Issue: April 2018
April 16, 2018
2 min read

Speaker: Metal allergy testing not needed for most painful TKAs

Research showed no benefit to skin patch and lymphocyte transformation testing to identify metal allergy in patients.

Issue: April 2018
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In primary or revision total knee arthroplasty, surgeons should use standard implants and not be worried about patients having a metal allergy, a presenter said.

“Recognize that the overwhelming majority of painful total knees have a cause other than hypersensitivity. Look for infection, loosening, instability, pathology in the hip and spine, or regional pain syndrome. That is where most of those problems are,” Mark W. Pagnano, MD, said during a symposium on TKA implants. “The overwhelming majority of revision knees are best done using a revision system you use routinely. Standard implant choice is likely the right choice.”

Mark W. Pagnano, MD
Mark W. Pagnano

Because of the confusion and ambiguity related to metal allergy in TKA, Pagnano noted it is important to define whether a patient is allergic or hypersensitive. Confusion over metal-sensitive patients stems, in part, from surgeons, he said.

“Allergy is an almost irresistibly convenient explanation for the poorly functioning total knee replacement,” Pagnano said. “The surgeon in this circumstance is seemingly absolved of responsibility, so it is a compelling thing to bring forward to patients.”

Industry partners have contributed to the confusion by promoting hypoallergenic implant materials without much supporting science, he noted.

Coronal and rotational malposition of implants
This patient was told by an orthopedic surgeon and internist metal allergy was the cause of her pain. Coronal and rotational malposition of the implants was identified and she improved with revision surgery and standard implants.

Source: Mayo Clinic

“There is a growing group of allergists and companies that are catering to testing [patients] for the metals used in common orthopedic implants,” Pagnano said.

These factors lead to patient confusion, according to Pagnano. He said patients may hear about a friend with a painful TKA who was told they were allergic, may read about hypoallergenic implants that are being used and may even seek related tests.

Testing for metal hypersensitivity is “largely useless,” Pagnano said. Research has shown no increased risk of TKA failure among patients with a positive skin patch test and no differences in outcomes when hypoallergenic material was used in patients with either a positive or negative skin patch test. – by Casey Tingle

Disclosure: Pagnano receives IP royalties from DePuy Synthes and Stryker; and is a board or committee member for the Hip Society and the Knee Society.