Background: The purpose of this study was to compare the
cost-effectiveness of unicompartmental knee arthroplasty as an alternative to
total knee arthroplasty in patients with degenerative arthritis limited to
either the medial or lateral compartment.
Methods: A decision model was created for the treatment of end-stage
unicompartmental knee arthritis. A literature review was used to identify
possible outcomes and their probabilities following treatment with either
unicompartmental or total knee arthroplasty. Each outcome was weighted for
quality of life with use of a utility factor, and effectiveness was expressed
in units of quality-adjusted life years. Gross costs were estimated from
Medicare reimbursement data for the relevant Current Procedural Terminology
and Diagnosis-Related Group codes.
Results: Sensitivity analysis demonstrated that the
cost-effectiveness of unicompartmental knee arthroplasty is dependent on the
assumption that its durability and functional outcomes approach those of total
knee arthroplasty. Specifically, it is necessary for the survival of
unicompartmental implants to be within three to four years of the assumed
survival of total knee implants for unicompartmental arthroplasty to remain a
cost-effective alternative. Under these assumptions, the use of
unicompartmental arthroplasty is a cost-effective choice as it results in
incremental gains in effectiveness at a cost of less than $50,000 (in 1998
United States dollars) per quality-adjusted life year gained.
Conclusions: This study supports unicompartmental knee arthroplasty
as a cost-effective alternative for the treatment of unicompartmental
arthritis when the durability and function of a unicompartmental replacement
are assumed to be similar to those of a primary total knee replacement. This
suggests that, with appropriate patient selection, the currently available
literature supports unicompartmental arthroplasty as a cost-effective
alternative to total knee arthroplasty.
Level of Evidence: Economic and decision analysis, Level
II. See Instructions to Authors for a complete description of levels of