Cellular grafting procedure helps young patients with knee disorder get active

Apr 2 2008

At 14 years old, Adam Vasser of Los Altos, Calif., was an active kid who loved baseball.

Then a mysterious virus attacked his heart, making a heart transplant necessary to save his life.

He underwent long-term steroid treatment to prevent transplant rejection, which left him with an excruciating knee disorder called osteonecrosis. Now 23 and nearing graduation from college, after enduring 15 surgeries for his knee and heart, he's finally been able to return to sports.

Thanks to a new surgical technique used on Vasser's left knee called "cellular grafting," the 23-year-old is out cycling and refereeing soccer games on a virtually pain-free knee. The procedure was done for the first time on three young patients with steroid-induced osteonecrosis of the knee by orthopedic surgeon Stuart Goodman, MD, PhD, and is described in a preliminary report to be published in the April issue of the Journal of Arthroplasty.

"Even though a knee sounds like a little thing after all Adam's been through, it was big to get it fixed," said Adam's mother, Karen Vasser of Los Altos, who took her son from one doctor to another looking for help. "He was real athletic so the knee was one of the things that prevented him from getting back."

The new surgical technique involves transplanting cellular material from the pelvic area into the knee. Two years after surgery, Goodman said, all three patients had returned to nearly normal activity and knee function with no complications.

"It's a fairly simple procedure," said Goodman, the Robert L. and Mary Ellenburg Professor in Surgery at the Stanford University School of Medicine.

Osteonecrosis of the knee is a rare disorder. When it occurs in young people, it's most often the result of steroid therapy and is called secondary osteonecrosis. The bones in the knee start to die from a loss of blood supply, leading to severe pain, progressive arthritis and eventually the need for artificial joint replacement.

"Many patients do OK without surgical treatment," Goodman said. "With those patients, I wait and prescribe pain medication." But for young patients who still have a lifetime of activity ahead of them, Goodman wanted alternatives.

When Vasser first started looking for knee treatments, he was told by several doctors to simply use crutches until the knee collapsed and then get an artificial knee replacement. Pain medication was discouraged because of its effects on his kidneys after all the heart transplant treatment drugs. He, too, was searching for a better answer when he met Goodman.

All three of Goodman's patients were between the ages of 18 and 21 and suffering from steroid-induced osteonecrosis. Among the two other patients, one had a diagnosis of Crohn's disease and the other had been treated with high-dose steroids for severe optic nerve swelling associated with the use of minocycline.

The 60-minute surgery, called osteoprogenitor cellular grafting, involves scooping out the dead bone and then filling the space in with new cellular matter.

"The key is to arrest or reverse the death of the bone," Goodman said. "If the cartilage is good, you get the dead bone out and give the cartilage a better foundation. If you have a salvageable joint in a young knee, you get in viable cells to repopulate that area of dead bone."

Goodman theorized that instead of using traditional bone grafting - a more invasive and painful solution - a better method might be using bone cells. The bone cells include young stem cells and progenitor cells that can actually grow into new bone. He withdrew bone marrow from the pelvic area, concentrated the stem cells and progenitors, then used a scaffolding device to help the cells adhere to the defect in the knee.

Based on the success of these three surgeries, Goodman recommends a longer-term follow-up study with a larger number of patients.

Vasser underwent the knee surgery the summer after he graduated from high school. He described a painful, monthlong recuperation period, but said that since then his knee has improved to be almost like new five years later. His mother showed a photo of him crouching behind the home plate, playing umpire in a baseball game the year following surgery.

"My knee has felt good ever since," Vasser said. "It's much stronger than it used to be. It used to lock up. Towards the end before the surgery, it got really bad. I'm refereeing, riding a bike. It doesn't affect it. It's fine."