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By the time Lynnette Simpson came under the care of the expert surgical team at the University of Utah, the 58-year-old grandmother had been through 40 surgeries, many of which stemmed from a car wreck when she was 17. Her 41st operation, however, placed her in a unique category. In the fall of 2019, Lynnette became the first patient at University of Utah Health to have a total knee replacement done by a surgeon with the help of ROSA, which stands for Robotic Orthopedic Surgical Assistant.
Lynnette traces the roots of her knee problems to a childhood accident, when, jumping from a wall, she landed badly and hurt her knees. "They were really swollen and painful," she recalls. Her parents didn’t worry about it. "Back then you had to be dead or bleeding out before they took you to the doctor," she says.
Her right leg bothered her on and off over the years and as an adult, while out pursuing her favorite recreation, hiking, she mashed-up her left knee in a fall, leaving it full of bone spurs and torn cartilage. When her doctor told her she had to get her knees replaced, "I talked to other people who didn’t have a good experience getting their knees done," she says. Consequently, "I drug my feet for years not wanting to get it done." She put the surgery off for a decade, even though chronic knee pain made her "grouchy" she says, particularly since she has grandchildren and "I couldn’t get out and play with them." Finally, her knees reached a point of collapse where she had no choice. "It got to be where the bones weren’t where they were supposed to be any more. I either had to do it or the knees would cave in on me."
Doctors couldn’t operate on her knees in her hometown of Blanding, in southern Utah, because she has a blood clotting disorder, so she was referred to Christopher Pelt, MD, an orthopedic surgeon specializing in joint replacement surgery, at the University of Utah Orthopaedic Center.
Pelt had previously worked with Lynnette to help her with her right knee, which she had done a year prior. Post-operation, her leg was somewhat swollen and she had to keep it elevated for some time. Before the operation, she dragged her right leg behind her. After the surgery, she found she was dragging her left foot.
"I was dragging that right leg for years, just pulling it along. So, as it got better, I was dragging the other one, which really inhibited how far I could hike. I could maybe walk for an hour before I had to stop."
In early fall 2019, Pelt called Lynnette to tell her he’d like her to be his first patient on whom he would perform a total knee replacement aided by a robotic assistance system. Robotic technology, Pelt explains, has been shown to be beneficial in orthopaedic surgery for partial knee replacements.
"Alignment matters when we’re putting in joints. You put them in catawampus and they can subside or fail. The loads that are shared across the joint need to be shared equally, otherwise asymmetric loads will push through the bone, push the implants loose and lead to premature failure or early wear." But while robotic technology has been successfully used for partial knee replacements, robotic-assisted total knee replacements are relatively new.
Pelt operated on Lynnette using Zimmer Biomet’s ROSA for the first time. ROSA uses mobile tracker arrays and routine x-rays of the limb obtained in clinic, which are then emailed to a Canadian-based laboratory. The lab sends back a personalized three-dimension plan for the surgery. It details the patient’s knee alignment, the size of their bones; the planned implant position and implant size, along with the precise bone cuts needed.
When Pelt puts in a new knee, he says, "It’s sort of like taking your car to the tire shop. We want to realign the front of the car and give them new tires." He starts the surgery by testing the patient’s ligament tensions and bending the knee and moving it side to side. Those movements mean that along with the three-dimensional bone modeling, ROSA can capture the movement and also provide an assessment of the patient’s own soft tissue tension. "That creates a personalized patient plan that we execute using the assistance of ROSA’s robotic arm."
What ROSA does, Pelt says, is provide information throughout the surgery that allows him and his team to understand a patient’s unique differences when it comes to precise bone measurements and the tensions in their soft tissues. "This whole surgery is a game of millimeters," he says. "Making millimeter changes can make all the difference. The robotic system allows us to put the knee where the patient’s body is telling us it should be as opposed to us telling the knee where it should be and making it work."
Four out of five patients nationally do very well with the total knee replacement, Pelt says, but one out of five may have an outcome that’s less than they had hoped for, and it’s not clear why. It’s early in terms of gathering data from Pelt’s operations using ROSA to see whether it can make improvements for the one-in-five patients who don’t have a completely positive outcome after knee replacement.
"We don’t yet know that this technology can make the difference," Pelt says, but he and the other surgeons at University of Utah Health using ROSA plan to study it.
What Lynnette noticed with the recent left knee replacement she had done with ROSA compared to the first right knee replacement she had without it a year before was the nature of her recovery. "I kind of felt like the left one was less painful. It didn’t have the swelling of the right one and felt more comfortable right away."
The surgeries have given Lynnette back not only her ability to go out on long walks without having to stop because of pain, but also to enjoy the outdoors with her grandchildren. "I don’t walk like a penguin anymore," she says. "My legs are straight. Now I can go pretty far and pretty fast. It is perfect. My goal is no pain and I got that. And to hike better. And I got that."
**Dr. Pelt is an Associate Professor in the Department of Orthopaedic Surgery at University of Utah Health. He also works with ROSA manufacturer, Zimmer Biomet, receiving payments for speaking, consulting and research with the company. He does not receive payments for the use of ROSA or the implants he uses.