A Randomised Controlled Study Investigating the Effect of Patient Pelvic Positioning and Method of Acetabular Component Insertion on Acetabular Component Inclination During Total Hip Arthroplasty (THA).

Total Hip Arthroplasty (THA) is one of the most commonly performed orthopaedic operations worldwide. The main aim is overall improvement in levels of patient pain and mobility. Such surgery involves implantation of both an acetabular and femoral component. With the patient in the lateral decubitus position, the Orthopaedic Surgeon assumes that the pelvis is in a neutral position with respect to all three body planes at the time of acetabular component implantation. With regard to THA, the current orthopaedic literature demonstrates a clear relationship between acetabular component positioning, polyethylene wear and risk of dislocation. Problems with edge loading, stripe wear and squeaking are also associated with higher acetabular inclination angles, particularly in hard-on-hard bearing implants. The important parameters of acetabular component positioning are depth, height, version and inclination. Control of acetabular component inclination, particularly in the lateral decubitus position, is difficult and remains a challenge for the Orthopaedic Surgeon. Accurate implantation of the acetabular component within the 'safe zone' of radiological inclination is dependent on: Operative version Operative inclination Pelvic position (Primarily, but not exclusively, abduction / adduction.) This study aims to investigate the effect of patient pelvic positioning and method of acetabular component insertion on acetabular component inclination during Total Hip Arthroplasty (THA).