A comparison of the surgical practice of potential revision outlier joint replacement surgeons with non-outliers: A case control study from the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man

BACKGROUND: The National Joint Registry for England, Wales, Northern Ireland and the Isle of Man (NJR) has monitored the performance of consultant surgeons performing primary total hip (THR) or knee replacements (KR) since 2007. The aims of this study were: 1) To describe the surgical practice of consultant hip and knee replacement surgeons in the National Joint Registry for England and Wales (NJR), stratified by potential outlier status for revisions. 2) To compare the practice of revision outlier and non-outlier surgeons.

METHODS: We combined NJR primary THR and KR data from 2008-2017 separately with relevant anonymised NJR outlier notification records. We described the surgical practice of outliers and non-outliers by surgical workload, implant choice, and patients' clinical and demographic characteristics. We explored associations between surgeon-level factors and outlier status with conditional logistic regression models.

RESULTS: We included 764,888 primary THRs by 3213 surgeons and 889,954 primary KRs by 3084 surgeons performed between 2008-2017. One hundred and eleven (3.5%) THR and 114 (3.7%) KR consultant surgeons were potential revision outliers. Surgeons who used more types of implant had increased odds of being an outlier (KR: OR/additional implant = 1.35, 95%CI 1.17-1.55; THR: OR = 1.12, 95%CI 1.06-1.18).

CONCLUSIONS: The use of more types of implant is associated with increased risk of being a potential revision outlier. Further research is required to understand why surgeons use many different implants and to what extent this is responsible for the effects observed here.