A growing number of hip replacement patients – especially those with Stryker Corp’s Trident components – are experiencing squeaky hips. It seems that such artificial hips made with ceramic materials and touted as being more durable, are prone to squeaking, even during light walking. One study in the Journal of Arthroplasty found that 10 of 143 patients who received ceramic hips from 2003 to 2005 developed squeaking. No squeaks occurred in a control group of 48 who received metal and plastic hips. “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 Manhattan.
Most artificial hips consist of a socket implanted in the pelvis, into which a spherical head is fitted. The head is attached to a spike anchored into the thigh bone. Durability is critical as no one wants to outlive their artificial hips and undergo a second, more extensive surgery when older and less able to handle surgical trauma. Ceramics—which have been in use since the 1960s—were promoted as lasting longer than the 15 years for traditional steel and plastic joints; however, each joint type has known or suspected problems. Metal-on-metal devices slowly shed tiny ionized particles some feel promote cancer and the newest plastics are not as durable as other materials, raising worries that fragments can lead to bone-destroying inflammations.
Over 250,000 Americans receive total hip implants yearly in a procedure that costs close to $45,000. While any artificial hip can occasionally make any number of noises, it wasn’t until Stryker Corp. began marketing Trident ceramic hips in the United States in 2003 that the previously rare squeaking began. Tens of thousands of hips have been replaced by Stryker and other makers and now people are complaining that their squeaking hips are interfering with daily life. No one really understands why this is occurring, and now there are concerns the noises might be pointing to more serious problems and malfunctions.
Investigators reviewing the problem report that while the reason is unclear, squeaking appears to be linked with extreme flexing of the ceramic implants and some surgeons are afraid the ceramic material might shatter, leaving a patient with so many inflammatory shards that a doctor could never find them all. “Catastrophic failure has been a concern in the past, with older ceramic components,” said Dr. James M. Bried, a surgeon in Poway, California. Patients and surgeons are concerned squeaking points to premature wearing down, something that could force a second surgery and doctors who have removed ceramic hips say they find dark stripes indicating accelerated wear on the ceramic heads. Dozens are undergoing a second surgery and have sued Stryker.
Stryker was the pioneer and market leader in ceramic joint replacement, but now doctors say Stryker has not taken patients’ concerns seriously. Last fall, the Food and Drug Administration (FDA) issued a warning to Stryker, saying it had failed to take steps needed to prevent squeaking and other problems. Also, last year Stryker recalled ceramic hip parts made at its Cork, Ireland, factory when it determined some parts failed to meet its sterility specifications.
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