Histological characteristics of knee menisci in patients with osteoarthritis.

Existing data indicate knee menisci in patients with osteoarthritis (OA) show tearing, maceration, and fragmentation, but little is known about the change in histological structure. The aim of this study was to evaluate the change in the menisci histological structure in patients with clinically diagnosed knee OA. Fourteen patients undergoing surgical treatment of knee OA (OA group) and 14 cadaveric knees (control group) were assessed. Demographic data, medical history, synovial fluid, OA severity, medial meniscus (MM) tissue, and lateral meniscus (LM) tissue were collected from the OA group. Three nonconsecutive 10 μm cross-sectional tissue slices of menisci were analyzed for percentage of tissue calcification. Exact Mann-Whitney tests and Spearman correlation coefficients tested for relationships between variables. The major change in the histological structure of the menisci in patients with OA was calcification of the matrix, which was significantly greater in the OA group compared with the control group for MM (OA: 11.9%, cadaver: 5.17%; P < 0.001) and LM tissues (OA: 11.1%, cadaver: 4.2%; P < 0.001). A correlation between percent calcification of the MM and LM tissues existed in the OA group (ρ = 0.56, P = 0.04) but not the control group (P = 0.20). The most pronounced pathological change in the histology of menisci was calcification of the cartilage matrix, significantly greater in the OA group than the control group. A strong correlation between percent calcification of MM and LM tissues in patients with OA indicates changes in fibrocartilage matrix of menisci progress similarly in the medial and lateral compartments of the knee. Clin. Anat. 30:805-810, 2017.