THE SHORT OBLIQUE FRACTURE OF THE DISTAL FIBULA WITHOUT MEDIAL INJURY- AN ASSESSMENT OF DISPLACEMENT

Eighteen patients with ankle injuries presenting as short oblique frac tures of the distal fibula with no clinical or radiographic evidence o f injury to the medial ankle were studied for fracture displacement, P lain radiographs and computed tomography were used for analysis. All f ractures were clinically diagnosed as supination-external rotation sta ge 2 (SE-II) injuries under the Lauge-Hansen scheme. All exhibited sli ght 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 ti bial plafond, as evidenced by no abnormality of the medial joint space in all patients. In the majority of patients, the relationship betwee n the talus and distal fibula also appeared undisturbed, with fracture displacement being confined to a change in position of the proximal f ibular fragment relative to the tibia as compared with the contralater al ankle. In a minority of cases, in addition to the above-described d isplacement of the proximal fibular fragment, the distal fibular fragm ent was noted to shift slightly laterally relative to the talus, with mild widening of the lateral joint space. Occult-associated avulsion f ractures off the distal tibia were present in 39% of the cases.