Reduction Quality of Open vs Percutaneous Techniques for the Posterior Malleolus

Abstract

Category: Ankle; Trauma Introduction/Purpose: Ankle fractures with posterior malleolar involvement are common. Fixation of the posterior malleolus (PM) in these injuries remains controversial & currently, there is no evidence to guide operative decision making for the PM. This study compares radiographic & clinical outcomes between percutaneous & open fixation techniques of the PM. Methods: All ankle fractures between 01/2010 & 01/2018 with surgical stabilization of the PM were reviewed from a level 1 trauma center. High-energy (i.e. pilon), open & pathologic fractures were excluded. Orthopaedic Trauma Association (AO/OTA) fracture pattern, PM articular surface comminution, incarcerated fragments & loose bodies were recorded based on pre-operative CT scans. Patients were either treated with direct reduction (DR) or percutaneous reduction (PR). Intra-operative & serial post- operative radiographs were used to measure PM articular reduction & graded as satisfactory (2mm articular step-off). Medical records were reviewed for fixation technique & complications. Patient-reported outcomes measurement information system (PROMIS) scores were used to compare clinical outcomes. Univariate methods including x2, Fischer exact test, One-way ANOVA were used & a multivariate nominal logistic regression model was constructed to evaluate predictors of a satisfactory reduction. Results: A total of 120 patients (ages 19-84) were included. DR through an open approach was performed in 91 patients & PR in 29. The DR cohort had a higher rate of satisfactory reduction (92.3% vs 75.9%, p=0.04). Articular comminution was identified in 65 (50.4%) & this morphology had a higher rate of satisfactory reduction with ORIF (94% vs 66.6%, p=0.04). There was no difference in reduction quality for non-comminuted fractures treated open or percutaneously (90.2% vs 83.3%, p=0.64). Incarcerated fragments or loose bodies were identified in 58 (48.3%) of fractures. There was a trend for improved reduction quality in the DR group for this morphology (p=0.08). Multivariate analysis identified that open approach is associated with a satisfactory reduction (p=0.02). No difference in complication rate between groups or PROMIS scores (p>0.05) for 64 patients with average final follow up of 19 months (range 6-60 months) were found. Conclusion: This study demonstrates that DR of the PM via an open approach in low energy ankle fractures leads to improved radiographic outcomes compared to percutaneous techniques without a difference in complication rate. This study also highlights the utility of a pre-operative CT scan to better assess the morphology of the posterior malleolus as articular comminution, interposed fragments or loose bodies were common findings that are difficult to assess on plain radiographs & may alter surgical plan if present. However, no difference in PROMIS scores were seen between direct and percutaneous reduction techiniques.