Knee injury may be treated by regrowing your cartilage

In 2019, however, he slipped and fell while frolicking with his young nephew in a natural waterfall during a Memorial Day outing at Georgia’s Kennesaw Mountain National Battlefield Park. “I didn’t think too much of it at the time,” says Oates, who lives in Raleigh, N.C., where he manages a moving-and-storage company. “My right knee hurt, but I ran through the pain. But my knee would swell, and it was impacting my stride.”

In January, he finally had an MRI, which showed he had torn his meniscus, a common sports injury to the cartilage that cushions the area between the shinbone and thighbone. But there was more. The scan also revealed an area under the kneecap where the cartilage had worn away, which often portends full-blown osteoarthritis — and possible knee replacement — years later. Unlike bone, which has the ability to heal, cartilage cannot restore itself once injured.

Until recently, Oates had few options, one of them to give up running entirely with the hope that his knee would not further deteriorate. He couldn’t live with that. “Running is my Zen time,” he says. “I couldn’t take a ‘you can’t run again.’ ”

Today, however, he says he hopes to benefit from a relatively new and innovative technique that regenerates cartilage from a sample of cells taken from his knee and grown in a lab, where they are embedded on a collagen membrane. The surgeon then implants the membrane back into the knee, where new cartilage tissue forms over time.

“It’s the first procedure that uses a patient’s own knee cartilage cells to try to regrow cartilage that has been lost or damaged,” says Seth Sherman, associate professor of orthopedic surgery at Stanford University Medical Center and chair of the Sports Medicine/Arthroscopy Committee for the American Academy of Orthopaedic Surgeons.

Sherman points out that the approach, approved by the Food and Drug Administration in 2016, has been in use for years in other countries with “robust evidence” to support its efficacy. “That’s why I like to use it,” Sherman says. “It’s a huge deal.”

It’s unclear how many of these cartilage-restoring operations have been performed in the United States since its introduction here, but experts say its use is rapidly growing.

“There are over a thousand of these procedures performed yearly in the United States,” says Joseph Barker, the Raleigh orthopedic surgeon who operated on Oates. “This new technology is certainly increasing in popularity as more surgeons become aware of it and are trained in performing the procedure. The number of cases has been steadily increasing by about 25 percent a year since 2017.”

The procedure is among the latest examples of regenerative medicine, a budding field that relies on the body’s natural properties to promote healing and restore function.

“Regenerative medicine and orthopedic surgery are starting to work together,” says John Ferrell, a D.C.-area sports medicine physician who specializes in regenerative treatments. “Even though its current application is still limited, I see it ushering in a new era of the combination between the two practices, which is very exciting.”

Barker extracted the cartilage cells while repairing Oates’s meniscus, and implanted the membrane into Oates’s knee in September.

“The beauty of this procedure — why it is so great and cutting edge — is that you can restore an area that has no cartilage left by putting in a patient’s own normal cells,” Barker says. “When it’s all done, it’s a completely normal knee.”

The downside is that the treatment requires two procedures — one to remove the cells and a second to put them back — and a long, restrictive recovery period that can take as much as a year before full function returns. Initially, the patient must lie flat in bed (hooked up to a continuous passive motion machine to prevent scar tissue from forming) for as long as six weeks to allow the cells to adhere to the bone and proliferate.

“Those cells are like newborn babies in there,” says Nicholas DiNubile, a Pennsylvania orthopedic surgeon. “If you put weight on them, they won’t grow.”

Oates, who underwent the implant on Sept. 8, spent six weeks flat on his back in bed. He has since progressed from two crutches to one, and hopes to be using a cane before the end of the month. He’s also wearing a straight leg brace for the next few months.

Full recovery — which includes a gradual return to easy daily activities, followed by moderate moves, such as walking or pool running, and then full sports functioning, such as running — takes nine to 12 months following surgery. But experts believe the alternative is worse.

When the lesions are left untreated, they become larger, often causing damage on the other side of the knee, “and that’s essentially arthritis,” says Barker, who also is a team physician for the Carolina Hurricanes hockey team and North Carolina State University.

The name of the procedure is a mouthful — autologous cultured chondrocytes on porcine collagen membrane — commonly called MACI.

“With it, you can hold off and maybe prevent the development of arthritis, as well as a knee replacement,” Barker says. “It’s a significant advancement in the prevention of arthritis.”

It’s not for those with full-blown osteoarthritis, since there must be normal surrounding cartilage remaining for the implant to heal appropriately. Also, MACI cannot correct the underlying spurs and cysts that can develop with arthritis.

“By then, it’s too late to use it,” DiNubile says. “You can fix those potholes early on, but you can’t repave the whole road. It’s a way to replace cartilage before it becomes debilitating osteoarthritis, and it’s a game-changer. It’s about saving knees, not replacing them.”

The ideal candidates are ages 18 to 55, who are physically active and have isolated areas of cartilage loss.

“The treatments depend less on your actual age, but the age of your joints and your expectations and activity levels,” Sherman says. “MACI can be used on any part of the knee joint, on any cartilage defect in the knee. It preserves the joint, restores the cartilage, allowing the patient to return to his or her sports, or other activities, pain-free.”

The manufacturer of MACI is Vericel, a company based in Cambridge, Mass., that develops cell therapies. The company cultures the cartilage cells and produces the cell-embedded membrane. To be sure, insurance policies vary, but insurance typically covers some or most of the procedure — which can be expensive — costing about $30,000 or more, experts say.

Studies suggest it is more effective than another procedure, microfracture surgery, often used before cartilage cell regeneration came along. It involves creating small holes in the bone under the cartilage defect that stimulate the growth of fibrocartilage, a type of cartilage that resembles scar tissue. Fibrocartilage isn’t as strong or durable as hyaline cartilage, the native cartilage found in the knee and the type that MACI produces, experts say.

“Former high level athletes or college athletes who do pounding sports — football players, soccer players — used to do microfracture surgery,” Ferrell says. “The area would look better at first, but it wouldn’t last. As soon as they started to run and jump and play on it, they would have symptoms again.”

While so far limited to the knee, experts think eventually the procedure could help restore cartilage lost in other joints, for example, shoulders, ankles or hips.

“The hope is that this is just the beginning,” Barker says.

Oates is upbeat, despite knowing he will be sidelined from running for most, if not all, of the coming year.

“It’s a minor setback,” he says. “I see the ultimate reward as bigger than the sacrifice.”

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