Barnes-Jewish Hospital | Washington University Physicians
breakthroughs in patient care


BY Stephanie Stemmler

Robot-assisted surgery often offers surgeons improved precision and greater flexibility compared with standard surgical procedures. And that level of precision often means shorter hospital stays, less pain and faster recovery for patients.

All that holds true for the use of robotics in partial knee replacement surgery, also called unicompartmental knee arthroplasty or UKA. In fact, a team of Washington University orthopedic researchers found that using robotics during UKA yielded results that were up to 10 times more accurate than doing the procedure without robotic assistance. The study was published in The Bone & Joint Journal, March 2021.

Robotic technology helps guide the surgeon to achieve precise alignment. Photo COURTESY OF STRYKER

“I won’t do a UKA anymore without a robot because of the dramatic results of our study,” says Robert Barrack, MD, Washington University orthopedic surgeon at Barnes-Jewish Hospital and Barnes-Jewish West County Hospital. “I believe robotic-aided surgery will become the standard of care for this kind of orthopedic procedure in the near future.”

Unicompartmental knee arthroplasty may be an option for a person with knee arthritis limited to only a portion of the knee joint. The appeal of a partial versus total knee replacement is that, in addition to improved recovery and less pain, the incidence of major complications is lower. And patients report that the resulting knee often feels more like the original.

During UKA surgery, Barrack says, “we only remove damaged bone and cartilage from a small area and then resurface the bone with metal and plastic components.” He adds: “We can do the procedure on the inside of the knee (medial) or outside (lateral) to alleviate pain depending upon the location of cartilage wear.”

There is, however, a known problem with non-robotic partial knee replacements. Globally, up to 15% of these procedures fail within 10 years. Why? Barrack says that, because the incision is small, as are the implants, there is a narrow margin of error in placing the new knee components. Veering even a few millimeters from ideal placement increases the risk of failure down the road.

Robotics helps surgeons navigate that narrow margin of error. Using this technology, a surgeon can merge a preoperative CT scan of a patient’s knee with tracking devices placed on the patient’s upper and lower leg bones. A camera creates a 3D model of the knee, aligning it with the actual knee shown in the CT scan. The technology then allows the surgeon to visualize the proper surgical path, which is highlighted in bright green on a computer monitor.

“As I guide the robotic arm with its attached tools, I can see exactly where I need to align the components in three dimensions,” explains Barrack. But the surgeon remains in control. “The system is called a semi-autonomous robot: It helps establish the boundaries and identifies where to cut, but the surgeon is controlling the cutting tools.”

To date, Washington University orthopedic surgeons have completed hundreds of robotic UKA surgeries at Barnes-Jewish Hospital and Barnes-Jewish West County Hospital. Surgical teams will begin performing robotic total knee replacements in the summer of 2021.

What’s on the horizon for this quickly advancing field? The Food and Drug Administration has approved the use of robot-assisted technology for some hip surgeries. And it’s also possible this technology can be used in procedures involving the shoulder and spine.

“Robot-guided systems won’t entirely replace manual procedures,” says Barrack. “But there is definitely a place for them in partial knee replacement and other surgeries, and their use will only increase in coming years.”

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