Retrospective cohort study of the economic value of providing microprocessor knees to the population of Medicare fee-for-service K2 beneficiaries with a knee disarticulation/above knee amputation.

Background: Microprocessor knees (MPKs) improve the functional mobility, quality of life, and safety of individuals with a knee disarticulation or above knee amputation and are cost-effective when adjusting for quality-of-life years gained. However, few studies have been conducted on the K2 population, and to this point, the Centers for Medicare and Medicaid Services has not covered MPKs for the K2 population.

Objectives: The aim of this study was to determine the extent to which MPK provision to the K2 population is cost effective at the person and population levels. A secondary objective was to determine the effectiveness of MPKs at reducing injurious falls within the K2 population.

Study Design: A retrospective cohort study using Medicare fee-for-service claims data from the Centers for Medicare and Medicaid Services.

Methods: Propensity score weighting using inverse probability treatment weights was used to balance beneficiary characteristics and a generalized linear regression with log-link function and Gamma distribution was run to determine per-member-per-month cost and prosthetic device cost. A 10-year Congressional Budget Office-style score was conducted. A logistic regression was run for the fallers analysis.

Results: Microprocessor knee provision to K2 beneficiaries reduced injured fallers by 18.5% and resulted in medical savings of $1,351 per-member-per-month, amortizing the $25,075 difference between the MPK and nonmicroprocessor knee in 19 months. Providing MPKs to K2 users resulted in cumulative Medicare savings of $410.3 million over 10 years.

Conclusion: The MPK prosthetic device could provide meaningful safety benefits to the K2 population and result in fiscal savings to Medicare at both the person and population levels.