The sporting world was transfixed a year ago June as Tiger Woods hobbled around the Torrey Pines Golf Course on a bad knee on his way to one of the most dramatic U.S. Open victories ever.
Most were simply amazed at Woods’ true grit. But to a group of people who work across the street from the golf course in La Jolla, that amazement was coupled with an intense curiosity about what the world’s greatest golfer had actually done to his knee.
It was a highly educated guess, based in large part on data from an electronic device he implanted in 67-year-old Sue Carpenter’s artificial knee, one of only four such “e-knees” in the United States, all implanted by Colwell. The e-knees have given the Shiley Center researchers specific data on the force put on a knee when it is subjected to a myriad of activities from walking to running to the swinging of a golf club.
The data from hundreds of swings by Carpenter showed that when the retired physical therapist hits a golf ball it goes 65 mph, and she puts four-and-a-half times her body weight on one knee. Woods hits the ball 130 mph, so they were able to extrapolate that he puts nine times his body weight on his knee.
That kind of force, Colwell and his colleagues guessed, was enough for Woods’ already partially torn anterior cruciate ligament to give way and his femur to slide on top of his tibia, and break his tibial plateau.
Such insights have made the Shiley Center the world’s foremost authorities on the forces put on artificial knee joints. Now, Colwell and his colleagues are trying to render all their work obsolete by finding a cure for osteoarthritis through stem cell therapy. And in May the center took a big step in that direction when it won a $3.1 million grant from the California Institute of Regenerative Medicine.
“[The grant] puts them at the forefront of stem cell research,” Suzanne Peterson, a scientist at the Scripps Research Institute for Regenerative Medicine.
Darryl D’Lima, the Shiley Center’s director of orthopaedic research, was more emphatic: “If anybody is going to make a breakthrough soon, it will be us,” he said.
The battle to cure osteoarthritis does not have the prominence as the races to cure diseases like Parkinson’s or Alzheimer’s disease, and it is a far less dramatic disability than ones that come from spinal cord injuries. But the impact of arthritis is huge — both economically and on quality of life.
Half of all people over the age of 45 in the United States have some form of osteoarthritis. And the costs of medical treatment and lost wages cost the economy upwards to $120 billion a year, according to the Centers for Disease Control and Prevention. Included in the costs are the more than 1 million knee and hip replacements done each year.
“People have been trying to fix cartilage since the 1700s,” Colwell said. “Yet there is not one thing that medical science has done to change the progression of arthritis. As far as disability, this overwhelms heart disease, cancer, all of them.”
However, there is a sense in the community of scientists who work in the field that a therapy for osteoarthritis will be among the first successful stem cell-based therapies — coming before cures for Parkinson’s or the other high-profile diseases.
“We look at the best science and what is feasible,” said Don Gibbons, a spokesman for the state’s stem cell institute. “And right now some of the best science that is feasible is in that field.”
While scientists still don’t know what causes osteoarthritis, the disease is easy to understand. It is, quite simply, the gradual deterioration of cartilage, which is the white, glistening tissue at the top of bones that keep them from grinding together. So medical science has to figure out how to reconstruct cartilage, which should be an easier task than reconstructing most other bodily tissues.
Reconstructed heart tissue must not only be able to beat, but also conduct electrical impulses. Recreating cartilage, on the other hand, is similar in concept to resoling a shoe. And joints aren’t life-threatening organs.
“It is a safer way of easing into stem cell treatment,” D’Lima said. “If you are dealing with Parkinson’s, and you inject stem cells into someone’s brain, it could be a catastrophe, but you can put metal or plastic in a knee and someone can walk on it.”
Yet some of the very things that make cartilage safe and simple also make it hard to regenerate in practice. Cartilage cells are inactive cells in that they don’t have a blood supply or nerve supply. So they don’t regenerate, and they are harder to manipulate than heart cells or bone cells.
“You can break your leg at the age of 90 and it will heal,” Colwell said. “But if you injure your cartilage at seven, it doesn’t.”
All told, the Shiley Center has about 40 research projects underway, ranging from studies on the genetics of osteoarthritis to spinal fusion programs. None, however, has led to as many insights as the e-knee program.
Among other things, they have discovered that when walking, people put from one-third to half the stress on their knees than predicted by models that had been used for decades. And, as Woods’ injury highlights, they found that swinging a golf club puts as much stress on the knee as jogging or playing tennis.
“They called and told me that what they found in my knee could show where Tiger could have the injury he had,” said Carpenter, who is from is from Binghamton, N.Y. “I couldn’t believe it, it seems just too incredible.”
What is incredible to Colwell is that he and his colleagues feel close to curing a disease that has vexed him for his entire career. “I think this is around the corner,” he said. “I don’t think it is another 100 years.”
Full disclosure: voiceofsandiego.org Chairman Buzz Woolley is among the donors to the Shiley Center for Orthopaedic Research and Education.
The original version of this story misidentified Darryl D’Lima’s title. D’Lima is the Shiley Center for Orthopaedic Research and Education’s director of orthopaedic research. We regret the error.