Day case hip and knee replacement in England: a population-based cohort study using linked National Joint Registry and Hospital Episode Statistics data

Background:
In response to rising demand, disruptions from the COVID-19 pandemic, and the need for improved cost-effectiveness, the way hip and knee replacements are being delivered is rapidly changing. Increasingly, they are being performed as day case procedures without an overnight stay in hospital. This study assessed the safety of this for a national cohort of NHS-funded procedures in England.

Methods:
Data from the National Joint Registry, Hospital Episode Statistics, and Civil Registration of Deaths databases were linked to identify patients who underwent total hip replacement (THR) and total or unicompartmental knee replacement (TKR/UKR) in England between 2010 and 2022. Outcomes including 30-day readmissions, 90-day serious adverse events, and 1-year reoperations were compared between day case and one-day stay inpatients using adjusted flexible parametric survival models.

Results:
The study included 7485 day case and 60,747 one-day stay inpatient procedures. Day case surgery was associated with a higher risk of 30-day readmission for THR (adjusted relative risk (RR) 1.28, 95% CI 1.07 to 1.53) and TKR (RR 1.28, 95% CI 1.10 to 1.48). A learning curve was observed where the first 6-day case THRs and the first 4-day case TKRs per unit carried significantly higher readmission risk. There were no differences in 90-day serious adverse events. However, day case TKR was associated with an increased risk of reoperation within 1 year (RR 1.50, 95% CI 1.15 to 1.96; NNTH 84), most commonly manipulation under anaesthesia (MUA). No significant differences were found for UKR.

Conclusions:
Day case UKR appears safe. Day case THR is generally safe, and although there is a higher risk of readmission in the first six procedures at each unit, other safety outcomes are not different. However, day case TKR carries an increased risk of reoperation, mainly for MUA which is typically performed for postoperative stiffness.