Effect of pelvic rotation on the placement angle of acetabular prosthesis in total hip arthroplasty

Abstract

To study the effect of pelvic rotation in three-dimensional direction on the actual placement angle of acetabular prosthesis in total hip arthroplasty. Pelvic CT imaging data of normal adults were collected, and three-dimensional reconstruction of pelvic acetabulum was performed with computer software to simulate the rotation of the pelvis around X, Y and Z axes perpendicular to the sagittal, transverse and coronal planes of the human body. Radiographic inclination(RI) and radiographic anteversion (RA) of the acetabular cup were measured when the acetabular prosthesis was implanted at a standard angle. The correlation analysis was used to quantify the relationship between the rotation angle of each axis and the actual angle of acetabulum. The pelvic rotation along the X-axis and Y-axis had little effect on the RA of the acetabulum, but had a great influence on the RI and showed a linear correlation. The regression equations were RA=0.682 4X+10.256(r²=0.308 4) and RA=-0.714 1Y+10.424(r²=0.999 8). The pelvic rotation along the Z-axis had little effect on the RA, but had a linear correlation with the RI, and the regression equation was RI=1.0Z+46(r²=1.0). The anteroposterior rotation of the pelvis or the longitudinal rotation along the body significantly affected the acetabular anteversion, but had little effect on the abduction angle. On the contrary, the left and right deviation of the pelvis on the coronal plane could significantly affect the acetabular anteversion angle, but did not affect its anteversion angle.