The theory behind the all-metal hip implant was to allow those younger hip implant recipient patients to be able to go for a longer period of time before they were required to undergo revision surgery. The prior hip implant designs were primarily made from ceramic and polyethylene, and while these materials exhibited a reasonable success rate, they simply did not last long enough, with a typical length of time before revision surgery being approximately 8-10 years. The all-metal hip implants were expected to last almost double that amount of time, making them an exciting, innovative new development in hip implants. Problems soon began to arise with the metal-on-metal hip implants, with several models being recalled due to the risk of metallosis.
No Recall, Lawsuits on the Horizon
While the DePuy Pinnacle Acetabular Cup System has not yet been recalled, DePuy is nonetheless one of the many hip implant manufacturers facing lawsuits over hip implants. The Pinnacle is actually an older design of the DePuy ASR implant, and, like the ASR, implements a metal ball against a metal acetabular cup. There are variations of the Pinnacle Acetabular Cup System, however, including some with ceramic cups. DePuy also offered a choice of liners with the Pinnacle Acetabular Cup System, including a metal liner. Patients who have a ceramic cup and a metal liner could face an easier revision surgery as the surgeon can simply remove the metal liner and replace it with a polyethylene version.
How Metallosis Occurs
The metal-on-metal designs—including the Pinnacle’s use of a metal liner—results in metal components rubbing against one another during times of patient activity. This friction results in tiny metal shards being sent out into the body, primarily in the surrounding tissues and in the bloodstream. These cobalt and chromium ions are extremely toxic to humans even though it appears that some bodies will tolerate small or moderate levels of the metals more readily than others. When these metal ions lodge in the surrounding hip area, the tissues will become inflamed, resulting in pain and difficulty in walking or other movements. Metallosis—tissue inflammation, deterioration or tissue death and bone loss—can occur, leading to a total failure of the hip implant and a potentially dangerous revision surgery.
Symptoms of Metal Toxicity
Even more insidious, as the metal ions continue to travel through the body and enter the bloodstream, metal toxicity can occur. Some of the symptoms of a buildup of cobalt and chromium in the bloodstream can include: Neurological disturbances including anxiety, depression, irritability and memory loss, cardiovascular issues, renal and thyroid problems, the development of pseudo-tumors, loss of hearing and/or vision, balance issues such as vertigo, chronic headaches, alterations in DNA, infection and illness in the body due to the increased lymphocyte production and even the development of cancerous cells.
Chances of Experiencing Hip Implant Problems
While all humans naturally have cobalt in their body in very low amounts (less than 0.41 micrograms per deciliter) one study found that some recipients of a metal-on-metal hip implant had cobalt levels as much as thirty-nine times higher than normal, and chromium levels twenty-eight times higher than normal. Even among those metal hip implant recipients who have yet to experience any negative health effects from the implant, statistically speaking there is a good chance they will experience problems at some point in the future.
How FDA Approval Was Obtained
Many manufacturers of the all-metal hip implants gained FDA approval by “riding in on the coattails” of prior approved implants under the 510(k) process which approves medical devices which are substantially similar to another device previously approved. This means than many important safety tests including clinical trials were not required. If you are the recipient of a DePuy Pinnacle Acetabular Cup System, it’s important to have regular tests done to monitor the levels of cobalt and chromium in your body. If you have experienced any pain or other unusual symptoms, contact your physician immediately.