Baseline meniscal extrusion associated with incident knee osteoarthritis after 30 months in overweight and obese women

Objective: To investigate the association between baseline meniscal extrusion and the incidence of knee osteoarthritis (KOA) after 30 months in a high-risk population of overweight and obese women, free of clinical and radiological KOA at baseline. Methods: 407 middle-aged overweight women (body mass index - BMI ≥ 27 kg/m2) were evaluated at baseline and after 30 months of follow-up. Meniscal extrusion was defined as grade ≥2 on MRI according to MRI Osteoarthritis Knee Score (MOAKS). The primary outcome measure was KOA after 30 months follow-up, defined using the following criteria: either incidence of radiographic KOA (Kellgren & Lawrence grade 2 or higher), or clinical osteoarthritis (OA) according to the American College of Radiology (ACR) criteria, or medial or lateral joint space narrowing (JSN) of ≥1.0 mm. Using generalized estimating equations (GEE), we determined the association between knees with and without meniscal extrusion and both outcomes, corrected for the baseline differences. Results: 640 knees were available at baseline of which 24% (153) had meniscal extrusion. There was a significantly higher incidence of KOA according to the primary outcome measure in women with meniscal extrusion compared to those without extrusion (28.8%, odds ratio - OR 2.39, 95% CI 1.53, 3.73). A significantly higher incidence was found for the development of radiographic KOA (12.4%, OR 2.61, 95% CI 1.11, 6.13) and medial JSN (11.8%, OR 3.19, 95% CI 1.59, 6.41). Meniscal extrusion was not significantly associated with clinical KOA and lateral JSN. Conclusion: Meniscal extrusion was associated with a significantly higher incidence of KOA, providing an interesting target for early detection of individuals at risk for developing KOA