It’s been very well documented in research that wear particles are a given with hip replacement, but what exactly are hip replacement wear particles, and are they anything to be concerned about? First, in order to understand wear particles, you need to understand the materials manufacturers use to create these artificial-hip devices.
A hip replacement involves cutting off the head of the femur (the long bone of the upper leg), drilling into the center of the femur, and inserting a rod-like device with a ball at the end to re-create the head of the femur. The surgery also involves preparing the acetabulum (the socket the ball fits into on the pelvic bone) by resurfacing and lining it. There are a number of materials that can be used for the ball (artificial femur head) and the socket (acetabulum shell and lining) as shown below:
- Metal on Metal (MoM): The ball and the socket lining are made of some type of metal (e.g., titanium, cobalt, steel, etc.).
- Metal on Polyethylene (MoP): Typically, the ball is made of some type of metal, and the socket lining is made of polyethylene (plastic).
- Ceramic on Metal (CoM), Ceramic (CoC), or Polyethylene (CoP): In all of these cases, the ball is made of a durable and specialized ceramic (yes, similar to but stronger than your ceramic dishes), and the socket lining is made of metal, ceramic, or polyethylene. Despite their strength, they are still ceramic, and stress can create fractures, or breaks, in the material.
Despite the variety of materials that are now on the market for hip replacement devices, you’d think manufacturers would be getting better at minimizing wear particles, but things just seem to be getting worse. Studies have shown that wear particles aren’t just a problem with metal devices—they are a problem with all hip replacement devices.
What Are Hip Replacement Wear Particles, and Are They a Problem?
Simply put, hip replacement wear particles are debris that sloughs off the device with normal wear and tear. In other words, as we normally move (e.g., walk, sit, etc.), the contact of one material against the other over time creates shedding of the materials. So is this a problem? Absolutely! In fact, it should top your list of biggest concerns when considering whether or not to get a hip replacement. These tiny wear particles wreak havoc on our bodies. Let’s take a look at a few big issues related to wear particles from artificial hip devices.
Wear Particles in the Bloodstream
Metal particles found in the bloodstream of hip replacement patients explains why these patients have increased metal levels in their blood. This side effect is so well known that device manufacturers created the metal-on-polyethylene alternative to metal-on-metal hip devices; however, these have been shown to produce similar and in some cases higher increases in metal levels in the blood. Recalls and lawsuits have even resulted due to shards of metal wearing off of hip devices and causing device failure, inflamed tissues, and even bone death.
Wear Particles and the Development of Pseudotumors
Pseudotumors are tumor-like formations that can occur just about anywhere in the body. In most cases, their cause is uncertain; however, in the case of hip replacement patients, we do know that large pseudotumors (one inch or bigger) develop in one-third of patients following surgery. These large pseudotumors form when soot-like wear particles shed from the device, and they can put pressure on blood vessels and nerves in the area of the replaced joint, causing pain, inflammation, fluid buildup, and so on.
Wear Particles and Genetic Issues
Genetic studies have also found chromosome damage at the cellular level specifically due to wear particles from hip replacement and knee replacement devices. We’ve even seen studies linking cancer risks and joint replacement, so perhaps further studies will find this to be a result of the chromosome abnormalities created by the wear particles. It’s certainly something to be aware of, especially if you are considering or have had a hip replacement.
Hip replacement wear particles are produced from all types of hip replacement devices, so it’s important that you consider this before making the decision to undergo this highly invasive surgery. As with any surgery, you need to make sure the risks of having a hip replacement don’t outweigh the risks of not having the surgery, and while there are many, many risks associated with hip replacement, the dangers created by wear particles should certainly be a list topper.