Syndesmosis Injuries in Lateral Malleolar Fractures Accompanied by a Posterior Malleolar Fracture: A Nonfixed Posterior Fracture Fragment May Not Affect Postoperative Tibiofibular Joint Malreduction Rates.

Background: The fact that lateral malleolar fracture is accompanied by posterior malleolar fracture may adversely affect syndesmosis malreduction rates. We aimed to compare syndesmosis malreduction rates determined on postoperative radiographs between isolated lateral malleolar fractures and lateral malleolar fractures accompanied by posterior malleolar fractures.

Methods: We retrospectively examined 128 operative patients: 73 with isolated lateral malleolar fractures (group L) and 55 with lateral + posterior malleolar fractures (group LP). In group LP, no patients received posterior fragment fixation. In both groups, indirect syndesmosis fixation was performed with a single screw after open reduction and internal fixation of the lateral malleolus. Patient age, sex, fracture side, fracture type (Lauge-Hansen and Danis-Weber classifications), Kellgren-Lawrence osteoarthritis classification, syndesmotic incongruency on postoperative radiographs, syndesmotic malreduction of postoperative fibula fracture, fracture union time, complication rates, accompanying injuries, and preoperative and postoperative radiographic syndesmotic measurements (tibiofibular overlap, tibiofibular clear space, medial clear space) were recorded, and the groups were compared.

Results: Mean ± SD age was 44.32 ± 15.66 years in group L and 48.93 ± 14.03 years in group LP (P = .087). There were no significant differences in preoperative and postoperative tibiofibular distance, tibiofibular overlap, and medial clear space values between groups (P > .05). The prevalence of grade 2 fractures according to the Kellgren-Lawrence classification was significantly higher in group LP (P = .047). Postoperative syndesmosis malreduction was detected in 12 patients in group L and in nine in group LP (P = .991).

Conclusions: In lateral malleolar fractures accompanied by small-fragment posterolateral or avulsion-type posterior malleolar fractures, closed syndesmotic screw fixation does not cause syndesmosis malreduction.