The roles of callus and mechanical stimulation in the fracture healing process

Abstract

To identifying the roles of callus and mechanical stimulation in the fracture-healing process, we produced defects in the iliac bones of dogs which subsequently induced callus. The callus was harvested 3 weeks of the defect was produced and transplanted into a transverse fracture site of the femur in the same dog. In addition, an alternative model with transplantation of iliac cancellous bone into the transverse fracture site was produced. Animals with only femoral transverse fractures were used as controls. The healing process was histopathologically investigated in each group of animals. In addition to the above experiments, 3 weeks of appropriate external fixation followed by axial dynamization with a telescoping mechanism in the fixator was investigated with the same animal model. Histopathologic observation was performed 7 weeks after fracture. We found that the bone healing process at 2 weeks was most advanced in the control group, followed by the cancellous-graft group, and was worst in the callus-transplantation group. However, the control and the cancellous groups showed almost the same degree of healing after 4 weeks. In addition, facilitation of the bone-healing process appeared to be affected more by vascular migration than by bone growth factors. Finally, bone maturation seemed to be facilitated by axial dynamization even in the bone-healing process after callus transplantation as well as in ordinary fracture healing and healing after cancellous transplantation. © 1997, The Showa University Society. All rights reserved.