Smith & Nephew is well-known for its innovative contributions to the design of hip implants. For example, in 2003 the company introduced their own exclusive alloy comprised of oxidized zirconium. This oxidized zirconium appears to increase the hip implant durability and, unlike ceramic components does not fracture. According to Smith and Nephew the release of metal ions and debris are significantly reduced when this particular alloy is used in the hip implant components. Like many other hip implant manufacturers, however, Smith and Nephew has experienced trouble with another device—the metal liner used in the R3 Acetabular system was recalled on June 1, 2012. The metal liner has been linked to dislocation of the implant, inflammation, infection and bone fracture—all of which require revision surgery to correct.
The Smith & Nephew R3 Acetabular System is considered a modular system, allowing surgeons to match the patients size and activity level more closely to the implant. The R3 Acetabular System was only made available in the United States in 2009, yet just a short time after its release problems surfaced. Many of those problems came about when the metal liner interacted with the metal femoral head. The two metal components create friction during periods of activity, causing tiny metal ions to shear away and burrow into surrounding tissues or enter into the bloodstream. Since the release of the R3 Acetabular System over 7,700 patients across the globe received an R3 implant which implemented the metal liner, with an estimated 3,000 – 4,000 of those in the United States. The R3 Acetabular System is still in production, however after the recall of the metal liner, Smith & Nephew now offers zirconium and polyethylene plastic liners.
Should metallosis result from the metal liner rubbing against the metal femoral head, inflammation will occur, tissue destruction and death and even bone loss. Metal toxicity can cause such symptoms as memory loss, cardiovascular, neurological, renal and thyroid problems, disruption in DNA, gastrointestinal disorders, loss of vision and hearing, emotional problems including irritability, depression and anxiety, vertigo and balance problems, the formation of pseudo-tumors and gastrointestinal disorders.
Metal toxicity symptoms can be relatively mild or can be very severe, depending on the individual body’s reaction to cobalt and chromium, however there are really no “safe” levels of these metals in the body. When metallosis has caused significant amounts of bone and tissue to deteriorate or die, the implant is in danger of total failure as it continues to pull away from the femoral bone. Even though the Australian National Joint Replacement Registry found few instances of metal poisoning among recipients of the R3 Acetabular system, many patients nonetheless experienced significant levels of metal sensitivity and allergic reactions, from mild to severe.
Recipients of the Smith and Nephew R3 Acetabular Hip Implant System in which a metal liner was used, should consult their physician and arrange to have regular blood monitoring done to measure the levels of cobalt and chromium. The patient’s doctor may also suggest that the patient have an MRI, a bone scan and x-rays to determine whether the implant is experiencing any level of failure. Any pain experienced in the hip and groin region is cause for concern and should be reported promptly to the recipient’s physician.