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. 2002 Dec;37(4):512-515.

Commentary: Functional Ankle Instability Revisited

Hans Tropp  1
Affiliations

Commentary: Functional Ankle Instability Revisited

Hans Tropp. J Athl Train. 2002 Dec.
No abstract available

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Figures

Figure 1
Figure 1
A model of the body as an inverted pendulum. The ankle is asymmetric due to muscular effort, which produces rotation of the center of gravity around the center of pressure. The ankle is not stuck to the ground, and it is not the ankle torque itself that rotates the body. Frot indicates rotation force; mg, weight of the center of mass; Ta, ankle torque; and Fr, reaction force.
Figure 2
Figure 2
Transection of the ankle in the subtalar- and talocrural-joint axes. The different muscle tendons affect the ankle by their strength and position. The posteromedial muscles are strongest and counteract the force shown by the path of the center of pressure. COP indicates center of pressure; EHL, extensor hallucis longus; EDL, extensor digitorum longus; AT, anterior tibialis; PT, posterior tibialis; FDL, flexor digitorum longus; FHL, flexor hallucis longus; TS, tendon sheath; PL, peroneus longus; and PB, peroneus brevis.
Figure 3
Figure 3
The subtalar-joint axis passes through the talus. A, Normally, an external everting torque is produced by the reaction forces acting around an everting lever arm (Le). B, If the ankle is inverted, the reaction force might produce inversion through an inversion lever arm (Li). Te indicates external everting torque; Ti, external inverting torque; and Freaction, reaction force.
Figure 4
Figure 4
This series of drawings shows the A, neutral; B, everted; and C-E, inverted positions. The subtalar-joint axis is marked just medial to the anterior tibial tendon. The inverted foot moves the axis laterally to the line of action of the reaction force, leading to a potentially dangerous situation: giving way.
See this image and copyright information in PMC

References

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