190. Impact of Bone Marrow Lesion on the Progression of Knee Osteoarthritis in the Sekoia Study

Abstract

Background: OA is a common, degenerative joint disease that affects around 80% of those aged over 75 years. Many factors appear to influence progression, the rate of which is very variable. Previously established factors include sex, obesity, and prior knee injuries. While imaging of OA was traditionally achieved using radiographs, more recently, a role has been established for MRI. In this study we examined the relationship between bone marrow lesions (BML) visualized using MRI and subsequent progression of knee OA, using the placebo arm of a randomized controlled trial of a therapy for OA. Methods: 559 men and women over 50 years with clinical knee OA (K&L 2-3) were recruited to the placebo arm of the SEKOIA study (98 centre; 18 countries). Minimal tibiofemoral joint space on plain radiograph of the knee was assessed by two independent readers at baseline and yearly follow-up (up to 3 years). In a subset of 176, knee MRI was performed at baseline. Individuals with a BML of grade 2 or above at the tibiofemoral joint were classified as BML positive. Results: The mean (S.D.) age of study participants was 62.8 (7.5) years. 73% were female and the mean (S.D.) BMI at baseline was 29.8 (5.1). Just over one third of those studied had BMLs (38.6%). The prevalence of BMLs did not differ significantly by age or BMI. On average, joint space reduced by -0.18 (0.30) mm and -0.13 (0.23) mm per year in men and women respectively. Those with BMLs had a significantly higher level of annualized joint space narrowing, with the relationship remaining robust after adjustment for age, sex and K&L grade; beta (95% C.I) -0.10 (-0.18, -0.02) mm/year. Age, sex, and baseline K&L grade did not influence rate of joint space narrowing. Conclusion: The rate of joint space loss was similar in men and women. BMLs on knee MRI predicted rate of radiographic joint space loss indicating a more rapid progression of disease. This relationship was independent of age, sex, and baseline K&L grade.