Sciatic nerve injury and its effect on bone regeneration in distraction osteogenesis zone in rat / 中华显微外科杂志

ABSTRACT

Objective:To evaluate the effect and mechanism of bone regeneration in distraction osteogenesis zone after the repair of sciatic nerve in rats.Methods:Between January 2021 and August 2021, 60 healthy adult male Sprague-Dawley rats were divided randomly into 3 groups Group A, B, and C. In groups B and C, right sciatic nerve transection and anastomosis were performed. Then after 8 and 12 weeks, the 3 groups were treated with extension external fixation (Ilizarov technique) of right femur osteotomy to make distraction osteogenesis model. Electrophysiological changes of peripheral nerves were monitored by electromyography (EMG) pre-and postoperatively in all the femoral lengthening rats. The formation of callus was examined by X-ray every week after operation. The rats were sacrificed on 2nd, 4th, 6th weeks after the bone transport operation. Four-point bending test and histological staining examination were carried out to determine the osteogenesis in the distracted area. SPSS 21.0 was used for statistical analysis. Data of measurement were expressed as (Mean±SD). A non-parametric test was used to assess the statistical difference between groups. Graphs were plotted by GraphPad Prism 8.0 and considered statistically significant when P<0.05. Results:The results of Sciatic nerve function index (SFI), Compound muscle action potential (CMAP) and Motor nerve conduction velocity (MNCV) in group A were better than the group B and group C in both of before and after the surgery. At the 2nd and 4th weeks of the consolidation stage, X-ray showed that bone formation in group B was superior to groups A and C; HE and Safranin O staining showed that local capillary and cartilage formation in group B was significantly more than in groups A and C; Immunohistochemical staining showed that the expression levels of Osteopontin(Opn) and Osteocalcin(Ocn) in the distraction area of group B were higher than that of groups A and C. At the 6th week of the consolidation stage, the four-point bending test showed that the bone quality of group B was better than groups A and C. The differences of the results between groups shown above had statistical significance ( P<0.05). Conclusion:Bone regeneration in the distraction area of the bone lengthening group with sciatic nerve injury was better than that of the bone lengthening group without a never injury. This might be in relation to the fact that a distractive osteogenesis caused the secondary injury to the repaired nerve. The electrophysiological results showed that periodic changes took place in the repaired sciatic nerve caused by the stretch of femoral lengthening, and the injurious changes of sciatic nerve would be gradually relieved in 6th week after surgery.