Ankle (talocrural) joint


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:

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.

Ligamentous restraint:


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

Ankle motion interacts with motion at other le joints

in a closed chain:

Last updated 7-6-00 Dave Thompson PT
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