Hip and Knee Replacements: Breaking Up is No Laughing Matter

Rutherford, NJAs the population continues to age, joint replacement surgeries are becoming more commonplace. Specifically, hip and knee replacement surgery allows patients to recapture some of the mobility they once enjoyed in their younger years.

However, like any surgery, the procedure is not without risk. And advances in technique, and materials used may, for some, succeed in reducing hospital stays and therefore lessen the impact on the health care system. However for others, problems following surgery can be complicated by being sent home early - and there have been some cases, a few bizarre in nature, that resulted not from the surgery itself or materials used, but from incidents which happened in the post-operative environment. One woman who was accidentally dropped during transport after surgery developed an E coli infection of the area surrounding her replaced hip. She found litigated and was awarded U.S. $120,000.

While advances in surgical technique may improve healing and reduce time spent in hospital, it is the actual prosthesis itself that appears to be causing problems for many patients.

Hip and knee replacement prosthesis are made of a specialized polyethylene material designed to last for years of service. However, it appears that a sterilization process used by several manufacturers is succeeding to weaken the prosthesis material, causing it to wear out far too soon. A second surgery would be required to replace the worn joint.

Some prosthetic joints have required replacement within two years of initial surgery. Given the fact that recovery times for replacement surgery can take up to six months (recovery times vary according to the individual, and surgical procedure used), it's little wonder that so many lawsuits have been launched against various manufacturers. The requirement for more surgery barely 18 months after recovering from the first one is anything but good news for an active senior.

The culprit in the accelerated wear of the replacement hip and knee joints is gamma irradiation in air. The process has been found to adversely affect the new joints once implanted in the body, causing them to break down. Small pieces can flake off and become painfully lodged in the hip, and knee joint. In an effort to rid itself of these foreign objects, the body's immune system will often turn indiscriminately on healthy bone, bringing on decay and worsening the condition known as osteolysis.

In one example, the Hylamer modified polyethylene device was introduced by DePuy Orthopaedics in 1987 to reduce wear in total joint replacement components. DePuy used the gamma irradiation process through air to sterilize the products. In the late 1990's however, Hylamer products were withdrawn from the market, and in 2001 the British government's Medical Devices Agency issued a voluntary recall of knee implant Hylamer liners sterilized with gamma irradiation through air. The recall was issued after a study of patients in a single hospital showed an extremely high failure rate of 67.6 per cent within five years, or thirteen times the expected failure rate for the device.

The problems associated with gamma irradiation in air have become widely known, to the point where manufacturers have begun using ethylene oxide, or gas plasma, to sterilize the components and reduce the risk of oxidation that is now known to weaken the polyethylene, making it more brittle and prone to breaking down. Better attention paid to packaging, shell-life issues, and keeping joint replacements away from exposure to air until surgical insertion, combine to afford an improved outlook.

However, that doesn't help the thousands of people who are trying to walk around with replaced hip and knee joints that are, literally, falling to pieces.

The number of hip and knee replacements worldwide is closing in on one million each year as the population ages. The United States accounts for roughly half that number alone.