Every year, a half million Americans are sidelined by injuries to the cartilage in their knees. The smooth, viscous tissue normally cushions the tips of the thigh and shin bones, letting them turn on each other as freely as ice against ice. But when the cartilage gets chipped or torn, as Clukey’s was, the bones start to grate on each other. Because cartilage doesn’t heal on its own, even a minor knee injury can lead to crippling arthritis. But as scientists learn to grow the substance in lab dishes, those small nicks and tears become less daunting. No one knows just how much disability ACI might prevent–only a few dozen people have tried the new procedure, and long-term studies are just getting started. But experts say it could revolutionize sports medicine. “This is a tremendous advancement,” says Dr. Harlen Hunter, a St. Louis surgeon who traveled to Boston recently to learn the technique. “It opens a whole new era.”
The excitement started just over a year ago, when Swedish researchers published a report describing the new technique and recounting its effect on 23 patients. The procedure involved several costly steps–arthroscopy to harvest cartilage cells, lab work to cultivate them, open-knee surgery to implant the new cartilage and arthroscopy to check the results. But some of the results were impressive. Of the 16 patients with lesions on the tips of their thigh bones, 14 got results deemed “good” or “excellent.” Three years after surgery, all 14 had sound joints and active lives. One patient, a 28-year-old bowling champion, was reportedly bending without pain for three hours a day.
On the strength of the Swedish findings, Americans are now racing to try ACI themselves. Only 60 have been treated since Dr. Thomas Minas of Boston’s Brigham and Women’s Hospital and Dr. Bertram Zarins of Massachusetts General performed the first U.S. operations last spring. Because full recovery takes a year or more, the results can’t yet be judged. Even so, injured sports enthusiasts are calling surgeons out of the blue to request the operation-and surgeons are flocking to Cambridge to attend training seminars at Genzyme Corp., the biotech company that controls the cartilage-growing technique. During the two-day sessions (for which Genzyme covers all expenses), the surgeons attend lectures and watch video demonstrations, then pair up at lab tables to practice on knees from butchered calves. Genzyme is now training 50 surgeons a month.
Skeptics worry that the new technique is being marketed too quickly. “The work out of Sweden is exciting,” says Dr. Richard Coutts, a cartilage researcher and surgeon in San Diego, “but it hasn’t been rigorously validated.” A procedure that succeeds in one clinic sometimes fails in others. And though the Swedish patients got good results, the study didn’t include other treatments for comparison. Surgeons can sometimes shore up a wounded knee simply by perforating the damaged cartilage and letting the underlying bone cells generate a smooth, scablike sheath.
For now, the best candidates for ACI are people under 50 with recent injuries to the cartilage at the tip of the thigh bone. Most insurers won’t start paying the $35,000 tab for cartilage implantation until its benefits are better established. But the price should come down as the technique is refined. And if ACI lives up to its promise, surgeons may someday use it to restore damaged joints throughout the body–even after arthritis has set in. The Swedes are already experimenting on ankles and shoulders. But for patients like Dale Clukey, a working knee would be miracle enough.
Because cartilage doesn’t heal on its own, small injuries can be crippling. But a new procedure may change that.
Using an endoscope, surgeons extract a tiny sample of healthy cartilage from the knee of the injured patient.
When placed in a soup of enzymes for several weeks, a few hundred thousand cartilage cells beget tens of millions.
In a separate operation, surgeons inject the new cartilage into the wound and. cover it with a snippet of bone tissue.
