In the 1980s, orthopedic surgeon Dr. K. Donald Shelbourne discovered that his patients who cheated during rehab and exercised their knees sooner than they were supposed to recovered faster than those who dutifully followed a doctor's orders.
Shelbourne still advocates a fast return to activity at his clinic in Indianapolis, which specializes in ACL surgery and rehab. He characterizes it as an "ACL superstore" with surgeons and physical therapists working under one roof to coordinate the patients' care.
Coordination is key, Shelbourne says: If physical therapy is left entirely up to the patient and therapist -- as is more typical -- therapists are often afraid to push patients too hard, fearing that "if something goes wrong, the surgeon will blame them."
In the first week after surgery, the priority for Shelbourne's patients is to keep the swelling down. After that, they do physical therapy for an hour twice a day. Shelbourne says his patients usually return to play six weeks after surgery and are fully recovered within three to four months.
Other surgeons take a more conservative approach, typically advocating physical therapy three times a week after ACL surgery. They tell their patients, even professional athletes, to expect to be out for six to nine months.
"I've used a certain protocol, and pushed it, and beyond that it's counterproductive," Chang says. He adds that recent research suggests that recovery from surgery to repair the rotator cuff, the complex structure of muscles, tendons and fibrous material that stabilizes the shoulder joint, can also be slowed by coming back too quickly.
It all adds up to a slight shift in medical strategy.
"In the last 10 to 15 years, there's been an attempt to stress rapid rehab," says Tasto. "In some cases that's been successful and in some cases we feel we've pushed the envelope a bit too far and seen recurrent injuries.... If we are returning people to play before the biological process has taken place, then the patient is at risk."
ONE day doctors may be able to give the biological healing process a boost.
"The key is going to be to change the biological environment to promote healing," says Dr. Kurt Spindler, a professor of orthopedics and director of the Sports Medicine Center at Vanderbilt University in Nashville, Tenn.
The tendons, ligaments and cartilage that tend to get frayed in active athletes aren't very good at healing themselves, Spindler explains. It might be possible, however, to encourage damaged tissue to regenerate using natural chemicals called growth factors.
Researchers have already identified several compounds that promote bone growth. These might, Spindler says, be useful for treating stress fractures -- tiny cracks in bone that result from repeated pounding, like the abuse taken by the feet of runners. But no one has tested this idea.
Researchers have also found growth factors for soft tissues such as tendons, ligaments and cartilage. These connective tissues are crucial for holding joints together and keeping them in working order, but in adults, their cells are relatively inactive. When an injury happens, they don't make the collagen and other materials needed to make repairs.
Growth factors might spur them to action and improve healing, says Dr. David McAllister, an associate professor of orthopedic surgery at UCLA. One possibility would be to use engineered viruses that carry the genetic instructions for growth factors, collagen or other compounds to shuttle these substances into the injured joint.
Researchers have had some preliminary success in animal studies, delivering growth factor genes that stimulate healing of injured cartilage in rabbit knee joints, for example. But such treatments are a long ways from leaving the lab.
Another approach that may be closer to reality involves coaxing stem cells to form replacement cells for the injured tissue.
A trial getting underway at USC is the first attempt to use stem cells to repair injured knee cartilage.
Gil Solomon, a 53-year-old triathlete in West Hills, is participating in the trial, which uses stem cells extracted from the bone marrow of adult volunteers.
Solomon says he started having knee pain last February. A physician himself, he suspected the problem was tendinitis. "I knew it would take time [to heal], and for the most part I was good, but there were times when I became frustrated and tried to see if it was ready," he says. So he'd run a little more than his trainer told him to.
"Sure enough, I was worse for a period of time afterward.... Unfortunately, the athlete mentality is to push though the pain, which is often the wrong thing to do," he says.
On Dec. 9, Solomon had surgery to repair what turned out to be a torn meniscus, the pad of cartilage that sits between the thigh and shin bones. A week after that, he got an injection of either stem cells or a placebo.
He says he hopes he got the stem cells, but he won't find out for two years.