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DEPUY KNEE AND HIP PROSTHESES FAILURE?
Lawsuits have been filed against Johnson & Johnson and Depuy arising out of the alleged failure of the Defendants’ allegedly defective ultra high molecular weight polyethylene knee joint and hip replacement prostheses. According to the allegations in the complaints, the prostheses at issue have been sterilized with gamma radiation, resulting in premature failure of the product.
If you or a member of your family has a Johnson & Johnson/Depuy Knee Prosthesis made of ultra high molecular weight polyethylene, you may have a claim.
Contact Audet & Partners, immediately to protect your rights.
In an article posted at http://www.cen.uiuc.edu/~kgordon/assign4.html, it is noted that:
"Ultra high molecular weight polyethylene is a polymer. The word "polymer" comes from the Greek word "polumeres," which means having many parts. Thus, a polymer is simply many units of atoms that are bonded together to form a long chain. In the case of ultra high molecular weight polyethylene (UHMWPE), many polyethylene chains that are extremely long are bound together to form one UHMWPE chain. UHMWPE has a greater toughness and wear resistance than regular polyethylene, but it can wear down in a process that is known as oxidation. During oxidation, oxygen reacts with polyethylene chain ends that do not have enough electrons. When the oxygen bonds to the free ends of the polyethylene chains, other molecules that would normally bond to the polyethylene chain cannnot bond to it, and thus the material is degraded or weakened. When stress is applied to the oxidized UHMWPE, it will wear at a rate that is faster than normal.
"UHMWPE particles produced during the articulating motion of an implant are foreign to the body, and as a result the body reacts to them in an unusual way. When the body reacts to a foreign material in acute, short-term inflammation, phagocytosis occurs. During phagocytosis, a macrophage travels to the foreign body via the white blood cells and attempts to dispose of the foreign material.
"When phagocytosis fails, and the macrophages cannot dispose of the foreign material in the body, acute inflammation progresses to chronic, or long-term, inflammation. Sometimes during chronic inflammation, white blood cells induce self-injury to the body. This is known as an autoimmune reaction."
[Emphasis added]
Unfortunately, as stated above, the method used to sterilize these prostheses is well known to cause oxidation. An article posted at http://www.medical-devices.gov.uk/ notes that:
"The degradative effect of irradiation on polyethylene and other polymers has been known for many years. Chapiro, in his text in 1962, described the mechanisms behind the oxidative degradation of polymers. He noted that ionizing radiation interacted with long chain polymers, forming free radicals. In an example, polyethylene was shown to degrade to form a hydrogen radical and a polyethylene radical. The chain scission which was caused in this reaction led to two possible outcomes. Either cross-linking between the polymeric radicals or, in the presence of oxygen, oxidation of the polymeric chains could occur. In the former case, polymeric chains effectively became longer, and a network structure was formed. In the latter case of oxidation, the polymeric radical could be terminated through the addition of, for example, one of the hydrogen radicals or an oxidation free radical. This termination would lead to lowering of the molecular weight."
