Robodoc makes operating-room debut Robot helps in hip-replacement surgery in Calif.

November 09, 1992|By Los Angeles Times

In what is cited as a medical first, surgeons in Sacramento, Calif., have used a specially designed robot to help them perform a hip replacement surgery. Although robots have been used by surgeons in the past to help align instruments for brain surgery, the Sacramento procedure apparently marks the first time when the robot has actively participated in an operation.

The unidentified patient was reported in stable condition.

The surgical robot -- actually, a 7-foot-long flexible arm with a drill on the end -- was used Saturday in the surgery to produce a precisely drilled cavity in the leg bone to hold a long titanium pin for the ball-and-socket joint. The idea is to get such a good match between the cavity and the pin inserted into it that no cement will be necessary to hold the prosthesis in place.

"Our hypothesis is that if we do the surgery more precisely, then the outcome will be better," veterinarian Howard Paul told the Sacramento Bee in an interview Saturday.

Sutter General Hospital spokesmen yesterday refused to release any information about the operation other than to say that it was successful and that the patient was "in stable condition and resting comfortably."

Sacramento orthopedic surgeon Dr. William Barger performed the surgery using the robot that he had developed in conjunction with Dr. Paul while both were on the orthopedics faculty at the University of California, Davis School of Medicine. The pair have formed a Sacramento company, Integrated Surgical Systems Inc., to market the robotic arm, which they call Robodoc.

The team was scheduled to release further information about the operation at a news conference in Sacramento today.

About 200,000 Americans undergo hip replacement surgery every year when their own hips become painfully damaged, most jTC often from the complications of arthritis. The new procedure employing the robot surgeon would not be appropriate for all of the patients, however.

Conventional hip replacement is fairly successful in patients over the age of 65. In those cases, the titanium pin is cemented into the leg bone, called the femur, and the joint is expected to last for the rest of the patient's life.

But younger patients who are more active put much more stress on the prosthesis. Because of that stress, the cement tends to deteriorate over about a five-year period, once again leaving the patient with a painful joint that often needs to be replaced a second time.

In such patients, therefore, surgeons prefer to insert the pin into the femur without cement. That necessitates constructing a very precise cavity so that the pin does not slip and slide around in it. But creating such a precise hole, usually about 8 to 10 inches deep, with hand-held tools is extremely exacting and requires exceptional skill.

Robodoc was developed to circumvent the need to use such crude tools.

In practice, the robot arm is attached to the hip and femur with three cylindrical pins that hold it steady. Using data obtained with a sophisticated X-ray imaging device called a Computed Tomography scanner, a computer directs the arm and drill so that the hole is positioned precisely.

An external "fixator," similar to the frameworks used to hold a fractured wrist immobile while it heals, is attached to the femur to prevent it from moving during the surgery.

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