Risk factors for post-traumatic osteoarthritis of the ankle: an eighteen year follow-up study.

Long-term studies evaluating risk factors for development of ankle osteoarthritis (OA) following malleolar fractures are sparse. We conducted a retrospective cohort study including consecutive patients treated by open reduction and internal fixation for malleolar fracture between January 1988 and December 1997. Perioperative information was obtained retrospectively. Patients were evaluated clinically and radiographically 12-22 years postoperatively. Radiographic ankle OA was determined on standardised radiographs using the Kellgren and Lawrence scale (grade 3-4=advanced OA). Uni- and multivariate regression analyses were performed to determine risk factors for OA. During the inclusion period, 373 fractures (372 patients; 9% Weber A, 58% Weber B, 33% Weber C) were operated upon. The mean age at operation was 42.9 years. There were 102 patients seen at follow-up (mean follow-up 17.9 years). Those not available did not differ in demographics and fracture type from those seen. Advanced radiographic OA was present in 37 patients (36.3%). Significant risk factors were: Weber C fracture, associated medial malleolar fracture, fracture-dislocation, increasing body mass index, age 30 years or more and length of time since surgery. Advanced radiographic OA was common 12-22 years after malleolar fracture. The probability of developing post-traumatic OA among patients having three or more risk factors was 60-70%.