After completion of this chapter, the physical therapist should be able to do the following:
Discuss the biomechanics and functional anatomy of the foot and ankle.
Discuss the various injuries that occur at the ankle and foot.
Discuss the various treatment options for rehabilitating the ankle and foot.
Discuss the various functional exercises and appropriate progressions.
Discuss the effect of first ray position, forefoot varus, forefoot valgus, and calcaneal varus on the foot and lower extremity.
Describe a biomechanical examination of the foot.
Describe techniques for orthosis fabrication.
Discuss appropriate running footwear options.
Identify specific pathomechanics and/or pathology associated with the foot and ankle and the appropriate treatment options.
Functional Anatomy and Biomechanics
The ankle or talocrural joint is a hinge joint formed by articular facets on the distal tibia, the medial malleolus, and the lateral malleolus, which articulate with the talus. The talus is the second largest tarsal bone and main weightbearing bone of the articulation linking the lower leg to the foot. The relatively square shape of the talus allows the ankle only 2 movements about the transverse axis: plantarflexion and dorsiflexion. Because the talus is wider on the anterior aspect than posteriorly, the most stable position of the ankle is dorsiflexion as the talus fits tighter between the malleoli. In contrast, as the ankle moves into plantarflexion, the wider portion of the tibia is brought into contact with the narrower posterior aspect of the talus, creating a less-stable position than dorsiflexion.5
The lateral malleolus of the fibula extends further distally so that the bony stability of the lateral aspect of the ankle is more stable than the medial. Motion at the talocrural joint ranges from 20 degrees of dorsiflexion to 50 degrees of plantarflexion, depending on the patient. An individual requires 20 degrees of plantarflexion and 10 degrees of dorsiflexion for walking, and up to 25 degrees of plantarflexion for running for normal gait.2,3
Talocrural Joint Ligaments
The ligamentous support of the ankle consists of the articular capsule, 3 lateral ligaments, 2 ligaments that connect the tibia and fibula, and the medial or deltoid ligament (Figure 26-1). The 3 lateral ligaments include the anterior talofibular, posterior talofibular, and calcaneofibular ligaments. The anterior and posterior tibiofibular ligaments bridge the tibia and fibula and form the distal portion of the interosseous membrane. The thick deltoid ligament provides primary resistance to foot eversion. A thin articular capsule encases the ankle joint.
Ligaments of the talocrural joint
A. Lateral aspect. B. Medial aspect.
The muscles passing posterior to the lateral malleolus will produce ankle plantarflexion along with toe flexion. Anterior muscles serve to dorsiflex ...