The purpose of this study is to get more reliable biomechanical data on the changes in the periprosthetic strain after total hip arthroplasty on cadaveric pelvic ring, especially around the acetabular cup and to evaluate the strain patterns by performing finite element study.

We have done bilateral cementless total hip arthroplasty on cadaver pelvic ring. One acetabular subchondral bone was preserved and the other acetabular subchodral bone was removed during total hip arthroplasty. We evaluated the patterns of strain at periacetabular area by compressive load test using strain gauge. The 3-dimensional finite element model was constructed, and computer- simulated load tests were performed.

In case of preserving subchondral bone, strain distribution was more concentrated on the posterior and posterosuperior wall. In case of removing subchondral bone, strain distribution was more wide and strain values were larger, and the anterior portion showed maximal strain. The maximal strain values were below 150 microstrain by 25 kg load in single limb stance, but it was between 300-700 microstrain by 45 kg and 65 kg. The finite element analysis revealed the similar strain values obtained from the cadaveric load test, and the same change in the pattern of strain distribution according to the preservation or removal of the subchondral bone.

In cementless total hip arthroplasty, early partial weight bearing and preservation of subchondral bone seems to be preferable to preserve physiologic pattern of the strain distribution and to reduce the values of maximal strain.