From the FDA's web site last revised on 2/11: Web site for Orthopedic surgeons re the MOM hip implants/http://www.fda.gov/MedicalDevices/ProductsandMedicalProcedures/ImplantsandProsthetics/MetalonMetalHipImplants/ucm241667.htm
- Despite the recommendations of other international regulatory agencies, the FDA currently believes there is insufficient evidence to correlate the presence of localized lesions, clinical outcomes, and/or the need for revision with specific metal ion levels for individual patients.
- At this time, there is insufficient scientific data to provide a rigorous science-based recommendation for a threshold value of metal ion levels in the blood that would serve as a trigger for intervention or revision
- At this time, the utility of routine screening of asymptomatic patients using diagnostic soft tissue imaging and/or blood metal ion testing has not been established. Moreover, findings of lesions on soft tissue imaging, or of elevated blood metal ions, in the absence of symptoms, though reported in a limited number of research studies for some MoM hip implant patients, are difficult to interpret because:
- The exact incidence or prevalence of asymptomatic lesions and their natural history is not known
- The correlation between elevated blood metal ions and development of future local or systemic system adverse reactions is not well established