Patient specific cup anteversion in total hip arthroplasty: a computed tomography study investigating the use of the transverse acetabular ligament to control cup placement

Application of transverse acetabular ligament in total hip arthroplasty: a systematic review

INTRODUCTION

In total hip arthroplasty (THA), the correct position of the acetabular component directly determines the outcome of the surgery, or the success of the surgery. Therefore, how to accurately locate the position of the acetabular component has become a very critical step in THA. As an important anatomical structure of the hip joint, the transverse acetabular ligament (TAL) is helpful for acetabular component orientation in THA. The aim of this systematic review was to investigate application of TAL in THA.

MATERIALS AND METHODS

A systematic literature search of PUBMED, EMBASE, and Cochrane Library was performed (January and February 2023) using keywords "total hip arthroplasty," "total hip replacement," "total hip replacements," "total hip arthroplasties," "total hip prosthesis," and "transverse acetabular ligament" in all possible combinations. Reference lists of included articles were reviewed. Study design, surgical approach, patient demographics, TAL identification rate, appearance of the TAL, anteversion and inclination angle and rate of dislocations were recorded.

RESULTS

In total, 19 studies met the screening criteria. Study designs were prospective cohorts (42%), retrospective cohorts (32%), Case series (21%), and randomized controlled trial (5%). Twelve of the 19 (63.2%) studies investigated the application of TAL as an anatomical landmark for locating acetabular component position in THA. Analysis revealed that TAL is a reliable anatomical landmark for acetabular component orientation within the safe zone in THA.

CONCLUSIONS

TAL can reliably be used to align the acetabular component in the safe zone for anteversion and inclination in THA. However, TAL has individual variation influenced by some risk factors. More randomized controlled studies with larger numbers of patients are needed to investigate the precision and accuracy of TAL as an intraoperative landmark in THA.

LEVEL OF EVIDENCE

IV.

Three-Dimensional Templating for Acetabular Component Alignment During Total Hip Arthroplasty

Appropriate placement of the acetabular cup is an important determinant of implant stability and longevity. Malposition of acetabular cups negatively influences prosthesis survival and leads to an increased dislocation rate. The objective of the study was to determine the role of 3-dimensional templating in obtaining accurate acetabular component placement in total hip arthroplasty. In this computed tomography-based study, the authors identified 93 patients who underwent primary total hip arthroplasty with computer-assisted navigation. Using 3-dimensional planning, the authors templated the acetabular component at an inclination of 40° and anteversion of 20°. To classify acetabular cup coverage by bone, the acetabulum was used as a clock face with the center of the transverse acetabular ligament (TAL) as 6-o'clock. Analyses revealed that 72% of cups were uncovered between 9- to 1-o'clock for right hips. On the left side, 88% of cups were uncovered between 11- to 3-o'clock. Across all hips, 74% of cups had a 1-o'clock position at the most lateral aspect. Further analysis revealed that 46% of acetabular cups had a teardrop at the same level of the most inferior aspect of the cup, whereas only 37% of cups had a teardrop above the inferior aspect of the cup. Finally, the acetabular component was aligned with the TAL in 76% of hips, retroverted to the TAL in 16%, and anteverted to the TAL in 8%. The current study demonstrates a useful gross intraoperative reference tool to standardize cup position without the need for additional equipment and reliance on anatomical landmarks. [Orthopedics. 2017; 40(4):e708-e713.].

An in vivo comparison of the orientation of the transverse acetabular ligament and the acetabulum

Aligning the acetabular component with the Transverse Acetabular Ligament (TAL) to ensure optimal anteversion has been reported to reduce dislocation rates. However, to our knowledge in vivo measurement of the TAL angle has not yet been reported in a large cohort of normal hips. CT scans of 218 normal hips were analyzed. The TAL and four acetabular rim anteversion angles were measured (superiorly to inferiorly) relative to the anterior pelvic plane. The mean TAL anteversion angle was 20.5° ± 7.0°, and the acetabular rim angles from superior to inferior were 11.0° ± 12.9°, 19.9° ± 8.8°, 20.9° ± 6.2° and 25.1° ± 6.2° respectively. Both the TAL and the acetabular rim were significantly more anteverted in females than in males. The TAL anteversion angle was comparable to the predominant orientation (central rim section) of the native acetabulum while the superior acetabulum was comparatively retroverted and the inferior was relatively more anteverted.