MIGRATION OF ACETABULAR COMPONENTS, INSERTED WITH AND WITHOUT CEMENT,IN ONE-STAGE BILATERAL HIP-ARTHROPLASTY - A CONTROLLED, RANDOMIZED STUDY USING ROENTGENSTEREOPHOTOGRAMMETRIC ANALYSIS

Twenty-one patients who had primary osteoarthrosis were managed with a bilateral total hip arthroplasty with insertion of a Charnley femoral component. In each patient, one hip was randomly allocated to have a Harris-Galante acetabular component inserted without cement, and the c ontralateral hip was treated with an all-polyethylene Charnley acetabu lar component fixed with cement. The clinical result was satisfactory in all patients. All forty-two hips were followed, with respect to mig ration of the acetabular component, with use of roentgenstereophotogra mmetric analysis for a median of twenty-seven months (range, twenty-th ree to forty-nine months). Each patient served as his or her own contr ol. Maximum migration in any direction was 1.7 and 2.1 millimeters, an d maximum rotation was 2.2 and 2.0 degrees for the Harris-Galante and Charnley acetabular components, respectively. There was no significant difference in migration between the two designs of acetabular compone nts (p = 0.98, p = 0.75, and p = 0.06 for the transverse, longitudinal , and sagittal axes, respectively). However, the Harris-Galante acetab ular components rotated significantly more than the Charnley acetabula r components around two of the three axes (p = 0.008, p = 0.08, and p = 0.03 for the transverse, longitudinal, and sagittal axes, respective ly). The Charnley hip implant has been used clinically for a long time , with successful results. Comparison of new designs of implants with the Charnley prosthesis is therefore important. Roentgenstereophotogra mmetric analysis provides a potential for detection of problems with f ixation at an early stage rather than afterlong-term follow-up. No maj or difference in terms of skeletal fixation was found between the two designs of components after short to medium-term follow-up.