Abstract
The most important determinant of treatment of malleolar fractures is stability. Stable fractures have an intact deep deltoid ligament and do not displace with functional treatment. If the deep deltoid/medial malleolar complex is disrupted, the talus is at risk of displacement.
We developed clinical criteria for potential instability and applied them to a prospective series of patients. Criteria included: a medial clear space of < 4mm; medial tenderness, bruising or swelling; a fibular fracture above the syndesmosis; a bimalleolar or trimalleolar fracture; an open fracture; a high-energy fracture mechanism. Patients with a medial clear space of < 4mm and none of these criteria were considered to have stable fractures, while those with a medial clear space of > 4mm were considered to have a displaced fracture.
We studied 152 consecutive skeletally mature patients with undisplaced, potentially unstable malleolar fractures treated by the senior author between 1st January 1998 and 31st December 2007. Patients were treated in a below-knee walking cast (136 patients) or a functional ankle brace (16 patients) for six weeks. Weight bearing was encouraged throughout. Weight bearing radiographs were obtained at one week and six weeks. Displacement was defined as talar displacement with a medial clear space > 4mm. Demographic, clinical and radiological data were collected prospectively.
There were 88 male and 64 female patients, with a median age of 43 years. Criteria for possible instability were: medial tenderness, 115 patients; proximal fibular fracture, 29 patients; bimalleolar fracture, 17 patients; other criteria, 15 patients. Three fractures displaced (risk of displacement 2.0%, 95% CI 0.4–5.7%). All displaced within the first week and were treated by open reduction and internal fixation. One bimalleolar fracture developed a symptomatic medial malleolar non-union which was treated by percutaneous screw fixation (risk of non-union 5.9%, 95% CI 0.1%–28.7%). All the other fractures achieved clinical union by 8 weeks.
Correspondence should be addressed to: Mr Andrew H. N. Robinson, Editorial Secretary, Department of Trauma and Orthopaedics, BOX 37, Addenbrooke’s Hospital, Cambridge CB2 2QQ, England.
