SLR - February 2021 - Alex J. Bischoff

Comparison of the Efficacy of Posterior-Anterior Screws, Anterior-Posterior Screws and a Posterior-Anterior Plate in the Fixation of Posterior Malleolar Fractures with a Fragment Size of  > 15 and < 15%

Reference: Wang Z, Sun J, Yan J, Gao P, Zhang H, Yang Y, Jin Q. Comparison of the Efficacy of Posterior-anterior Screws, Anterior-posterior Screws and a Posterior-anterior Plate in the Fixation of Posterior Malleolar Fractures with a Fragment Size of ≥ 15 and < 15. BMC Musculoskelet Disord. 2020 Aug 22;21(1):570

Level of Evidence: 3

Scientific Literature Review

Reviewed By: Alex J. Bischoff, DPM
Residency Program: Grant Medical Center – Columbus, OH

Podiatric Relevance: The posterior malleolus plays an integral role in the anatomical stability of the distal tibiofibular syndesmosis in large part due to the attachment of posterior-inferior tibiofibular ligament. However, indications for, and hardware utilized during surgical management of posterior malleolar fractures is controversial. Many providers base their surgical decisions off articular involvement >25 percent and displacement >2 millimeters. The purpose of this study was two-fold: to investigate the efficacy of posterior- anterior screws, posterior-anterior plate, and anterior-posterior screws in the treatment of posterior malleolar fractures, and secondly to assess the fixation  in the context of fracture size (> or < 15 percent articular surface involvement). 

Methods: This was a retrospective study involving 243 unilateral ankle fractures treated by a single surgeon at a single institution. The posterior malleolar fracture was >15 percent of the articular surface in 136 patients, and <15 percent in 107 patients. Of each size group, patients were randomly selected to receive PA screw, AP screw, or PA plate fixation, according to patient desire. Uniquely, surgical technique for each fixation group included direct visualization and reduction of the posterior malleolus fragment through a posterior-lateral approach. Also, each group followed the same order of fixation by first addressing the lateral malleolus, then posterior malleolus, then medial malleolus, and lastly the distal tibiofibular syndesmosis. Each patient received the same post-operative course. Radiographic imaging, American Orthopaedic Foot and Ankle Society (AOFAS) scores, and range of motion (ROM) of the ankle were utilized at final follow up (18.9 months) for outcomes evaluation. Statistical analysis was obtained with p-value and significance level set at p = 0.05.

Results: Each fracture healed. In fragment size >15 percent group there was no significant difference in AOFAS or ROM scores. In fragment size <15 percent group the AOFAS score was significantly decreased in the PA plate fixation group, and the dorsiflexion ROM was significantly increased compared with the PA screws and AP screws groups.

Conclusions: The findings of this study demonstrate no significant difference in functional outcome regardless of fixation type when the posterior malleolus fracture encompasses >15 percent of the articular surface. The perceived reasoning for this is that each fixation group, including the AP screws fixation, had direct visualization of the fragment through a posterolateral incision. Thus, this study illustrates the importance of direct visualization in this fracture type. In fracture fragments which encompass <15 percent of the articular surface, PA and AP screws had superior functional outcomes. Thus, one may conclude that the study poses an argument for utilization of screw fixation only rather than plate fixation, regardless of fragment size. As a foot and ankle surgeon, it is important to recognize that a posterior plate may be less functional for a patient than screw fixation. With that being said, there is still no one correct answer on when to fixate, and how to fixate posterior malleolar fracture. Careful consideration to case specific factors may aide the provider in this critical decision process.

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