Dynamic change of acetabular component position in total hip arthroplasty based on the spinopelvic classification: a prospective radiographic study.

AI in the sitting position was lower in patients with normal spinal alignment and stiff spine despite larger RA in the standard anteroposterior radiographs. Consequently, with more anteversion in the normal spinal alignment and stiff spine group, spinopelvic parameters can help guide cup placement to prevent short-term dislocation post-THA.