Ankle (talocrural) joint

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	Planes and axes of motion Arthrokinematics Ligamentous restraint Interactions with other le joints Movement during the gait cycle

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Arthrokinematics

Talar dome is convex Tibio-fibular mortise is concave	Nashed, A.H., Murthy, R., & Fink, G. (1996). Calcaneus fracture - lateral view. NetMedicine Radiology Library. [On-line]. Available: http://www.netmedicine.com/xray/img_xr/foot12az.jpg

Therefore, in an open chain:

during plantar flexion	talus rolls posteriorly and glides anteriorly on tibio-fibular surface.
during dorsiflexion:	talus rolls anteriorly and glides posteriorly on tibio-fibular surface. As the talus glides posteriorly, its relatively wide anterior margin contacts the tibio-fibular mortise and actually spreads the tibia and fibula apart. As it does so, the talus locks against the sides of the ankle mortise and close-packs the ankle joint.

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Ligamentous restraint:

ligament	elongates with / limits:
medial collateral (deltoid)	valgus angulation of talus/calcaneus
lateral collateral	varus angulation of talus/calcaneus
plantar calcaneonavicular (spring)	collapse of foot's medial arch

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Ankle motion interacts with motion at other le joints

in a closed chain:

• ankle plantar flexion contributes to knee extension.

• ankle dorsiflexion contributes to knee flexion.

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Last updated 7-6-00 Dave Thompson PT
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