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This article is from the In-Depth Report The Science of Basketball
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Saving Troubled Knees

Silk scaffolds, grafts from pigs and green tea extracts might someday help keep injured and vulnerable joints active

Any sport that involves body contact, jumping, landing, pivoting or zigzagging raises the players risk of injury and osteoarthritis, particularly when athletes get back in the game before a damaged joint heals. Most at hazard are those who play soccer, football, basketball or tennis and those who perform gymnastics.

Women are particularly susceptible to tearing an ACL [see box on page 65]. Women's gymnastics has as high a rate of ACL injuries as men's spring football, which is when collegiate teams practice and play scrimmage games, says Jennifer Hootman, an athletic trainer and epidemiologist with the Centers for Disease Control and Prevention. In Norway, which often takes home the trophy in women's team handball competitions, Hewett says something like one in five women who play that sport tears her ACL.

Gimme a Graft!

For torn ACLs, treatment generally involves trying to connect the knee back together in some way, Fu says. In the 1950s surgeons tried to stitch together the torn ends of the ACL. Unfortunately, that didnt work too well, says Martha Murray, head of the sports medicine research laboratory at Children's Hospital Boston. Patients with sewn-up ACLs would eventually find that their knees were as unstable and prone to buckling as before the repair.

Of course, not everyone with a torn ACL needs surgery. If you are not very active, if your lifestyle is such that you go swimming and walking but dont engage in activities that require sharp changes in direction--like basketball or tennis--you may be able to live without surgery, Fu says. Such individuals might be able to get by merely with physical rehabilitation to strengthen their leg muscles and help stabilize the joint.

Nowadays people who opt for surgery usually receive a graft to stand in for the torn ligament. The surgeon removes the damaged ACL and replaces it either with a strip of the patellar tendon (a tough tissue that connects the kneecap to the tibia) or with the hamstring tendons (which attach the muscles on the back of the thigh to the tibia). Another option increasingly popular with elite athletes is to use an allograft--tissue from a cadaver. I keep hearing at national and international meetings that surgeons who take care of professional sports teams--including basketball, football and soccer--are now using allografts as a first-line choice for ACL repair, says Andrew Chen, team physician for the U.S. Ski and Snowboard Association and an orthopedic sports medicine surgeon in Littleton, N.H. Although allografts actually take a longer time to integrate into the body after reconstruction, recipients may feel like the recovery time is shorter because they do not need to deal with the additional pain from where their own tendon was harvested. With so many high-profile players onboard, a lot of athletes are saying, Put in an allograft, and if I blow it out, we can always put in another. This is my time to shine, Chen remarks.

Of course, allografts dont grow on trees. Although they do not need to be matched the same way a transplanted organ does, graft tendons must be healthy and strong, and thus they tend to come from donors somewhere between 18 and 35 years old. Lack of a suitable graft can sometimes postpone surgeries for weeks or months. To get around those problems, Kevin Stone, an orthopedic surgeon in San Francisco, is turning to pigs. Pig ligaments are similar to human ligaments, and we can get them young, healthy and strong every time, he says. He and his colleagues have developed a method for stripping the porcine tissue of the proteins that would trigger rejection and have shown that the grafts are safe for use in humans. One individual in their initial safety study went on to win the Canadian masters downhill ski championship--three times.

A Longer, Better Surgery?

Regardless of where a graft comes from, Fu says surgeons need to pay more attention to where the graft goes: in other words, they should look to each patient's particular anatomy to determine where to anchor the new ligament to the bone. The traditional procedure--called a single-bundle replacement--involves simply attaching one end of the graft to the femur and the other end to the tibia.

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