Experimental and clinical studies have documented that meniscal allografts show capsular ingrowth in meniscectomized knees. However it remains to be established whether meniscal allograft transplantation can prevent degenerative changes after total meniscectomy. In this study, functional changes in articular cartilage after meniscus transplantation in rabbits were evaluated quantitatively. Thirty rabbits were divided into five groups. Group A and Group C were subjected to meniscectomy. Group B and Group D underwent meniscal transplantation immediately after meniscectomy. Group E had delayed transplantation 6 weeks after meniscectomy. Six nonoperated knees served as controls. Using image analysis with QwinPro software ffunctional changes of articular cartilage were examined 6 weeks (Groups A, B) and 1 year (Groups C, D, E, controls) after surgery by measuring the lactate dehydrogenase (LDH) activity in chondrocytes as a measure of their vitality and the proteoglycan content of the extracellular matrix as a measure of its quality. All experimental groups demonstrated a significant decrease in proteoglycan content of the cartilage as compared with the control group. At 6 weeks and 1 year follow-up, no significant differences were found between the postmeniscectomy group and immediate transplant group. The delayed transplant group showed a significantly decreased proteoglycan content as compared with the postmeniscectomy group. Compared to the control group, no significant differences in cellular LDH activity were found in the postmeniscectomy group and immediate transplant group at 6 weeks and 1 year. However, delayed transplantation caused diminished vitality of chondrocytes. No significant differences were found between the postmeniscectomy group and immediate transplant group at 6 weeks and 1 year. The delayed transplant group showed a significant decrease in LDH activity as compared with the postmeniscectomy group. It can be concluded that immediate meniscal transplantation in rabbits did not significantly reduce degenerative changes of articular cartilage whereas delayed transplantation leads to even more degenerative changes than meniscectomy.
We examined the cellular responses to various particles injected into the knees and the intramedullary femoral cavities of rats in the presence of polymethyl-methacrylate (PMMA) plugs. The intra-articular particles were mainly ingested by synovial fibroblasts. Increased numbers of macrophages were not detected and there was only a slight increase in synovial thickness. Cellular responses in the intramedullary space were similarly mild and bone resorption around the PMMA plug did not occur. Bone formation was inhibited only by polyethylene particles. In contrast to current views, our study shows that wear particles
