An anatomic study of the short oblique fracture of the distal fibula and ankle stability.

The short oblique fracture of the distal fibula occurring as a stage 2 supination-external rotation injury was investigated in respect to its effect on ankle stability in a series of cadaver dissections. Approximately 25 and 20 degrees of external rotational displacement of the distal fibula and talus, respectively, as well as approximately 1 mm of direct lateral talar shift were noted to be possible with this injury. This degree of rotational or lateral talar displacement was seen to result in tibiotalar joint incongruity. The deltoid ligament effectively prevented talar eversion but not the initial 2 to 3 mm of lateral talar displacement. Ankle stability in respect to medial talar shift was not compromised by removal of the medial malleolus.