Orthopedic Solutions To Knee Problems

Saturday, April 09, 2005

Ray Stubblebine/Reuters
Jason Kidd is back in action after undergoing a novel form of knee surgery.

Older Knees Now Have New Option

For active people in their 30’s and 40’s who are starting to experience knee pain from years of running, skiing or basketball, the sports pages may point to a solution: microfracture surgery, commonly performed on the knees of professional athletes to regenerate cartilage eroded from overuse or sheared off from injury.

The treatment has prolonged the careers of many professionals, including Jason Kidd of the New Jersey Nets, who had the operation in July. But it is also gaining in popularity among people who do not earn a living in sports.

The surgery was pioneered by Dr. Richard Steadman of the Steadman- Hawkins Clinic in Vail, Colo., who estimates he has performed it 2,700 times since he developed it in the early 1990’s.

The surgery is performed using an arthroscope and takes 20 to 35 minutes, said Dr. Kevin Plancher, an orthopedic surgeon in Greenwich, Conn., who often performs the operation. First, the area of cartilage erosion – imagine a divot on an ice rink – is scraped with a curet to remove any calcified cartilage remnants that could interfere with the formation of new cartilage. "The cleaner the surface, the more potential there is for regrowth," Dr. Steadman said.

Next, tiny holes, called microfractures, are punched into the bone with an awl resembling a small curved ice pick. These tiny perforations allow stem cells to escape from the marrow cavity, starting the formation and growth of repair tissue that is similar to the original cartilage.

A video of a microfracture surgery that also featured two follow-up observations illustrated the effects of the procedure. A month after the surgery, blood gathered in the area of the picks, and new cartilage had started to mature. Six months later, islands of new cartilage filled in the gaps.

Dr. William Rodkey, director of basic science research at the Steadman-Hawkins foundation, said that patients were required to be on crutches up to eight weeks and to spend at least six hours a day with a machine that moves the knee in a continuous passive motion, because the tissue remains delicate during maturation, which takes at least a year.

"For reasons we don’t know, passive motion, which rocks your knee like a cradle, promotes healthy growth cells and promotes a more durable tissue," said Dr. Nicholas DiNubile, an orthopedic consultant for the Philadelphia 76ers and the Pennsylvania Ballet.

The longer recovery period compared with other arthroscopic knee procedures, which typically allow patients to walk out of the hospital without crutches, can pay off. A long-term evaluation of 72 cases, led by Dr. Steadman and published last year in the journal Arthroscopy, found that 80 percent of patients 45 and younger who had the microfracture procedure showed major improvement in function and experienced less pain. The benefits extended, on average, at least 11 years after surgery, the researchers reported.

In 2003, a study of 25 pro football players treated with microfracture documented that 19 of them (76 percent) returned to play the season after surgery and continued to play for an average of 4.6 additional seasons.

Older knees, however, may not fare as well. "Patients over 65 may have more problems with the crutch-walking and the rehab," Dr. Rodkey said. "And, in general, one would expect younger patients to have more stem cells in their marrow, and, therefore, do better."

Arthritic knees with major cartilage degeneration are not ideal candidates, either. "The threshold size of the defect seems to be around 2.5 centimeters," said Dr. David Altchek of the Hospital for Special Surgery in Manhattan, who operated on Jason Kidd’s left knee.

"Defects larger than this have marginal response," Dr. Altchek said, because if the surrounding cartilage is too worn down, it cannot contain the blood clot.

Many surgeons will not perform the procedure on people with markedly bowed legs or knock-knees, conditions that can put too much pressure on the area that has cartilage defect, so that new cartilage will probably just wear down again.

Being overweight is also an obstacle.

"The fact is that obesity not only causes arthritis, but it makes it more likely to progress," Dr. DiNubile said. "We have the technology to repair potholes on the joint surface, but we can’t repave the road."

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