With the increasing frequency of total knee arthroplasty (TKA) surgeries and the ever-increasing implant options available to orthopaedists for these cases, it is important that we carefully analyze new devices and technologies. We have already seen too many instances in which the enthusiasm for (and use of) a new implant outpaced the evidence for its efficacy and safety, leading to problems for patients, surgeons, and manufacturers alike.
The results of the randomized trial by Nam et al. in the July 3, 2019 issue of The Journal start to tackle this issue. The authors compared operative times, patient outcomes, and radiographic measures between patients who received either a recently introduced cementless or traditionally cemented cruciate-retaining TKA implant of the same design (the Triathlon TKA implant from Stryker). They found no clinically meaningful or statistically significant differences between the two groups in terms of Oxford Knee Score or Knee Society Score at any point during the average 2-year follow-up. In addition, nearly equal percentages of patients in each group reported being “extremely” or “very” satisfied with their functional outcome at 2 years, and radiographically, the researchers found no significant difference between the groups in terms of radiolucency behind the tibial or femoral implants. The one notable between-group difference was operative time, with the cementless cohort having a mean surgical time roughly 11 minutes less than that of the cemented cohort.
These results are encouraging in that they show improved operative efficiency with none of the aseptic loosening that has historically been a concern with cementless knee implants. Still, the authors make it clear that “the burden of proof remains with cementless fixation,” largely because cementless implants cost more than their cemented counterparts. Those higher costs need to be justified by improved outcomes (including implant survivorship), decreased complications, or both in order for cementless implants to displace cemented ones as the “standard of care.”
We are not there yet, but the findings from Nam et al. justify further surveillance of this cementless device. Future high-quality studies incorporating joint registry data and longer patient follow-up will hopefully provide the supporting evidence with which the joint-arthroplasty community can decide whether this relatively new cementless technology should be the implant of choice for certain patient populations.
Chad A. Krueger, MD
JBJS Deputy Editor for Social Media