Cartilage lesions and the development of osteoarthritis after internal fixation of ankle fractures: a prospective study.

BACKGROUND The role of the location and severity of the initial cartilage lesions associated with an ankle fracture in the development of posttraumatic osteoarthritis has not been established, to our knowledge. METHODS We performed a long-term follow-up study of a consecutive, prospectively included cohort of 288 ankle fractures that were treated operatively between June 1993 and November 1997. Arthroscopy had been performed in all cases in order to classify the extent and location of cartilage damage. One hundred and nine patients (47%) were available for follow-up after a mean of 12.9 years. The main outcome parameters were the American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot score for clinical evaluation and a modified Kannus osteoarthritis score for radiographic assessment of the development of posttraumatic osteoarthritis. RESULTS Cartilage damage anywhere in the ankle joint was associated with a suboptimal clinical outcome (odds ratio, 5.0 [95% confidence interval = 1.3 to 20.1]; p = 0.02) and with a suboptimal radiographic outcome (odds ratio = 3.4 [95% confidence interval = 1.0 to 11.2]; p = 0.04). An association was also found between the development of clinical signs of osteoarthritis and a deep lesion (>50% of the cartilage thickness) on the anterior aspect of the talus (odds ratio = 12.3 [95% confidence interval = 1.4 to 108.0]; p = 0.02) and a deep lesion on the lateral aspect of the talus (odds ratio = 5.4 [95% confidence interval = 1.2 to 23.5]; p = 0.02). A deep lesion on the medial malleolus was associated with the development of clinical signs of osteoarthritis (odds ratio = 5.2 [95% confidence interval = 1.9 to 14.6]; p < 0.01) and radiographic signs of osteoarthritis (odds ratio = 2.9 [95% confidence interval = 1.1 to 7.9]; p = 0.03) of osteoarthritis. There was no significant correlation between cartilage lesions on the fibula and the long-term outcome. CONCLUSIONS Our findings show that initial cartilage damage seen arthroscopically following an ankle fracture is an independent predictor of the development of posttraumatic osteoarthritis. Specifically, lesions on the anterior and lateral aspects of the talus and on the medial malleolus correlate with an unfavorable clinical outcome.