Clinical evaluation of growth potentiality of autogenous costochondral graft in Temporomandibular joint on New Zealand white rabbit- an experimental study

Background: Costochondral graft has been used as a substitute for a growth center in the damaged Temporomandibular joint (TMJ) in the growing children. But the relapse of the TMJ ankylosis along with facial deformity is the most common outcome after the surgery for the resorption or overgrowth of the graft. While an exploration of the human Temporomandibular joint seems to be unethical after reconstruction with an autogenous costochondral graft for study purposes, therefore we sought to determine the growth potential of the graft by clinical evaluation. Material and methods: An experimental study was done on 96 New Zealand white male rabbits, which were divided into batches. Each batch (total 2 batches) contained 24 experimental and 24 control rabbits of known ages and species; growing (3-4) and adult (12-18) months old. TMJ arthroplasty with a costochondral graft using either 1mm or 4 mm thickness of cartilaginous cap done in both age groups. Follow-up was done regularly in batches comparing with control up to 4th, 12th, and 24th weeks of surgery to find out any relationship of behavioral change, clinical presentation, and macroscopic growth of the graft. Results: There was a relationship among the rabbits with their behavioral change, clinical presentation, and presence of growth center in the graft. Growth was found in 60% cases, 40% was growing, and 20% in adults. Conclusions: Costochondral graft had a 60% growth potentiality. The failure rate of 40% may be due to some unknown factors. Grafts grew in a greater number of growing rabbits than adults. Long time follow-up had a strong role in the growth of the graft. In conclusion, clinical evaluation of the rabbit model provided a fair estimation of the growth process.