Analysis of a femoral hip prosthesis designed to reduce stress shielding

The natural stress distribution in the femur is significantly altered after total hip arthroplasty (THA). When an implant is introduced, it will carry a portion of the load, causing a reduction of stress in some regions of th e remaining bone. This phenomenon is commonly known as stress shielding. In response to the changed mechanical environment the shielded bone will remo del according to Wolff's law, resulting in a lass of bone mass through the biological process called resorption. Resorption can, in turn, cause or con tribute to loosening of the prosthesis. The problem is particularly common among younger THA recipients. This study explores the hypothesis that throu gh redesign, a total hip prosthesis can be developed to substantially reduc e stress shielding. First, we describe the development of a new femoral hip prosthesis designed to alleviate this problem through a new geometry and s ystem of proximal fixation. A numerical comparison with a conventional intr amedullary prosthesis as well as another proximally fixed prosthesis, recen tly developed by Munting and Verhelpen (1995. Journal of Biomechanics 28(8) , 949-961) is presented. The results show that the new design produces a mo re physiological stress state in the proximal femur. (C) 2000 Elsevier Scie nce Ltd. All rights reserved.