A retrospective comparison of single screw vs dual screw fixation of Medial Malleolus Fractures on rate of non-union and malreduction

J. Aamir, R. Caldwell, S. Long, S. Sreenivasan, J. Mavrotas, A. Panesa, S. Jeevaresan, V. Lampridis, L. Mason

Background: Medial Malleolus Fractures (MMF) are frequently managed by orthopaedic surgeons and are one of the most treated fractures of the ankle. Currently, there is a lack of consensus on the number of screws used in fixation when attempting lag-screw fixation of MMF.

Aim: To compare the outcomes of MMF with patients which have either undergone single-screw (SS) or dual-screw (DS) fixation.

Methods: Patients who had undergone surgical fixation of their MMF were identified from 2012 to 2022. Analysis of their pre-operative, intra-operative and post-operative radiographs was performed to determine the initial type of injury and surgical outcomes.

Results: A total of 653 patients were identified across a 10-year period. There were 271 patients (41.50%) in the SS group and 382 patients in the DS group (58.50%). When comparing the outcomes of SS to DS, a non-union rate of 19.19% (52/271) was found in the SS group as compared to 18.85% (72/382) in the DS group. Re-operation occurred in 14.76% (40/271) in the SS group and 13.02% (44/382) in the DS group. These comparisons were not statistically significant. There was a malunion rate of 11.07% (30/271) in the SS group as compared to 3.93% (15/382) in the DS group, which was statistically significant (p<.001). On multi regression analysis, factors which gained significance for development of non-union was non-fixation of syndesmosis (p= .039), ankle dislocation on arrival (p<.001) and non-restoration of fibular length (p<.001). Other factors which showed significance for failure to achieve medial anatomical reduction was non fixation of syndesmosis (p<.001).

Conclusion: Use of a SS, rather than DS showed a significant increase in anatomical reduction but did not increase non-union or reoperation rate. Syndesmosis fixation has clear impact on the stresses on the medial malleolus, and surgeons should have a low index of suspicion of injury and fixation.