Chapter 10: The Ankle and Foot

Structure and Function

Proximal and Distal Tibiofibular Joints

The proximal tibiofibular joint is typically composed of a slightly convex tibial facet and a slightly concave fibular facet, although the joint surfaces can vary in configuration in between individuals (Fig. 10.1A).^1,2 This synovial joint is surrounded by a joint capsule that is reinforced by anterior and posterior ligaments (Fig. 10.1B, C), as well as the tendon of the popliteus muscle.^1-3

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. 10.1B, C).^1-3

Osteokinematics

The proximal and distal tibiofibular joints are anatomically distinct from the talocrural joint but function to serve the ankle. The proximal tibiofibular 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.^1-3

Arthrokinematics

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 (medial rotation) toward the tibia. The fibular glides distally and slightly posteriorly during inversion, while gliding proximally and slightly ventrally during eversion.⁴ These small motions of the fibula appear to be related to the asymmetrical shape of the dome of the talus (wider anteriorly), as well as the asymmetry in size and orientation of the lateral and medial facets of the talus that articulate with the fibula and tibia.¹

Capsular Pattern

The capsular pattern is not defined for the tibiofibular joints.

Talocrural Joint

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.^1-3 The joint ...