Meniscus tears accelerate joint space loss and lateral meniscal extrusion increases risk of knee arthroplasty in middle‐aged adults

We sought to use publicly available data from the Osteoarthritis Initiative (OAI), a multicenter prospective cohort study, to determine the rate of joint space loss and likelihood of knee arthroplasty due to magnetic resonance imaging (MRI)‐diagnosed meniscal tears or meniscal extrusion in middle‐aged adults with no to mild knee osteoarthritis. Participants (n = 2199; mean age, 60.2 years) with Kellgren‐Lawrence osteoarthritis grades 2 (mild) (48.7%) or 0 to 1 (none) (51.3%) underwent knee MRIs at enrollment and were followed radiographically for 8 years and for total knee arthroplasty (TKA) for 9 years. Rate of joint space loss and risk of arthroplasty due to meniscal tears and/or extrusion were determined by multivariate modeling. Prevalence of baseline medial meniscus tears was 21.3% and lateral tears was 12.8%; 26.9% had medial meniscal extrusion (79.6%,