Metallosis is a dangerous and extremely painful condition associated with hip and knee joint replacements as well as prosthetic devices placed in the shoulders, wrists and elbows. Metallosis is associated with metal-on-metal and metal-backed joint implants that abrade against each other causing soluble metal ions to invade the bone and soft tissue where they trigger an aggressive immune response. Women are at a greater risk of developing metallosis due to their bone structure, which places pressure and tension on the joints. Individuals who are small in stature or carry extra weight also tend to develop metallosis faster than other groups.
Patients who received a total hip or knee replacement to repair weight-bearing joints have the highest risk of developing metallosis. Over the past 40 years, roughly five percent of joint replacement patients have developed metallosis. In patients who received metal-backed prosthetics with polyethylene components, as many as 25 percent of people developed metallosis. The incidence of this painful and potentially debilitating health condition is also higher in patients who received metal-on-metal implants, such as the recently recalled DePuy ASR system.
The grinding and abrading of metal joint components releases tiny metal molecules that begin a foreign body reaction and cause dangerously elevated metal levels in the body. Metallosis occurs with titanium-based joint implants as well as those made with chromium and cobalt although the toxicity of these metals varies. When the body detects metal particles, the immune system goes into overdrive causing inflammation, swelling and other painful conditions. In the joints, metallosis causes synovitis, which is the inflammation of the synovial tissue and membranes that line the joints. Synovitis is a painful condition associated with gout that causes unbearable pain and makes joint movement difficult due to swelling and increased pressure.
The presence of metal ions is also linked to pseudotumors that form around the implant site. Pseudotumors are thickened nodules that resemble tumors but are actually inflamed cells and tissue filled with fluid. Pseudotumors are often accompanied by rashes that are linked to internal necrosis. If left untreated, pseudotumors cause osteolysis or self-destructive bone death. Advanced metallosis leads to other problems with the current implant and makes it difficult to successfully complete corrective surgical procedures. When the surrounding tissue and bone are attacked by the immune system, the implant can become loosened and bone fractures form in the surrounding area.
In a small number of individuals, metallosis is linked to metal poisoning and dangerously elevated levels of metal ions in the blood serum. Metals such as cobalt can cause acute toxicity and conditions like cobaltism that are dangerous for the circulatory system, cognitive health and the organs. Metallois is a cumulative condition that takes years to fully develop. For this reason, ongoing testing and medical monitoring for chromium, cobalt and other metals are imperative.