Arthroscopic assessment of medial malleolar reduction

Ankle fractures treated with open reduction internal fixation are fixed in an effort to reestablish anatomic bony alignment and avoid a malunion, thereby diminishing the risk of post-traumatic arthritis. For a medial malleolar fracture, an articular step-off is likely more related to the risk of post-traumatic arthritis than is a cortical step-off. However, the external cortical alignment is often used to judge the adequacy of reduction, as the articular component of the fracture is not as readily visualized. Arthroscopy has been used in various articular fractures as an aid to diagnosis and treatment. The current study prospectively assessed both the quality of medial malleolar reduction on the articular side using arthroscopy and the adequacy of using cortical cues to guide the articular reduction.

Twelve consecutive patients were enrolled in this prospective diagnostic study. All patients had medial malleolar fractures that required fixation. The outcome variables of interest were extra-articular fracture displacement and articular surface displacement.

After reduction and provisional fixation, 10 of the 12 patients had an anatomic reduction based on cortical cues. On arthroscopy 7 of the 12 patients had an anatomic reduction. Four of the patients had a slight gap (<1 mm) at the anterior edge of the fracture. The last patient had an anterior gap just under 2 mm. Two patients had impaction of the medial malleolus that made reduction difficult and was recognized during arthroscopy after obtaining a reduction based on cortical cues.

The cortical reduction of the medial malleolus often matched up with the articular reduction. However, in some patients, impaction of the medial malleolus made it so that the two did not match up. There are some cases in which extra-articular cues are insufficient to evaluate for intra-articular reduction.