Summary

Using a Markov model the value of technology to balance a TKA effectively is assessed; value is dependent on improvement in QALY, revision rate reduction and annual surgical case volume

Abstract

Introduction

Most early aseptic revision total knee arthroplasty (TKA) can be attributable to technical errors at the time of initial surgery. Instability remains a leading cause of early failures. While technology can minimize these errors by giving the surgeon real time information on alignment and knee joint balance, the clinical value remains undetermined. Therefore, the purpose of this study is to determine the value of achieving a balanced knee at the time of TKA to the surgeon, hospital/ ambulatory surgery center (ASC), and the patient.

Methods

A Markov model was developed to determine the value, arising from reduced revisions and improved outcomes, associated with improved TKA joint balance. A hypothetical patient cohort, with an average age of 67 years old, was modelled for 5 years post-op. The unit of measurement for cost and utility was the US dollar and quality-adjusted life-year (QALY), respectively. Cost-effectiveness was determined using an Incremental Cost Effectiveness Ratio (ICER) of $50,000/QALY. ICER values were calculated based on surgeon volume (yearly TKAs: low = 40, medium = 73, high = 163), hospital volume (low = 200, medium = 500, high = 700), and ASC volume (low = 19, medium = 87, high = 329). Differences in QALY outcome and revision rate were also dependent on surgeon volume. A sensitivity analysis was performed to evaluate the influence of QALY improvement (Delta-QALY) and Revision Rate Reduction (Delta-Revision) on value generated compared to a conventional TKA cohort. The impact of each variable was evaluated by iterating over a range of Delta-QALY (0-0.046) and Delta-Revision (0-30%), then calculating the value generated while satisfying the ICER threshold. Finally, the impact that varying surgeon and hospital/ASC case volumes on outcomes, was analyzed.

Results

The total value of a balanced knee for the first 5 years was $8 750, $6 575 and $4 417, for low, medium and high-volume surgeons, respectively. Change in QALY accounted for >90% of the value gain with a reduction in revisions making up the rest. The total value of a balanced TKA cohort is $350 000, $480 000, and $720 000 for low, medium and high-volume surgeons, respectively. Medium and high-volume hospitals and ASCs showed improved value of >$750K over the cohort assuming average improvements in revision rates and QALY.

Conclusions

The value of improved TKA joint balance was quantified using a MARKOV model simulation. Increase in value through superior balance is dependent on improvement in QALY, revision rate reduction and annual surgical case volume. Over a 5-year period, change in QALY had the greatest impact on value compared to reduction in revision rate. The derived model can provide healthcare providers with insight into the expected increase in value received through delivering a balanced joint, per improvement in patient outcomes and revision rate reduction.