Characterization of a consistent radiographic finding in chronic anterior cruciate ligament deficiency: the posteromedial osteophyte.

Often found in patients undergoing total knee arthroplasty (TKA) is an osteophyte, at the posterior lateral corner of the medial tibial plateau, that prevents anterior translation. This osteophyte does not occur in the presence of an entirely normal anterior cruciate ligament (ACL) with normal vascularity. Although similar findings have been reported in animal studies, to our knowledge this has never been documented in humans. To determine the incidence of this finding in our patient population, anteroposterior and lateral x-rays of the affected knee of 90 patients undergoing TKA were reviewed. Forty-two percent (43/102 knees) had radiographic signs of this stabilizing osteophyte. This finding confirms previous animal research and may lead to a better understanding of how the knee adapts to improve stability in a chronic ACL-deficient state.