Costal cartilage transplantation for treatment of growth plate injury in a rabbit model

OBJECTIVES The purpose of this study is to evaluate the effects of allogenic costal cartilage transplantation on preventing bony bridge formation and angular deformities for the treatment of partial growth plate injury using a rabbit model. METHODS An experimental model of partial growth injury was created by resecting the medial part of the proximal tibial growth plate in male six-week-old New Zealand White rabbits. The rabbits were divided into four groups: no surgery; no transplantation; bone wax transplantation; and allogenic costal cartilage transplantation. The angular deformities of the tibia and bony bridge were analysed using radiographs and microcomputed tomography, and the repair of the injured growth plate cartilage and bony bridge formation rate were histologically evaluated. RESULTS On radiographic evaluation, the varus deformities in the costal cartilage group were significantly improved compared with the no transplantation group at four and eight weeks after operation and with the bone wax group at eight weeks after operation. Micro-computed tomography showed that the bony bridge formation was prevented in the bone wax and costal cartilage groups. Histological findings showed that the bony bridge formation in the bone wax and costal cartilage group was decreased. In addition, the growth plate was continuous and stained with safranin O and immunohistochemically stained for type II collagen. CONCLUSION Transplantation of costal cartilage improved angular deformities and decreased bony bridge formation in the partial growth plate injury. Costal cartilage might be a suitable graft for the treatment of growth plate injury.