Abstract
(1) Rabbit femurs were operated on to immobilize them with plates and screws, or intramedullary nails. Bone morphometric studies were carried out on these femurs. (2) Mechanical breaking studies were performed in these femurs using TENSILON R.T.M. 1-T. (3) Dog radii were fractured experimentally. External fixation was applied to a fractured radius using a Dynamic Axial Fixator. Trabecular bone specific volume and relative osteoid volume were measured by bone morphometric technique. (4) The healing processes of human tibial and femoral fractures were clinically investigated by radiology. The cortical porosity ratio was higher in the plating group than in the intramedullary nailing group. Respectively results were : (1) The cortical porosity ratio increased with increasing thickness. (2) The maximum loading level was higher and the gradient of the curve was steeper in the thin plate group than in thick plate group. (3) The appropriate time to bear axial load was concluded to be reasonable at two weeks after fracture. (4) So-called primary fracture healing was evident in only a few cases. In intramedullary nailing group, fracture healing was mainly by bridging callus. This mode of healing was more distinct in cases in which the zone around the nail and/or screw was radiolucent. In the conservatively treated group, fracture healing was by uniting of developing callus formation.
