Supination Adduction Ankle Fractures Are Associated With Arthritis and Poor Outcomes

OBJECTIVE To compare complications and functional outcomes between supination adduction type II (SAD) injuries and torsional ankle injuries (TAI). DESIGN Retrospective cohort. SETTING Level 1 trauma center. PATIENTS AND METHODS Patients (n = 1531) treated for ankle fractures (OTA/AO 43B or 44) over 16 years were identified. The most recent 200 consecutive adult patients treated for TAI (OTA/AO 44, not SAD) served as controls. MAIN OUTCOME MEASURES Complications, unplanned secondary procedures, and patient-reported functional outcome scores, as measured by the Foot Function Index and Short Musculoskeletal Function Assessment. RESULTS Sixty-five patients with SAD injuries (4.2%) were included. They were younger (43.2 vs. 47.7 years, P = 0.08) and more commonly involved in a motorized collision, (58.5% vs. 29.0%) and more often multiply injured: other orthopaedic injuries (66.2% vs. 31.0%) and other nonorthopaedic injuries (40.0% vs. 7.5%, all P < 0.001 vs. TAI). Overall complication and unplanned secondary procedure rates were not different between groups. Those with a SAD injury had more posttraumatic arthrosis (80.0% vs. 40.9%, P = 0.004), but no differences were noted in infection, wound healing, malunion, or nonunion. The mean functional outcome scores were worse for SAD patients over 6 years after injury among all the Foot Function Index and Short Musculoskeletal Function Assessment categories; however, these differences were not significant. CONCLUSIONS SAD injuries represented 4.2% of all ankle fractures, occurring in younger patients through higher-energy mechanisms and more often associated with polytrauma. Despite 80% of SAD patients developing posttraumatic arthrosis, secondary procedures were not more common, and functional outcomes after a SAD injury were not different from TAI. LEVEL OF EVIDENCE Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.