Robotic-assisted surgery can improve longevity of knee replacement

Forty-nine-year-old James Benfante's knee pain got so bad he dreaded walking from the train station to his job or even standing in line.

Working out in the gym became all but impossible. He decided it was time for knee replacement surgery, and he did what many people do nowadays: he went online to get the latest information.

Mr. Benfante, who lives in Yorktown, New York, says he learned that robotic-assisted surgery enables orthopedic surgeons to perform the procedure with pinpoint accuracy, and this was important to him.

The FDA-approved system starts with a CT scan to create a 3D virtual model of the patient's unique anatomy. During the procedure, a robotic arm assists surgeons in performing an ultra-precise knee replacement customized for each patient.

Mr. Benfante wanted a joint replacement specialist trained in the use of the robotic system and found Dr. Geoffrey Westrich, director of Research in the Adult Reconstruction and Joint Replacement Service at Hospital for Special Surgery (HSS).

"The extreme accuracy provided by the robotic-assisted system could potentially improve the longevity of a knee or hip replacement. This is an important consideration, especially for younger patients," says Dr. Westrich. "Studies have shown that optimal alignment and positioning of the implant are critical for the long term success of a joint replacement."

Another major advance is a cementless knee replacement in which cement is no longer needed to attach the implant to the bone.

This, we feel, may also lead to a joint replacement that lasts longer and may not require a revision surgery in the future. The cementless knee replacement, which is FDA-approved for use with a robotic system, combines two of the most recent knee replacement advancements into one high tech procedure that aims to benefit patients."

Dr. Westrich

The length of time a joint replacement will last is an important consideration, especially for younger patients in their 40s or 50s, like Mr. Benfante.

The standard knee implant used in joint replacement usually lasts a long time – generally 15 to 20 years – but it doesn't last indefinitely. When the implant wears out or loosens, patients generally need a second knee replacement, known as a revision surgery. Dr. Westrich believes the cementless knee replacement implanted with robotic-assisted surgery could change that.

"The combination of these two major technological advances has dramatically changed the way I do knee replacements," said Dr. Westrich.

Statistics show that increasing numbers of younger people are having a joint replacement because they don't want arthritic pain to slow them down. Once they have a knee replacement, these active patients generally put more demands on their joint, causing more wear and tear, according to Dr. Westrich.

With a conventional cemented prosthesis, chances are they'll need another surgery down the road. This often has to do with loosening of the implant from the bone, much like a cemented crown on a tooth.

In a standard knee replacement, the components of the implant are secured in the joint using bone cement. It's a tried and true technique that has worked well for decades. But eventually, over time, the cement starts to loosen from the bone and/or the prosthesis.

"With the new cementless prosthesis, the components are press fit into place for 'biologic fixation,' which basically means that the bone will grow into the implant," Dr. Westrich explains. "In addition, more accurate positioning of the implant is critical, and robotic-guidance allows for pinpoint accuracy."

With biologic fixation, many joint replacement specialists believe that loosening over time could be less likely. "A total knee replacement could potentially last much longer, even for a patient's lifetime," Dr. Westrich says.

"Cementless implants have been used in total hip replacement surgery for many years and essentially replaced cemented implants for the same reason. Because of the knee's particular anatomy, it has been much more challenging to develop a cementless prosthesis that would work well in the knee," he explains. "Now I believe the time has come. Major advances in design, technology and biomaterials have paved the way for a viable cementless knee implant."

Candidates for the cementless procedure are generally patients under 70 with good bone quality to promote biological fixation. In addition to younger patients, the cementless implant may also prove to be a good option for patients with excess weight who tend to put more stress on their joint replacement, sometimes causing the cement to loosen prematurely.

Studies are under way to see how patients with cementless knee replacements do over the long term. As for Mr. Benfante, he says his quality of life has improved tremendously since his knee replacement. "I'm 100 percent after the surgery, no questions asked. In some ways, I'm probably better than I was," he says. "I don't experience pain. I can go for a walk." He is also back to one of his favorite activities - working out at the gym.

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