Increased Rate Of Dislocation Of Total Hip Arthroplasty With Cementless Implants: Accuracy Of Acetabular Inclination.

Abstract

Accurate positioning of acetabular component in total hip arthroplasty is essential for stability. There is some evidence that cementless components are more difficult to position than cemented and have a higher dislocation rate. Our aim was to obtain information about rates of dislocation from the National Joint Registry (NJR) of England and Wales and to compare accuracy of acetabular component position of cemented and cementless implants. Methods: We made an enquiry of the NJR regarding number of dislocations during 2004-9 and compared rates of dislocation for cemented and cementless implants. We examined 126 post operative radiographs at our institution, assessing the angle of acetabular inclination to determine if there was a difference in the number of implants positioned within <±5° of the target angle. Results: There was a significant difference in rate of revision for dislocation with cementless implants (262/69,822) compared with cemented (266/92,928; c=12.1, p<.001; odds ratio 1.35, 95% confidence interval 1.14 to 1.60). Discussion: The greater accuracy of acetabular component positioning of cemented implants with, perhaps consequent, higher rates of revision due to dislocation should be considered when selecting mode of fixation for THA.