Imaging description

A 13-year-old male patient had a twisting injury of the right ankle. Radiographs of the right ankle (in temporary cast) demonstrated a fracture of the right medial malleolus with a medially displaced fracture fragment (Fig. 88.1a). The fracture was noted to have metaphyseal, physeal, and epiphyseal components consistent with a Salter–Harris type IV injury. In addition, there was mild separation of the distal tibia and fibula, suggesting an injury of the tibiofibular syndesmosis. The patient was referred to orthopedic surgery for surgical fixation. A postsurgical radiograph of the right ankle demonstrated anatomic alignment of tibia and fibula with stabilizing screws in the medial malleolus and through the distal tibiofibular syndesmosis (Fig. 88.1b).

Importance

In 1931, McFarland described a pediatric fracture of the medial malleolus of the distal tibia that extended across the physis and sometimes into the metaphysis. These fractures were therefore previously described as McFarland fractures. The Salter–Harris classification has since become more frequently used to characterize pediatric fractures (Fig. 88.2). Salter–Harris I fractures extend through the physis. Type II fractures pass through the physis and metaphysis. Type III fractures extend through the physis and epiphysis. Type IV fractures pass through the epiphysis, physis, and metaphysis. Salter–Harris type V injury is a compression or crush injury of the physeal plate, associated with growth disturbance at the physis (Fig. 88.2). An avulsion fracture of the medial malleolus of the distal tibia that extends through the physis and epiphysis is therefore characterized as a Salter–Harris III or IV fracture depending upon whether there is extension of the fracture line into the metaphysis. The medial collateral ligament (MCL) of the ankle, also called the deltoid ligament, can be involved. The MCL is a strong ligamentous complex that is an important stabilizer of the ankle. The MCL components include a deep layer which courses from the medial malleolus to the talus and a deltoid-shaped superficial layer that extends from the medial malleolus to the navicular, the spring ligament, and the calcaneus. The importance of this fracture is that it often occurs in children and any disruption or damage to the developing growth plate can result in growth arrest.