ANALYSIS OF OPTIMAL RANGE OF SOCKET ORIENTATIONS IN TOTAL HIP-ARTHROPLASTY WITH USE OF COMPUTER-AIDED-DESIGN SIMULATION

A three-dimensional computer-aided design model of a total hip replace ment was used to study the effects of anteversion and abduction of the acetabular component and anteversion and varus-valgus angulation of t he femoral component on the range of hip flexion and extension that co uld be obtained without component impingement. Impingement of the comp onent was defined as impingement between the neck of the femoral compo nent and the edge of the acetabular component. To achieve an angle of hip flexion greater than 90 degrees and an extension angle greater tha n 30 degrees without component impingement, the optimal angulations we re found to be between 1 and 30 degrees of anteversion and 30 and 50 d egrees of abduction of the acetabular component, as well as 10 degrees of anteversion of the femoral component. When the valgus angulation o f the femoral component was reduced from 7 to 0 degrees, the allowable range of flexion without impingement increased under the same conditi ons of acetabular-component orientation and femoral-component antevers ion. Significant inverse correlations were found between the anteversi on angle of the acetabular component and both the lumbar lordosis angl e and the sacrohorizontal angle.