Effects Of Sympathetic Innervation Loss On Rat Mandibular Distraction Osteogenesis

Distraction osteogenesis (DO) is an effective technique which induces new bone along the vector of pull at the broken end of bone. It was applied first in orthopedic surgery for correction of limb length discrepancy, and now utilized in the treatment of craniofacial micrognathia and bone defect widely. Although many technical problems in DO has been solved, there is still have room for improvement. Meanwhile, such technology also provides an ideal model for deep study of bone tissue regeneration and repair.The regulating effect of sympathetic nerve system on bone mass is always the hotspot in clinical and basic research. However, the focus lies in the research of effects of nervous system on limbs bone fracture healing and osteoporosis. Distraction osteogenesis as endogenous tissue engineering bone has different"osteanagenesis"process with common fracture healing. The effects of sympathetic nerve system on new bone formation in DO is worthy for highlighting. However, the report on such aspect is not available. Jaw sympathetic nerve is governed by cervical sympathetic trunk. This project plans to research the effects of sympathetic innervation loss in DO on new bone formation, thus to provide important evidence for clarifying the mechanism of nervous system in osteogenesis, and contribute to the improvement of DO technique. Three parts were included in this study:1 To create a rat model of mandibular distraction osteogenesis.Objective:To create a rat model of mandibular distraction osteogenesis. Methods: 6 male Sprague-dawley rats were anaesthetized, complete osteotomies were created on the right hemimandibles and customized distraction decices attached. After 5 days latency period, distraction was activate at 0.2mm BID for 10 days. The rats were sacrificed at consolidation time of 1, 14 and 28 days, and then the regenerated callus underwent general observation and histomorphome- tric. Results: All the 6 rats completed the experiment, the right mandibular was lengthened successfully, the length increased was 65% of what was predicted. The distraction gap of all mandibles was filled with fiber osteoid organization first, and then to mature bone. Trabecular bone became mature gradully, from woven bone to lamellar bone. Conclusion: These data validate our rat mandibular distraction model.2 To create a rat model of sympathetic innervation loss in craniofacial.Objective:To create a rat model of sympathetic innervation loss in craniofacial by transaction of cervical sympathetic trunk (TCST). Methods:6 adult male Sprague-dawley rats, divided into three equal groups. Group 1 rats had sham surgery which only detach bilateral superior cervical ganglion (SCGx) but not remove; group 2 had the right SCGx removed; group 3 had bilateral SCGx removed. Successful removal was confirmed by observation of Horner's syndrome on the operated side (ptosis of the eyelid). A ganglion was resected and underwent histological observation. Results: Group 1 didn't demonstrate Horner syndrome, group 2 subjected to right TCST demonstrated Horner syndrome of the right eyelid, and the group 3 underwent bilateral TCST demonstrated bilateral Horner syndrome. Conclusion: We can create a rat model of sympathetic innervation loss in craniofacial by sympathectomy.3 The effect of sympathetic innervation loss on rat model of mandibular distraction osteogenesisObjective: To evaluate the effect of sympathetic innervation loss on rat model of mandibular distraction osteogenesis. Methods: 30 adult male Sprague-dawley rats were divided into two groups randomly. Experimental rats had bilateral TCST and then underwent right mandibular DO, control rats only underwent right mandibular DO. The rats were sacrificed at consolidation time of 1, 14 and 28 days for Micro-CT bone morphology analysis and histomorphometric. Results: The groups of sympathetic innervation loss presented a greater amount of mineralized bone trabeculae and more regular arrangement compared to the Control. Group in the distracted area. Conclusion: The sympathetic innervation loss can accelerate callus mineralization in distraction osteogenesis.