By Denise Grady and Reed Abelson

New York Times News Service

A surgeon recommended a hip replacement, but Kenneth Cevoli said no thanks.

“They’re really quick to try to give you fake joints and make a bunch of money off you,” he said.

At 71, Cevoli, a high school guidance counselor in Teterboro, New Jersey, coaches cross-country, teaches mogul skiing, surfs and works summers as a lifeguard on Cape Cod, Massachusetts. Despite pain in his left hip and knee, he questioned the need for major surgery, worrying it would sideline him for too long.

Instead, he tried an increasingly popular treatment, in which stem cells are extracted from a patient’s own bone marrow and injected into worn or injured joints to promote healing.

Many people have become captivated by the idea of using stem cells to fix their damaged joints, and some claim to have been helped.

But there is no clear evidence these treatments work, and their safety has yet to be established. Most researchers, including those at the National Institutes of Health, think efforts to sell therapies involving adult stem cells, which can develop into different types of cells to replenish tissue, have gotten ahead of the science.

Even so, hundreds of clinics have popped up around the country to meet the demand. Some of the clinics also inject joints with platelet-rich plasma, a solution of platelets extracted from the patient’s own blood. A few employers have even agreed to provide insurance coverage for the treatments.

There is almost no regulatory oversight of orthopedic procedures using bone-marrow extracts or platelets, which are regarded as low risk. While the Food and Drug Administration insists that it does have the authority to regulate stem cell treatments, it adopted an industry-friendly approach in 2017 by giving companies a three-year grace period in which to describe their products or treatments so the agency can determine whether they meet the criteria of drugs that would require agency approval. So far, few companies have submitted any information.

In the meantime, rogue clinics offering other kinds of procedures have flourished, accused of blinding people by injecting cells into their eyes, mixing stem cells with smallpox vaccine to treat cancer or causing severe infections by administering contaminated blood from umbilical cords into patients’ joints or spines. In some of the worst cases, patients had already been harmed before the agency took any action, and the patients took legal steps themselves, suing the clinics that injured them.

“We had our day job clearly cut out for us,” said Dr. Scott Gottlieb, who was FDA commissioner until April. There is, he added, a lot of “really bad stuff.” Gottlieb spoke in an interview after leaving office. A spokeswoman for the agency said current officials declined to be interviewed. But she said the agency had taken about 45 enforcement actions against stem cell businesses in the past year, including two court cases and various types of warning letters.

Many scientists are skeptical about the treatments being offered and have called for stricter oversight.

“I believe strongly that it isn’t ethical to charge patients for unproven therapies like these and raise what are likely to be false hopes,” said Paul Knoepfler, a stem cell researcher at the University of California, Davis.

He said some properly conducted studies on platelet-rich plasma suggested it might help, but others did not. As for stem cells extracted from bone marrow, Knoepfler said well-controlled studies were even scarcer, also with mixed results. Rigorous studies are essential, because symptoms from arthritis and injuries can wax and wane, making it hard to determine whether treatments work.

In part because of the scant data, no stem cell or platelet treatments are approved by the FDA for orthopedic problems, and most insurers don’t cover them. Still, many patients pay thousands of dollars out of their own pockets.

Cevoli was treated in December by a doctor in Wayne, New Jersey, affiliated with a company called Regenexx, one of the boldest players in the growing industry. Based in Des Moines, Iowa, the company has dozens of affiliated clinics around the country, specializing in treating orthopedic problems with patients’ own platelets or stem cells from their bone marrow. Regenexx has persuaded some large, self-insured employers to cover its treatments.

The doctor in Wayne injected stem cells and platelets into Cevoli’s knee, fitted him with a brace and sold him a vitamin supplement made by Regenexx to promote healing. The procedure cost $6,900, and was not covered by insurance.

Four months later, Cevoli said he thought the procedure was helping. He skied during the winter, and has begun running a few times a week.

“There was pain involved, and there is still swelling,” he said. “The strength is starting to increase significantly in that left knee. I’m advised that there will be more of an improvement to come in the next couple of months.”

As for clinical trials, Regenexx says it is conducting them now. As a result, patients rely on testimonials and other informal evidence. But experts caution that word-of-mouth experiences are not a substitute for rigorous studies.

“The power of anecdotes is just amazing when it just catches on,” said Donna ­Messner, president of the Center for Medical Technology Policy, a nonprofit research group. “This is how snake oil has been sold for generations.”