Study on design of the femoral stem of a total hip prosthesis.

A total hip prosthesis of superior strength and well fitted to the proximal femoral medullary canal of a typical healthy Japanese was made. Various types of hip prosthesis femoral stems were studied for strength. They included a Muller middle neck standard stem, a Charnley round back stem, an SOM stem, and one which we devised. First, proximal femoral X-ray films were taken of 72 healthy male lower extremities, 79 healthy female lower extremities, and 18 cadavour femura, all from Japanese over 60 years of age. Then, various measurements were made from these X-ray films, and 3 kind of prostheses (large, medium, and small) were made from SMo (SUS 316L). Second, a Muller, a Charnley, and an SOM prosthesis were constructed of SMo, and they were studied for their strength. Strain at the portion under the greatest strain was least in the prosthesis we devised