LAUSR

OBJECTIVES To define the risk and incidence of post-traumatic ankle arthritis requiring ankle arthroplasty or fusion after ankle fracture in a large cohort, and compare that rate to matched healthy patients from the general population. DESIGN Multiple databases were used to identify patients either treated surgically or non-surgically for ankle fractures. Each patient was matched to four individuals from the general population (13.5 million) with no prior treatment for ankle fracture. Ankle fusion and replacement incidence was compared using Kaplan-Meier analysis. MAIN OUTCOME MEASUREMENT Incidence of arthroplasty or fusion in all patients managed for rotational ankle fractures. RESULTS We identified 44,133 and 88,266 patients who had undergone operative management of ankle fracture (OAF) or non-operative management of ankle fracture (NOAF) by an orthopaedic surgeon, respectively. 306 (0.65%) patients who had OAF eventually underwent fusion or arthroplasty after a median 2.8 and 6.9 years, respectively. Among NOAF, n=236 (0.17%) patients underwent fusion or arthroplasty after a median of 3.2 and 5.6 years, respectively. Surgical treatment, older age, co-morbidity and post-injury infection significantly increased the risk of fusion/arthroplasty. Compared to matched controls, the risk of fusion/arthroplasty was not independent of time, following an exponential decay pattern. OAF patient risk of fusion/arthroplasty was >20 times the general population in the three years post-injury, and approached the risk of NOAF by 14 years. CONCLUSIONS Compared to a matched control group, and after adjustment for medical co-morbidity, rotational ankle fractures requiring surgical open reduction internal fixation increased the likelihood of arthroplasty or fusion by 3.5 times. This study allows for accurate prognostication of patient risk for arthroplasty or fusion, using patient and injury specific risk factors, both immediately following the initial injury and then subsequently during follow up. LEVEL OF EVIDENCE Level of Evidence = II (prognostic study).