“Does soft tissue balancing have to be a soft science?” asked a team from Columbia University Irving Medical Center in New York City. Their study, “No Benefit to Sensor-guided Balancing Compared With Freehand Balancing in TKA: A Randomized Controlled Trial,” was published in the August 2022 edition of Clinical Orthopaedics and Related Research.
Freehand Balancing in TKA or Sensor-Guided Balancing?
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Nana Sarpong, M.D., M.B.A., co-author and orthopedic surgeon at Columbia University Medical Center New York Presbyterian Hospital in New York City, explained the background of the study to OTW. “Freehand soft tissue balancing in TKA [total knee arthroplasty] has traditionally relied on the surgeon’s subjective and often nebulous assessment with associated variability. Soft tissue balancing using more objective measurements reportedly results in decreased pain, improvement in function, and a potentially decreased revision rate in some studies.”
“A sensor-guided balancing device that allows surgeons to objectively quantify ligament balance by offering intraoperative data during TKA has been developed, but to date, its evaluation consists of smaller retrospective studies that have demonstrated a possible correlation between the use of these sensors and improved clinical outcomes.”
“More recent studies have been retrospective, focused on single patient-reported outcome measures (PROMs) without assessments of knee ROM [range of motion], and have relatively short-term follow-up. Hence, we conducted a randomized controlled trial comparing freehand balancing with the use of a sensor-guided balancing device.”
While the majority of prior studies are retrospective, small, with short follow up times, says Dr. Sarpong, this study included data at three months, one year, and two years.
“The mean operative time in the sensor-guided cohort was significantly longer than that in the freehand cohort. However, there was no difference in the mean knee ROM or PROMs at three months, one year, and two years postoperatively between the freehand and sensor-guided TKA cohorts.”
“Our study consisted of three very experienced surgeons who perhaps after several thousand knee replacements, do not need to rely on the technology in question for soft tissue balance assessment. In their hands, the routine use of this technology is not useful. However, there may be benefits seen in more inexperienced knee arthroplasty surgeons.”
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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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