Total hip arthroplasty (THA) can be performed using either femoral and acetabular components provided by the same manufacturer (matched components) or components from different manufacturers (unmatched components). We hypothesized that there would be no difference in outcomes following the use of unmatched compared to matched components.
Data from a nationwide joint registry, the New Zealand Joint Registry (NZJR), were analyzed to assess long-term outcomes of using unmatched implants in THA.
The NZJR has recorded a total of 108,613 primary THAs. We excluded combinations with less than 50 implantations, leaving 99,732 arthroplasties (90.5%). The unmatched group consisted of 24,537 (24.6%) THAs. Revision procedures were required in 3434 (4.6%) of the matched group, at a rate of 0.72/100 component years and 1078 (4.4%) of the unmatched group, a rate of 0.69/100 component years (P = .049). THAs with metal-on-metal or ceramic-on-metal bearings were overrepresented in the matched group. When analysis was repeated with these implants excluded, there was no longer a difference in revision rate between groups (4.0% revisions, 0.65/100 component years and 4.3% revisions, 0.67/100 component years [P = .742]).
Survival analysis showed 17-year survival for matched components and unmatched to be within 95% confidence intervals at all time points.
There was a small, statistically significant improvement in Oxford Hip Scores for the unmatched group compared with the matched group.
Data from the NZJR confirm that the use of unmatched components in THA has no adverse effect on outcomes.