PURPOSE. To examine changes in
acid mucopolysaccharides and
collagen expression during meniscal degeneration, tearing, and repair, using menisci excised from knee joint surgeries. METHODS. Menisci excised from 23 patients aged 15 to 80 years who underwent meniscal surgery for flap and
bucket handle tears (n=11) and
total knee arthroplasty (TKA) for
osteoarthritis (n=12) were examined histologically. Staining images were converted to greyscale images to measure the mean grey levels, which indicated densitometry. Comparisons were made between acutely injured menisci and menisci with and without degeneration (from patients with
osteoarthritis) in terms of
acid mucopolysaccharides,
collagen types I, II, and III expression. RESULTS. In menisci with no degeneration,
acid mucopolysaccharides,
collagen types I and II were expressed throughout the entire meniscus except for the circulating area.
Collagen type III was intensely expressed at the exterior peripheral border and on the surface. During progression of meniscal degeneration, the expression of
acid mucopolysaccharides increased, and the expression of
collagen types I, II, and III decreased. In acutely injured menisci,
collagen types II and III disappeared first, followed by
collagen type I, resulting in the abrogation of fibre construction. CONCLUSION. In normal menisci,
acid mucopolysaccharides and
collagen types I, II, and III were well-balanced, and meniscal function was maintained. When the limits of repair were exceeded, the meniscus tissue deteriorated owing to the disappearance of
collagen types II and III and a decrease in
collagen type I, resulting in the abrogation of meniscus fabric construction.