An intact cyma line shows integrity of the midtarsal joints. The midtarsal joint separates the talus and calcaneus from the navicular and cuboid and resembles a wave (cyma) on all 3 views of the foot ( Figure 7.3a,b). On the AP pronation oblique view (b) the medial side of the 3 rd and 4 th metatarsal should align with the medial side of the lateral cuneiform and cuboid respectively. On the AP (dorsoplantar) view (a) the medial side of the 2 nd metatarsal should always align with the medial side of the middle cuneiform. Advanced imaging should be performed only after consultation with a radiologist.įigure 7.5 The alignment of the midfoot is best assessed on standing views. If the pain is in the heel, lateral and axial (Harris) views of the heel are indicated. Weight-bearing views are better when tolerable. Standard imaging of the ankle in the emergency department should include anteroposterior (AP), mortice and lateral projections and for the foot AP, oblique and lateral. Commonly occurring ossicles are the os tibiale externum (medial to the navicular), os trigonum (posterior to the talus), and os peroneum (adjacent to the cuboid). Although these are normal variants, they can also be the sites of pathology. Radiographs may show variation from the normal anatomy because of the presence of sesamoids, fused or partly fused bones, or accessory ossification centres ( Figure 7.3a,b). Midfoot: cuneiforms-3, medial 4, middle 5, lateral 6, cuboid 7, navicula. Loss of articular parallelism and alteration of joint space width is always abnormal.įigure 7.2 (a) AP view and (b) oblique view of foot. The joints are complex, but the articular surfaces are parallel and the joint spaces equidistant and symmetrical. It can be divided into the forefoot, midfoot, and hindfoot. The foot ( Figure 7.2a,b) is a complex structure of interdependent bones designed for weight bearing and movement. (d),(e) Lat view of ankle and drawing: 1, tibia 2, fibula 3, medial malleolus 4, lateral malleolus 5, plafond 6, dome 7, talus 8, calcaneum 9, posterior malleolus 10, anterior colliculus 11, posterior colliculus 12, anterior tubercle 13, peroneal groove 14, cuboid 15, anterior process 16, navicular 17, base of fifth metatarsal 18, Achilles tendon. (c) AP ankle ligaments: A, Achilles tendon ATiF, anterior tibiofibular ATF, anterior talofibular B, bifurcate CF, calcaneofibular D, deltoid IO, interosseous MC, medial collateral PTiF, posterior tibiofibular PTF, posterior talofibular. It is made up of a body, neck, and anterior process and has a fragile blood supply that extends through the ankle joint capsule, which means that fractures of the talar neck may result in avascular necrosis of the body.įigure 7.1 (a),(b) AP view of ankle and drawing: (1), Tibia (2), fibula 3, medial malleolus 4, lateral malleolus 5, plafond 6, dome 7, talus 8, calcaneum 9, posterior malleolus 10, anterior colliculus 11, posterior colliculus. The talus articulates inferiorly with the calcaneus and anteriorly with the navicular. Lateral collateral ligament, which includes anterior talofibular, posterior talofibular and calcaneofibular ligaments.Medial collateral ligament complex (deltoid ligament).The bony structure of the ankle is stabilised by three main groups of ligaments: The tibia and fibula form a ring with the proximal and distal tibiofibular joints. The ankle ( Figure 7.1a–f) is a virtual hinge joint shaped as a mortice. Injuries to the feet, however, often masquerade as ankle injuries. Clinically, it should be possible to distinguish which area has been injured, and imaging of both is rarely needed. Injuries of the feet often result in a request for radiographs of the ankle and foot.
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