This website is dedicated to providing public information regarding DePuy Hip recall and other related information to the recall. None of the information on this site is intended to be formal legal or medical advice, nor should any information on this site be construed as advice that should be used in lieu of information from your attorney or physician.
Thursday, February 16, 2012
What is a pseudotumor and what is the occurance of them in post hip patients?
Pseudotumors are a rare but important complication occurring with all types of hip replacements.The true prevalence of pseudotumors is debated.Potential causes of pseudotumors may include foreign-body reaction, hypersensitivity, and wear debris.The conduct of clinical trials on the incidence, causes, and treatments of pseudotumors has been inadequate as few investigators have used a randomized controlled design to compare various implant types
Pseudotumors are sterile inflammatory lesions found in the soft tissues surrounding metal-on-metal (MOM) and metal-on-polyethylene hip arthroplasties. In patients with MOM hip arthroplasties, pseudotumors are thought to represent an adverse reaction to metal wear debris. However, the pathogenesis of these lesions remains unclear.
A recent study conducted in Canada on the occurrences of pseudotumors showed that the incidences less than .1%.
I like this description below written by by Patricia Walter :
Patients and prospective patients are always concerned about the complications that could occur after a hip resurfacing surgery. The typical problems include femur neck fractures, dislocations, loose acetabular cups, improperly positioned acetabular cups, high metal ions, infections, pseudotumors, ALVAL and metalosis.
There has been a lot of discussion among patients on discussion groups about the high metal ion issue and pseudotumors. I am not a doctor or medically trained. I am a Patient Advocate, Hip Resurfacing Patient and Mechanical Engineer. I had the opportunity to attend the Second Annual U.S. Comprehensive Course on Total Hip Resurfacing Arthroplasty October 24–25, 2008 Los Angeles, CA. I listened to discussions about the metal ion issues and pseudotumors. I am going to explain what I learned in simple, non-medical terms since that is all I can do.
As an observer, I learned that the high metal ion issue has occurred in a small number of cases as a post op problem after a hip resurfacing. One of the most likely reasons, according to the experienced surgeons and presenters at the course, was the incorrect placement of the acetabular cup which resulted in additional wear on the bearing surface between the acetabular cup and the femur cap component. The hip resurfacing device is really a metal bearing made of High Carbon Cobalt-Chromium alloys. A bearing is designed to equally spread out the load over the load bearing components. If the components are not aligned properly, then only part of the bearing is loaded resulting in much more wear in that area possibly causing a high metal ion level. It was also explained that women seem to have more problems with high metal ions than men. Perhaps, this is due to the fact that most women use smaller sized hip resurfacing devices which causes more loading on the bearing surfaces than the men's larger sized devices.
When there is an abnormally high metal ion release from misplaced components, it seems to cause the surrounding tissue and bone to react adversely. The surrounding tissue and bone tends to become abnormal. Some doctors call the tissue reaction pseudotumors, AVAL (aseptic lymphocyte dominated vasculitis associated lesion), & others call it metalosis. Whatever name given to the abnormal reaction, it is not good to have this happening around the hip device since it could become loose, pain could result and possibly more severe medical reactions could happen.
[From connie: While the idea of the occurrence of a pseudotumor or AVAL or whatever you want to call the adverse reaction, the idea of the component installation causing the problem is questioned now. I just read a study showing that it is likely a patient sensitivity issue to the metal not a badly placed implant.]