Computer guided surgery tightens knee replacements


The anticipation is already building for competitive rower and triathlete, G. Evan Evans. At 52, she's ready to kick her athletic career into a smoother gear.

"Really the first thing I want to do is get back in my boat, that's going to be wonderful," Evans said.

For most of her life, Evans has struggled against both the competition and chronic knee pain. The result of an injury she suffered while still a teenager.

But despite the discomfort, she worried a total knee replacement could effectively limit her ability to compete.

"I have been waiting for medical science to catch up to me," Evans said.

"So this is going to show the computer what the deformity of the leg is," Orthopedic Surgeon John Velyvis, M.D., said.

That breakthrough technology turned out to be a computer guided partial knee replacement.

In an operating room at Saint Francis Memorial Hospital in San Francisco, Velyvis prepared to resurface Evan's knee with more precision than he says he could ever achieve by hand.

"You're preserving all the good parts of the knee, the ACL, the PCL, the side of the knee and only re-surfacing the damaged portion, and it needs to be very accurately done," Velyvis said

The system, known as the Navio, works something like a GPS.

Signals pass back and forth between surgical instruments and a powerful computer system.

First, Velyvis plots the area where the partial implant will be placed, which is then displayed as a graphic map.

With all the coordinates in place, Velyvis shave away bone to create a snug pocket in the precise shape of the implant.

A camera system monitors the progress and can slow or stop the cutting action if it nears the plotted boundaries.

Once the surfaces are ready, Velyvis fits the upper and lower caps into place.

"With this new robotic technique, the fit was absolutely perfect," Velyvis said.

While still under anesthetic for the pain, Evans was able to leave the hospital a few hours after the surgery on a stable knee.

She now hopes a steady rehab program will allow her to quickly return to the modest list of sports she's looking forward to.

"Snow shoeing, surfing, getting back to rowing and sculling. Maybe I can do a swim bike," Evans said.

The robotic system is covered by insurance. And doctors say in some cases it's allowed them to perform partial knee replacements on patients who had previously been candidates for total knee replacement.

Written and produced by Tim Didion

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