# Acetabular Component Positioning Using the Transverse Acetabular Ligament as an Anatomical Landmark in Primary Total Hip Arthroplasty: A Prospective Study

## TL;DR

This study shows that using the transverse acetabular ligament as a guide during hip replacement surgery helps achieve accurate implant placement, improving outcomes.

## Contribution

The study introduces the transverse acetabular ligament as a reliable anatomical landmark for acetabular cup positioning in primary total hip arthroplasty.

## Key findings

- Using the TAL resulted in a mean inclination of 43.4° and anteversion of 20.8°, within the safe range.
- The technique was statistically significant in achieving optimal cup orientation.
- AVN was the most common indication for surgery among the studied patients.

## Abstract

Introduction

Total hip arthroplasty (THA) is a well-established procedure aimed at relieving pain and enhancing mobility in patients suffering from various hip pathologies, such as avascular necrosis (AVN), post-traumatic arthritis, ankylosing spondylitis (AS), and juvenile rheumatoid arthritis (RA). Precise placement of the acetabular cup is critical to reduce joint wear, dislocation, and component loosening, ultimately enhancing patient outcomes. The optimal positioning of the acetabular cup involves anteversion between 5° and 25° and inclination between 30° and 50°. The transverse acetabular ligament (TAL) has been proposed as a reliable anatomical landmark to guide cup placement in primary THA. This study evaluates the accuracy of acetabular component positioning using TAL as a reference by analyzing post-operative inclination and anteversion angles via CT scans.

Methodology

A prospective study was conducted at the Department of Orthopaedics, Vydehi Institute of Medical Sciences and Research Centre, Bengaluru, India, involving 27 patients (22 males, 5 females) aged 18-80 years undergoing primary THA with TAL as the guiding landmark. Patients with revision hip arthroplasty, prior acetabular fractures, or surgeries around the hip were excluded. During surgery, the acetabular cup was aligned parallel to the TAL using the posterolateral approach. Post-operative CT scans were performed to assess the inclination and anteversion angles. Descriptive statistical analysis was conducted using IBM SPSS Statistics for Windows, Version 23 (Released 2016; IBM Corp., Armonk, New York, United States) with significance set at p < 0.05.

Results

The mean inclination angle measured post-operatively was 43.4° ± 4.5°, while the mean anteversion angle was 20.8° ± 4.4°. These values were found to be statistically significant at a 1% level of significance (p < 0.001). The majority of patients (55.7%) underwent THA due to AVN, followed by post-traumatic arthritis (18.6%), AS (11.3%), RA (11.3%), and neck of femur (NOF) fracture (3.1%). The results demonstrate that using TAL as a landmark provides a reliable technique for achieving optimal acetabular cup orientation.

Conclusion

The use of the TAL as an anatomical guide during THA effectively positions the acetabular component within the recommended safe zones of inclination and anteversion. This technique offers a reliable, reproducible method for improving surgical outcomes and minimizing post-operative complications. Further research with larger cohorts and multi-center trials is recommended to validate these findings.