Knees are not simple structures. They are made up of three distinct compartments (condyles). Lucky people have only one part go bad.

A new surgical procedure for a partial knee replacement provides patients in pain from osteoarthritis of the knee with a very efficient recovery. Knee specialists at Tucson Orthopaedic Institute are using “minimally invasive surgery” tools and techniques to relieve patients at an earlier stage, hoping to avoid years of limited activity and to delay a total knee replacement.

A mere three or four-inch incision (compared with 10-12) allows the surgeon to remove the diseased portion of the joint and insert a prosthetic device called a “unicompartmental knee.” The following day, the patient can usually go home, and typically within a week return to full activity.

“Knee replacement has been dramatically improved due to advances on several fronts,” Tucson Orthopaedic Institute surgeon Jay A. Katz, M.D. explains. With more precise cutting instruments surgeons can work in a small space without detaching muscle. A new spinal anesthetic gives the patient a choice of staying awake during surgery or “coming to” shortly after surgery. Then the CPM (continuous passive motion) machine in the recovery room gets the knee moving right away instead of 24 hours later.

“It used to take patients two months to recover 100 degrees of flexion, which is required for a person to stand up from a chair,” Katz remembers. Traditional anesthetics sedated patients for longer periods of time and made the patient feel nauseated. A new drug, Duramorph, contains a low dosage of morphine to block just the sensation of pain. “You wake up and it’s worn off and usually you can start to work on your knee.” Katz says nurses have called him to tell him they can hardly believe the difference.

James Levi, M.D., another Tucson Orthopaedic Institute staff surgeon, recalls that he had lost interest in performing unicompartmental knee surgery until new instruments were invented in the 1980s that allowed more precision in cutting into bone. Then, when it became possible to operate within a much smaller incision, he watched the success rate climb. His wife developed a single compartment knee problem, and the couple decided to try it, turning to a Chicago surgeon who had been involved in the “uni knee” research.

“By then the data showed this kind of replacement had a 94-98% rate of survival for ten years, and a second look at patients had indicated the procedure might even slow the progression of the disease,” stated Levi.

Levi’s wife’s surgery was on a Wednesday and she was driving her car the following Tuesday. Levi decided to train in these new techniques and began performing this surgery again. He has now done the procedure more than 100 times and is still impressed.

Katz, Levi and their colleagues are now on the leading edge of orthopaedic research. The Tucson Orthopaedic Research Center sponsors data collection on surgical outcomes. The research team conducts trials of new prosthetic devices for several companies. This enables the surgeon to more effectively select the very best implant for each individual patient. Each physician has independent authority to choose whatever products he thinks will work best for each case.

The growing choice of biomaterials makes it possible to almost customize replacement parts. An implant must be biocompatible and can be of more than one material. The “uni knee” is metal and polyethylene. Special coatings make the different materials comfortable working together snugly and smoothly.

Katz says while people generally accept the idea of living with some pain in their later years, medicine now recognizes the interconnectedness of physical problems. Notably, exercise is a critical deterrent to heart disease, and knees that hurt all the time will curtail someone’s activity. Minimally invasive surgery to replace a knee can keep a person from spiraling downward.

Although a partial knee replacement is not the answer for every patient with osteoarthritis of the knee (currently, 80% need total replacement), it will help many, many people, and with minimally invasive procedures, age is not a barrier. In fact, Katz says, the new approach is much less stressful for an elder. One “highly motivated” 83-year-old patient of his walked 750 ft. after surgery without even a cane, and the following day climbed two flights of stairs.

The Institute has two locations. The East office is located at 2424 N. Wyatt Drive, Tucson, phone 784-6200, and the Northwest facility is located at 6130 N. La Cholla, Suite 121, Tucson, AZ, phone 382-8200. For more information, please call the Tucson Orthopaedic Institute at (520) 784-6200.

KUAT-TV News Story with James H. Levi, M.D.

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