Pedunculated Synovium Grafts in Articular Cartilage Defects in Rabbits

A rabbit model was used to assess the nature of healing tissues in hyaline cartilage defects and to compare the healing in defects treated with pedunculated synovium grafts to those in defects without synovial grafting. Both knees of 28 1-year-old rabbits were operated. A 3× 2-mm cartilage defect that exposed cancellous bone was created in the non-weight-bearing area of each medial femoral condyle. Each right-knee defect was covered with a pedunculated synovial graft obtained from the same joint, and the left-knee defects were left uncovered as controls. Groups of rabbits were sacrificed at 3, 6, 12, and 24 weeks postsurgery. Sections from each knee were stained with hematoxylin-eosin and safranin O-fast green staining, and were immunohistochemically stained for type II collagen. The healing at each site was histologically scored, and the intensity of staining for type II collagen was graded. At 12 and 24 weeks, statistical comparisons of histological scores revealed significantly more hyaline cartilage tissue in the synovium-grafted defects. At 24 weeks, these same defects showed significantly more type II collagen. Thus, pedunculated synovium transplantation appears to hold promise as a method for repairing hyaline cartilage defects.