Go ahead. Log on to www.youtube.com and type the phrase "squeaking or squeaky hip replacements" in the search box. What pops up is an array of home videos, most featuring senior patients, who are documenting a noise their replacement joint makes with each step. For some, the noise resembles the sound of air released in sporadic bursts from a child's balloon. For others, the noise – all clichés aside – sounds just like a fingernail quickly scraping down a blackboard. For some of the patients, the sound is a popping, occasionally accompanied by the squeak.

 

K. David Moore, MD, who heads the University of Alabama at Birmingham Center for Joint Replacement, has watched – and listened to – several of the YouTube entries. "It's impressive," he acknowledged, adding, "It's been known in the joint-replacement community for three or four years that some of these hips seem to squeak. The magnitude of it I don't think was initially appreciated."

 

Moore was referring specifically to ceramic-on-ceramic total hip arthroplasties, which research now is pointing to as the primary culprit. "All hips make some noise," Moore noted, but the ceramic-on-ceramic varieties much more so than metal on metal, metal on polyethylene, metal on polyurethane and even ceramic on polyethylene.

 

The popular media first took notice when famed golfer Jack Nicklaus, who received one of the early ceramic-on-ceramic replacements in 1999, later mentioned during an ESPN interview that his hip squeaked. What made that comment so notable was that Nicklaus was a spokesperson for the Stryker Corp.'s ceramic-on-ceramic hip, now implicated as the leading squeaker by most researchers. (Medical News' requests to Stryker for an interview or statement were not acknowledged.) At the American Academy of Orthopaedic Surgeons' annual meeting in March, squeaking hip replacements were a recurring topic. More than one poster presentation was the result of studies specifically on the Stryker Trident acetabular component. Based on their findings, one group of authors associated with the Desert Orthopaedic Center in Las Vegas, Nev., recommended against the use of a particular Stryker Trident ceramic-on-ceramic combination because the squeaking may be the manifestation of concerning and unintended wear. Not to mention that annoying noise.

 

For patients who have undergone painful and costly hip-replacement surgery and its lengthy rehabilitation, the squeaking is a frustrating and at times embarrassing side effect. Research suggests that as many as 7 to 10 percent of ceramic-on-ceramic surgeries result in some squeaking, but most cases don't warrant additional surgery to fix the problem. But for the patients whose hip squeaking adversely affects their daily life, additional surgery is the only remedy.

 

Herrick J. Siegel, MD, a UAB colleague of Moore's, said he has treated several patients referred to him because of hip-replacement squeaking. For those patients, he has removed the artificial joint's ceramic liner and replaced it with a plastic one. That has worked, he said. Siegel said ceramic "had a lot of promise when we first started using the material, and many surgeons have gone away from it a little bit because of this possible risk of squeaking." Siegel said ceramic's rigidity made the material initially so attractive, but the unforgiving surface may just be too difficult for the body to lubricate. A lack of lubrication preventing the joint's smooth glide is, in fact, the leading hypothesis among researchers trying to figure out the squeaking's cause.

 

That's certainly Kenneth St. John's theory. An associate professor at the University of Mississippi Medical Center, St. John is a researcher with the Department of Biomedical Materials Science. "I have a machine that takes eight hip joints and walks them at one cycle per second. It mimics the motion and the loading at the hip, modeling the walking motion so that we can look at the wear and resistance of the materials," he explained. So far, St. John has conducted one study of the possible ramifications of the squeaking.

 

"It has something to do with how they're lubricated, I'm sure. If you think about anything that squeaks, like a squeaky hinge, you put a little oil on it and it stops squeaking. I think it relates to how the tissue fluids are getting between the two components," he surmised. "It could very well have to do with the patient's personal physiology; in other words, everybody's fluids in a total joint may have different mechanical properties, different viscosity. Some oils are thicker than other oils, and some patients' fluids around the joint may be thicker than other patients' fluids."

 

St. John concurred with Siegel's comment regarding ceramic's rigidity. "There isn't any give," he said, and thus no flexibility to allow for the easy flow of lubrication fluid. So what's the fix? "I think it probably has to do with adjusting the clearances so you change the lubrication properties," he said.

 

St. John added that studies regarding the lubrication of replacement joints are difficult because the fluid present around a replacement in the body "isn't the fluid that's normally present around a normal joint. It varies."

 

Last year, The New York Times jump-started the noisy-hip discussion with its story headlined "That Must Be Bob. I Hear His New Hip Squeaking." Today, poor Bob and others like him are facing the decision of whether to undergo a second surgery to ensure a peaceful evening stroll. Bob and his ilk also face another decision: whether to call an attorney.