During the last five years, tens of thousands of people in North America have gotten total hip replacements that cost close to $45,000 a person.

Most of those people received artificial hips made of ceramic materials that were promoted as being more durable than older models.

But for reasons not yet fully understood, many of those people say their hips have started to squeak, raising questions about whether the noises herald more serious malfunctions.

“There is something amiss here,” said Dr. Douglas E. Padgett, chief of adult reconstructive and joint replacement service at the Hospital for Special Surgery in New York.

Click here to read this New York Times story, in which people say their squeaking hips are interfering with their daily lives.