Increasing evidence has shown that biomechanical forces often drive the progression of knee osteoarthritis (OA). Attention should be given to the changes in adjacent joints and their relation to knee OA. The purpose of the present study was to examine the changes in Achilles tendon thickness of individuals with knee OA and to evaluate the correlation between Achilles tendon thickness and knee OA severity in a case-control prospective observational study. A total of 93 participants with no previous ankle injuries were recruited. Of the 93 participants, 63 had knee OA of the medial compartment and 30 served as controls. The subjects underwent a clinical examination that included measurements of weight, height, Achilles tendon thickness, and 1-leg heel rise. The subjects also underwent a computerized gait test and completed the Hebrew version of the Western Ontario and McMaster Osteoarthritis Index and 36-item short-form (SF-36) health survey. Significant difference was found in Achilles tendon thickness between the subjects with knee OA and the healthy controls (17.1 ± 3.4 versus 15.1 ± 3.1; p = .009). Significant differences were also found between the 2 groups in the 1-leg heel rise test, Western Ontario and McMaster Osteoarthritis Index scores, SF-36 scores, and all gait measures. Significant correlations were found between the Achilles tendon thickness and the following measures: weight (r = 0.46), body mass index (r = 0.55), Kellgren and Lawrence OA severity grade (r = 0.25), 1-leg heel rises (r = −0.50), and SF-36 score (r = −0.25). Subjects with knee OA presented with a thicker Achilles tendon compared with the healthy controls. Furthermore, a significant correlation between Achilles tendon thickness and knee OA severity was found. A comprehensive assessment of the Achilles tendon and ankle joint should be a part of the knee OA evaluation process.
Level of Clinical Evidence: 3