Most hip implant surgeries are uneventful, but last week I told you about problems associated with one brand of hip implants often used by orthopedic surgeons in this area and promised to go into more detail this week. Hip replacements are usually done to cure the pain of painful arthritis that occurs naturally or after trauma like that experienced in auto accidents. One manufacturer has had considerable trouble with its implants because of the way they are made.
Depending on where you come from its name is pronounced "De-pwee" or "De-pie." Either way, it's a Johnson & Johnson company whose product is a metal on metal design that has a cup that's too shallow for the ball. The result is loose fragments of metal floating in the joint and loosening of the implant. The loosening and the metal fragments cause damage that often result in another painful and very costly surgery to replace the DePuy implant with a better designed implant.
Patients who have the DePuy ASR or ASR XL models can have crunching or popping noises in the hip, difficulty standing or walking, hip fracture or dislocation, unusual fatigue, muscle inflammation or infection, and death of some of the muscle tissue around the implant.
That's not the whole story. Excessive friction between the metal cup and the metal ball release cobalt and chromium ions into the body causing, among other things, heavy metal toxicity or aseptic lymphocytic vasculitis associated lesions resulting in bone loss. Metallosis causes its own unpleasant consequences. Among them are spontaneous dislocation, nerve palsy, groin and thigh pain, fatigue, and intense pain at the site of the hip replacement.
An orthopedic center at the University of Oxford, England, found that benign tumors called pseudo tumors can form around the hip prosthesis. Additionally, progressive bone deterioration is not uncommon. Metalosis can also result in muscle necrosis, that is, muscle death, around the site of the surgery. The release of metal ions in the blood stream, caused by the metal on metal construction of hip implants, is of great concern due to potential long term toxicology including immune system changes, chromosomal damage, and cancer according to researchers at Cambridge University.
It is known that the metal ion levels from this type of prosthetic design are significantly higher than normal values in the body, and changes in the immune system to cobalt and chromium ions were in fact detected by researchers at the Rush University Medical Center in Chicago. Surgery for a fractured thighbone or other bones and accelerated future revisions nearly completes the list of problems, so if you have one of these implants and are having any adverse symptoms, it is in your best interest to consult with your orthopedic surgeon as soon as possible.