Abstract
Introduction
Analysis of registry data shows that few units achieve results better than 99·98% control limits. Implant selection is considered a predictor of outcome variation in joint replacement. We analysed the outcomes of a unit with statistically “better than expected” results and compared to all other units within the National Joint Registry for England, Wales, Northern Ireland and Isle of Man (NJR). We sought to determine whether improved implant survival following primary total hip replacement (THR) is a centre effect or mediated by implant selection.
Methods
We identified 664,761 THRs in the NJR. The exposure was the unit in which the THR was implanted and the outcome all-cause revision. Net failure was estimated using Kaplan-Meier and adjusted analyses used flexible parametric survival analysis.
Results
The crude 10-year revision rate for THRs was 1·7% (95% CI: 1·3, 2·3) in the exemplar centre and 2·9% (95% CI: 2·8, 3·0) elsewhere (log rank test P<0·001). Of 6,230 THRs performed in the exemplar centre, 99·9% used the same femoral stem. After restricting analyses to this stem, crude survival from other units was 2·3% (95% CI: 2·2, 2·4) (log-rank test p=0·05). Age and sex adjusted analyses, restricted to the same stem/cup combinations as the exemplar centre, show no demonstrable difference in restricted mean survival time between groups (p=0·28).
Conclusion
These results suggest the “better than expected” performance of an exemplar centre can be replicated by adopting key treatment decisions, such as implant selection. These decisions are easier to replicate than technical skills or system factors. This is an important and easily applicable lesson for all branches of medicine highlighting the potential pre-eminence of decision making over technical expertise.
