Proximal and Distal Tibiofibular Joints
The proximal tibiofibular joint is formed by a slightly convex tibial facet and a slightly concave fibular facet and is surrounded by a joint capsule that is reinforced by anterior and posterior ligaments. The distal tibiofibular joint is formed by a fibrous union between a concave facet on the lateral aspect of the distal tibia and a convex facet on the distal fibula (Fig. 10.1A). Both joints are supported by the interosseous membrane, which is located between the tibia and the fibula (Fig. 10.1B). The distal joint does not have a joint capsule but is supported by anterior and posterior ligaments and the crural interosseous tibiofibular ligament (Fig. 10.1C).
A: The anterior aspect of the proximal and distal tibiofibular joints of a right lower extremity. B: The anterior tibiofibular ligaments and the interosseous membrane. C: The posterior aspect of the tibiofibular joints and the posterior tibiofibular ligaments of a right lower extremity.
The proximal and distal tibiofibular joints are anatomically distinct from the talocrural joint but function to serve the ankle. The proximal joint is a plane synovial joint that allows a small amount of superior and inferior sliding of the fibula on the tibia and a slight amount of rotation. The distal joint is a syndesmosis, or fibrous union, but it also allows a small amount of motion.
During dorsiflexion of the ankle, the fibula moves proximally and slightly posteriorly (lateral rotation) away from the tibia. During plantarflexion, the fibula glides distally and slightly anteriorly toward the tibia.
The capsular pattern is not defined for the tibiofibular joints.
The talocrural joint comprises the articulations between the talus and the distal tibia and fibula. Proximally, the joint is formed by the concave surfaces of the distal tibia and the tibial and fibular malleoli. Distally, the joint surface is the convex dome of the talus. The joint capsule is thin and weak anteriorly and posteriorly, and the joint is reinforced by lateral and medial ligaments. Anterior and posterior talofibular ligaments and the calcaneofibular ligament provide lateral support for the capsule and joint (Fig. 10.2A and B). The deltoid ligament provides medial support (Fig. 10.3).
A: A lateral view of a left talocrural joint with the anterior and posterior talofibular ligaments and the calcaneofibular ligament. B: A posterior view of a left talocrural joint shows the posterior talofibular ligament and the calcaneofibular ligament.