Numerical Optimization Of The Canal Fit Of Cementless Femoral Prostheses

In this paper we present the theoretical and numerical basis of a computer based method of determining the optimum shape of standard femoral prostheses to provide the best possible fit to the anatomic range of human femora. Acceptable fits are selected on the basis of three criteria (i) a total "fit" score, (ii) restoration of femoral head position to within f 5 mm, and (U) an acceptable level of femoral neck osteotomy. In primary cementless hip replacement, it is predicted that custom prostheses will be required for 9% of cases if a system of only 7 sizes is used routinely and 4% of cases if a system of 8 sizes is routinely used, even if both systems are optimally designed.