Influences of different pelvic position on acetabular component angle in total hip replacement

Abstract

Objective To investigate the effect of pelvic position angle on the angle of acetabular prosthesis by computer navigation system. Methods Computer navigation technique was used to simulate total hip arthroplasty (THA) on the whole pelvis. The anteversion and abduction angle of acetabular prosthesis were measured when the pelvis rotated around horizontal axis, long axis and sagittal axis. Results With the increase of the angle of the pelvis on the horizontal axis, the angle of the acetabular prosthesis was linearly decreased (Y=-1.32X+1, r=-0.982, P<0.001) and the abduction angle showed a linear increase (Y=0.398X+3, r=0.975, P<0.001). The obliquity and abduction angle of the acetabular component increased linearly angle (Y=0.764X+2, r=0.998, P<0.001; Y=0.394X+4, r=0.975, P<0.001) with the increase of the backward inclination. With the increase of the rotation angle of the pelvis to the left in the long axis, the anteversion angle of the acetabular component increased linearly (Y=1.42X+21, r=0.985, P<0.001), and the abduction angle decreased linearly (Y=-0.67X+3, r=-0.976, P<0.001). With the increase of the right rotation angle of the pelvis, the anteversion and abduction angle of the acetabular component showed a linear increasing trend (Y=0.75X+2, r=0.997, P<0.001; Y=3.94X+4, r=0.990, P<0.001). With the increase of the sagittal axial oblique angle of the pelvis, the antegrade angle of acetabular prosthesis increased linearly (Y=0.39X+19, r=-0.993, P<0.001), and the abduction angle decreased linearly (Y=-0.75X+7, r=-0.964, P<0.001). The antegrade angle of acetabular prosthesis decreased linearly (Y=-0.11X+11, r= -0.990, P<0.001) with the increase of the right tilt angle of the pelvis, while the abduction angle increased linearly (Y=0.92X+4, r=0.994, P<0.001). Conclusion The change of pelvic position angle has great influence on the angle of acetabular prosthesis placement, suggesting that the different pelvic position is very important during operation. Computer navigation can reduce the influence of pelvic position angle on the angle of acetabular prosthesis placement. Key words: Arthroplasty, replacement, hip; Surgery, computer-assisted; Pelvis; Acetabulum