Introduction Meniscal tears are commonly found on MRI and increase the risk for radiographic knee osteoarthritis (OA). While meniscectomy is recommended when knee pain is severe or functionally disabling, it is unclear how to best treat meniscal tears without these symptoms. The aim of this longitudinal study was to examine the effect of weight change on knee cartilage and pain in a cohort of community-based adults with and without meniscal tears detected by MRI.

Methods 250 adults with no history of knee OA or knee injury were recruited from the general community and weight-loss clinics. MRI of the knee, Western Ontario and McMaster University Osteoarthritis Index (WOMAC), weight and height were measured at baseline and again at follow-up approximately 2 years later.

Results Medial meniscal tears were present in 36 (18%) of the cohort. In those with medial meniscal tears, after adjustment for confounders, percentage weight change was significantly associated with percentage change in medial tibial cartilage volume (β 0.2% 95% CI 0.08% to 0.3% p=0.002) and knee pain (β 11.6% 95% CI 2.1% to 21.1% p=0.02). That is, for every 1% gain in weight, there was an associated 0.2% increased loss of medial tibial cartilage volume and 11.6% increase in pain. In those with no medial meniscal tear, neither change in medial tibial cartilage volume (β 0.02% 95% CI −0.01% to 0.10% p=0.53) or pain (β 1.9% 95% CI −2.2% to 6.1% p=0.36) were significantly associated with change in weight.

Conclusions This study demonstrated that among adults with medial meniscal tears, weight gain is associated with increased cartilage loss and pain, while weight loss is associated with the converse. This suggests attention to weight is particularly important in the management of people with medial meniscal tears.