Tag Archive | computer navigation

Patient-Specific Instruments’ Effects on TKA Revision

Whenever we introduce new technology or techniques in hopes of improving orthopaedic surgery, at least one of two criteria should be met: The new technology should improve the outcome at a maintained cost, or it should decrease cost while maintaining at least an equivalent outcome. If neither of these conditions is met, we need to think twice about adopting it. To help us answer these “value” questions, we need relevant data. This is why studies such as the one by McAuliffe et al. in the April 3, 2019 issue of The Journal are so important.

The authors use the Australian Orthopaedic Association National Joint Replacement Registry to compare the rate of revision between 3 types of primary total knee arthroplasty (TKA):

  1. Those performed with image-derived instrumentation (IDI, i.e., patient-specific cutting jigs)
  2. Those performed using computer navigation
  3. Those using neither technology

McAuliffe et al. found no significant differences between groups in terms of cumulative percent revision at 5 years. Subgroup analysis revealed a higher rate of revision (hazard ratio [HR] 1.52, p = 0.01) for the IDI group relative to the computer-navigated group when patients were ≤65 years old. In addition, the IDI group had a much higher rate of patellar revision when patients received posterior-stabilized knees (HR of 5.33 when compared with the computer-navigated group, and HR of 4.16 when compared with the neither-technology group).

This study seems to suggest that whatever the benefits of IDI may be in terms of attaining a “proper” mechanical axis during TKA, IDI does not translate into a lower revision rate. And when these revision data are viewed in the face of the added costs associated with IDI, it makes little sense to advocate for the widespread use of this technology for TKA at this time.

While this study focused on TKAs, the take-home message can be extended. Orthopaedic surgery is by nature complex, requiring that multiple steps be performed in harmony to produce an optimal outcome. It is easy for us to focus on (and measure) a couple of key outcome variables and base our opinions of a technique’s or technology’s success on such findings. But when it comes to “novel” techniques and technological “breakthroughs,“ we need a lot of data on many different variables before we can make meaningful conclusions, change our practice, and advise our patients.

Chad A. Krueger, MD
JBJS Deputy Editor for Social Media

New Patient-Outcomes Data Hint at Benefits from Computer-Navigated TKA

computer navigation knee for OBuzzLike the vast majority of orthopaedic surgeons, I do not use computer navigation for total knee arthroplasties (TKAs). My hospital does not own the equipment, I have not asked for it, and I feel confident in the outcomes for my patients using current conventional techniques. Moreover, we have not had published data suggesting that using computerized navigation actually improves the one thing we care most about: patient outcomes.  However, the two-year data presented by Petursson et al. in the August 1, 2018 issue of JBJS may represent a tipping point.

The authors report on 2-year results from a double-blind, prospective randomized trial evaluating outcomes in 167 patients following TKAs performed using conventional techniques or computer-guided navigation. Both patients and observing radiologists/physical therapists were blinded to the technique used.

Among the many patient-reported measures used to compare 2-year outcomes, the authors found that scores for 3 subscales favored the computer-navigation group. Specifically, the symptom and sports-and-recreation subscales of the KOOS and the stiffness subscale of the WOMAC showed significantly greater improvements in the group that underwent computer-navigated TKA. These results led Petursson et al. to conclude that TKAs completed with the assistance of computer navigation provided better pain relief and function at two years postoperatively.

These are important findings, as this is one of the largest randomized, double-blind analyses comparing computer navigation versus conventional TKA. While previous studies had found computer navigation to be useful in terms of obtaining neutral mechanical alignment, data showing improved patient outcomes was either lacking or revealed no clinically important between-group differences.  These 2-year data suggest that this is no longer the case.  However, it is important to note that the study does not explicitly state whether patients were still blinded to their treatment at the time when the 2-year follow-up data was collected.  If they were no longer blinded at that point of follow-up, the results would need to be viewed from a more tempered perspective.

Either way, it is important to note that in this study—as in previous research investigating similar questions—TKAs completed using conventional techniques also yielded large improvements in patient-reported outcomes. Still, because patients and surgeons alike continue to be intrigued by the possibilities that technological advances in arthroplasty may offer, studies like this are vital.

Chad A. Krueger, MD
JBJS Deputy Editor for Social Media