A prospective study on functional outcomes of distal tibiofibular syndesmotic injuries associated with bi- or tri-malleolar fractures treated by open reduction internal fixation of posterior malleolus fracture

Abstract Background: Distal tibiofibular syndesmotic (DTS) injuries, often associated with bi- or tri-malleolar fractures, are critical for ankle stability. Posterior malleolus (PM) fractures, present in 7–44% of ankle fractures, complicate treatment due to their impact on joint congruity and syndesmotic integrity. Despite debate over fixation criteria, surgical intervention is recommended for fragments involving >25% of the articular surface. This study evaluates functional and radiological outcomes of open reduction internal fixation (ORIF) for posterior malleolus fractures in such injuries. Methods: A prospective observational study was conducted on 30 patients (mean age: 40.67 years; 63.3% male) with syndesmotic injuries and Posterior malleolus fractures (56.7% bi-malleolar, 43.3% tri-malleolar). Fractures were classified using Lauge-Hansen (40% supination-external rotation) and Weber (50% Type B) systems. ORIF was performed via a posterolateral approach, with functional outcomes assessed using the American Orthopedic Foot and Ankle Society (AOFAS) score at 4, 8, and 12 weeks postoperatively. Radiological union and complications were monitored. Results: Functional Outcomes: Mean AOFAS scores improved significantly from 59.8 (post-op) to 88.7 at 12 weeks (P< 0.01). At final follow-up, 56.7% had excellent, 30% good, and 6.7% fair/poor outcomes. - Radiological Outcomes: Mean union time was 8.77 weeks, with 50% united by 8 weeks and 93.3% by 12 weeks. - Complications: Superficial infections (13.3%) and delayed union (6.7%) were noted, with no intra-operative complications. Conclusion: ORIF of Posterior malleolus fractures in syndesmotic injuries yields excellent functional recovery and high union rates, particularly in young adults. Early surgical intervention restores ankle stability and articular congruity, reducing long-term complications. The posterolateral approach is effective for direct fragment reduction and fixation.