“New” but Not Necessarily “Improved”
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.