The short oblique fracture of the distal fibula without medial injury: an assessment of displacement.

Eighteen patients with ankle injuries presenting as short oblique fractures of the distal fibula with no clinical or radiographic evidence of injury to the medial ankle were studied for fracture displacement. Plain radiographs and computed tomography were used for analysis. All fractures were clinically diagnosed as supination-external rotation stage 2 (SE-II) injuries under the Lauge-Hansen scheme. All exhibited slight displacement on plain radiographs and were treated nonoperatively. Computerized tomography using axial cuts across the fracture site and ankle mortise revealed normal positioning of the talus beneath the tibial plafond, as evidenced by no abnormality of the medial joint space in all patients. In the majority of patients, the relationship between the talus and distal fibula also appeared undisturbed, with fracture displacement being confined to a change in position of the proximal fibular fragment relative to the tibia as compared with the contralateral ankle. In a minority of cases, in addition to the above-described displacement of the proximal fibular fragment, the distal fibular fragment was noted to shift slightly laterally relative to the talus, with mild widening of the lateral joint space. Occult-associated avulsion fractures off the distal tibia were present in 39% of the cases.