Hip replacement surgeries are among the most performed surgical procedures, but in some cases the device fails, resulting in revision surgery to remove and replace the device. On average, artificial hips can last 20 years or more before being replaced, but one type and size of hip implant was found to fail more often than traditional hip implants.
Last month, the Canadian Institute for Health Information released a report that studied the factors influencing how long artificial hip implants lasted. Researchers reviewed data from 56,942 surgeries throughout Canada (except Quebec) from 2003-2011. They found that metal-on-metal large-diameter modular implants in particular had a 5.9 percent chance of failing within five years compared with 2.7 percent chance among traditional implants.
Traditional hip replacements are made with plastic or ceramic parts. But in the past decade, many manufacturers have started marketing all-metal implants. These metal-on-metal implants were designed to be more durable and were a particularly attractive choice for younger, more active patients.
Just a few years after the devices were introduced worldwide, however, medical device regulators began receiving reports of failures in just five years or less. Surgeons noted that many of these failures – loosening, fractures, dislocations – were being caused by inflammation and damage in the tissue surrounding the metal implant. They also found that bits of metal were flaking off the devices as they rubbed together, inflaming the tissue but also leeching into the bloodstream causing a type of blood poisoning known as metallosis.