The foot has a wide range of normal motion including flexion, extension, inversion, and eversion. In addition, supination and pronation are part of the normal range of foot motion. The foot contains two arches: a longitudinal arch (midfoot) and a transverse arch (forefoot). Weight is normally distributed equally on the forefoot and the heel. Weight is not equally distributed on the metatarsal heads, as the first bears twice as much weight as the remaining four. The maximum weight applied to the foot occurs during the push-off phase of walking and running.
The foot contains 28 bones and 57 articulations (Figs. 23–1 and 23–2). Conceptually, the foot can be divided into three regions: the hindfoot (talus and calcaneus), the midfoot (navicular, cuneiforms, and cuboid), and the forefoot (metatarsals and phalanges).
The foot is divided into a hindfoot, a midfoot, and a forefoot. Chopart's joint separates the hindfoot from the midfoot and Lisfranc's joint separates the midfoot from the forefoot.
Medial (A) and lateral (B) views of the foot.
Foot fractures are common and account for 10% of all fractures. They are generally the result of one of three basic mechanisms of injury–direct trauma, indirect trauma, and overuse.
Routine radiographs of the foot include the anteroposterior (AP), oblique, and lateral views (Fig. 23–3). These radiographs can be difficult to interpret because bones overlap in all projections. The AP radiograph is used to best assess the medial two tarsometatarsal joints, while the oblique image provides the best view of the lateral three tarsometatarsal joints.1 This alignment is important and will be altered in patients with Lisfranc fracture–dislocations. The lateral radiograph is best for detecting calcaneus fractures.
Normal radiographs of the foot. A. Anteroposterior (AP), B. oblique, and C. lateral images.
The radiologic diagnosis of foot fractures is frequently complicated by the secondary ossification centers and sesamoids (Fig. 23–4). Commonly seen sesamoids include the os trigonum, os tibiale externum, os peroneum, and os vesalianum. Sesamoids can be distinguished from fractures by their smooth sclerotic bony margins.
The sesamoids of the foot. These bones are commonly confused for fractures.
The calcaneus is the largest of the tarsal bones and serves as a springboard for locomotion and as an elastic support for the weight of the body. It is the most frequently fractured tarsal bone, representing 60% of all tarsal fractures and 2% of all fractures in general.2,3
The anterior portion of the calcaneus is the body. Fractures of the body may be intra-articular or extra-articular. The posterior portion of the calcaneus is the tuberosity. At the base of the tuberosity are the medial and lateral processes that serve as points of insertion for the plantar fascia. The Achilles tendon inserts on the posterior portion of the tuberosity. The principal articulation of the calcaneus is with the talus, forming the subtalar joint. Three articular surfaces exist—an anterior, middle, and posterior articular facet. The sustentaculum talus is a medial extension of the calcaneus that supports the anterior and middle articular facets. The peroneal tubercle is on the lateral surface and provides a groove for the peroneal tendons and a site of attachment for the inferior peroneal retinaculum.
Fractures may occur at any of these sites. Excluding avulsion fractures, 75% of calcaneal fractures are intra-articular (involving the subtalar joint), and 75% of these are depressed.4 Extra-articular fractures account for 25% of calcaneus fractures and include anterior process, sustentaculum tali, lateral calcaneal process and peroneal tubercle, medial calcaneal process, and the tuberosity.
Intra-articular calcaneal body fractures are not only the most common, accounting for 75% of calcaneus fractures, but also most likely to result in long-term disability (Fig. 23–5).
Calcaneal body fractures—intra-articular.
It is uncommon that a calcaneal body fracture does not involve the subtalar joint. While patients with extra-articular fractures have a better prognosis than patients with intra-articular fractures, they may still change the articular configuration of the calcaneus and result in long-term problems.
The most common mechanism is a fall from a significant height where the weight of the body is absorbed by the heel. In most individuals, a height of 8 feet or higher is needed to produce such a fracture, but in older, osteoporotic patients, falls from shorter distances can produce these injuries.
The patient will present with pain, swelling, and ecchymosis on the sole of the foot with loss of the normal depressions along both sides of the Achilles tendon. Fracture blisters usually develop within the first 24 to 48 hours and may be clear or blood-filled. If extensive, they may delay surgery to avoid higher rates of postoperative infections.5
Despite these findings, the diagnosis can be missed because significant associated injuries distract the patient and clinician. Occasionally, the patient may not complain of significant heel pain and may be able to bear weight, ...