Polyethylene Wear in Joint Replacement and Osteolysis
An integral part of almost all artificial hip or knee joints is a plastic part of the prosthesis usually referred to as a liner in hips and an insert in knees. As the liner or insert is responsible for absorbing the impacts experienced by the implant, it is imperative that the liner or insert be as durable as possible. Extensive wear of the liner or insert can result in failure of the entire implant, the release of foreign bodies into the patient, and bone loss known as osteolysis. At the very least, extensive wear of the liner or insert will result in the need for a revision surgery to remove the worn liner or insert and to replace it with a new liner or insert.
The liners used in hip implants and inserts used in knee implants are generally manufactured from a type of polyethylene known as ultra-high molecular weight polyethylene or UHMWPE. UHMWPE is used for this purpose because of its extreme durability.
Gamma Radiation In Air Renders Polyethylene Liners and Inserts Defective
In the first half of the 1990's it became widely known in the orthopedic device industry that a method used to sterilize implants was causing polyethylene liners and inserts to become brittle, defective, and prone to an extreme form of wear called delamination. The sterilization method was the exposure of the liner or insert to gamma radiation while in air. They discovered that sterilizing the polyethylene with gamma radiation in air caused greatly increased wear while sterlizing it with gamma irradiation in an inert gas such as nitrogen or argon actually made the polyethylene much stronger. After identifying the benefits of avoiding gamma irradiation in air, most manufacturers switched to other methods of sterilizing hip liners and knee inserts that created much more durable polyethylene.
However, some manufacturers continued to use gamma radiation in air to sterilize their liners and inserts and store them for extended periods even after becoming aware that it rendered their product defective. At least two manufacturers switched to a safer form of sterilization, but instead of discarding their aged liners previously sterilized with gamma radiation in air, they disposed of them by selling the defective liners for surgical implantation in patients. The sale of gamma irradiated in air polyethylene hip liners and knee inserts appears to have continued until fairly recently.
Our attorneys have represented patients across the country in relation to this issue. As you might expect, these are expensive cases to litigate and as a result our clients typically prefer that we do their case on a contingency basis. That means that we only get paid if and when your case is settled or you prevail at trial. In the event that there is no recovery, we receive no fee.
If you believe that your hip liner or knee insert failed because it was defective, our attorneys will be glad to review your case to determine whether we feel there are sufficient grounds for us to represent you in pursuing a case against the manufacturer. Click here for our online potential case evaluation form.
Typically in order to review a case, we need the orthopedic surgeon's office chart, the operative reports for the original joint replacement surgery and the revision surgery, and the device record for the original surgery from the hospital chart (this shows the product and lot numbers of the components of the device). We also need pictures of the liner or insert if you have it. In most instance is is still possible to do the case if the device has been discarded, but it can sometimes be much more difficult.
