Is the posterior malleolus reliably reduced by fibula fixation alone? A prospective CT-based study.

Background: Posterior malleolus fractures have the potential to be automatically reduced after fibula fixation, thus not requiring fixation. Nevertheless, there are no data in the literature supporting this theory. We have performed a prospective CT study to evaluate the quality of indirect posterior malleolus fragment reduction via ligamentotaxis in ankle fractures.

Purpose: To examine the role of ligamentotaxis in posterior malleolus reduction.

Study design: Prospective, Computed Tomography study.

Methods: We included seventy-one patients with ankle fractures who did not undergo direct fixation of the posterior malleolus. Postoperative CT scans compared the injured and normal ankles, assessing reduction quality based on fragment translation.

Results: The fractures were classified as Mason type 1, 2A, 2B, and 3. The results showed that indirect reduction was anatomical in 91.3 % of Mason type 1 fractures, 54.5 % of Mason type 2A fractures, 31.25 % of Mason type 2B fractures, and 76.2 % of Mason type 3 fractures. Mason type 2 fractures exhibited the most variability in reduction quality. The incisura anatomy was additionally affected, with a significant decrease in the normal notch retroversion.

Conclusion: Indirect reduction of the posterior malleolus via ligamentotaxis yields unpredictable results related to the fragment morphology, making preoperative CT evaluation highly suggested for ankle fracture treatment. Our study indicates that the posterior malleolus cannot be always reduced through fibula fixation in patients with Mason 2 and Mason 3 fracture types, with those fractures requiring direct fixation. Further research is needed to evaluate the clinical importance of malreduced posterior malleolar fragments on ankle joint function.