilaterally [measured vertically witha sliding calliper – Manutant (Manutan nv, Brussels,Belgium), accuracy 0.03 mm]. Next, the assessor repeatedthis procedure with the athlete actively retracting bothshoulders while keeping the thorax fixed against the table.The data collected during this measurement were adjusted bydividing by the body length, which resulted in a score enteredas cm/cm. Each position was measured once (Fig. 2).

Scapular upward rotation (Inclinometry)

One gravity referenced inclinometer (Plurimeter-V, La Con-version, Switzerland; accuracy to 11) (Green et al., 1998) wasused to measure humeral elevation, and a second inclinometerwas used to measure upward rotation of the scapula. Thegravity-referenced inclinometer is calibrated on the basis of

Table 1. Descriptive characteristics of the athletes

Athletes with shoulderpain (n 5 36)

Athletes without shoulderpain (n 5 36)

Age (years)Mean 33.4 33.1SD 11.3 10.9Range 18–60 18–56

Gender

Male 19 (52.8%) 19 (52.8%)Female 17 (47.2%) 17 (47.2%)Height (cm)

Mean 176.9 178.2SD 10.5 9.8Range 156–194 158–195

Duration of contiguous overhead activities (years)Mean 12.8 11.9SD 8.8 9.5Range 1–35 1–37

Type of sportTennis 9 (25%) 9 (25%)Volleyball 16 (44%) 12 (33%)Baseball 2 (6%) 1 (3%)Badminton 7 (19%) 10 (28%)Handball 2 (6%) 4 (11%)

Fig. 2. Measurement of forward shoulder posture (acromialdistance).

Scapular positioning in overhead athletes

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gravity. The starting position of the movement to be measuredis therefore fixed, minimizing placement error. All athleteswere assessed in a relaxed, standing (barefoot) position.Scapular upward rotation was measured during total shoulderabduction using a standardized reliable protocol as describedby Green et al. (1998).

Athletes were asked to perform full extension at the elbow,neutral wrist position and with the thumb leading. Theinclinometer is attached perpendicular to the humerus, justunder the deltoid insertion using a Velcro tape. Athletes were

then asked to move both arms into abduction and to stop at451, 901, 1351 and at full range of humeral abduction (Fig. 3).At each of these positions, the degree of upward rotation of the scapula was measured using the second inclinometer. Thiswas achieved by manually aligning the base of the inclin-ometer along the spine of the scapula. Additionally, wecreated four phases of humeral elevation: phase I (restingposition to 451), phase II (45–901), phase III (90–1351) andphase IV (1351 to end range). Only positions that can bemeasured reliably with the Plurimeter-V inclinometer wereincluded in this study. For standardization, each athlete getsone test-rehearsal before the test was performed.

Scapular motor control (KMRT)

The athlete is supine with the humerus abducted to 901, theelbow flexed 901 and the humerus in 301 of horizontalabduction (hand to the ceiling with the humerus in the planeof the scapula). All angles were measured by using aninclinometer. The athlete is taught to perform medial rotationat the glenohumeral joint while keeping the scapula still in itsneutral position. This test is scored positive when scapularforward tilt, downward rotation or elevation occurs (Fig. 4).The KMRT is performed until 601. Normative research datasuggest that during medial rotation to 601, in non-painfulshoulders the glenoid does not anterior translate 44 mm, andthe scapula does not translate 46 mm (Morrissey et al., 2008).Accuracy of palpation is critical to the test. Recent studyconcluded that this manual landmark identification can be

tracked accurately by palpation (Morrissey et al., 2008).For this experiment, test scoring was twofold: first, this test

is scored positive (score5 1) when the assessor feels that thescapula forward tilts or elevation occurs (A-list). Second,difficulties in breathing, performing difficulties, unable toperform 601 medial rotation, glenohumeral anterior transla-

tion, fatigue, the need of external feedback and externalsupport are also scored (score5 1 if present – B-list) (Comer-ford & Mottram, 2001). Finally, this gives rise to a total scoreon a 117-points scale (Table 2). We state the scapula to have alack of motor control when the score is 1 on the A-list, 43 onthe B-list or both. For standardization, each athlete gets onetest-rehearsal before the test was performed.

SDQ

The SDQ covers 16 items to evaluate functional statusdisability in athletes with shoulder disorders and is suggestedto be responsive and ready for use in clinical trials andlongitudinal studies (Van der Windt et al., 1998; Van derHeijden et al., 2000). All 16 items describe a possible pain-provocation during the last 24 h of the athletes daily activities.The questionnaire is completed with yes, no or not applicable.It is scored by the summation of all yes-answers, divided by allanswered questions (yes or no) and subsequently multiplied by100. This results in a score between 0 (no disabilities) to 100(very disabled). In this study, the Dutch version of the SDQwas used.

Reliability of outcome measures

Previous study on the inter-tester reliability of scapularobservation conclude that the observation at rest and duringmovement is a clinically applicable tool for assessing patternsof scapular positioning and movement (McClure et al., 2009;Struyf et al., 2009). The k values for the observation of tiltingand winging at rest were 0.48 and 0.42, during unloadedmovement 0.52 and 0.78 (Struyf et al., 2009). Validity of thescapular dyskinesis test was demonstrated (Tate et al., 2009).The measurement of the acromial distance was found reliable(both relaxed and during retraction, ICCs40.88) (Nijs et al.,2005) and is suggested to be indicative for pectoralis minormuscle length (Borstad & Ludewig, 2005). Overall, measure-ment of upward rotation by means of analogue inclinometersreached very good intrarater reliability (ICC5 0.88) (Watson

et al., 2005). The KMRT has been validated against dynamicultrasound (Morrissey, 2005). However, reliability data for theKMRT are currently lacking. Cross-sectional comparisonshowed similar overall validity and patient acceptability asthe UK version (Paul et al., 2004). Participants of that cross-sectional comparison rated the Dutch version of the SDQ as

Fig. 3. Measurement of scapular upward rotation with twoinclinometers.

Fig. 4. Measurement of scapular motor control using theKMRT.

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best for the relevance to their shoulder problem (Paul et al.,2004).

Statistical analysis

Means, standard deviations and ranges were calculated for allmeasured and normalized data. A one-sample Kolmogorov– Smirnov goodness-of-fit test was used to identify normaldistribution. The athletes’ painful shoulder is always com-

pared with the same side in the pain-free group. An indepen-dent-samples t-test was used when analyzing the differencebetween the athletes with and without shoulder disorders forthe inclinometry and acromion–table (AT) distance. Forcomparisons between the painful and pain-free shoulderwithin the athletes with shoulder pain group, the pairedsample t-test and the chi-square test were used for theparametric and non-parametric data, respectively. The chi-square test was used to identify differences for the outcome of the KMRT and observation protocol. The Pearson andSpearman correlations were computed for examining associa-tions between the scores of the SDQ, demographic featuresand the clinical measures and between the clinical measuresmutually. Because the body length correlated with the mea-surement of the distance between the posterior border of the

acromion and the table, the data were adjusted for the bodylength, creating an acromial distance index (i.e. the outcome of the measurement of the distance between the posterior borderof the acromion and the table was divided by the body lengthin cm and multiplied by 100). The scapulohumeral rhythm wascalculated by dividing the total humeral elevation by thescapular upward rotation. Groups were matched for age,gender and BMI without the knowledge of other outcomemeasures. Data were analyzed using SPSS version 12.0, forWindows (SPSS Inc., Chicago, Illinois, USA). The poweranalysis was performed using SigmaStat 3.1 (Systat SoftwareInc., San Jose, California, USA). Except for the power

analysis, data were analyzed using SPSS version 12.0, forWindows (SPSS Inc.).

ResultsVisual observation for tilting and winging

The observation protocol for scapular tilting andwinging did not show significant differences between

the athletes with and without shoulder pain. Table 3shows all observations for present or absent tiltingand winging. Within the group of athletes withshoulder pain, tilting was found to be more presenton the painful side (12/36; 33%) then on the pain-freeside (8/36; 22%) (Po0.01). Winging was found tomore present on the pain-free side (5/36; 14%) thanon the painful side (4/36; 11%) (Po0.01). No differ-ences were seen between men and women.


The athletes with shoulder pain presented with amean AT-distance of 83.6 28 mm at rest and53.8 22 mm during bilateral retraction. The ath-letes without shoulder pain presented with a meanAT-distance of 84.9 25 mm at rest and54.6 22 mm during bilateral retraction. Table 4shows the results of the AT distance index [correctedfor BL (cm) 100] between athletes with and with-out shoulder pain. No significant differences werefound between groups or between men and women.Within subgroup analysis did not show any signifi-cant differences in the AT-distance index.

Scapular upward rotation (inclinometry)

When comparing scapular upward rotation betweenthe two groups using two inclinometers, no signifi-cant differences were found. Table 5 shows the resultsof the upward scapular rotation during humeralelevation in both groups. No significant differenceswere found between men and women. However,when analyzing the women only, the athletes withshoulder pain did show a significant loss of upwardrotation (351) compared with the pain-free women

(421

) (P5

0.049).

Table 2. 117-point scale for scoring the kinetic medial rotation test

Correct pattern ScoreA-list(0 or 1)

Efficiency ScoreB-list(0 or 1)

Compensationscapular

Difficulty breathing

Difficult to performNo movementpossible (601)FatigueExtra feedback neededExternal support neededGlenohumeralcompensation

Sum /1 /7

Table 3. Observation of winging and tilting of the scapula between case and control

Observation Athletes with shoulder pain

Painful side (A) Pain-free side (B) A-matched side B-matched side

Winging Present 4 (11%) 5 (14%) 5 (14%) 5 (14%)Absent 32 (89%) 31 (86%) 31 (86%) 31 (86%)

Tilting Present 12 (33%) 8 (22%) 10 (27%) 6 (17%)Absent 24 (67%) 28 (78%) 26 (72%) 30 (83%)


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Table 6 shows the positive KMRT scores in bothathletes with and without shoulder pain.

No significant difference was found betweengroups. Within the shoulder pain group, 77%(n5 10) of the positive MRT scores were on thepainful side, in contrast to 23% (n5 3) on the pain-free side (P5 0.017). No significant differences were

noted between the left or right shoulder within thepain-free subgroup (data not shown). No significantdifferences were observed between men and women.

Discussion

This case–control study highlights several interestingaspects of the clinical evaluation of scapular posi-tioning and scapular motor control. Although theclinical assessment protocol was not able to identifystatistically significant differences in scapular posi-

tioning or motor control between athletes with orwithout shoulder pain, there appear to be somesignificant differences between the athletes sympto-matic and asymptomatic shoulder.

Visual observation for tilting and winging

First, tilting appears to be more present on thepainful side and winging on the asymptomatic side.This finding reinforces earlier research in which it hasbeen shown that subjects with a protracted scapula(or short pectoralis minor muscle length) demon-strate similar scapular positioning as subjects withshoulder impingement syndrome (Solem-Bertoft

et al., 1993; Lukasiewicz et al., 1999; Ludewig &Cook, 2000; Borstad & Ludewig, 2005). In addition,both tilting and AT-distance are suggested to beindicative for pectoralis minor muscle length (Borsaet al., 2003; Nijs et al., 2005). Scapular asymmetry inthe sagittal plane (increased scapular tilting) waspreviously seen in patients with the shoulder impin-gement syndrome between their asymptomatic andsymptomatic shoulders (Lukasiewicz et al., 1999).However, when comparing dominant vs non-domi-nant shoulder, these differences significantly reoccur.This reinforces the results from a recent study in

healthy overhead athletes, which concluded that thedominant-side scapula was more anteriorly tiltedthan the non-dominant-side scapula (Oyama et al.,2008). We need to recognize that scapular asymmetry

Table 4. Measurement of forward shoulder posture (acromial distance index) corrected with body length

Case vs control N Mean [(cm/BL) 100] SD [(cm/BL) 100] Power

AT distance (relaxed) Pain-free athletes 36 4.77 1.45 0.863Athletes with shoulder pain 35 4.70 1.54

AT distance (retracted) Pain-free athletes 36 3.07 1.20 0.913Athletes with shoulder pain 35 3.04 1.26

SD, standard deviation; AT, acromion–table.

Table 5. Scapular upward rotation (inclinometry) during humeral elevation between the different groups

Case vs control N Mean (1) SD (1) Power

Scapular upward rotation at rest Pain-free athletes 36 7.72 6.68 0.662Athletes with shoulder pain 36 8.53 7.00

Scapular upward rotation at 451 humeral abduction Pain-free athletes 36 3.08 7.39 0.721Athletes with shoulder pain 36 3.75 7.27



Maximal scapular upward rotation Pain-free athletes 36 39.44 10.46 0.53Athletes with shoulder pain 36 37.22 9.68

Ratio phase 1 Pain-free athletes 36 16.13 15.19 0.99Athletes with shoulder pain 36 16.15 1.83




Overall gh/st ratio Pain-free athletes 36 3.66 0.82 0.59Athletes with shoulder pain 36 3.81 0.99

SD, standard deviation.

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in healthy overhead athletes often occurs. However,as tilting is related to shoulder impingement syn-drome, we suggest assessing the scapula for thisasymmetry is needed in order to create a baselineevaluation of the athlete.


The AT-distance measurements are put into perspec-tive with the body length. Our results are in line withthe normative data presented in a previous study onthe AT-distances relative to the body length in 105healthy subjects (Struyf F, Nijs J, Horsten S, Mot-tram S, Meeusen R, unpublished observation).Adults presented with a mean AT-distance (correctedto BL) of 4.12 cm/cm and 2.67 cm/cm for the relaxedand retracted position, respectively, while the presentstudy showed a mean AT-distance of 4.77cm/cm and3.07 cm/cm. When we address non-relative distances,our results are slightly higher than a previous studyin patients with shoulder pain. Nijs et al., (2005)reported a mean (relaxed) AT-distance of 7.2 vs4.6 cm during retraction. Our results are approxi-

mately 1.0 cm larger, which could be due to the studypopulation. More specific, Nijs and colleagues im-plemented a sample of convenience of 29 patients,mainly recruited in private practices for physicaltherapy, while our study included overhead athlete’s.The repetitive movements performed by overheadathletes may increase the AT-distance and hencetrigger forward shoulder posture. This might increasethe risk for developing shoulder disorders amongoverhead athletes.

Scapular upward rotation (inclinometry)

Third, inclinometry for measuring scapular upwardrotation did not reveal any significant differencesbetween both groups or between the symptomaticand asymptomatic shoulder. These observations arein line with previous studies (Lukasiewicz et al., 1999;Graichen et al., 2001; He ´ bert et al., 2002). Assuggested by Lukasiewicz et al. (1999), this couldbe caused by the faulty use of neuromuscular strate-gies in both shoulders. Compared with the study of McClure et al. (2001), our athletes with shoulder painattained lower degrees of scapular upward rotation

[mean (SD)5 37.21 (9.71) vs 501 (4.81) in theMcClure’s study]. Although overhead athletes con-stantly perform activities which require sufficientupward scapular rotation, they demonstrate lessupward rotation. Although the athletes withoutshoulder pain did not report any pain, these resultsmight indicate that they are at increased risk fordeveloping shoulder problems.

Controversy still exists about the overall ratio of glenohumeral to scapulothoracic (gh/st) movement(Freedman & Munro, 1966; Poppen & Walker, 1976;McQuade & Smidt, 1998; Johnson et al., 2001). First,most studies assume a 01 starting position of thehumerus, whereas others actually measure the restingposition. Second, differences in measurement techni-ques and methodology can create a wide range of reported ratios. Finally, the comparison across dif-ferent studies is difficult due to inter-individualvariability. The mean ratio of glenohumeral to sca-pulothoracic motion in the athletes with shoulderpain was 3.8:1 in our study vs 1.7:1 (McClure et al.,2001) and 2.1:1 (Graichen et al., 2001) in otherstudies. The study of McClure implemented healthysubjects, whereas Graichen also examined patientswith shoulder impingement syndrome. Previous re-search in patients with atraumatic shoulder instabil-ity demonstrate similar results with an increasedratio in the patient group (Von Eisenhart-Rotheet al., 2005). The implementation of subjects withshoulder pain appears to increase the gh/st ratio.

No significant differences were noted between menand women. Surprisingly, when analyzing womenonly, the athletes with shoulder pain showed a

significant loss of upward rotation in comparisonto pain-free women. In contrast, earlier research of 160 healthy men and women did not find anysignificant differences between men and women onshoulder posture variations (Raine & Twomey,1997). One explanation for this discrepancy couldbe the influence of shoulder pain. Based on theseobservations, it is postulated that shoulder painmanifests differently in men and women. Furtherstudy is required to examine this issue.


Finally, this study also addressed scapular motorcontrol. The KMRT did not show significant differ-ences between both groups, but there were some strongsignificant differences between the painful shoulderand the pain-free shoulder within the athletes withshoulder pain subgroup. More than three-quarters of the impaired subgroup demonstrated with positivescores on their symptomatic side. However, poorscapular motor control was prevalent among theathletes without shoulder disorders as well, possibleexplaining the lack of significant differences in motor

Table 6. Positive KMRT scores

Pain-free athletes Athletes withshoulder pain

10/36 (28%) 13/36 (26%)

On painful side: 10/36

On pain-free side: 3/36P 50.017


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control between the two groups. The athletes withoutshoulder disorders are all performing overhead activ-ities and have therefore an increased risk for develop-ing shoulder disorders. In addition, the KMRT wasvalidated in a sample of convenience of normal sub-

jects (Morrissey et al., 2008). However, baseball pitch-ers, tennis and handball players have been repeatedlyfound to have an increased range of external rotation

with a corresponding decreased range of internalrotation in their throwing shoulder compared withthe contralateral shoulder when assessed at 901 of abduction (Borsa et al., 2008). This could have causedextra positive scores on the KMRT in both case andcontrol group. Likewise, this could have increased theside-to-side differences.

Except for the KMRT and the visual observationduring humeral elevation, an important limitation of this study is that in the main outcome measures onlystatically held positions were used rather than dy-namic motion. Statically held positions may notrepresent functional movement patterns. Secondly,no identification of the type of shoulder disorder wasperformed in this study. Pain, as the only inclusioncriteria, may neglect relevant differences between thevarious shoulder disorders. More specifically, themost frequently seen shoulder pathologies are ac-companied with different scapular motion patterns(Ludewig et al., 2009). While patients with shoulderimpingement syndrome, rotator cuff diseases orglenohumeral joint instability are accompanied witha reduced scapular upward rotation, patients withadhesive capsulitis show an increase in upward rota-tion. Additionally, patients with shoulder impinge-

ment syndrome or rotator cuff diseases can show lessposterior tilting, while no evidence for this alterationis found in patients with other shoulder pathologies.Future study should include differentiation of shoulder pathologies.

As the athletes age ranged from 18 to 60 years, it ispossible that age differences alter scapular position-ing and motor control. Although no differences inscapular positioning were noted between unimpairedadults, clinicians should be aware of the decreasingmuscular system during aging. Since the scapularmuscular system is the major contributor to scapularpositioning, differences in scapular positioning and

motor control in adults may exist (Dayanidhi et al.,2005; Nijs et al., 2005).

The majority of researchers in the field applyexpensive and specialized equipment for assessingscapular positioning. In contrast, the results obtainedin this study were all gathered with clinical tests.Although three-dimensional electromagnetic track-ing systems allow us to increase scapular assessment

accuracy, the use of these measurement tools in theclinic are limited. However, our methods of measur-ing scapular motion should be validated againstaccurate motion analysis. Finally, the findings fromthis study can only be generalized to inter-individualdifferences in athletes who compete in overheadsports.

Perspectives

This study puts extra emphasis on the clinical eva-luation of overhead athletes with various shoulderdisorders. Scapular asymmetry in the sagittal plane,observed visually as tilting and a lack of scapularmotor control are highly related to the athletes’shoulder pain. Both observation of tilting and theKMRT are therefore suggested to be discriminativein distinguishing symptomatic and asymptomaticshoulders. Future research needs to be directed tounravelling the basic mechanisms that control thescapular motion and study the effects of varioustreatment methods in patients with a variety of shoulder pathologies.

Key words: scapula, athletes, clinical, assessment,

pain.

Acknowledgements

This study was financially supported by a research grant(G826) provided by the Department of Health Sciences,Artesis University College Antwerp, Antwerp, Belgium.

We certify that no party having a direct interest in theresults of the research supporting this article has or will confera benefit on us or on any organization with which we areassociated.

The study protocol was reviewed and approved by themedical ethics committee of the University Hospital Brussels(2006/137).

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Scapular Positioning in Overhead Athletes With and Without Shoulder