The zirconia ceramic femoral heads form the "ball" portion of a hip prosthesis, connecting the femoral stem to the pelvis. Apparently, St. Gobain changed its manufacturing process in early 1998. Part of the heating process appears to have made the ceramic more prone to fracturing. The failures typically occur 13 to 27 months post-operation. While the expected failure rate is one-one hundredth of a percent, one of the recalled lots is demonstrating a fracture rate of 8 percent.
The FDA announcement comes following determinations by the French Agency for the Medical Safety of Health Products and the United Kingdom Medical Devices Agency to suspend sales of the implants in Europe.
The recall applies only to unimplanted femoral heads. The FDA reports that zirconia implants are used in less than 6 percent of the hip implant procedures performed in the United States, out of about 150,000 to 200,000 hip implant procedures performed each year. The FDA is not recommending that persons with the implants have replacement surgeries unless they experience failure, particularly because not all of the affected devices will fail and there is no way to predict in advance which implants will be problematic in the future. Thus far, the agency has collected at least 14 reports of fractures in the recalled implants. However, the agency is instructing physicians not to implant any unused implants and to monitor patients with the implants. A failure is usually marked by a "pop," followed by pain, grinding, and loss of range of motion in some instances.
The following companies are also participating in the recall: Apex Surgical, LLC; Biomet, Inc.; DePuy Orthopedics, Inc.; Encore Orthopedics, Inc.; Osteoimplant Technology Inc.; Smith & Nephew, Inc.; Stryker Howmedica Osteonics; and Zimmer, Inc.
The recall is the second hip-implant-related recall in the last year. In December 2000, Sulzer Orthopedics, Inc. recalled approximately 40,000 hip implants because the joints allegedly had lubricant residue on them, causing bonding problems. The Inter-Op acetabular shill implants-which are used for complete hip replacement procedures-are designed to bond to nature bone through a socket-like device that is inserted into a portion of the pelvis and a shell that attaches to a ball-like device inserted into the femur. With the allegedly defective Inter-Op implants, when bonding problems occur, implantees develop severe groin pain and an inability to bear weight on the leg where the implant is located. Approximately 26,000 U.S. residents received the implants.
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