The aim of this study was to compare unicompartmental and total knee replacement (UKR and TKR), emulating the design of the Total or Partial Knee Arthroplasty Trial (TOPKAT) using routinely-collected data. The primary outcome in TOPKAT was patient-reported outcomes, with secondary outcomes including post-operative complications and implant survival.
Five US and UK healthcare databases, part of the Observational Health Data Sciences and Informatics (OHDSI) network, were analysed. Opioid use from 91 to 365 days after surgery, as a proxy for persistent pain, was assessed. Post-operative complications (venous thromboembolism, infection, readmission, and mortality) were considered over 60 days following surgery and implant survival over five years following surgery. Propensity score matched Cox proportional hazards models were fitted for each outcome. Calibrated hazard ratios (cHRs) were generated for each database to account for observed differences in control outcomes and these were combined using meta-analysis.
In total, 32,379 and 250,377 individuals who received UKR and TKR were matched and included in the analysis. UKR was associated with a reduced risk of post-operative opioid use (cHR from meta-analysis: 0.81 (95% CI: 0.73 to 0.90)). UKR was also associated with a reduced risk of venous thromboembolism (cHR: 0.62 (0.36 to 0.95)), but little difference was seen for infection (cHR: 0.85 (0.51 to 1.37)) and readmission (cHR: 0.79 (0.47 to 1.25)). There was insufficient evidence to conclude there was a reduction in risk of mortality. UKR was also associated with an increased risk of revision (cHR: 1.64 (1.40 to 1.94)).
UKR was associated with a reduced risk of opioid use compared to TKR, which may indicate a reduced risk of persistent pain after surgery. UKR was associated with a lower risk of venous thromboembolism. UKR was also, however, associated with an increased risk of revision compared to TKR.