ROBODOC Cedric Ortiguera, MD, performs robotic knee replacement surgery at the Mayo Clinic campus in Jacksonville, Fla.

The difference between a so-so and a spectacular knee replacement is often the slimmest of margins — 1 mm of shaved bone or 1 degree of implant placement — a bridge that a robotic arm can gap better than a surgeon's hands.

"We're good at putting the implant in and making it look good on an X-ray, but it doesn't feel right to a fair percentage of patients," says Cedric Ortiguera, MD, an orthopedic surgeon at the Mayo Clinic campus in Jacksonville, Fla.

It's estimated that 20% of joint replacement patients are less than thrilled with their newly replaced knee. Despite the perfect post-op X-ray, the restored range of motion and the vanquished pain, the artificial implant feels, well, artificial. It just doesn't feel normal — the patient can tell which knee was operated on.

"We're all after that 20%," says hip and knee replacement specialist Neil P. Sheth, MD, an assistant professor of orthopaedic surgery at Pennsylvania Hospital in Philadelphia, Pa. "Most hip replacement patients can't remember which hip they had done a year later. We're trying to get there with knees."

More and more surgeons like Dr. Ortiguera and Dr. Sheth are turning to a new partner to improve outcomes: a robotic arm that helps docs prepare the bone with sub-millimeter accuracy and place the implant with spot-on precision.

"Robotic technology adds a new level of accuracy and precision to how we insert the implants that's very difficult to reproduce with your hands," says Dr. Ortiguera. "Plus, we can balance the ligaments better so patients will feel better with the knee."

While the robot plays a vital role, it doesn't perform the surgery alone and it's not a substitute for a surgeon's skill. "I do the surgery, I'm holding an instrument. The robot guides my hand," says Dr. Ortiguera. "It won't make a bad surgeon a good surgeon, but it can help make a good surgeon better."

ROBOTIC GUIDANCE Robot-assisted knee replacement improves the accuracy of bone preparation, as well as implant alignment and fixation.

Reproducible results
Of the robot's many advantages, its greatest might be the ability to achieve reproducible results and all but eliminate variation in patient outcomes. In "Robots in Orthopaedic Surgery: Past, Present, and Future," William L. Bargar, MD, of the Sutter Joint Replacement Center, University of California—Davis School of Medicine in Sacramento, Calif., says, "Just as the industrial revolution standardized production methods and controlled quality, so can the use of robotics allow the surgeon to obtain accuracy and reproducibility to control quality and eliminate variation of outcomes."

Dr. Ortiguera offers to use the robotic arm on every knee replacement patient, but finds it's especially helpful to achieve reproducible implant positions from one partial knee replacement to the next.

"There's a higher failure rate in partial replacements than in full replacements, in large part because the results are very dependent on proper implant placement and proper knee alignment," says Dr. Ortiguera. "It's very important for us to balance the soft tissues of the ligament that support the knee and we have a hard time doing that without robotic technology."

Dr. Ortiguera has been using the robot for partial knees since 2010. A couple months ago, Mayo Jacksonville added robot-assisted total knee arthroplasties. In the first 5 weeks, he's done about 20.

The robot adds about 15% to 20% more time to a knee arthroplasty, according to Dr. Ortiguera, much of it spent on inserting pins in the tibia and femur to transmit data back to the computer in order to determine optimal alignment of the implant, based on how the joint moves. "It will slow you down a bit, but you're providing a better product to the patient," he says.

Unmatched accuracy is your reward for longer cases. Studies have shown that robotic arm assistance is more accurate than manual techniques. Take bone milling, for example. A robot is 4 times more accurate in preparing the bone than a surgeon sawing the bone surfaces by hand.

"If I asked you to saw a straight line on a piece of wood by hand and compared your cut to the robot's, the robot's would be 4 times more accurate," says Dr. Ortiguera.

Dr. Sheth appreciates how well robots can mill around bone spurs, deformities and rods in femurs during complex primary joint replacements.

A show of seriousness
In his strategy plan for 2018, Dr. Sheth suggested that his hospital invest in an orthopedic robot. "It's very simple. You either want to compete in this marketplace or you don't. If you want to compete, you have to put money into this to be able to offer cutting-edge technology for patients," says Dr. Sheth, who predicts that robotic-assisted joints will be the standard of care in the near future.

Dr. Sheth sees 2 main benefits to the robot: identifying the joint line — how much bone you take from the end of the thigh bone to the top of shin bone — and preserving all 4 ligaments by removing just the part of the knee that's arthritic. He's one of only 20 surgeons to have used a new knee replacement design to perform bi-cruciate retaining knee replacements, a technically challenging surgery that preserves all 4 knee ligaments. He's done 15 so far, each made infinitely easier because the robot milled the bone more accurately and faster than he could. OSM