The effects of meniscus injury on the development of knee osteoarthritis: data from the osteoarthritis initiative.

Background: Osteoarthritis (OA) is a leading cause of pain and disability, and the knee is one of the most commonly affected joints. Many have speculated that injury to the meniscus may play a key role in the development of knee OA; however, the exact relationship of meniscus injury and knee OA is unknown.
Purpose: To examine the rate of meniscus injuries in patients with and without incident radiographic knee OA and to explore how the type, size, and location of the meniscus injury affects the development of OA.
Study Design: Case-control study; Level of evidence, 3.
Methods: A secondary case-control analysis was conducted of the Knee Osteoarthritis Initiative (OAI) database, which is a prospective, longitudinal, multicenter cohort study of knee health in patients at risk for knee OA. Eligible patients included those without radiographic OA at baseline in 1 knee. Thirty-two patients who developed radiographic OA in a previously unaffected knee after 2 years of follow-up were matched to 64 age-, sex-, and body mass index-matched patients who did not develop OA. The study analyzed the relationship between the development of OA and the presence of a meniscus tear or degenerative signal, meniscus extrusion, tear type, and size of injury on the baseline magnetic resonance imaging scans. Conditional logistic regression was used to identify significant predictors of OA.
Results: The rate of medial meniscus lesions (tear or degeneration) was not significantly higher in those who developed incident OA (85%) compared with the control patients (68%; P = .07). However, medial meniscus extrusion (odds ratio [OR], 3.03; 95% confidence interval [CI], 1.4-6.5), complex tears (OR, 5.0; 95% CI, 1.0-25), and tears with large radial involvement (OR, 5.92; 95% CI, 1.7-7.5) were more common at baseline in cases compared with controls.
Conclusion: Knees with meniscus tears with greater radial involvement and extrusion are at greater risk for later development of radiographic OA.