Why Women Are More Prone to Metallosis from the DePuy ASR Hip Implant
December 22, 2010
Women are reporting more problems, and a higher failure rate, with the DePuy ASR XL Acetabular hip replacement system than men. It turns out they're also more prone to some of the serious side effects of the poorly-designed implant, including metallosis.
Metallosis is a build-up of cobalt and chromium ions in the soft tissue of the body, particularly around the joints. Metallosis has been noted in people with all kinds of metal-on-metal joint implants and replacement systems - hips, knees, shoulders, wrists, elbows. Typically, the metallic build-up is minor enough that the body's immune system does not have a drastic response to the presence of metal in the system.
Not so with the DePuy hip implant. The engineering of the implant is causing far more friction than usual for a metal-on-metal implant, which means that the amount of metallic debris being released into the tissue surrounding the implant is far greater than with other implants of this type.
Especially so for women.
More Strain, More Problems
The design of the ASR XL Acetabular system is oriented around the idea of a greater range of motion. In order to accomplish this goal, the engineers removed the plastic liner from the inside of the hip implant and made the acetabular cup quite shallow so that patients could move their legs in a wider arc.
In theory, all of these design changes should indeed allow for a greater range of motion-assuming that that the implant will hold together.
Which it doesn't.
Women are affected more than men because of serious design flaws in the DePuy hip implant. The femoral head moves constantly back and forth as the hip implant's owner moves normally, and that puts stress on the acetabular cup. In an implant with a deeper acetabular cup than the DePuy ASR hip implant, there is more material to accommodate the strain of motion. The force is distributed over a bigger surface, which means that the implant overall can hold up to that strain better.
In women, that surface area gets even smaller. The already-shallow hip implant is made smaller overall to accommodate a woman's smaller frame. Women have naturally wider hips and larger hip sockets than men do, which means that the shallow acetabular cup becomes in effect even shallower.
And the smaller the surface area of the implant, the more likely the material will break down rapidly - releasing metal ions into the body as it does. Those metal ions accumulate in the soft tissues surrounding the hip joint, causing metallosis.
Essentially, the smaller the implant, the greater the amount of metal ions building up in the bloodstream. This means women aren't just susceptible to metallosis - they're also more likely to see the problems that develop as a result of metallosis, including metal hypersensitivity, heavy metal poisoning (which includes chromium poisoning and cobalt poisoning) and tissue and bone deterioration.
Metallosis' Risks to Pregnant Women
To ensure proper fetal development, every woman needs to be in the best possible health. Every guide for expectant mothers puts heavy emphasis on proper nutrition and exercise as well as giving up stimulants like caffeine and alcohol. Heavy metal poisoning can seriously impair a pregnant woman's normal bodily processes in ways that could present a danger to her pregnancy.
As previously mentioned, there is a healthy and normal level of chromium and cobalt found in the body. However, due to the DePuy ASR hip design, particularly on smaller sized implants, cobalt and chromium levels become elevated to the point that it becomes metallosis.
Excess amounts of chromium and cobalt can be a serious problem for pregnant women. Currently, not as much is understood about the potential side effects of excess levels of chromium, but cobalt at levels higher then 1 microgram per liter (or 1 parts per billion) raises some cause for concern. Cobalt poisoning has been shown to cause problems with DNA development, cardiomyopathy, and hypothyroidism, for example.
We're Here to Answer Your Questions
If you are pregnant and concerned about the affects that the DePuy hip implant may have on your pregnancy, please give our offices a call at 1-800-677-7095 or send us an email through our online form. We'll give you all the information we have about the problems presented by the DePuy ASR Acetabular system and give you our best advice on your legal rights moving forward.
If you'd like to learn more about metallosis, the construction of the DePuy ASR Acetabular System, or how women are affected more than men by the DePuy hip recall, we recommend these articles:
What Is Metallosis?
Glossary of Medical Terms Related to teh DePuy ASR Acetabular System
How the ASR XL Acetabular System is Constructed
Why Women Are Affected More than Men by the DePuy Hip Recall