Effect of Growth Hormone on Early Bony Regeneration in Distraction Osteogenesis

ABSTRACT

The purpose of this project was to study the effect of growth hormone on early bony consolidation in distraction osteogenesis of a dog mandible. Sixteen dogs were used for this study. An external distraction device was applied to the mandibular body and the mandibular distraction was started five days after the operation at a rate of 1 mm per day up to a 10-mm distraction. Dogs in the growth hormone group received a daily subcutaneous injection of 1 IU of recombinant human growth hormone per kilogram of body weight per week. Normal saline was injected in the control group. Bone mineral density was higher in the growth hormone group than the control group in the whole period. Bone mechanical strength was 300% higher in the growth hormone group than that in the control group. However, results were more suggestive than conclusive. Upon histological examination, the formation of a substantial amount of active woven bone was observed throughout the distracted zone in 6 weeks in the growth hormone group. In the control group, new bone was generated from the edge to the center of the distracted zone. But, the most central area of the distracted zone was filled with fibrous tissue in 6 weeks. In conclusion, growth hormone appears to be effective in early bony consolidation in distraction osteogenesis.