Orthopaedic surgeons have long been aware of the role that implant prices play in the total cost of care for arthroplasty procedures, but methodical breakdowns of implant costs in relation to the cost of other aspects of care have generally been lacking. In the March 4, 2020 issue of The Journal, Carducci et al. detail the impact of implant costs on the total cost of care in a study of 6 lower- and upper-extremity arthroplasty types performed at a single, high-volume orthopaedic specialty hospital.
Using a uniform method called time-driven activity-based costing, the authors calculated the total costs of >22,200 inpatient primary total joint arthroplasties, and then broke down those total costs by categories, including implant price and personnel costs. It was no surprise that, as a percentage of total cost, implant costs were highest for low-volume surgeries (as high as 65% for total ankle arthroplasty) and lowest for high-volume procedures (e.g., 40% for total knee arthroplasty). Nevertheless, across the board, implant price was the most expensive component of total cost.
Implant prices are individually negotiated between a hospital and an implant supplier and are usually protected by nondisclosure agreements, so the data from this investigation may not match up with data from any other institution. Unfortunately, the future of implant-cost research will be tied to the complex issue of return-on-investment for implant-manufacturer stockholders as it relates to negotiations with individual hospitals and health systems.
The profound impact of implant price on the total cost of all the joint arthroplasties studied by Carducci et al. also begs the questions as to how “generic” implants (those not manufactured by the major orthopaedic producers) will ultimately influence the market—and whether “branded” implants, with their 30% to 50% markups, provide any functional benefit for patients. We will need further well-designed research to address those questions.
Marc Swiontkowski, MD
The retrospective multicenter study of 1,570 primary total knee arthroplasties (TKAs) by Kazarian et al. in the October 2, 2019 issue of JBJS focused on evaluating the impact of surgeon volume and training status on implant alignment. But the most surprising (and concerning) finding was that even among high-volume attendings—the best-performing of the three surgeon cohorts studied—the proportion of TKA alignment “outliers” was still high.
The authors radiographically measured 3 postoperative TKA alignment parameters: medial distal femoral angle (DFA), medial proximal tibial angle (PTA), and posterior tibial slope angle (PSA). Using established thresholds for “outliers” and “far outliers” for those 3 measurements, the authors compared the radiographic findings among surgeries performed by high-volume attendings (≥50 TKAs/year), low-volume attendings (<50 TKAs/year), and trainees (supervised residents or fellows).
As has been shown in similar studies of total hip arthroplasty (THA), the group of high-volume attendings outperformed the low-volume attendings and the trainee group on nearly all measurements assessed in this study. Interestingly, in terms of TKA alignment, the low-volume attending group and the trainee group performed similarly.
Kazarian et al. express concern that “even the most accurate cohort in our study, [the high-volume attendings], placed only 69.0% of knees in optimal alignment for all 3 measurements.” While the authors admit that implant alignment is not a perfect proxy for clinical outcomes, they argue that “gross alignment outliers are likely to have an impact on knee function, kinematics, and wear characteristics.” Citing literature suggesting that the use of robotic-arm assistance may improve TKA alignment, the authors surmise that employing such technology to assist low-volume surgeons or trainees might optimize alignment and improve outcomes, despite the added up-front cost of the technology.