[Stress analysis following femoral shaft osteotomy fixed using various plates with different rigidities in a simulation test].

A pair of human cadaver femora were used for electric measurement under simulation-bearing test, which was performed on intact bone and osteotomy bone fixed by 3 types of plate with different rigidities respectively. The results indicated that the plates with uniform thickness did not adhere to the principle of identical strength. The stress was significantly greater between the two central screw holes. However, the device of trapezoidal plate conformed to the principle of identical strength, and the safety factors of it are proposed. The osteotomy site was subjected to compression stress in standing phase with load on both femora, but subjected to bending stress with load on single femur. The total compression stress at the osteotomy site was significantly greater than that on intact bone when the load was added to twice of the body weight with load on both legs. We believe that stress shielding can be overcome by using optimized plate and normal bearing.