Features August 2019 Issue

Robot-Assisted Joint Replacement

Surgical robots can help fine-tune and improve accuracy of joint replacement.

Does the thought of having a robot perform your surgery seem scary? Don't worry. We aren't at a place where robots can replace surgeons. However, highly advanced, computerized robotic systems are proving to be valuable surgical assistants, including for joint replacement.

"The robot allows us to position the implant and make cuts very precisely," says Cleveland Clinic orthopaedic surgeon Robert Molloy, MD.

Who Needs Joint Surgery?

Joint replacement surgery is often recommended when osteoarthritis seriously limits the ability to function and can no longer be effectively managed with nonsurgical methods, such as exercise, physical therapy, pain medications and injections.

Several joints can be surgically replaced. In 2018, over 370,000 hips and more than 680,000 knees were replaced. The surgery involves cutting away some bone in the joint and inserting an implant, usually made of metal and plastic. The implant allows for the return of smooth movement in the joint. The surgery has a high success rate for relieving pain and improving mobility.

Success With Partial Knee

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Ekkasit919 | Getty Images

If you need joint replacement surgery, you may discover your surgeon is assisted by a robot.

The idea of using robots to assist with joint replacement surgery arose about 15 years ago when a system was developed for partial knee replacements. When it comes to knees, most people need a total knee replacement. But about 5% to 6% of people with arthritic knees are eligible for a partial replacement because the arthritic damage is confined to one side of the joint.

With partial knee replacement, only the inner (medial) or outer (lateral) portion of the joint is replaced. Compared with total knee replacement, people who have a partial replacement usually have an easier recovery, less pain and fewer complications. However, the failure rate is higher, meaning revision surgery is required. "With robotic surgery, it's been demonstrated that the longevity of implants is equivalent to total knee replacement," says Dr. Molloy.

More recently, the robotic technology has been adapted for total knee replacements and hip replacements, greatly expanding its use.

How Does It Work?

With robot-assisted joint replacement surgery, the surgeon can accommodate for each person's unique anatomy. "During knee replacement surgery, we place markers in the thigh bone and the shin bone and then we map out the ends of the bones," says Dr. Molloy. The computer detects the markers and overlays a map of the knee joint over a computed tomography (CT) image that was taken before the surgery. The surgeon can then very accurately position the components of the implant.

"With traditional surgery, if I have one patient who is really bow-legged and someone else who is really knock-kneed, I'm putting the components in the same position for them both," says Dr. Molloy. To get the implant in the best balanced position, the surgeon will then manipulate the soft tissues around the joint.

"I'm making the patient accommodate what I can do with standard surgical instruments," Dr. Molloy explains. With robotic surgery, the components are positioned in ways that are specific to the patient, which minimizes the amount of work that has to be done on soft tissues. "We're making the components accommodate to the patient," he says.

The robotic arm positions and guides the saw used to cut the bone. Dr. Molloy uses the analogy of a drill press in woodworking. The surgeon moves the saw, but the robot positions it so it can operate only in one plane. It's very precise. "The robot won't let you cut outside predetermined boundaries," he says. This means there's less likelihood of damaging surrounding ligaments and tendons.

"With robot-assisted surgery, there is greater precision, enhanced protection of surrounding tissues, and less need to manipulate tissue to create a balanced knee," says Dr. Molloy.

Does It Improve Outcomes?

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MedicalArtInc | Getty Images

Total knee replacement involves inserting an implant to restore smooth movement.

"At the first visit three weeks after surgery, patients have less swelling, less pain and better range of motion than with traditional surgery," says Dr. Molloy. It's too early to know whether this will translate to even better long-term outcomes than can be achieved with traditional surgery. That's because robots have been used for total knee replacement and hip replacement for only a few years.

"For robotic partial knee replacement, we can demonstrate a decreased failure rate," says Dr. Molloy. If that is any indication, the advantages of using robots should mean better outcomes.

The technology continues to be studied and fine-tuned to improve it. With robotic hip replacement surgery, "we can be extremely precise in terms of positioning the components," says Dr. Molloy. But there are other aspects of the surgery that are still being worked out. "We need more research and data before we can get the best advantage from robotic hip surgery," he says.

As more robot-assisted joint replacement surgeries are done and positive outcomes are reported, surgeons are becoming more interested in it and more medical centers are acquiring the equipment. If hip or knee replacement surgery is in your future, you may discover that your surgeon's best assistant is a robot.

Comments (1)

Very interesting, thanks. If one is in late 70s with bone on bone in both knees, shots, etc not working, but have a 3-4 year life expectancy. It seems like risk my congestive heart failure, diabetic body would be too great. What do you think? thanks.

Posted by: joan | August 11, 2019 1:55 PM    Report this comment

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