A Cut Above

Robotic-assisted technology is improving the accuracy and precision of total knee replacements—a procedure that’s on the rise throughout the nation

By Erin Weeks

What do George W. Bush, Al Roker and Jane Fonda have in common? They’re among the estimated 4.7 million Americans living with knee replacements. Doctors perform more than 600,000 total knee replacements each year, making it one of the most common surgical procedures in the country. And as baby boomers age and develop arthritis—the leading cause of joint damage—those numbers are expected to skyrocket. A new generation of robot-assisted technology has hit the joint replacement scene in recent years, improving the results of these life-changing procedures, and aiming to meet the growing demand for the surgery. In October 2019, the first pair of Mako Robotic-Arm Assisted Technology systems (shown below at right) arrived at Roper St. Francis hospitals to be used for total knee replacements, also known as total knee arthroplasty. “We think this is how all knee replacement surgeries will be done in the future, and we’re glad to be offering it,” says Roper St. Francis Healthcare affiliated orthopedic surgeon Dr. John McCrosson. Below, Dr. McCrosson explains the benefits of the new technology.

HC: When is a total knee replacement necessary and what does the surgery entail?
JM: The knee, which is the largest joint in the body, is the meeting point of three bones: the femur (or thigh bone), tibia (shin bone) and patella (knee cap). In a healthy knee, certain protective elements are present and work together to keep the bones from rubbing against each other. These include articular cartilage, a smooth substance that covers the bones, and synovial membrane, which lubricates the cartilage. When trauma to the joint or a disease like osteoarthritis or rheumatoid arthritis damages these barriers, the bones rub together, causing pain, stiffness and joint damage. If more conservative treatment measures have failed, total knee replacement—a procedure in which surgeons remove diseased cartilage and bone in the knee before implanting a replacement joint made entirely of metal and plastic—may be recommended.

HC: How does the Mako system work?
JM: First we take a pre-operative CT scan of the patient’s knee. The Mako software generates a 3D model of the joint, which lets us analyze its anatomy and the state of damage within the joint—information that informs the size and location of the implant.

Dr. John McCrosson

In the operating room, the surgeon works with a robotic tool that provides real-time spatial feedback, helping the doctor cut the bone precisely where intended in order to achieve the best alignment with the implant. The surgeon can disregard the robotic tool and use standard instruments at any point, but this technology in the hands of a skilled surgeon should give the highest chance for precision and success.

HC: What are the benefits of Mako-assisted surgery?
JM: With any knee replacement, the goal is for the patient to be able to resume physical activity free of pain. Using information gathered from the pre-op CT scan, we are able to choose an implant that is best suited for the patient’s unique anatomy, and the robotic-assisted surgical tool helps us position the implant more precisely. This increased precision reduces the risk for post-operative discomfort in the joint; minimizes the odds that subsequent surgeries, known as revisions, will be needed; and can shorten the time it takes to rehabilitate from the procedure.