Anatomical alignment of the acetabular component using transverse acetabular ligament in total hip replacement: a prospective cohort study.

Optimal positioning of the acetabular component is crucial in total hip replacement surgery to minimize postoperative dislocation rates. The transverse acetabular ligament (TAL) has been proposed as a useful anatomical landmark for cup orientation. This prospective cohort study included 122 patients who underwent total hip replacement at E Hospital, Hanoi, between January 2021 and December 2022. Orientation angles of the TAL and acetabulum were assessed preoperatively using CT with multiplanar reconstruction and MRI arthrography, and intraoperatively with a handmade protractor developed at our institution. The mean anteversion of TAL on CT and MRI was approximately 10°, with a mean inclination of 45-46°. Intraoperatively, the mean TAL anteversion was 10.2° and the acetabular anteversion was 12.0°, while the mean TAL inclination was 44.9° and the acetabular inclination 41.9°. These findings demonstrate significant correlations between TAL orientation and acetabular alignment across imaging and intraoperative measurements. TAL is a readily identifiable landmark, and its use can facilitate accurate, patient-specific acetabular cup positioning within the safe zone, thereby enhancing surgical outcomes.