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Although metal allergy with total joint replacement exists, the prevalence of
this condition is unknown, according to Joshua J. Jacobs, MD.
"Metal allergy [with] orthopedic implants has been well documented in
isolated cases," Jacobs said during his presentation at the American Academy of
Orthopaedic Surgeons 2012 Annual Meeting/Orthopaedics Research Society
symposium. "The true prevalence is unknown. Clinically significant
symptomatologies seem to be rare in total knee replacements and
metal-on-polyethylene total hip replacements, but much more common in metal-
on-metal total hips.
Based on case reports and device literature, Jacobs said that metal allergy
exists and has been seen as a temporal association. It can have different
presentations and many involve a rash. In some examples, patients suffer skin
reactions after implantation of total joint replacement devices. In other cases,
the reaction goes away after the implant is removed for nonunion or refracture,
only to return after re-implantation.
"In my mind, those sorts of cases prove to me that this is a real clinical
entity," Jacobs said.
Using patch testing, 14% of the general population would be sensitive to
nickel and 10% would be sensitive to cobalt and chromium. However, Jacob said
that patch testing may be flawed because it may have no bearing on what is
occurring happening in deep tissues.
"Metal-on-metal allergy is the cause of clinical symptomatology, such as pain
and swelling," Jacobs said. These allergies present as skin reactions such as
dermatitis, or patients may have a history of allergy to jewelry. The responses
to these allergies can present as stiff knees, pseudotumors, necrosis or
unexplained pain, Jacobs said.
"In patients with metal-on-metal surface replacements, there is a direct
correlation between serum metal levels and metal sensitivity determined by
[lymphocyte transformation testing] LTT," Jacobs said. "Current diagnostic
methods, both patch testing and in vitro, do require more robust clinical
validation, but it can be useful in preop screening for patients with in vitro
metal allergies when there is a history of reaction to jewelry."
Jacobs JJ. Clinical manifestations of metal allergy. Adverse
reactions to byproducts of joint replacements (AAOS/ORSI). Presented at
the American Academy of Orthopaedic Surgery 2012 Annual Meeting. Feb.
7-11. San Francisco.