Does the transverse acetabular ligament-guided cup anteversion fulfil the functional requirements in total hip arthroplasty?

Abstract

The transverse acetabular ligament (TAL) plays a pivotal role in determining cup anteversion during total hip arthroplasty (THA). Meanwhile, the kinematic alignment (KA) technique focuses on restoring the native hip anatomy and adjusting cup orientation based on the TAL. This study aims to investigate whether utilizing the TAL or TAL-based KA as a guide for aligning cup anteversion satisfies the functional requirements of THA. This retrospective study included 92 patients (107 hips; 40 men and 52 women). TAL anteversion was assessed using computed tomography scans. Radiographic inclination angles were standardized at 40°. The analysis involved comparing the ratios of TAL and TAL-based KA to determine their alignment with the criteria of the Lewinnek safe zone (LSZ), combined sagittal index (CSI) ante-inclination (AI) criteria, and patient-specific safe zone (PSSZ). The mean TAL anatomical anteversion (AA) angle was 18.90 ± 5.56°. No significant difference was observed between the left and right sides (<i>p</i> = 0.185). Men had an average TAL AA angle of 17.26 ± 5.09°, whereas women had 20.29 ± 5.61°, indicating a significant difference in TAL anteversion between sexes (<i>p</i> = 0.005). For TAL, 104 cups (97.2%) were aligned according to the LSZ criteria, while 54 hips (50.47%) met the CSI AI criteria. The PSSZ criteria were met by 20 hips (18.69%). The distribution of TAL-based KA was consistent with these results. The TAL or TAL-based KA for aligning cup anteversion does not consistently satisfy the functional requirements of THA. Level III.