[Biomechanical and biological bases of the third type of fracture healing]

Fracture healing may take place in the form of direct repair by laminar bone with a little callus, and it is called the third type of fracture healing or an optimal form of fracture healing. The results of stress analysis of electric measurements on the femoral shaft after osteotomy, which is fixed with plates, in simulation to load tests demonstrated that if the design of the plate is reasonable, even the load is added over twice of the body weight, the compression stress subjected to osteotomy site may be greater than that or nearly the same as that in the intact bone. In another animal experiment, a model of the third type of fracture healing of the canine tibial shaft osteotomy fixed with trapezoid compression plate (TCP) was established with polychromatic sequential labeling. The results of 3-point bending tests indicated that the strength and the rigidity of the healing bone may be greater than normal region. The mechanical and biological bases of the third type of fracture healing are provided by these experiments.