Fracture Healing in a Denervation and/or Nerve Ending Interpositioning Model in the Rat

Abstract

Background: In this experimental study, we aimed to determine the possible changes in fracture healing due to denervation and/or nerve ending interpositioning. Methods: 50 Wistar Albino type male rats were divided into three study groups. A standard transverse diaphysial fracture in the femurs of the same side of all subjects under anesthesia was created and the fracture were fixed intramedullarily. While preserving the structural integrity of the sciatic nerve in the first group, neurectomy to the nerve in the second group was performed. In the third group, following the sciatic nerve cut, the proximal end of the nerve were interposed the fracture line. After a 28-day observational period, the callus formation in the subjects was examined radiologically, biomechanically and histopathologically. Results: Among all groups, the third group subjects showed significant increase in radiological area measurements when they are compared to the second group rats. There was no significant difference in biomechanical measurements of fractured femurs of the three groups. In histopathological evaluations, it was observed that denervation had increased the thickness of the cartilage and the number of the chondrocytes and osteoclasts significantly but decreased the number of fibroblasts compared to the control group. In addition to the denervation nerve ending interpositioning increased the bone thickness and the number of the osteoblasts but decreased the number of the osteoclasts significantly. Conclusions: While radiological observations exhibit that nerve ending interpositioning has resulted more hypertrophic callus formation, histopathological evaluations led us to that denervation created partial (immature) callus formation and nerve ending interpositioning demonstrated larger but immature callus formation.