Optimal orientation of implanted components in total hip arthroplasty with polyethylene on metal articulation

Abstract

Background. In marly studies related to the total hip arthroplasty, it has been found that incorrect alignment of the total hip component is one of the major factors influencing mechanical failures. Although various recommendations for cup orientation have been presented, there were few studies that Seek to determine a proper orientation of the implants based oil the human motion data. The objective of this study is to determine all optimum orientation of the hip implant considering various daily activities. Methods. Firstly, the cup orientations free of impingement were Calculated for a given set of implant geometric parameters and file required range of motion for daily activities measured ill 10 subjects. Next, file optimum values for the cut) orientation and stem anteversion avoiding impingement and minimizing cup wear were determined for the proposed motion criteria. Findings. Different CLIP orientation was obtained its optimum for each combination of the neck angles (40 degrees and 50 degrees) and oscillation angles (120 degrees and 135 degrees). The corresponding optimum stem anteversion was also different when different neck angle was used. Interpretation. As the margin for the impingement-free orientation of the Clip was small, the optimum cup orientation and stem anteversion should be adopted specific for each combination of the neck angle and oscillation an-le. (C) 2008 Elsevier Ltd. All rights reserved.