SLR - October 2018 - Brittany A. Brower

Posterior Malleolus in Trimalleolar Ankle Fractures: Malleolus Versus Transyndesmal Fixation

Reference: Tosun B, Selek O, Gok U, Ceylan H. Posterior Malleolus in Trimalleolar Ankle Fractures: Malleolus Versus Transyndesmal Fixation. Indian J Orthop. 2018 May-Jun; 52(3):309–314. doi: 10.4103/ortho.IJOrtho_308_16.

Scientific Literature Review

Reviewed By:
Brittany A. Brower, DPM
Residency Program: John Peter Smith Hospital, Fort Worth, TX

Podiatric Relevance: Treatment of posterior malleolar ankle fractures remains controversial. Historically, recommendations have been made to only fixate a posterior malleolus fracture when the fragment involves >25 percent of the articular surface. This is based on evidence of decreased joint space contact area stemming from posterior tibial fragment size and resulting in tibiotalar instability rather than on the goal of restoring rotational ankle stability. This study compares the results after posterior malleolus and transsyndesmal fixation, while considering the reduction quality, development of posttraumatic ankle osteoarthritis and functional outcomes in trimalleolar ankle fractures.

Methods: This retrospective study was conducted between 2009 and 2014 looking at 49 consecutive trimalleolar ankle fractures in patients with and without posterior malleolus fixation. All posterior malleolus fractures were evaluated using computed tomography. Group I consisted of 29 patients with posterior malleolar fractures that were left untreated. The medial and lateral malleolus fractures were fixated, and transsyndesmotic fixation was determined based on instability. Group II consisted of 20 patients with posterior malleolus fractures fixated with either screws alone or plate screw using a posterolateral approach. Twenty-one of these 49 patients were male (43 percent). The mean age was 47 years (range 20–82 years). Reduction quality, development of posttraumatic ankle osteoarthritis and functional outcomes were evaluated.  

Results: The mean follow-up was 12 to 51 months with a mean of 15 months. Average size of the posterior malleolar fragment was 21.3 percent in Group I and 28.9 percent in Group II. Eight of the 20 patients in Group II who received fixation of the posterior malleolus fragment had a fragment smaller than 25 percent. Eleven patients had plate fixation, and nine patients had lag screw fixation. The median value of reduction of the tibial joint surface in Group I and II were 1 mm and 0 mm respectively. Fifteen patients in Group I required transsyndesmotic fixation; however, only one was performed in Group II. Statistically significant differences were found indicating increased ankle arthrosis in group I compared to group II, and the American Orthopaedic Foot and Ankle Society score was significantly lower in Group I compared to group II.  

Conclusion: Posterior malleolar fracture fixation is closely related to successful radiological and functional outcomes after trimalleolar fractures. Transyndesmotic screw fixation may not be needed in the cases where posterior malleolus fracture is fixated. The authors recommend that all posterior malleolar fractures be fixated regardless of size. 

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