STJA Loc and Rot Equil Theory_PAC2001

8/8/2019 STJA Loc and Rot Equil Theory_PAC2001

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Subtalar Joint Axis Location andSubtalar Joint Axis Location andRotational Equilibrium Theory ofRotational Equilibrium Theory of

Foot FunctionFoot Function

Kevin A. Kirby, DPM, MSKevin A. Kirby, DPM, MS

Journal of the American Podiatric MedicalJournal of the American Podiatric Medical

AssociationAssociation 91(9): 46591(9): 465--487.487.
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IntroductionIntroductionMore recent theories on foot functionMore recent theories on foot function

Sagittal Plane Facilitation ModelSagittal Plane Facilitation Model

Rotational Equilibrium TheoryRotational Equilibrium Theory


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Primary WeightPrimary Weight--bearing Structuresbearing Structures

Kirby, Leondorf & Gregorio (1988Kirby, Leondorf & Gregorio (1988)

)

N=100N=100Anterior Axial Projection of the FootAnterior Axial Projection of the Foot

Primary anatomical weightbearing structures during closedPrimary anatomical weightbearing structures during closedkinetic chain gait are the medial calcaneal tubercle and 5kinetic chain gait are the medial calcaneal tubercle and 5thth

metatarsal head.metatarsal head.


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GRF NormalGRF Normal


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STJ AxisSTJ Axis OrientationOrientation

Courses posteriorCourses posterior--

laterallateral--plantar toplantar to

anterioranterior--medialmedial--dorsaldorsal

1616 medial to sagittalmedial to sagittal

planeplane

4242 superior tosuperior totransverse planetransverse plane


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Root et al. (1971)Root et al. (1971)


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Root et al. (1971)Root et al. (1971)


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Clinical Assessment of STJ AxisClinical Assessment of STJ Axis

PositionPosition

Kirby KA, Methods of Determination of PositionalKirby KA, Methods of Determination of Positional

Variance in the Subtalar Joint Axis.Variance in the Subtalar Joint Axis. Journal of theJournal of the

American Medical AssociationAmerican Medical Association 1987; 77(5): 281987; 77(5): 28--

234.234.


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Plantar Parallel PositionPlantar Parallel Position


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STJA clinical approximationSTJA clinical approximation
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Quantification of STJAQuantification of STJA


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Subtalar Joint Axis DeviationSubtalar Joint Axis Deviation

hi t k d t i th i t d i htt // li kt t


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STJ Axis PositionalSTJ Axis Positional VarianceVariance

Within Normal LimitsWithin Normal Limits

MediallyMedially--DeviatedDeviated

LaterallyLaterally--DeviatedDeviated

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STJA Normal OrientationSTJA Normal Orientation


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Medially Deviated Subtalar JointMedially Deviated Subtalar Joint

AxisAxis

medial to the WBRmedial to the WBR

structures of the footstructures of the foot

slightly internallyslightly internally

rotatedrotated

supinatory momentsupinatory moment

present in functionalpresent in functionaloverpronatorsoverpronators


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Medially Deviated STJ AxisMedially Deviated STJ Axis


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Internally rotated & mediallyInternally rotated & medially

translated talustranslated talus


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Superior view:Superior view: talartalar positionposition


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Posterior view convexityPosterior view convexity


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Common injuries associated withCommon injuries associated with

MDMD--STJASTJA

PlantarPlantar fasciitisfasciitis

Hallux limitusHallux limitus 22ndnd MTP jointMTP joint

capsulitiscapsulitis

AbdAbd.. HallucisHallucis strainstrain

Sinus tarsi syndromeSinus tarsi syndrome

MedialMedial tibialtibial stressstress

syndromesyndrome

PFPSPFPS

Pes anserinusPes anserinus bursitisbursitis

PT tendonitis andPT tendonitis and

tendon dysfunctiontendon dysfunction


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Laterally Deviated STJ AxisLaterally Deviated STJ Axis

lateral to WBRlateral to WBR

structures of the footstructures of the foot

slightly externallyslightly externallyrotatedrotated

pronatory momentpronatory moment

present in functionalpresent in functional

underpronatorsunderpronators


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Laterally Deviated STJ AxisLaterally Deviated STJ Axis


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Externally rotated & laterallyExternally rotated & laterally

translated talustranslated talus


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Superior view:Superior view: talartalar positionposition


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Posterior view concavityPosterior view concavity


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ProminentProminent peroneus longusperoneus longus &&

brevisbrevis tendonstendons


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Common injuries associated withCommon injuries associated with

LDLD--STJASTJA

Inversion ankleInversion ankle

sprainssprains

PeronealPeroneal tendonitistendonitis


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STJA orientationSTJA orientation


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Medial Heel Skive TechniqueMedial Heel Skive Technique

Prescribed for a mediallyPrescribed for a medially--deviated STJA anddeviated STJA and

injuries associated with same;injuries associated with same;

Originally created for children; andOriginally created for children; and

Appears to be clinically more effective than aAppears to be clinically more effective than a

BlakeBlake--Inverted or Root Functional design.Inverted or Root Functional design.


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RationaleRationale

Increase Supination MomentIncrease Supination Moment

OROR

ORF Inferior to Medial Calcaneal TubercleORF Inferior to Medial Calcaneal Tubercle


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Indications & ContraindicationsIndications & Contraindications

IndicationsIndicationsIndications

pediatric flexible pespediatric flexible pes

planusplanus

posterior tibialisposterior tibialis

dysfunctiondysfunction higher level ofhigher level of

pronatory controlpronatory control

ContraindicationsContraindicationsContraindications

plantar heel pain (heelplantar heel pain (heel

spur syndrome, plantarspur syndrome, plantar

heel bursitis or medialheel bursitis or medial

calcaneal neuritis)calcaneal neuritis)

lateral ankle instabilitylateral ankle instability


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Medial Heel Skive TechniqueMedial Heel Skive Technique

Negative Cast BalancingNegative Cast Balancing

Positive Cast ModificationPositive Cast Modification

Land marking & Positioning of MHSLand marking & Positioning of MHS

Design ParametersDesign Parameters


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Essential LandmarksEssential Landmarks


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Positioning the SkivePositioning the Skive


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Medial Heel SkiveMedial Heel Skive


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Medial Heel Skive DepthMedial Heel Skive Depth


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Shell ParametersShell Parameters

33--5mm polypropylene shell5mm polypropylene shell

ExtrinsicExtrinsic rearfootrearfoot postpost

Minimal MLA dressingMinimal MLA dressing

Lateral phalangeLateral phalange

18mm+ heel cup18mm+ heel cup


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So what?So what?

This model may provide a new set of subjectThis model may provide a new set of subject

inclusion criteria that can be added to existinginclusion criteria that can be added to existing

parameters;parameters;

Evaluating 3Evaluating 3--D moments about the STJA mayD moments about the STJA may

provide us with new insights intoprovide us with new insights into::

the mechanism of running injuries,the mechanism of running injuries,

orthotic efficacy; andorthotic efficacy; and shoe prescription.shoe prescription.


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Thanks forThanks for comincomin out!out!

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STJA Loc and Rot Equil Theory_PAC2001