Cost-effectiveness of unicompartmental compared with total knee replacement: a population-based study using data from the National Joint Registry for England and Wales

Objectives: To assess the value for money of unicompartmental knee replacement (UKR) compared with total knee replacement (TKR). Design: A lifetime Markov model provided the framework for the analysis. Setting: Data from the National Joint Registry (NJR) for England and Wales primarily informed the analysis. Participants: Propensity score matched patients in the NJR who received either a UKR or TKR. Interventions: UKR is a less invasive alternative to TKR, where only the compartment affected by osteoarthritis is replaced. Primary outcome measures: Incremental quality-adjusted life years (QALYs) and healthcare system costs. Results: The provision of UKR is expected to lead to a gain in QALYs compared with TKR for all age and gender subgroups (male: <60 years: 0.12, 60–75 years: 0.20, 75+ years: 0.19; female: <60 years: 0.10, 60–75 years: 0.28, 75+ years: 0.44) and a reduction in costs (male: <60: £−1223, 60–75 years: £−1355, 75+ years: £−2005; female: <60 years: £−601, 60–75 years: £−935, 75+ years: £−1102 per patient over the lifetime). UKR is expected to lead to a reduction in QALYs compared with TKR when performed by surgeons with low UKR utilisation but an increase among those with high utilisation (<10%, median 6%: −0.04, ≥10%, median 27%: 0.26). Regardless of surgeon usage, costs associated with UKR are expected to be lower than those of TKR (