A new femoral component design based on the trabecular systems of the proximal femur.

This investigation presents a new design of the femoral component used in total hip arthroplasty. The design utilizes a tensile component which screws into the femoral stem from the lateral side of the femur. The potential advantages of utilizing such a component are 1) PMMA cement may be not needed to hold the implant in place, 2) better stress distribution in the region of the greater trochanter is achieved, 3) reduced stress levels in the implant, and 4) the femoral stem may be shortened to reduce the amount of reaming required. Two dimensional, plane stress finite element models of the proximal end of a normal femur, a femur with the new implant design, and a femur with a control Charnley-Cobra femoral component were developed. Loads simulating a one-legged stance were applied on the models. The normal and shear stresses, the octehedral shearing stress and the directions of principal stress were calculated for comparison with the normal femur. There was distinct improvement in bone stress distribution for the femur with the experimental implant as compared to the femur with the control prosthesis. The stress concentration normally observed in the mid-shaft area of the Charnley femoral stem was also not seen in the new design.