Hip implants are routinely done these days to counteract the painful effects of arthritis. What was unusual until recently was the failure of the implants. They usually perform admirably. However, enter DePuy, a Johnson and Johnson company, and things changed. It engineered, manufactured, and promoted a hip implant that has been a catastrophe.
This is not unlike the situation with drugs and other medical devices that were inadequately tested before they were put on the market or that the manufacturers delayed recalling after learning their products were dangerous. In the case of the DePuy hip implants, which are identified as the DePuy ASR and the DePuy ASR XL models, the problems are so bad that people who have gotten those implants are having to get another surgery to replace the defective implants.
The cost of replacement is many thousands of dollars, and the unfortunate victims of DePuy's and Johnson and Johnson's carelessness experience a great deal of pain with the corrective surgery. Unfortunately, those problems are merely the tip of the iceberg. The DePuy implants are constructed of 2 parts, a metal ball and a metal socket. That is, they are metal on metal implants. Other implant manufacturers make metal to polyethylene implants. The difference is significant. Early metal on metal designs of the 1950s and 1960s were encouraging in terms of stability and low wear but, as a whole, didn't meet expectations for design and manufacturing reasons irrelevant to their problems today.
As the early manufacturing difficulties were resolved, their popularity again increased in the mid-1990's, but a DePuy implant is different from other metal on metal implants. The DePuy design has an obvious design defect. The cup is too shallow for the ball. What happens as a result? According to researchers who presented papers at the 2010 meeting of the American Academy of Orthopedic Surgeons, three serious negative events occur with metal on metal systems when the cups are too small.
They are production of a higher amount of metal ions in the joint, an increased failure rate of implants due to the additional metal debris there, and less tolerance to suboptimal positioning of the implant by the surgeon. Hundreds, maybe thousands of these implants that were just recalled by DePuy a few months ago, are being worn by total hip replacement patients in this area now.
This is of concern not only because of the profound pain they can cause but also because of grave health problems that can be caused by the metal ion release of the metal on metal construction. I will give you those details next time. In the meantime, if you want more information about what to do if you have one of these implants, call or email me.