tions utilized by podiatric physi-cians in the ‘70’s thru ‘90’s werelimited to foot orthotic therapy andshoe modifications.

In 1995, a modified version ofContinued on page 174

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rence. Despite the fact that podi-atric medical education providedstellar training in lower extremitybiomechanics and taught the path-omechanics of virtually every neu-romuscular disease, treatment op-

By Douglas H. Richie Jr. DPM

IntroductionPrior to 1995, the dispensing of

ankle-foot orthoses (AFOs) by podi-atric physicians was a rare occur-

Properly designed devices can positivelyaffect gait.

Goalsand Objectives

1) To provide an overviewof the various mechanisms ofaction of ankle-foot orthoseson the lower extremity.

2) To compare the effectsof solid versus articulatedankle-foot orthoses on theknee and midfoot joints.

3) To review research rele-vant to ankle braces andankle-foot orthoses and theireffects on balance and pro-prioception.

4) To provide evaluation,prescription and castingguidelines to optimize treat-ment outcomes with ankle-foot orthoses.

Continuing

Medical Education

TheBiomechanicsof Ankle-FootOrthoses

Orthotics &Biomechanics

apy relevant to podiatric practice.Guidelines for evaluation, casting,and prescription of these deviceswill be provided to optimize out-comes with this powerful treatmentintervention.

DefinitionsandTerminology

An orthosis isdefined as: An ex-ternally applieddevice used tomodify the struc-tural or function-al characteristicsof the neuro-musculo-skeletalsystem.1 An or-thosis has alsobeen defined as:An apparatusused to support, align, prevent, orcorrect deformities or to improvethe function of movable parts ofthe body.2 Orthoses is the plural of

orthosis.The term “orthotic” has

been traditionally used asan adjective, i.e., “orthoticdevice.” Today, most dictio-naries list both an adjectiveand a noun usage of theterm “orthotic” and consid-er it synonymous with theterm “orthosis.”

Lower extremity or-thoses function by affectingjoint moments. A momentis also known as a forcecouple, which acts at a dis-tance from an axis of rota-tion of a specific joint inthe body. This force is mea-sured in Newton-meters.

Joint moments can beproduced externally andinternally. External mo-ments are produced by in-ertia and ground reactionforces. Internal momentsare produced by active andpassive structures withinthe body itself, such asmuscles, l igaments andjoint capsules. In the scien-tific literature, the term“moment” refers to inter-nal moment, produced byanatomic structures whichare actually resisting exter-nal moments which are

produced by physical forces. Wheninternal structures fail, orthosescan modify external forces andmoments to allow the body tofunction in a “normal” manner.

An externaldevice used tosupport or im-prove function ofthe foot andankle can takemany physicalforms. This or-thotic can be assimple as a feltpad placed underthe metatarsals oras sophisticatedas a compositebrace controllingfoot and anklemotions.

Orthotics pre-scribed for lower extremitypathologies include foot orthoses(FOs), ankle-foot orthoses (AFOs),knee orthosis (KOs) and knee-ankle-foot orthoses (KAFOs). Podi-atric physicians primarily prescribeor dispense FOs and AFOs.

Bowker has described four dif-ferent ways in which an orthosismay modify the system of externalforces and moment acting across ajoint.3 The first three patterns ofaction are peculiar to ankle-foot or-thoses, while the last patternwould also include the action offoot orthoses.

Restriction of RotationalMotion at a Joint

Restriction of rotational motionthrough control of joint momentsis the most common reason for pre-scribing ankle foot orthoses in po-diatric medicine. An AFO may limitthe range of motion about any par-ticular axis, or may limit the num-ber of axes about which motionmay occur. For example, an anklefoot orthosis can limit inver-sion/eversion motion of the anklejoint, while preserving dorsiflex-ion/plantarflexion.

Control of joint moments by anorthosis requires a three-point fixa-tion. This strategy applies threecontrolling forces to the limb: oneplaced over the joint center, withthe other two forces applied proxi-mal and distal to the joint and act-

Continued on page 175

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an ankle-foot orthosis, utiliz-ing podiatric biomechanical

principles (i.e., Richie Brace) wasintroduced to the profession. Sincethat time, the majority of podiatricphysicians have expanded theirtreatment protocols to include AFOtherapy into non-operative inter-ventions for many lower extremitypathologies. These treatments havenot been limited to podiatric de-vices, but now include almost everytype of sophisticated brace, whichwere previously dispensed only byorthotists.

Bracing the lower extremity canbe challenging and rewarding forthe podiatric physician. However,evaluating patients with significantdeformity and gait impairment re-quires the highest level of under-standing of lower extremity biome-chanics. This article is intended toprovide an overview of the biome-chanics of ankle-foot orthotic ther-

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MedicalEducation

Internal moments

are produced

by active and

passive structures

within the body

itself such as

muscles, ligaments

and joint capsules.

Figure 2: Straps and pads applied to a podiatricankle foot orthosis can control translational forces,i.e., internal/external rotation of the tibia

Figure 1: A three-point force systemis applied by anankle-foot ortho-sis. Control ofjoint moments byan orthosis re-quires a three-point fixation.This strategy ap-plies three con-trolling forces tothe limb: oneplaced over thejoint center, withthe other twoforces appliedproximal and dis-tal to the joint and acting in opposite directionsto each other.

SEPTEMBER 2009 • PODIATRY MANAGEMENTwww.podiatrym.com 175

joint, which can occur after acutetrauma or as a result of a chronicdegenerative process.

Braces which limit transla-tional motion require four pointsof fixation. This requires a rigidbrace which incorporates strapsand pads applied tightly to theskin surface. This feature is incor-porated into podiatric ankle footorthoses which are designed tocontrol excessive transverse planerotation of the ankle joint which

occurs in chronic ankle instabili-ty and adult-acquired flatfoot(Figure 2).

Control of Axial Forces Acrossa Joint

Axial loading of joints in thelower extremitycan contribute topain and disabil-ity when the ar-ticular cartilageis damaged, orthe underlyingbony structuresbecome de-formed. Anankle-foot ortho-sis can off-load aspecific jointwhen it is prop-erly designed totransfer load toother anatomicstructures. Anexample of sucha device is thepatellar tendon-bearing orthosis.3

ing in opposite directions to eachother (Figure 1). Applications ofthese forces proximal and distal tothe subtalar and ankle joint are notpossible with foot orthoses, but canbe accomplished with ankle footorthoses.

Ankle-foot orthoses can apply amoment to a joint not only to re-strict motion, but also position asegment into a preferred align-ment. For example, a fixed posi-tion solid AFO can maintain thefoot at a pre-determined align-ment at the ankle joint. For dropfoot conditions, a solid AFO canhold the foot at a 90 degree angleto the leg. Clinicians must careful-ly evaluate available joint range ofmotion when prescribing AFO de-vices. If a patient has a fixed equi-nus deformity, fitting a neutral-po-sitioned, 90 degree solid AFO willbe impossible. Similarly, whenthere is a fixed varus alignment ofthe hindfoot, application of anAFO can only correct the foot posi-tion to the available range of ever-sion at the ankle and subtalarjoint.

Restrict Translational Motionat a Joint

Since normal joint motion inthe lower extremity is rotational,any translational motion could beconsidered abnormal. Translationalmotion occurs when there is loss ofligamentous integrity around the

AFOs... Control of Lineof Action ofGround-Reaction Force

Ground-reaction forces passthrough the foot from heel striketo toe off and create a line of actionon every joint in the lower extremi-ty. These ground-reaction forceswill thereforecreate a mo-ment abouteach of thesejoints. Or-thoses can af-fect the align-ment ofground reac-tion forces tochange jointmoments. Thisis the primaryfunction offoot orthoses(Figure 4).

Foot or-thoses cannotapply a three-point forcesystem to thesubtalar jointor the ankle joint, but can possiblydo so at the midtarsal joint. Thus,kinematic studies of foot orthotictreatment effects have shown veryminimal improvements of align-ment of the rearfoot.4

Conversely, many studies havedocumented positive effects of footorthoses to alter joint moments ofthe lower extremity.5-10 Mundermanhas shown that the most importantfeature of foot orthoses to positive-ly affect lower joint moments iscontouring the device to the shapeof the foot.11 Thus, ankle foot or-thoses which contour the footplatecan be expected to offer the posi-tive effects on joint moments thatare found with foot orthoses alone.

Studies of Ankle FootOrthoses: Kinetics andKinematics

Kinetic and Kinematic effects ofankle-foot orthoses have been ex-tensively studied.12-16 However, mostof this research has focused on theeffects of ankle-foot orthoses on pa-tients with neuromuscular condi-tions. Few studies have been pub-lished on the effects of ankle footorthoses in healthy subjects, and

Continued on page 176

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Translational

motion occurs when

there is loss of

ligamentous integrity

around the joint,

which can occur

after acute trauma

or as a result

of a chronic

degenerative process.

Figure 3: A patellartendon weight-bear-ing brace

Figure 4: Foot orthoses can alter alignment of ground reactionforces to change moment to the subtalar joint

orthosis produced kinematic andkinetic effects which were similar tosubjects wearing no orthosis. Theunilateral solid ankle-foot orthosisproduced more abnormal anklejoint angles, moments and powersand more proximal compensationsat the knee, hip and pelvis than thehinged AFO during stair locomo-tion. Subjects wearing either ortho-

sis walked slowerduring stair loco-motion com-pared to thenon-braced con-dition.

Huang, et al.also comparedsolid and articu-lated ankle-footorthoses interms of restric-tion of motionat the ankle,hindfoot, andforefoot.19 Thesubjects all hadarthritis of theankle eitherpost-traumaticor osteoarthritis.A solid ankle-foot orthosis re-stricted anklemotion betterthan an articu-lated ankle foot

orthosis, but also caused greatersagittal plane motion across themidfoot joints.

Hartsell and Spaulding mea-sured passive resistive torque ap-plied throughout inversion range ofmotion of the ankle in healthy sub-jects and those with chronicallyunstable ankles.20 A hinged semi-rigid, non-custom ankle-foot ortho-sis demonstrated significant in-creased passive resistive inversion

torque forces and restricted overallinversion motion better than a laceup ankle brace.

What remains obscure is an un-

derstanding of the optimal rangeand plane of motion controlled byan ankle orthosis to achieve a de-sired treatment effect. The studiesjust cited have conclusively shownthat restriction of motion of anyjoint in the lower extremity willhave negative effects in the neigh-boring joints, both proximal anddistal.

Solid Versus Articulated AnkleFoot Orthoses: ClinicalConsiderations

The kinematic studies compar-ing solid versus articulated ankle-foot orthoses suggest that changesoccur during ambulation which canhave significant clinical conse-quences. Not only are forces or mo-ments transmitted to neighboringjoints, but also alterations of neuro-sensory feedback can adversely af-fect balance and proprioception.

When an orthosis eliminatesmotion at the ankle joint, signifi-cant adaptation must occur by the

patient to contin-ue ambulation.The primary ef-fects of a fixed or“locked” ankle po-sition during gait,achieved by wear-ing a solid AFObrace, are at theknee joint.

When theankle is fixed at 90degrees by an AFO,

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AFOs...

virtually no studies have beenconducted on sport applications

of these types of devices.Kitaoka, et al. studied the kinet-

ic and kinematic effects of threetypes of ankle foot orthoses intwenty healthy subjects walkingover ground.17 In the frontal plane,

all three orthoses (a solid AFO withfootplate, solid AFO with heel por-tion only, and articulated AFO withfootplate) significantly reducedmaximal hindfoot inversion, butdid not affect eversion. The solidankle AFO design significantly re-duced both plantarflexion and dor-siflexion of the ankle, while the ar-ticulated ankle AFO did not affectankle sagittal plane motion com-pared to the unbraced condition.Midfoot motion was reduced withthe articulated AFO, and increasedwith the solid AFO. Cadence wasreduced with the solid AFO’s. Allthree braces were associated withdecreased aft and medial shearforces compared to the non-bracedcondition.

Radtka, et al. studied the kineticand kinematic effects of solid andhinged (articulated) ankle foot or-thoses on nineteen healthy subjectsduring stair locomotion.18 A unilat-eral hinged (articulated) ankle-foot

Continuing

MedicalEducation

Figure 6: A heel rocker can slow or reduce knee flexion mo-ment when wearing a solid AFO

Figure 5: A solid AFO restricts ankle plantarflexion and causesknee flexionmoment to bring the forefoot to the ground

Excessive

transverse plane

rotation of the ankle

joint occurs

in chronic ankle

instability

and adult-acquired

flatfoot.

Continued on page 177

SEPTEMBER 2009 • PODIATRY MANAGEMENTwww.podiatrym.com 177

cles, there is a tendency for delayedknee extension at the end of mid-stance. A solid AFO will extend theknee in patients with weak quadri-ceps and prevent the “drop-down”normally seen at the knee of these

patients duringgait. A solid AFOcan also provideknee flexion mo-ment to preventrecurvatum defor-mity at the knee.By re-directingground-reactionforces posterior tothe center of rota-tion of the kneejoint, a flexionmoment, ratherthan extensionmoment, willoccur. This ismade possibleby orientingthe footplatealignment of

the AFO in slight dorsiflexion(Figure 7).

Balance andProprioception

The effects of ankle braceson postural control have beenextensively studied. Baier andHopf studied 22 athletes withfunctional instability of theankle joint compared to 22healthy athletes.23 A significantimprovement of postural con-trol, as evidenced by reducedmediolateral sway velocity, wasfound in the instability groupwhen wearing both a rigid andsemi-rigid stirrup ankle brace.However, other studies per-formed on both healthy sub-jects and on subjects with func-tional ankle instability havefailed to show any improve-ments of postural control withthe use of ankle braces.24-27

Similarly, studies of effectsof ankle-foot orthoses on bal-ance and proprioception do notprovide consistent findings.28

Yet, studies of treatment effectsof these devices commonly at-tribute any positive findings toimprovements in propriocep-tion.29,30 Interestingly, studies offoot orthoses, compared toankle foot orthoses, show

the contact phase of gait will beprolonged, as the ankle cannotplantarflex to bring the forefoot tothe ground. This places a signifi-cant externalknee flexion mo-ment to force thetibia forward andbring the forefootto the ground(Figure 5). Theknee can be pro-tected from thisdamaging force ifthe patient’s shoecan be beveled inthe heel (i.e., heelrocker) or if a padis placed in theheel section ofthe shoe (Figure6).21

A fixed-ankleAFO will alsocause abnormalknee joint moment during mid-stance. As the leg passes forwardover the foot, a lack of ankle jointdorsiflexion will prevent forwardmigration of the tibia which willthen cause an external knee exten-sion moment. This may cause painor even hyperextension of the kneeduring late mid-stance. Hullin hasshown that a rocker sole modifica-

tion of the shoe will decrease theknee extension moment caused bya fixed ankle AFO.22

This same effect of a solid AFOon knee moments can be used in apositive way to improve gait in pa-tients with muscle weakness. In pa-tients with weak quadriceps mus-

AFOs... much more consistentimprovements of balanceand postural control.31

The reason that foot orthoses,rather than ankle foot orthoses, canimprove postural control may relateto two mechanisms. First, the con-toured shape of a foot orthosis hasbeen speculated to improve the re-ceptor field for sensory feedback inthe proprioceptive loop between thefoot and the spinal cord.31 Many tra-ditional ankle braces and ankle footorthoses do not have contouredfootplates. Second, the limitation ofankle motion in restrictive AFO’sand certain ankle braces can ad-versely affect other sensory path-ways for proprioception.

When the ankle joint is locked,mechanoreceptors within the liga-

Continued on page 178

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Figure 8: An AFO attached to a leg with tibialvarum will invert the foot the same degree ofvarus deformity in the leg.

Figure 7: A solid AFO can direct groundreaction forces posterior to the knee axisof rotation to reduce a recurvatum de-formity.

The most

important feature

of foot orthoses to

positively affect

lower joint moments

is contouring

the device to the

shape of the foot.

recurvatum or excessive knee flex-ion during stance, a solid AFOshould be prescribed.

A plantarflexed foot position attouchdown may be due to: fixedequinus of the ankle, spasticity ofankle plantarflex-ors or weaknessof ankle dorsi-flexors. A hingedAFO with dynam-ic assist anklejoints can be pre-scribed for onlyone of these con-ditions: weakankle dorsiflexorswith a flacciddrop foot defor-mity. In cases ofspasticity, ahinged AFO witha plantarflexionstop is recom-mended.

During gait,and in static stance, balance andpostural control should be evaluat-ed. A modified Romberg test witheyes open will detect loss of posturalcontrol. This will commonly befound in patients with diabetes andwith adult-acquired flatfoot deformi-ty. Careful consideration should be

made about usingsolid AFO devicesand gauntlet stylebraces which limitankle joint motionin these patients.It is recommendedthat all patientswith balance prob-lems be prescribeda cane to usewhen wearingsolid AFO devices.A cane has beendemonstrated tonormalize posturalcontrol in neuro-pathic patients.37

Of f -we ight -bearing range ofmotion of theankle and subtalarjoints should becarefully evaluat-

ed before casting and prescribingan AFO. If the ankle joint is not ca-pable of dorsiflexing to neutral (90degree alignment of foot to leg)with the knee extended, then a

neutral solid AFO should not beprescribed. The footplate of thesolid AFO should be oriented to themaximum available dorsiflexionposition when there is restrictedankle dorsiflexion. A heel lift

should then beapplied to theshoe or to theAFO to assureproper alignmentof the leg andknee.

R e s t r i c t e dsubtalar joint mo-tion, particularlyin the direction ofeversion, maymandate modifi-cation of the AFOprescription. Incases of severe un-compensated rear-foot varus, com-monly seen inCharcot Marie

Tooth disease, traditional AFO’smay not be able to prevent lateralinstability. Lateral wedging of theforefoot and rearfoot of the AFOfootplate should be considered inthese cases. Also, pedorthic modifi-cations including a lateral shoeflare and/or lateral wedging of themidsole can improve stability incases of reduced rearfoot eversion.

In terms of posting AFO braces,the practitioner should be awarethat these additions will not onlytilt the footplate, but will tilt theentire leg portion of the brace.Therefore, adding a 3 degree fore-foot varus post to the footplate ofthe AFO will tilt the leg portion ofthe device 3 degrees inverted to thefloor. If the patient does not havean existing tibial varum alignmentof 3 degrees or more, posting thebrace will cause an ill-fitting braceand potential rocking between theheel and forefoot.

At the same time, a patient withsignificant genu varum or tibialvarum, exceeding 6 degrees, will re-quire a modification of the AFOprescription. Unlike wearing footorthoses where leg alignment willnot change orthotic alignment,ankle-foot orthoses create a new sit-uation not always familiar to thepodiatric physician. The frontalplane alignment of the leg to the

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AFOs...

ments cannot be stimulatedto provide proprioceptive

input.28 Secondly, restriction ofankle motion can inhibit thestretch reflex of the leg muscles andtendons, which are considered themost important component of thesomatosensory system for balanceand postural control.28,31

These factors become importantwhen considering bracing an indi-vidual with compromised balanceand postural control. Ironically,these patients may otherwise be themost likely candidates for AFOtherapy in podiatric practice: elder-ly, diabetic, and neurologically im-paired individuals.

In elderly patients, falls are theleading cause of accidental death.32,33

Studies have shown that patientswith diabetes are fifteen times morelikely to suffer catastrophic fallsthan their age-matched counter-parts.34 Whether due to sensory neu-ropathy of diabetes, or due to motorneuropathy from stroke, patientswith neurologic impairment are atrisk for falling.35-38

Lavery, et al. previously suggestedthat the efforts to off-load the neuro-pathic foot may have deleterious ef-fects on posturalcontrol.39 Studiesof ankle-footorthoses haveshown that AFOswhich restrictankle motion willinhibit posturalcontrol and de-crease velocityduring gait.40,41

Cattaneo, et al.showed that AFOswould improvestatic balance inpatients with mul-tiple sclerosis, butwould compro-mise dynamic bal-ance during gait.42

Evaluation andPrescriptionGuidelines

Patients should be carefully ob-served in gait before any jointrange of motion and muscle testingare performed. Knee flexion stabili-ty should be evaluated. In cases of

Continuing

MedicalEducation

When the ankle is

fixed at 90 degrees by

an AFO, the contact

phase of gait will

be prolonged, as the

ankle cannot

plantarflex to bring

the forefoot to

the ground.

The unilateral solid

ankle-foot orthosis

produces more

abnormal ankle joint

angles, moments and

powers, and more

proximal

compensations at the

knee, hip and pelvis

than the hinged AFO

during stair

locomotion.

SEPTEMBER 2009 • PODIATRY MANAGEMENTwww.podiatrym.com 179

technique is performed on a weight-bearing foot. In a previous articlepublished in Podiatry Management(Sept. 2007), the benefits of neutralsuspension casting for AFO braceswas demonstrated in comparison topartial and full weight-bearing cast-ing techniques.

When neutral suspension cast-ing techniquesare utilized, legalignment to thefloor in staticstance should betaken into con-sideration whenbalancing andfabricating theAFO brace.

F o o t w e a rshould be consid-ered and pre-scribed to matchthe AFO and pa-tient needs. SolidAFO braces willtranslate signifi-cant abnormal moments to the kneeboth during contact phase and latemid-stance. A padded heel, a heelrocker, and a forefoot rocker are allshoe modification which can neutral-ize most of these abnormal knee mo-ment forces. Solid AFOs and gauntletAFOs will not fit into the posteriormargin of the heel counter-insole

junction. This isbecause the solidplastic posteriorheel of the bracewill contact thetop-line of the heelcounter, which isalways tilted slight-ly forward. Thiswill push the braceforward in theshoe, and keep thefoot plate fromconforming to theposterior margin ofthe heel counter.Thus, solid AFOsand gauntlet braces

will mandate an increase of at leastone full shoe size.

Finally, the shoe upper is an es-sential component of the threepoint force system which AFOs uti-lize to correct foot and leg align-ment. The midfoot and forefootshoe upper sections (vamp and toe-box) should fit snugly and con-

floor in midstance will determinethe alignment of the entire AFO,including the footplate. In otherwords, the AFO, when attached tothe leg, will align the footplate tothe floor in the same alignmentthat the leg is oriented to the floor.Thus, when the tibia is aligned in10 degrees of varum, attaching anAFO to this leg will orient the foot-plate 10 degrees inverted (Figure 8).

Significant tibial varum or genuvarum will require that the foot-plate of the AFO be posted to thesame degrees of limb varus to pro-vide a stable interface between theAFO and the supportive surface. Al-ternatively, depending on thepathology, the footplate of the AFOcan be hinged and re-oriented torest flat on the supportive surfacewhile the leg upright portion of thebrace remains aligned in varus. Thisis recommended only when there isavailable range of motion in theankle and subtalar joints to evertthe foot away from the invertedtibia in order to bring the foot flaton the floor.

A partial weight-bearing cast,placing the foot flat on the floor,will capture any varus/valgus limbalignment which can be preservedin the fabrication of the AFO. How-ever, in mostcases, this tech-nique will elimi-nate the ability ofthe practitionerto position thefoot into subtalarneutral while themidtarsal joint islocked and stable.

The neutralsuspension cast-ing techniquecontinues to bethe preferredmethod of captur-ing an optimalmodel of the footfor functional foot orthoses fabrica-tion by podiatric physicians. Mun-derman has shown that the most im-portant feature of foot orthotic de-vices to improve kinetics and kine-matics of lower limb function is thecontouring of the device to theshape of the foot.11 Such contouringis lost when the impression casting

AFOs... form to the foot to pre-vent frontal, sagittal andtransverse plane movement.

SummaryAnkle foot orthoses have signifi-

cant advantages over foot orthosesto improve alignment and changejoint moments in the lower extrem-

ity. However, ap-plication of AFOscan also havedeleterious effectson a patient,which must beconsidered whenprescribing thesedevices. Ankle-foot orthoses, de-pending on de-sign, can havedamaging effectson the knee andmidfoot. Thesenegative effectscan be neutralizedby appropriate

shoe modifications.The effects of bracing the lower

extremity can also be positive ornegative in terms of balance andproprioception. Many patients whorequire AFO therapy are already atrisk for catastrophic falls. Practi-tioners should consider whethersolid vs. articulated AFO’s shouldbe prescribed, taking into consider-ation the desired treatment effectsversus the potential negative as-pects of limiting motion aroundthe ankle joint. �

References1 Dorlands Medical Dictionary,

W.B. Saunders, 2000.2 Bunch Wh, Keagy RD, Kritter A E,

et al: Atlas of Orthotics: BiomechanicalPrinciples and Application. 2nd Ed. C.V.Mosby, St. Louis, 1985; 151-159.

3 Bowker P, Condie DN, Bader DL,Pratt DJ. Biomechanical Basis of Orthot-ic Management. Butterworth Heine-mann, Oxford, 1993; 27-38.

4 Nigg BM, Stergiou P, Cole G, Ste-fanyshyn D, Mundermann A, HumbleN. Effect of shoe inserts on kinematics,center of pressure, and leg joint mo-ments during running. 2003, Med SciSports Exerc 35(2): 314-9.

5 Stefanyshyn DJ, Stergiou P, LunVMY, Meeuwisse WH, Nigg BM. Kneejoint moments and patellofemoral painsyndrome in runners. Part I: A case con-trol study; Part II: A prospective cohort

Continued on page 180

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Medical Education

A solid AFO will

extend the knee in

patients with weak

quadriceps and

prevent the “drop-

down” normally seen

at the knee of these

patients during gait.

A padded heel,

a heel rocker, and a

forefoot rocker are all

shoe modification

which can neutralize

most of these

abnormal knee

moment forces.

foot kinematics and ground reactionforces. Arch Phys Med Rehabil 2006;87:130-135.

18 Radtka SA, Oliveira GB, Lind-strom KE, Borders MD. The kinematicand kinetic effects of solid, hinged, andno ankle-foot orthoses on stair locomo-tion in healthy adults. Gait Posture2005; (2):211-8.

19 Huang YC, Harbst K, Kotajarvi B,Hansen D et al. Effects of ankle-foot or-thoses on ankle and foot kinematics inpatients with ankle osteoarthritis. ArchPhys Med Rehabil 87: 710-716, 2006.

20 Hartsell HD, Spaulding S J. Effec-tiveness of external orthotic support onpassive soft tissue resistance of thechronically unstable ankle. Foot AnkleInt 1997; 18:144-150.

21 Wiest DR, et al.: The influence ofheel design on a rigid ankle foot ortho-sis. Orthot Prosthetics 33:3, 1979

22 Hullin MG, Robb JE. Biomechani-cal effects of rockers on walking in aplaster

23 Baier M, Hopf T. Ankle orthoseseffect on single-limb standing balancein athletes with functional ankle insta-bility. Arch Phys Med Rehabil 1998;79:939-944

24 Kinzey SJ, Ingersoll CD, KnightKL. The effects of selected ankle appli-ances on postural control. Jour AthlTrain 1997; 32:300-303.

25 Palmieri RM, Ingersoll CD, Cor-dova ML, Kinzey SJ. The spectral quali-ties of postural control are unaffected by4 days of ankle-brace application. J AthlTrain 2002; 37:269-274.

26 Barkoukis V, Sykaras E, Costa F,Tsorbatzoudis H. Effectiveness of tapingand bracing in balance. Percept MotSkills 2002; 94:566-574.

27 Wikstrom EA, Arrigenna MA, Till-man MD, Paul AB. Dynamic posturalstability in subjects with braced, func-tionally unstable ankles. J Athl Train2006; 41:245-250.

28 Hijmansj M, Geertzen JAB, Dijk-stra PU, Postema K. A systematic reviewof the effects of shoes and other ankleor foot appliances on balance in olderpeople and people with peripheral ner-vous system disorders. Gait and Posture25: 316-323, 2007.

29 Sitler M, Ryan J, Wheeler B,MCBride J, Arciero R, Anderson J,Horodyski M. The efficacy of a semirigidankle stabilizer to reduce acute ankle in-juries in basketball: a randomized clini-cal study at west Point. Am J SportsMed. 1994; 22:454-461.

30 Surve I, Schwellnus MP, NoakesT, Lombard C. A fivefold reduction inthe incidence of recurrent ankle sprainsin soccer players using the sport-stirruporthosis. Am J Sports Med. 1994;12:601-606.

31 Richie DH. Effects of foot or-

thoses to treat chronic ankle instability.Jour Am Pod Med Assoc 97(1): 19-30,2007.

32 Stel VS, Smit JH, Plujim SMF, LipsP. Balance and mobility performance astreatable risk factors for recurrent fallingin older persons. J Clin Epidemiol 56:659-669, 2003.

33 Clark S, Rose DJ, Fujimoto K.Generalizadability of the limits of stabil-ity test in the evaluation of dynamicbalance among older adults. Archievesof Physical Med Rehab 78: 587-591,1997.

34 Cavanagh PR, Derr JA, UlbrechtJS et al. Problems with gait and posturein neuropathic patients with insulin-de-pendent diabetes mellitus. Diabetic Med9: 469-474, 1992.

35 Richardson JK, Ashton-Miller JA.Peripheral neuropathy. An overlookedcause of falls in the elderly. Postgradu-ate Medicine 99: 161-172, 1996.

36 Simoneau GG, Ulbrecht JS, DerrJA, Becker MB, Cavanagh PR. Posturalinstability in patients with diabetic sen-sory neuropathy. Diabetes Care 17:1411-1421, 1994.

37 Richardson JK, Hurvitz EA. Pe-ripheral neuropathy: a true risk factorfor falls. J Gerentol A Biol Sci Med Sci50: M211-15, 1995.

38 Simmons RW, Richardson C,Pozos R. Postural stability of diabetic pa-tients with and without cutaneous sen-sory deficit in the foot. Diabetes ResClin Pract 36: 153-160, 1997.

39 Lavery LA, Fleishl JG, LaughlinTJ, Vela SA, Lavery DC, Armstrong DG.Is postural stability exacerbated by off-loading devices in high risk diabeticswith foot ulcers? Ostomy Wound Man-age 44: 26-34, 1998.

40 Rao N, Aruin A. The effect ofankle-foot-orthoses on balance impair-ment: single case study. Jour ProsthOrth 1999; 11:15-21.

41 Nahornizk MT et al. Kinematiccompensations as children reciprocallyascend and descend stairs with unilater-al and bilateral solid ankle-foot or-thoses. Gait Posture 9: 199-206, 1999.

42 Cattaneo D, Marazzini F, CrippaA, Cardini R. Do static or dynamic AFOsimprove balance? Clinical Rehab 2002.

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study. Int Soc Biomech: 4th Sym-posium on footwear biomechanics,

p 86.6 Crenshaw SJ, Pollo FE, Calton EF.

Effects of lateral-wedged insoles on ki-netics at the knee. Clin Orthop, 2000,375: 185-192.

7 Neptune RR. Wright IC, Van denBogert AJ. The influence of orthotic de-vices and vastus medicalis strength andtiming on patellofemoral loads duringrunning. Clin Biomech 2000, 15: 611-618.

8 Calton EF, Crehshaw SJ, Dill SM,Pollo. The effects of lateral wedged in-sole on kinetics and kinematics at theknee. 4th Ann. Gait Clin MovementAnalysis Meeting, Dallas, Texas.

9 Nigg BM, Cole G, Stergiou P, Ste-fanyshyn D. The use of pressure mea-surements to determine the effect ofshoe orthotics on knee joint moments.In: Proceedings of the EMED Meeting,July, Munich, Germany.

10 Williams DS, Davis IM, Baitch SP.Effect of inverted orthoses on lower-ex-tremity mechanics in runners. Med SciSport Exer, 2003, 35(12): 2060-2068.

11 Mundermann A, Nigg BM, Hum-ble RN, Stefanyshyn DJ. Foot orthoticsaffect lower extremity kinematics andkinetics during running. Clin Biomech2003, 18(3)254-262.

12 Romkes J, Brunner R. Compari-son of a dynamic and a hinged ankle-foot orthosis by gait analysis in patientswith hemiplegic cerebral palsy. GaitPosture 2002; 15:18-24.

13 Franceschini M, Massucci M, Fer-rari L, Agosti M, Paroli C. Effects of anankle-foot orthosis on spatiotemporalparameters and energy cost of hemi-paretic gait. Clin Rehabil 2003; 17:368-372.

14 Wang RY, Yen L, Lee CC, Lin PY,Wang MF, Yang YR. Effects of an ankle-foot orthosis on walking ability inchronic stroke patients: a randomizedcontrolled trial. Clin Rehabil 2004;18:550-557.

15 Geboers JF, Drost MR, Spaans F,Kuipers H, Seelen HA. Immediate andlong-term effects of ankle-foot orthosison muscle activity during walking: arandomized study of patients with uni-lateral foot drop. Arch Phys Med Reha-bil 2002; 83:240-245.

16 de Wit DC, Buurke JH, NijlantJM, Izerman MJ, Hermens HJ. The effectof an ankle-foot-orthosis on walkingability in chronic stroke patients: a ran-domized controlled trial. Clin Rehabil1004; 18:550-557.

17 Kitaoka HB, Crevoisier XM, Harb-st K, Hansen D, Kotajarvi B, Kaufman K.The effect of custom-made braces forthe ankle and hindfoot on ankle and

Continuing

MedicalEducation

Dr. Richie is Ad-junct AssociateClinical Profes-sor, Departmento f A p p l i e dBiomechanics,C a l i f o r n i aSchool of Podi-atric Medicine atSamuel MerrittCollege. He canbe reached at drichiejr@aol.com

SEPTEMBER 2009 • PODIATRY MANAGEMENTwww.podiatrym.com 181

6) Abnormal transverse joint mo-

tion is seen in:

A) Cerebral palsy

B) Muscular Dystrophy

C) Charcot Marie Tooth Dis-

ease

D) Adult-Acquired Flatfoot

7) Foot orthoses and AFOs can

both:

A) Alter the line of ground-re-

action forces

B) Improve skeletal alignment

C) Reposition the ankle

D) Lock the knee

8) The most important feature of

foot orthoses to affect joint mo-

ments is:

A) Posting

B) Molding or contouring the

footplate

C) Topcover

D) Heel cup

9) Studies have shown that mid-

foot motion increases with:

A) Dynamic assist AFOs

B) Hinged AFOs

C) Solid AFOs

D) Patellar tendon bearing

AFOs

10) Proximal compensation at the

knee, hip and pelvis is seen with:

A) Solid AFOs

B) Dynamic assist AFOs

C) Hinged AFOs

D) Articulated AFOs

1) An orthotic is:

A) A metatarsal pad

B) A custom foot support

C) A pre-fabricated foot sup-

port

D) All of the above

2) Internal joint moments are

produced by:

A) Ground-reaction forces

B) Inertia

C) Cartilage

D) Tendons and ligaments

3) AFOs can limit motion better

than foot orthoses because they:

A) Have stronger plastic

B) Have special hinges

C) Apply three-point force

systems

D) Have special straps

4) AFOs can decrease the pain of

osteoarthritis of the knee by

A) Off-loading compressive

forces

B) Cushioning the bottom of

the foot

C) Locking the ankle

D) Assisting ankle joint motion

5) Abnormal translational joint

motion occurs when:

A) Muscles become weak

B) Ligaments are disrupted

around the joint

C) Proprioception is lost

D) Internal joint moments

increase

11) Which phase of gait is pro-

longed when wearing a solid

AFO?

A) Midstance

B) Heel rise

C) Terminal stance

D) Contact phase

12) Solid AFOs cause a signifi-

cant external moment causing:

A) Knee extension at con-

tact

B) Knee flexion at contact

C) Toe grasping

D) Calf spasm

13) During midstance, solid

AFOs can cause:

A) Pelvic tilt

B) Knee flexion

C) Knee hyperextension

D) Ankle plantarflexion

14) The negative effects of

solid AFOs at the knee can be

prevented by:

A) Rocker shoe soles

B) Special straps

C) Padded topcovers

D) Stronger plastic

15) Patients with weak quadri-

ceps muscles should be pre-

scribed a:

A) Hinged AFO

B) Solid AFO

C) Dynamic Assist AFO

D) Custom foot orthotic

Continuing

Medical Education

E X A M I N A T I O N

See answer sheet on page 183.

Continued on page 182

182 PODIATRY MANAGEMENT

16) If the footplate of a solid AFO is positioned

in dorsiflexion, the effect on the knee in static

stance is:

A) Flexion

B) Extension

C) Varus

D) Valgus

17) Drop foot can be controlled by a:

A) Foot orthosis

B) Rearfoot post

C) Standard hinged AFO

D) Solid AFO

18) A patient with midfoot arthritis can have

more motion and pain when wearing a:

A) Hinged AFO

B) Solid AFO

C) Dynamic Assist AFO

D) Foot Orthosis

19) Balance and Proprioception can be com-

promised by AFOs due to:

A) Restriction of joint range of motion

B) Restrict input of muscle spindles

C) Restrict input of joint proprioceptors

D) All of the above

20) Tibial varum deformity of 10 degrees will

orient the footplate of a neutral AFO:

A) Flat on the floor

B) 5 degrees inverted to the floor

C) 10 degrees inverted to the floor

D) 20 degrees inverted to the floor

E X A M I N A T I O N

(cont’d)

See answer sheet on page 183.

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183

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184 www.podiatrym.comPODIATRY MANAGEMENT • SEPTEMBER 2009

ENROL LMENT FORM & ANSWER SH E E T (cont’d)Continuing

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LESSON EVALUATION

Please indicate the date you completed this exam

_____________________________

How much time did it take you to complete the lesson?

______ hours ______minutes

How well did this lesson achieve its educationalobjectives?

_______Very well _________Well

________Somewhat __________Not at all

What overall grade would you assign this lesson?

A B C D

Degree____________________________

Additional comments and suggestions for future exams:

__________________________________________________

__________________________________________________

__________________________________________________

__________________________________________________

__________________________________________________

__________________________________________________

1. A B C D

2. A B C D

3. A B C D

4. A B C D

5. A B C D

6. A B C D

7. A B C D

8. A B C D

9. A B C D

10. A B C D

11. A B C D

12. A B C D

13. A B C D

14. A B C D

15. A B C D

16. A B C D

17. A B C D

18. A B C D

19. A B C D

20. A B C D

Circle:

EXAM #7/09The Biomechanics

of Ankle-Foot Orthoses(Richie)