Meniscal extrusion and bone marrow lesions are associated with incident and progressive knee osteoarthritis

Objective Whether meniscal extrusion and bone marrow lesions (BMLs) are independently associated with the risk of knee osteoarthritis (OA) is unknown. Methods Data was extracted from the Osteoarthritis Initiative (OAI) cohort. Participants were grouped according to the absence (Kellgren–Lawrence (KL) grade ≤ 1, n = 2120) or presence (KL ≥ 2, n = 2249) of radiographic OA (ROA). Baseline meniscal extrusion and tibial BMLs were assessed. Tibial plateau cartilage volume was assessed at baseline and 72 months, while radiographic disease was assessed at baseline and 48 months. Total knee replacement (TKR) was assessed at 72 months. Results In those with ROA, the presence of a baseline meniscal extrusion (independent of BMLs) was associated with accelerated cartilage volume loss (medial tibia: −2.1%/annum vs −1.5%; lateral: −2.6%/annum vs −1.6%; both P < 0.001), progressive ROA and TKR (Odds ratio (OR) range 1.4–1.8; 95% CI range 1.1–2.9). The presence of a baseline BML was associated with accelerated cartilage volume loss (medial tibia: −2.1%/annum vs −1.6%; lateral: −1.9%/annum vs −1.6%; P ≤ 0.02), progressive ROA and joint replacement (OR range 1.5–2.4; 95% CI range 1.1–3.4). In those with no ROA, a baseline medial meniscal extrusion was associated with accelerated cartilage volume loss (medial tibia: −2.1%/annum vs −1.2%, P < 0.001), and a baseline medial BML with incident ROA (OR 1.7, 95% CI 1.1 to 2.9). Conclusions The presence of baseline meniscal extrusion and BMLs are associated with incident and progressive knee of each other (OA) and represent important structural targets for the treatment and prevention of knee OA.