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.