OBJECTIVES

Unicompartmental knee arthroplasty (UKA) is a treatment option for single-compartment knee osteoarthritis. Robotic assistance has been shown to enhance the accuracy of bone preparation, implant position and improve survival rates of UKA, however its cost-effectiveness is unknown. This study assessed the cost-effectiveness of r-UKA compared to t-UKA method in patients with osteoarthritis.

METHODS

We developed a 5 year three state (revisions, re-revisions and mortality) Markov model to evaluate the expected costs and outcomes of the two strategies in 100 patients, mean age 64 years from the US payer’s perspective (Medicaid). We assumed a case volume of 100 patients per year and used a discount rate of 3%. Revision rates for t-UKA were taken from the British National Joint Registry (1.23%) and rates for r-UKA (0.8%) were obtained from a retrospective cohort study (N=128) and follow up 2.3 years. Univariate sensitivity analyses (SA) were conducted to verify the model’s robustness.

RESULTS

r-UKA was more costly $7,927,782 compared to $7,810,443 for t-UKA and had fewer revisions 4 compared to 16. r-UKA was associated with an incremental cost of $117,339 but resulted in 12 fewer revisions for 100 treated patients. The estimated cost per revision avoided was $9,945. SA showed that results did not differ by age or gender but were more favourable for those below 55 years. Extending the time horizon of the analysis resulted in r-UKA being cost-saving over 7 years. Cost effectiveness also depended on case volume and 32 cases needed to be seen per year for r-UKA to be cost effective at a willingness to pay threshold of $50,000 per revision avoided.

CONCLUSIONS

r-UKA is cost-effective compared with t-UKA over a 5 year period and becomes cost saving beyond 7 years. Results are dependent on case volumes and favours younger age groups.

*NAVIO™ System (Smith & Nephew, Pittsburgh, PA, USA)