Background: Alternative bearing surfaces offer the potential to
reduce wear and improve implant longevity following total hip arthroplasty.
However, these technologies are associated with higher costs, the potential
for unintended consequences, and uncertain benefits in terms of long-term
survival of the implants. The purpose of this study was to evaluate the
cost-effectiveness of the use of alternative bearings in total hip
Methods: A decision-analysis model was constructed to estimate the
cost-effectiveness of the use of alternative bearings for patients undergoing
total hip arthroplasty. Model inputs, including costs, clinical outcome
probabilities, and health utility values, were derived from a review of the
literature. Sensitivity analyses were performed to evaluate the impact of
patient age at the time of surgery, implant costs, and reductions in revision
rates on the cost-effectiveness of alternate bearing surfaces.
Results: In a population of fifty-year-old patients, use of an
alternative bearing with an incremental cost of $2000 would be cost-saving
over the individual's lifetime if it were associated with at least a 19%
reduction in the twenty-year implant failure rate when compared with the
failure rate for a conventional bearing. In a population of patients over the
age of sixty-three years, the same implant would be associated with higher
lifetime costs than would a conventional bearing, regardless of the presumed
reduction in the revision rate. Conversely, an alternative bearing that adds
only $500 to the cost of a conventional total hip arthroplasty could be
cost-saving in a population of patients over the age of sixty-five years, even
if it were associated with only a modest reduction in the revision rate. In a
population of patients over the age of seventy-five years, no alternative
bearing would be associated with lifetime cost-savings, regardless of the cost
or the presumed reduction in the revision rate.
Conclusions: The cost-effectiveness of alternative bearings is
highly dependent on the age of the patient at the time of surgery, the cost of
the implant, and the associated reduction in the probability of revision
relative to that associated with conventional bearings. Our findings provide a
quantitative rationale for requiring greater evidence of effectiveness in
reducing the probability of implant failure when more costly alternative
bearings are being considered, particularly for older patients.
Level of Evidence: Decision analysis, Level I. See
Instructions to Authors for a complete description of levels of evidence.