A review of five hip- and knee-implant innovations, initiated by the FDA in reaction to serious problems with metal-on-metal hip bearings, found that none offered meaningful functional or patient-outcome benefits over older designs. The systematic review of 118 studies and more than 13,000 patients, published in the BMJ, also found that three of the new designs—ceramic-on-ceramic hip bearings, modular femoral necks, and high-flexion knee implants—were associated with higher revision rates relative to established designs. The other two innovations—uncemented monoblock acetabular cups and sex-specific knee implants—provided no benefit over older designs but had comparable revision rates.
The BMJ authors claim that the purpose of the review was not to “criticise the surgical community or orthopaedic industry,” but rather to “highlight that the status quo regarding the introduction of new device technologies is not acceptable.”
The BMJ authors cite stepwise introduction of new implant technologies as one way to avoid exposing large numbers of patients to innovations whose safety and efficacy are unproven. In a 2011 JBJS supplement, authors (two of whom also co-authored the BMJ study) proposed using roentgen stereophotogrammetric analysis (RSA) and national joint registry data to facilitate phased clinical introduction of new implants.
When it comes to knowing the costs of the devices they implant, orthopaedic surgeons and residents are batting only .210 and. 170, respectively. More than 500 orthopaedic surgeons surveyed at seven US academic medical centers correctly estimated the cost of common orthopaedic devices only 21% of the time. Residents at the same institutions did so only 17% of the time. Many of these respondents (36% of surgeons and 75% of residents) admitted that their knowledge of device costs was “below average” or “poor.” All respondents tended to overestimate the price of low-cost devices and to underestimate the price of high-cost devices. The implication of that tendency, say the authors of the Health Affairs study, is that “physicians may underestimate the amount that could be saved by choosing the lower-cost alternative.” The biggest barrier to physicians knowing device prices is confidentiality clauses in the contracts between device vendors and hospitals. “Widespread dissemination of device prices is not an option at many institutions,” wrote the authors. It remains to be seen whether the proliferation of accountable care organizations, with their emphasis on cost-efficient care, will alter this situation. For more about cost variation in orthopaedic devices, see the JBJS article “Variability in Costs Associated with Total Hip and Knee Replacement Implants.”
Modularity in the heads and stems of total hip prostheses has afforded orthopaedic surgeons the ability to intraoperatively adjust version, limb length, and offset in ways that can optimize hip biomechanics. Modular implants have achieved these important objectives in thousands of patients over the last couple of decades. However, the rewards of modularity come with risks—some of them serious. Reports of these risks seem to have become more prevalent in the recent orthopaedic literature.
In this “Watch,” we bring to the attention of the orthopaedic community several femoral neck fractures in patients with implants that had modular head-neck and neck-stem designs. While some of these designs are no longer available from manufacturers, thousands of such devices have already been implanted. This “Watch” encourages surgeons to be wary about one specific aspect of modular hip designs: long femoral necks.