Dr. Parisi, a graduate of the Mayo Clinic, is one of about 40 orthopedic surgeons in the United States who have signed up with NASH, to travel to Cancún on their days off to treat American patients. NASH is betting that having an American surgeon will alleviate concerns some people have about going outside the country, and persuade self-insured American employers to offer this option to their workers to save money and still provide high-quality care. NASH, a for-profit company that charges a fixed amount for each case, is paid by the employer or an intermediary that arranged the treatment.

“It was a big selling point, having an American doctor,” Ms. Ferguson said.

The American surgeons work closely with a Mexican counterpart and local nurses. NASH buys additional malpractice coverage for the American physicians, who could be sued in the United States by patients unhappy with their results.

“In the past, medical tourism has been mostly a blind leap to a country far away, to unknown hospitals and unknown doctors with unknown supplies, to a place without U.S. medical malpractice insurance,” said James Polsfut , the chief executive of NASH. “We are making the experience completely different and removing as much uncertainty as we can.”

Medical tourism has been around for decades but has become more common in the past 20 years as more countries and hospitals around the world market themselves to foreigners.

There are, of course, risks to going outside the country, including the headache of travel and the possibility that the standards of care may be lower than at home. If something goes wrong, patients will be far from family and friends who can help — and it might be more difficult to sue providers in other countries.

Chasing Lower Costs

The high prices charged at American hospitals make it relatively easy to offer surgical bargains in Mexico: In the United States, knee replacement surgery costs an average of about $30,000 — sometimes double or triple that — but at Galenia, it is only $12,000, said Dr. Gabriela Flores Teón , medical director of the facility.

The standard charge for a night in the hospital is $300 at Galenia, Dr. Flores said, compared with $2,000 on average at United States hospitals.