Repair of articular cartilage on the surface of heat-treated bone by transplantation of cultured chondrocytes.

The present study addresses clinical problems associated with the degeneration of articular cartilage, which occurs when heat-treated bone with articular cartilage is used for re-implantation after resection of malignant bone tumors adjacent to the joints. We therefore evaluated the effect of transplantation of chondrocytes embedded in collagen gel on the surface of heat-treated bone. A cylindrical complex of bone and articular cartilage 6 mm in diameter was resected from rabbits' patellar grooves and treated in saline at 60 degrees C for 30 min. In Group A, articular cartilage was resected from the complex and the remaining bone was returned to the patellar groove. Then, autologous chondrocytes cultured in collagen gel were transplanted and covered with periosteum. As controls, the original complex of heat-treated bone and articular cartilage (Group B) and heat-treated bone directly covered with periosteum (Group C) was returned to the patellar groove. In Group A, histological study showed that round cells were mainly observed and the matrix was well stained with Safranin O in the repair tissue after 24 weeks. The repair tissue was as thick as the adjacent normal cartilage. Immunohistological study detected type-II collagen and chondroitin-6-sulphate (3B3+) in the matrix of the repair tissue, but not type-I collagen. The repair tissue was consequently cartilaginous in Group A. The repair tissue was not cartilaginous or was degenerative in the control groups. We believe that this modality of heat-treated joints will contribute to limb salvage reconstruction after resection of malignant bone tumors adjacent to the joints.