Ankle injury in an adolescent.
This patient fell off a climbing frame twisting her right ankle and presented to the accident and emergency department with pain, swelling and being unable to weight-bear. Examination revealed marked tenderness at the interval between the distal tibia and fibula anteriorly and diffuse swelling around the joint.
Plain radiographs showed a minimally displaced intra-articular avulsion-type fracture of the anterolateral corner of the distal tibia. The fracture represents a Salter-Harris III injury of the distal tibial epiphysis (Fig 1).
A CT scan was subsequently performed in order to confirm the diagnosis and to elucidate the exact direction of the fracture line with a view to fixation (Fig 2).
Open reduction and internal fixation was performed through an anterolateral approach. The articular surface was restored anatomically under direct vision and a 4mm by 26mm partially threaded cancellous screw inserted (Fig.3). The ankle was then immobilized in a below knee cast for 4 weeks. Weight-bearing commenced after removal of cast.
A Tillaux fracture is an antero-lateral fracture of the distal tibial with avulsion of the fragment due to the anterior tibiofibular ligament. Some authors call it a juvenile Tillaux fracture, if a Salter-Harris III is present. A fracture of the postero-lateral distal tibial epiphysis and avulsion due to the posterior tibiofibular ligament is called a Chaput fracture. The most common mechanism of injury is external rotation of the ankle. The anterolateral corner of the distal tibial epiphysis is the last part of the epiphysis to fuse and represents a weak point, during the phase of physeal closure. The medial physis fuses around age 13 to 14, whereas the lateral part of the physis fuses 6 months to 2 years later. This difference at the time of closure predisposes adolescents to this particular fracture.
This fracture typically presents as a painful, swollen ankle following a traumatic event without the patient remembering the position of the foot at the time of injury. It can be misdiagnosed as a sprain and the diagnosis often missed in the accident and emergency department.
These fractures are intra-articular injuries and require open reduction and internal fixation in order to prevent growth arrest and degenerative changes. CT scan is the preferred imaging modality in the assessment of the intra-articular element and to detect fracture displacement. Evaluation of Salter-Harris fractures are normally performed with CT scan but MRI can be done to demonstrate ligamentous involvement.
Differential Diagnosis List