Fracture Type, Postoperative Articular Congruency and Obesity of Patients Influenced on Long to Midterm Outcome of Posterior Malleolar Fractures in Ankle Injury

CATEGORY: Trauma; Arthroscopy INTRODUCTION/PURPOSE: One of the factors contributing to outcome of posterior malleolar (PM) fractures is the development of osteoarthritis. Previous studies suggested that fragment size of PM and postoperative articular congruency were influenced on generative ankle arthritis. Haraguchi et al. classify PM fractures according to pathoanatomy of injury. However, there was no study to investigate possible risk factors including the type of PM fracture for degenerative arthritis in ankle fractures including PM. The purpose of this study was to identify the risk factors for degenerative arthritis in ankle fractures including PM. We hypothesized that risk factors for posttraumatic arthritis could be identified from patient demographic and the extent of the pathologic condition associated with fractures. METHODS: We performed a retrospective review between 2004 and 2015 of consecutive patients who underwent operation with ankle fractures and available at minimum 5 years of follow up. The exclusion criteria included diabetic neuropathy, skeletal immaturity, tibial pilon fractures, polytrauma, open fracture. Patients were sorted into 2 groups according to the presence of arthritis change more than grade 2 at last follow up. Furthermore, the statistical analysis by binary logistic regression analysis included the significance of various risk factors including age at surgery, sex, diabetes, smoking, body mass index (BMI), dominant side, time interval between the trauma and surgery, type of PM fracture, PM fragment size and postoperative joint congruency, The functional outcomes were assessed with the Foot and Ankle Outcome Score (FAOS). RESULTS: A total 332 patients with mean follow up of 8.2+-2.4 years met the study inclusion criteria and underwent analysis. The overall rate of posttraumatic arthritic change was 31.3% (non-arthritis group: 228 patients, arthritis group: 104). It was significantly affected by the BMI (p=0.021; adjusted odds ratio, OR, >= 30, 7.23), Mason classification type 3 PM fracture (p=0.031, adjusted OR 4.23), >25% of articular surface of PM, and postoperative articular incongruence (p=0.029, adjusted OR 5.13). The other variables were not found to be significant risk factors. The mean scores in the group with arthritis were significantly lower than those in the group without arthritis (p=0.001) CONCLUSION: The overall results suggest that articular congruency should be considered during surgery along with meticulous attention to anatomic reduction of large fragment posterior malleolar fracture, especially in obese patients.