Tensile properties of articular cartilage are altered by meniscectomy in acanine model of osteoarthritis

Loss of or damage to the meniscus alters the pattern of loading in the knee joint and frequently leads to cartilage degeneration and osteoarthritis. T he mechanical properties of articular cartilage have been shown to reflect the extent of cartilage degeneration in human osteoarthritis and in experim ental models of joint disease, but there is little experimental data docume nting changes in cartilage mechanics following meniscectomy. We hypothesize d that the tensile properties of the surface zone of articular cartilage ar e altered following total medial meniscectomy. Twelve mongrel dogs underwen t complete resection of the medial meniscus in the right knee, and the femo ral cartilage was studied 12 weeks after the operation. We performed uniaxi al, tensile stress-relaxation tests to determine the equilibrium tensile mo dulus of surface-zone cartilage. Water and glycosaminoglycan content were a lso measured at site-matched locations. The tensile moduli of the cartilage decreased significantly following meniscectomy. The linear region modulus decreased by 40%,from 25.5 +/- 7.7 to 15.3 +/- 7.2 MPa. There was a weak (r = -0.45), but significant, correlation between the linear region modulus a nd the gross morphological grade for cartilage damage. Water and glycosamin oglycan content did not change following meniscectomy. Composition was not correlated with mechanical properties or morphological grade, suggesting th at cartilage structure may play a more important role than composition in d etermining the mechanical properties. The observed decrease in cartilage ma terial properties provides a quantitative measure of the loss of cartilage function following meniscectomy and reflects a pattern of change that is co nsistent with damage to the collagen-proteoglycan solid network.