Posterior Malleolus Fractures in Trimalleolar Ankle Fractures: Is Transyndesmotic Fixation Necessary?

Posterior malleolus (PM) fracture in trimalleolar fractures is closely associated with syndesmosis stability and affecting functional outcomes in comparison to bimalleolar fractures of the lateral and medial malleolus. The purpose of this study was to explore the role of posterior malleolus fixation for maintaining of the distal tibiofibular joint stability and intermediate-term outcomes on functional recovery and radiological appearances. In the last 7 years (2015-2022) we did ORIF for 98 consecutive trimalleolar ankle fractures which were evaluated retrospectively in patients with and without transsyndesmotic fixation. Group I consisted of sixty-four patients, in whom transsyndemotic fixation was performed. Thirty-four patients in Group II, no syndesmotic fixation was carried out in trimalleolus fractures. There were 58 male (59%), 40 female (41%) patients who had trimalleolus fractures with mean age 42 years (range 23-75)0 The mean follow up was 14 to 48 months with a mean of 16 months. American Orthopedic Foot and Ankle Society score was not significantly between two groups. Therefore, transyndesmotic screw fixation may not be needed in the cases where the posterior malleolar fracture is appropriately fixed, however, in our series, majority of the triamalleolus fractures were fixed with trans syndesmotic screws based on intra operatively radiological fluoroscopy screening with ankle in forced external rotation (ER) or Hook test after fixation PM fractures. The reduction of lateral malleolus fractures are critical for reduction of the PM fragments including maintaining correct length of the distal fibula, correction of the mal-rotation and centralization of the talus. PM fractures are reduced anatomically in intraoperatively fluoroscopic images, we may either fixing PM or trans syndesmotic fixation to maintain stability distal tibiofibular joint based on intraoperatively fluoroscopic screening assessments. The order of fixation trimalleolus fracture is critical for surgical management. For a trimalleolus fracture, firstly reduction of the lateral malleolus fractures then posterior malleolus, the last for medial malleolus fractures. Keywords : Ankle fracture, ankle malleolar fracture, posterior malleolus, syndesmosis, internal fixation