Are you considering a joint replacement surgery? What are the best materials for the surfaces that contact one another? These are called the bearing surfaces. Let’s look at the benefits of different materials to understand the proposed procedure. Knowing your options can make you feel less anxious about the surgery and what to expect for the life of your implant. The materials used in the implant typically depend upon various factors, including:
- Patient age
- Patient activity level
- Surgeon preference
- Particular deformities/abnormalities of the hip or knee
Not all implants are options for every patient. Here is a brief description of some of the most commonly used implants:
Ceramic on Plastic (polyethylene) - This type of implant uses metal parts that fit within the bone, but the bearing surface for the ball or head is made of ceramic material. The socket bearing or the cup is made of a special plastic called polyethylene. Ceramic head implants are designed to be the most resistant to wear. Early designs had the risk of breaking. The newer designs are much stronger and it is almost unheard of to have the newer ceramic femoral heads break. Ceramic heads are very hard and very smooth. As a result, they cause less wearing of the polyethylene. People who are sensitive to the nickel used in metal implants might be a good fit for the ceramic type. We use ceramic on polyethylene in the majority of total hip replacements.
Ceramic on Ceramic - This type of implant was very popular 10 years ago. It had very low wear. However, in some cases, it created an intolerable squeaking that required surgical revision. As a result, we do not use this type of bearing at this time.
Metal on Plastic - The metal femoral head is the most common type of head implant. The metals commonly used include cobalt-chromium, titanium, zirconium, and nickel. Metal-on-plastic is the least expensive type of implant and has the longest track record for safety and implant lifespan. New implants are continually in development to make these implants last as long as possible. We have had excellent results with this type of bearing. There is no risk of the metal breaking. The only downside is the small risk of reactivity to the metal in the femoral head. Although some laboratory studies have indicated higher wear than in ceramic on polyethylene hips, we have not seen any issues with this in our patients even out to 20 years followup.
Cartilage on Cartilage - This type of bearing is the most exciting yet distant type of hip replacement. In our lab, we are continuously working to make this type of hip replacement possible. We have developed instrumentation to allow for a fully biological cadaveric total hip replacement. The indications for this procedure are currently limited due to cost of the cadaveric tissue and the excellent outcomes with traditional hip replacement.
New implants are being developed and improved yearly but using an implant with a solid track record is typically recommended. Remember, in contrast to other technologies like electronics, newer is not always better for joint replacement implants.
Developing a trusting relationship between a patient and their surgeon is a crucial aspect of finding the implant that is best for you and ensuring a successful surgical outcome.
Amir Jamali, MD
If you're suffering from an orthopedic injury or degenerative joint disease and are considering a joint replacement surgery, visit us today to consult with Dr. Amir Jamali at www.jointpreservationinstitute.com>.