Cultured Chondrocyte Transplantation in the Damaged Growth Plate

The growth plate is responsible for longitudinal bone growth and is involved in 6–15% of children's fracture. Of these injuries, 25–35% have been reported to result in some shortening or deformity, but in only 10% are the deformities sufficiently severe to lead to functional problems. The problem of repair of a demaged growth plate in children has never been adequately solved. The purpose of this study is to clarify that allograft of cultured chondrocytes can survive in the growth plate defect and can prevent the angular deformity by avoiding the formation of bone bridge. The chondrocytes were obtained from the rib cartilage of rabbit weighing 500g. The chondrocytes were cultured by socalled micromass culture method. The rabbits were divided two groups; the group I in which medial proximal tibial growth plate was destroyed, and the group II in which the cultured chondrocytes were transplanted into the right medial proximal tibial physeal defect. Each group has 10 rabbits. The tibial growth was observed grossly, radiologically and histologically until 16 weeks after graft. The angular deformity was observed from 3 weeks after operation and histologically the fusion of growth plate was observed in all of group I. In group II, there were no angular deformity and no fusion of growth plate in 7 out of 10 rabbits. Allografted cultured chondrocytes survived and produced matrix in the physeal defects. Through this study it was inferred that allograft transplantation of cultued chondrocytes in the iatrogenical physeal defect is a useful method to keep the physeal growth without cessation. However, further studies will be necessary to prove that the longitudinal growth potential resides in the transplanted chondrocytes as growth plate cartilage.