Associations between obesity and the radiographic phenotype in knee osteoarthritis.

BACKGROUND/AIM Investigation of the association between obesity and the distinction of radiographic patterns in knee osteoarthritis. MATERIALS AND METHODS Seven hundred and thirty-four women underwent weight-bearing antero-posterior knee radiography. Osteophytes and joint space narrowing (JSN) were graded according to the OARSI atlas. Each subject was assigned to one of the following groups with respect to the maximum score: osteophyte-dominant, indeterminate, JSN-dominant, and radiographically normal. RESULTS Obese patients had a significantly more frequent osteophyte-dominant pattern compared to nonobese subjects (74.5% and 38%, respectively, P < 0.001). Logistic regression analysis demonstrated that obesity had a stronger association with an osteophyte-dominant pattern compared to a JSN-dominant pattern (OR and 95% CI = 7.16 (3.15-16.26) and 1.63 (0.96-2.78), respectively). Age had a very weak effect on the distinction to an osteophyte-dominant pattern and no effect on JSN dominance (OR and 95% CI = 1.1 (1.06-1.15) and 1.02 (0.99-1.05), respectively). CONCLUSION There might be an association between obesity and the radiographic phenotype in patients with knee osteoarthritis. The findings suggest that the association between obesity and the osteophyte formation is stronger than that of JSN.