As we age, it is normal that our bodies begin to deteriorate. Common areas prone to deterioration are the joints, i.e. knees, hips, etc. Wear and tear on these parts of the body can cause pain, stiffness, and difficulty walking. Physicians typically prescribe conservative treatment such as physical therapy, exercise and medications, but often times, joint deterioration requires total replacement or resurfacing. Hip replacements are one of the most common joint replacements.
There are several types of hip implants used in replacement surgery, five currently being available in the United States. These are, Metal-on-Polyethylene, Ceramic-on-Polyethylene, Metal-on-Metal, Ceramic-on-Ceramic, and Ceramic-on-Metal. All of these implants have different risks and benefits. The same implant can also react differently depending on the patient. The different types of implants refer to the different materials used to make the ball and sockets of the artificial hip. In metal-on-metal hip implants, both the ball and the socket of the device are made from metal. Some notable advantages of metal-on-metal hip implants are “bone conservation on the femoral side with possible lower dislocation rates”, better range-of-motion, more normal walking posture, increased activity, and “increased ease of insertion with proximal femoral deformities or retained hardware, and straightforward revision”.
However, there are many risks with these replacement surgeries. Common adverse effects regardless of the type of implant are hip dislocation, bone fracture, joint infection, local nerve damage, device loosening or breakage, difference in leg lengths, and bone loss. Even with these potential complications, data from an FDA study performed of patients from Australia and the U.K. shows that 95 percent of patients with any type of total hip replacement have not undergone revision surgery for at least seven years after their initial operation. Specifically with metal-on-metal implants, over 85 percent of patients have not have a revision for at least seven years after the initial implant. Interestingly, patients with larger heads, defined as 36mm or larger, had more revisions than those with smaller heads.
Although this is true for this study, there has recently been a massive recall for several different manufacturers of hip implants in the U.S. Consumer’s Union found that from 2002 to 2013 hip implant recalls six major manufacturers, Biomet, DePuy, Smith & Nephew, Stryker, Wright and Zimmer. However, these recalls came after the implants had already been used in hundreds of thousands of hip replacement surgeries. In total, more than 500,000 patients in the United States received metal-on-metal hip implants after they were claimed to be more durable and provide a greater range of motion when compared to older forms of artificial implants. However, it was later found that the manufacturers’ claims that the implants were more durable were false. These metal hip replacements began failing rather quickly. Common symptoms of hip replacement failure are regular and prolonged pain around the groin, hip, or leg, swelling near the hip joint, and difficulty walking. The key reason these metal-on-metal hip replacements are failing is due to the friction caused by the normal movement of the device. This friction releases microscopic shavings and metal debris into the tissue around the joint. Consequently, this can cause metallosis, a build up of metal fragments in the soft tissues of the body, which causes painful and inflamed joints and a high blood-metal count. Continue reading