A new cadaveric study from the University of Denver has compared the ability of a new image-free robotic assist total knee device to conventional total knee arthroplasty (TKA) instrumentation in terms of alignment accuracy and reduction of variability.
How Well Can Image-Free Robotic Assist Work for TKA?
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The research,“Image-Free Robotic-Assisted Total Knee Arthroplasty Improves Implant Alignment Accuracy: A Cadaveric Study,” was published in the December 31, 2021 edition of the Journal of Arthroplasty.
Co-author Chadd Clary, Ph.D., with the Center for Orthopaedic Biomechanics at the University of Denver in Colorado, explained the purpose of the study to OTW, “There is keen interest from the orthopaedic community about tools that increase surgical accuracy as a means to improving patient outcomes. In the last couple years, many new robotic assisted surgical systems have been introduced that claim to improve surgical accuracy.”
“This study highlights the key pre-clinical system level accuracy testing for a new image-free robotic assisted surgical system that was recently approved by the FDA for total knee arthroplasty.”
Utilizing 40 cadaveric specimens, five orthopedic surgeons did eight bilateral TKAs each, using the VELYS Robotic-Assisted System from Depuy Synthes, along with conventional instrumentation on contralateral knees.
The researchers found that the robotic-assisted cohort had “smaller resection errors compared to conventional instrumentation in femoral coronal alignment (0.64°±0.50° versus 1.39°±0.95°), femoral sagittal alignment (1.21°±0.90° versus 3.27°±2.51°), and tibial coronal alignment (0.93°±0.72° versus 1.65°±1.29°). All other resection angle accuracies were equivalent. Similar improvements were found in the femoral implant coronal alignment (0.91°±0.83° versus 1.42°±1.15°), sagittal alignment (1.51°±1.08° versus 2.49°±2.10°), and tibial implant coronal alignment (1.31°±0.84° versus 2.03°±1.44°). The robotic-assisted cohort had fewer outliers (errors > 3°) for all angular resection alignments.”
Dr. Clary stated to OTW, “The robotic-assisted surgical system demonstrated statistically significant improvements in coronal resection accuracy for both the femur and tibial resections compared to traditional instrumentation. Coronal knee alignment after total knee arthroplasty is important for managing stresses in the implant during daily activities and properly balancing the knee’s soft tissue envelope.”
“Some surgeons are either actively using robotic-assisted surgical systems in their practice or are considering trying them in the near future. The data from this study should give surgeons confidence that using this system will improve surgical accuracy and reduce the number of outliers in the patient population.”
NOTE: Depuy Synthes Orthopaedics sponsored this study via a research grant to the University of Denver.
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This is a fascinating development. In my practice we've seen similar outcomes with the revised protocol. The key differentiator seems to be patient selection criteria. Has anyone else noticed the correlation with BMI thresholds?
Great point. I'd push back slightly on the conclusion, the sample size in the cited study is too small to draw population-level inferences. That said, the directional signal is compelling and worth a larger RCT.
We implemented a similar approach last year. Early results are promising but we're still gathering 12-month follow-up data. Happy to share our protocol if anyone is interested.
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