Acetabular component placement is a crucial determinant in outcomes following total hip arthroplasty. Malalignment predisposes to impingement, increased rate of dislocation, wear of the bearing, osteolysis, and revision after THA. The study aimed to determine how reliably the transverse acetabular ligament could be identified during primary THA and its validity as a guide for acetabular component placement within the safe zone in THA.
Materials and Methods: In this prospective study, 52 patients undergoing total hip replacement during the period from August 2014 to January 2017 in Bowring and Lady Curzon Hospital and Victoria Hospital, Bangalore were included; in whom the acetabular component positioning was done using transverse acetabular ligament as a guide. 22 cases were done via modified lateral approach, while 30 cases were done via posterolateral approach. Acetabular reaming was done by placing the reamer parallel to TAL, starting with a reamer the diameter of the native femoral head. Following serial reaming, the final component is placed such that TAL should embrace it. The anteversion and inclination/abduction of the acetabular component was measured post-operatively by anteroposterior radiographs.
Results: TAL was identified in all cases, irrespective of the surgical approach used. The mean planar anteversion was 19.84° (± 3.8°), and the radiological inclination was 43.65° (± 3.2°). Anteversion was within the safe zone in 96.15% (n=50) of the cases, while inclination was within the safe zone in 84.6% (n=44) of the cases.
Conclusion: Transverse acetabular ligament can be reliably used as a guide in achieving patient-specific anteversion of the acetabular component within safe zone. A simple, reproducible technique, devoid of complex instrumentation. However, as inclination is influenced by factors in addition to TAL, TAL alone cannot be used for determining inclination of acetabular component positioning.