Background: Total knee arthroplasty is one of the most clinically successful and cost-effective interventions in medicine. However, implant malalignment, especially in the coronal plane, is a common cause of early failure following total knee arthroplasty. Computer-assisted surgery has been employed during total knee arthroplasty to improve the precision of component alignment. The purpose of the present study was to evaluate the cost-effectiveness of computer-assisted surgery to determine whether the improved alignment achieved with computer navigation provides a sufficient decrease in failure rates and revisions to justify the added cost.

Methods: A decision-analysis model was used to estimate the cost-effectiveness of computer-assisted surgery in total knee arthroplasty. Model inputs, including costs, effectiveness, and clinical outcome probabilities, were obtained from a review of the literature. Sensitivity analyses were performed to evaluate the impact of component-alignment precision with use of computer-assisted and mechanical alignment guides, total knee arthroplasty failure rates secondary to malalignment, and costs of computer-assisted surgery systems on the cost-effectiveness of computer navigation in total knee arthroplasty.

Results: Computer-assisted surgery is both more effective and more expensive than mechanical alignment systems. Given an additional cost of $1500 per operation, a 14% improvement in coronal alignment precision (within 3 degrees of neutral mechanical axis), and an elevenfold increase in revision rates at fifteen years with coronal malalignment (54% compared with 4.7%), the incremental cost of using computer-assisted surgery is $45,554 per quality-adjusted life-year gained. Cost-savings is achieved if the added cost of computer-assisted surgery is $629 or less per operation. Variability in published clinical outcomes, however, introduces uncertainty in determining the cost-effectiveness.

Conclusions: Computer-assisted surgery is potentially a cost-effective or cost-saving addition to total knee arthroplasty. However, the cost-effectiveness is sensitive to variability in the costs of computer navigation systems, the accuracy of alignment achieved with computer navigation, and the probability of revision total knee arthroplasty with malalignment.

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We present a 42-year-old woman with no history of diabetes or glucose intolerance who had a 5-year history of ulcerative necrobiosis lipoidica (NL). Despite failure of multiple medications, she experienced clearing of her ulcers after her treatment was changed to ustekinumab. We discuss our patient’s disease course and elaborate upon mechanistic reasons for her improvement related to ustekinumab therapy.