AbstractObjectiveTo investigate the association between surgeon volume and patient outcomes after elective shoulder replacement surgery to improve patient outcomes and inform future resource planning for joint replacement surgery.DesignProspective cohort study.SettingPublic and private hospitals in the United Kingdom, 2012-20.ParticipantsAdults aged 18 years or older who had shoulder replacement surgery, identified in the National Joint Registry, with linkage of participants in England to Hospital Episode Statistics data.Main outcome measuresThe main outcome measure was revision surgery. Secondary outcome measures were reoperation within 12 months, serious adverse events, and prolonged hospital stay (>3 nights) after shoulder replacement surgery.Results39 281 shoulder replacement procedures undertaken by 638 consultant surgeons at 416 surgical units met the inclusion criteria and were available for analysis. Multilevel mixed effects models and restricted cubic splines were fit to examine the association between a surgeon’s mean annual volume and risk of adverse patient outcomes, with a minimum volume threshold of 10.4 procedures yearly identified. Below this threshold the risk of revision surgery was significantly increased, as much as twice that of surgeons with the lowest risk (hazard ratio 1.94, 95% confidence interval 1.27 to 2.97). A greater mean annual surgical volume was also associated with a significantly lower risk of reoperations, fewer serious adverse events, and shorter hospital stay, with no thresholds identified. Annual variation in surgeon volume was not associated with any of the outcomes assessed.ConclusionsIn the healthcare system represented by these registry data, an association was found between surgeons who averaged more than 10.4 shoulder replacements yearly and lower rates of revision surgery and reoperation, lower risk of serious adverse events, and shorter hospital stays. These findings should inform resource planning for surgical services and joint replacement surgery waiting lists and improve patient outcomes after shoulder replacement surgery.