Background: There is renewed interest in total ankle arthroplasty as
an alternative to ankle fusion in the treatment of end-stage ankle arthritis.
Despite a lack of long-term data on the clinical outcomes associated with
these implants, the use of ankle arthroplasty is expanding. The purpose of
this cost-effectiveness analysis was to evaluate whether the currently
available literature justifies the emerging use of total ankle arthroplasty.
This study also identifies thresholds for the durability and function of ankle
prostheses that, if met, would support more widespread dissemination of this
Methods: A decision model was created for the treatment of ankle
arthritis. The literature was reviewed to identify possible outcomes and their
probabilities following ankle fusion and ankle 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 charge and reimbursement data for the relevant codes.
The effect of the uncertainty of estimates of costs and effectiveness was
assessed with sensitivity analysis.
Results: The reference case of our model assumed a ten-year duration
of survival of the prosthesis, resulting in an incremental cost-effectiveness
ratio for ankle arthroplasty of $18,419 per quality-adjusted life year gained.
This reflects a gain of 0.52 quality-adjusted life years at a cost of $9578
when ankle arthroplasty is chosen over fusion. This ratio compares favorably
with the cost-effectiveness of other medical and surgical interventions.
Sensitivity analysis determined that the cost per quality-adjusted life year
gained with ankle arthroplasty rises above $50,000 if the prosthesis is
assumed to fail before seven years. Treatment options with ratios above
$50,000 per quality-adjusted life year are commonly considered to have limited
cost-effectiveness. This threshold is also crossed when the theoretical
functional advantages of ankle arthroplasty are eliminated in sensitivity
Conclusions: The currently available literature has not yet shown
that total ankle arthroplasty predictably results in levels of durability and
function that make it cost-effective at this time. However, the reference case
of this analysis does demonstrate that total ankle arthroplasty has the
potential to be a cost-effective alternative to ankle fusion. This reference
case assumes that the theoretical functional advantages of ankle arthroplasty
over ankle fusion will be borne out in future clinical studies. Performance of
total ankle replacement will be better justified if these thresholds are met
in published long-term clinical trials.
Level of Evidence: Economic and decision analysis, Level
II-1 (clinically sensible costs and alternatives; values obtained from
limited studies; multiway sensitivity analyses). See Instructions to Authors
for a complete description of levels of evidence.