Research Links DePuy Pinnacle Acetabular Component to Revision SurgeriesNov 6, 2012
Recent research conducted at Penn Presbyterian Medical Center, Philadelphia, Pennsylvania, has revealed that some hip replacement devices, constructed with a polyethylene liner and an acetabular shell, are potentially prone to liner and shell separation. In every case studied, patients underwent a primary total hip arthroplasty with a Pinnacle acetabular component, which is manufactured by DePuy Orthopaedics. And, in every case, patients had to undergo revision surgery to remove and replace the defective components.
Meanwhile, lawsuits involving defective hip implants have been growing, mostly over all-metal or metal-on-metal devices. Prior lawsuits have centered on the hallmark problem with metal-on-metal hip implants, a defect that puts recipients at serious risk of permanent injuries like tissue and organ damage. The Pinnacle lawsuits have been building slower than others involving all-metal components; however, other varieties of the device exist that do not use metal-on-metal components.
Polyethylene Liner Failures
Polyethylene liners are meant to increase femoral head coverage, which is, in turn, meant to allow for larger femoral heads with smaller cup diameters and to provide improved stability without impingement risks, explained The Journal of Bone and Joint Surgery. In other words, these components are constructed to increase hip motion and stability and should be, in theory, able to allow surgeons to make fine adjustments to the device.
The research team presented four patient cases in which the liner dissociated-or split-from the acetabular shell, which then necessitated the need for revision hip surgery.
All four patients studied suffered from spontaneous splitting of their offset, face-changing polyethylene acetabular liners; had to undergo revision hip arthroplasty surgery between January 2007 and June 2010; and were female. The average age of the patients was 53 (ages 33 to 71), and all the women underwent original implantation with a combination of a Pinnacle acetabular component with an offset, face-changing polyethylene liner. According to the researchers, all four defects occurred without direct trauma and, in every case, patients reported squeaking sounds from the area of the implant. The Journal of Bone and Joint Surgery pointed out that when the removed liners were examined at the time of the revision surgeries, plastic deformation of the polyethylene liner rim was seen.
The average time from original implantation to revision surgery was 13.1 months, with a range from three to 36 months, said The Journal of Bone and Joint Surgery
Two patients said they suffered from nonlocalized hip pain and surgery revealed signs of metal transfer to the device's ceramic head and signs of metallosis in the joint. All four patients underwent revision surgery for the acetabular component and three of the patients also underwent replacement of the face-changing liner over stability concerns; one patient underwent revision to a neutral liner, said The Journal of Bone and Joint Surgery,
The defect was seen with Zimmer's Harris-Galante Porous I and II acetabular components; the culprit was determined to be failure of the locking mechanism, which is meant to secure the polyethylene liner to the metal acetabular shell. The weak locking mechanism can result in liner deformation, rim wear, and dissociation and failure of these implants. The researchers also noted that liner dissociations has been seen in devices with alternative bearings, including Zimmer's Metasul® Metal-on-Metal Liners and Stryker's Trident Tripolar Constrained Liner.
DePuy Pinnacle Lawsuits
Meanwhile, lawsuits involving metal-on-metal version of DePuy Orthopaedics' Pinnacle hip replacement device continue to move forward, with some 1,800 lawsuits currently pending. All allege that the all-metal model of the DePuy Pinnacle hip replacement device caused metallosis and other injuries similar to those seen with other metal-on-metal hip implants, including DePuy's recalled ASR hip implants. The DePuy ASR hip replacements were named in worldwide recall in August 2010, and plaintiffs in the Pinnacle litigation assert the metal-on-metal Pinnacle implants should have been recalled, as well.
Injuries Linked to Metal-on-Metal Hip Implant Devices
Like other metal-on-metal hip implants, the DePuy Pinnacle is prone to shed miniscule metal fragments through the implants' normal wear-and-tear. The all-metal version of the DePuy Pinnacle litigation is only one of several metal-on-metal hip implants that have raised safety concerns in recent years. Several studies have found that such devices can disperse dangerous amounts of chromium and cobalt into patients' bloodstreams, leading to a number of serious health problems, such as pain; swelling; dislocation; and metallosis, a reaction that leads to tissue and bone loss, the formation of pseudotumors, and long-term heart, kidney, nerve, and thyroid problems.