System improves surgical precision

WEST JORDAN — The orthopedic surgeon, the computer and even the surgical instruments are talking to each other during knee surgeries at Jordan Valley Hospital. And the resulting precision seems to promise better alignment, longer-lived synthetic knees and quicker recoveries for patients.

Jordan Valley recently purchased Stryker's Navigation System for knee replacement surgery, says Dr. Charles Beck, an orthopedic surgeon who has been pleased with the benefits to his surgical patients. While the fundamentals of knee-replacement surgery — the cutting of bone and implanting the new joint — haven't changed much, he says, computer navigation allows surgeons to "do that with a little less damage to the body. We pin with small pins, instead of more exposure, and cut less into muscle and bone than we did before. We avoid having bone marrow content spill into the joint, which may be one of the big advantages" for recuperation.

Most important, the alignment is much more precise.

Much of knee replacement surgery is carpentry, he notes. And the goal is to cut the bones in exactly the right place, something that's much easier with the computer guidance system. "We used to do X-ray or eyeball it. This is more accurate."

The goal is to create a weight-bearing line from hip to knee to ankle. The orthopedic surgeon points to different parts of the bone with an instrument. Two little guides that are pinned on either side of the joint send infrared signals to the computer, which literally paints a precise fit that takes alignment, shape, size and other factors into account. It maps out in precise detail a 3-dimensional model of the end of the femur and tibia, with all the landmarks.

With it, Beck says, a surgeon can get alignment right within a half degree. Eyeballing may be off by as much as 5 degrees, which increases wear and tear on the plastic-and-metal joint.

"If the force is not equally distributed, like a tire it's going to wear out. You want wear to be even and gradual," he says. "That means a better chance of possibly lasting the lifetime of the patient." It's too soon, he adds, to tell precisely how long a perfectly aligned artificial knee will last.

Proper alignment is more important for knees than for shoulders or hips. When the ligaments have been balanced correctly, the knee stays tight, avoiding instability problems, he says.