Photo courtesy of Journal of Orthopaedics
Manufacturers have addressed the loosening problem by developing new devices. But each has drawbacks. Joshua Jacobs, M.D., chairman of the orthopaedic surgery department at Rush University Medical Center in Chicago, says that many patients base their choice on advertising. Instead, he advises, "Find a physician who is knowledgeable about all the issues, and make a collaborative decision." The first device described below is available for knees and hips; the other two for hips only.
Metal on highly cross-linked polyethylene
Plus: This new plastic wears substantially less than conventional polyethylene.
Minus: It has a shorter track record and might be more prone to fracture.
Recommendation: Paired with metal in the hip, it offers durability with the fewest side effects, making it the best choice for most people.
But because the knee puts greater demand on the joint, and thus may increase the risk of fracture, our consultants still generally
recommend metal on conventional polyethylene for knee replacements.
Metal on metal
Plus: It wears less than metal on plastic, and offers a larger femoral head, reducing the chance of dislodgment.
Minus: It releases metal particles into the bloodstream that have unknown effects on the body and are particularly worrisome in
women of childbearing age. Moreover, a few patients have developed allergies to the metal debris.
Recommendation: This kind of device might make sense for young men in need of hip replacement whose work involves heavy labor, which increases
the risks of joint dislocation and wear.
Ceramic on ceramic
Plus: It's likely to wear out the slowest.
Minus: It poses a rare but serious risk of chipping or breaking. Moreover, up to 7 percent of patients have complained of squeaky
ceramic hips.
Recommendation: This might be an option for patients who need to get many decades out of their hip, such as very young men, or women of childbearing
age.
