Computer navigation potentially cost-effective for performing TKA

Computer-assisted TKA showed a $45,554 incremental cost-effectiveness ratio per quality-adjusted life-year, below the threshold commonly used by policy-makers.

Using computer-assisted navigation during total knee arthroplasty is potentially cost-effective and cost-saving, according to a study by researchers in California. "However, the cost-effectiveness is sensitive to variability in the costs of computer navigation systems, the accuracy of alignment achieved ... and the probability of revision total knee arthroplasty with malalignment," the study authors noted.

Erik J, Novak, MD, PhD, and colleagues at the University of California, San Francisco, investigated whether the improved alignment achieved from computer navigation during total knee arthroplasty (TKA) decreases failure and revision rates enough to justify its additional costs.

The researchers use a decision analysis model to estimate TKA cost-effectiveness, using data obtained from a literature review. They also performed sensitivity analyses to compare cost-effectiveness between surgery performed using either computer-assisted or mechanical alignment guides, according to the study.

Initial surgical outcomes included either neutral alignment or malalignment, defined as greater than 3° of varus or valgus mechanical alignment. Long-term outcomes included revision surgery with either neutral alignment or malalignment, the authors wrote.

The study focused on primary TKA performed on patients with osteoarthritis.

"A relatively conservative estimate of $1,500 (in 2006 United States dollars) per procedure was chosen for the baseline case, with a broad range of cost estimates examined in the sensitivity analyses to incorporate multiple scenarios based on differences in geographic region, hospital procedure volume and type of navigation equipment," the authors wrote.

They published their findings in the American edition of The Journal of Bone and Joint Surgery.

"In the base case analysis, computer-assisted surgery as compared with traditional mechanical alignment guides had an incremental cost of $871 and an incremental gain of 0.019 quality-adjusted life-year, yielding an incremental cost-effectiveness ratio of $45,554 per quality-adjusted life-year," they noted.

The researchers found that, as the cost of computer-assisted TKA increases, "a higher probability of neutral alignment ... would be required to produce cost-savings," they said.

Based on a 15-year time-horizon, "The incremental cost-effectiveness ratio of computer-assisted surgery compared to mechanical guides crosses the $100,000 per quality-adjusted life-year threshold at 12.13 years after [TKA] and the $50,000 per quality-adjusted life-year threshold at 14.56 years," the authors reported.

"On the basis of our base-case estimates, computer-assisted surgery could be considered a cost-effective technology with an incremental cost-effectiveness ratio of $45,554 per quality-adjusted life-year, which is below the $50,000 per quality-adjusted life-year threshold, a threshold that is commonly used by policy-makers for defining cost-effectiveness," they wrote.

"Our analysis demonstrates that the use of computer-assisted surgery in [TKA] can be cost-saving over the entire period of care when the initial cost of computer-assisted surgery is $629 or less per operation. Thus, as incremental costs decrease with improvements in the technology, the justification for using computer-assisted surgery increases," they noted. "Computer navigation could reduce the costs and improve the quality of life associated with [TKA] when one considers both the initial and downstream costs over a longer time-horizon."

The authors reported that their analysis model assumed a 15-year postoperative life expectancy for the patient to achieve the maximum benefits from surgery. Thus, a shorter postoperative time-horizon would have less of a corresponding benefit.

"Therefore, the cost-effectiveness of computer navigation in [TKA] will be more favorable when applied to younger patient populations with longer life expectancies," they said.

"As the costs associated with this technology decrease and the accuracy of computer-guided implant alignment improves, computer-assisted surgery has the potential to become a cost-saving technology while at the same time improving patient outcomes," the authors said.

For more information:
Novak EJ, Silverstein MD, Bozic KJ. The cost-effectiveness of computer-assisted navigation in total knee arthroplasty. J Bone Joint Surg Am. 2007;89-A:2389-2397.