Windlass Effect Ankle Joint

7/29/2019 Windlass Effect Ankle Joint

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OSTEOKINAMATICS OF ANKLE

BY

Dr.A.Sridhar


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Hicks Windlass Effect:

John Hicks (1954) was the first to describe thismechanism in the foot.

During the gait cycle, the foot plays two majormechanical functions:- It acts as a shock absorber (during initial

contact)

- Helps in propulsion (during propulsion)


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The bones and ligaments of the foot arearranged in a triangular arch form.


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Standing on level ground, the heads of themetatarsals and the calcaneus are in the samehorizontal plane

talus,

the navicular, and the cuneiform bones.


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The distal joint surface of the navicular hasindividual facets that articulate with the first,second, and third cuneiforms

Cuneonavicular and intercuneiformarticulations are planar joints that glide orslightly gap when moving apart

The cuneiform bones articulate distally withthe first 3 metatarsals


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Intermetatarsal support is provided by thetransverse metatarsal ligaments, the deepplantar aponeurosis, and the Lisfranc ligament

Intermetatarsal ligaments connect all adjacentmetatarsals except between the first andsecond metatarsals


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The Lisfranc ligament extends from the firstcuneiform to the base of the secondmetatarsal and prevents separation between

the first ray and second metatarsal. The second metatarsal is mortised between

the first and the third cuneiform bones,making it relatively immobile, whereas theother metatarsals have greater freedom of movement


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Suggested sesamoid functions

(1) to elevate the first ray so the first metatarsal canplantar flex during extension of theHallux

(2) to enhance the load-bearing capacity of thefirst metatarsal

(3) to improve the mechanical leverage for theattached intrinsic muscles.


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The first metatarsocuneiform joint combines with thesurrounding ligaments to form a stable segment.

The triangular base of the first metatarsal has a lateral joint surface, a medial joint surface, and an inferior joint

surface.

The metatarsal joint surface is concave, with a near-vertical central groove that aligns the metatarsocuneiform

joint axis in slight inversion relative to the foot.


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A mediodorsal and lateroplantar protuberance

is commonly found, which adds rotationalstability to the joint.


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During early stance (A), the medial longitudinal arch functions like acurved beam to support the weight of the body. At mid-stance (B), the

load is more vertical and the arch functions like a truss, with the plantaraponeurosis tightened for support in the foot.


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During early stance (A), themedial longitudinal arch

functions like acurved beam to support theweight of the body. At mid-

stance (B), theload is more vertical and the

arch functions like a truss,with the plantar

aponeurosis tightened forsupport in the foot.


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A plantar-flexedfirst ray foot

deformity has thefirst metatarsal

fixed in aplantar-flexed

position relativeto the heads of

the othermetatarsals


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The terms first ray rotation and first raypronation have been used interchangeablywhen describing the triplanar movement of the first metatarsal

The orientation of this axis primarily couplesdorsiflexion with inversion and plantar flexionwith eversion.


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A plantar-flexed first ray foot deformity alsocan cause dysfunction.

A rigid plantar-flexed first ray is identifiedwhen the first metatarsal is plantar flexed in afixed position relative to the other metatarsals


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Examining the mobility of the first ray andassessing the relatively static position of thefirst metatarsal are only part of a careful footevaluation.


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Windlass Effect Ankle Joint