Blood Dx spots knee, hip implant allergies before procedure

Hip and knee implant makers, take note: Researchers have come up with a blood diagnostic test that detects allergies to nickel, a metal commonly used in those products.

The test, developed by National Jewish Health in Colorado, could be a relatively inexpensive way to help boost patient safety and reduce healthcare costs by preventing repeat procedures.

It's not as though there aren't other allergy diagnostics for this already on the market. The researchers themselves note that a "skin patch test" can be used, but it takes a while to process and patients who need knee or hip implants often don't have a week or more to wait. Their blood test would work far sooner and could preemptively serve as a quick way to screen patients for whom ceramic implants might work better. Typically, the team explains, patients found to be allergic (with migraines, itching or other problems) who already have the implant in place can only solve the problem by having the joint removed and replaced. That's an expensive solution, better addressed by preventing the allergy-causing implant beforehand.

Metal hip implants have been in the news in recent months, in part because of the safety issues apparent in some of the products and the resulting health problems. Some hip components only partially rely on metal, and a perfectly well constructed implant could otherwise be incompatible with a patient due to allergic reactions. So detecting the problem before surgery is crucial. A viable allergy test used before hip and knee implant procedures would be an inventive way to blend a diagnostic tool and a device for maximum patient gain.

Not all implant patients are allergic to their new artificial hips and knees, of course. National Jewish Health allergist Dr. Karin Pacheco said in a statement that as few as 10% of patients are affected. Either way, the sheer volume of older patients in the future will make a preimplant allergy diagnostic all the more important. The hospital notes that more than 11,000 people per day will have hip and knee implant surgeries by 2030, a jump of 174% and 700%, respectively, for hip and knee replacements from where they are now.

Next up will be further testing of the nickel blood test and development of diagnostics to identify other potential implant allergic reactions, this time focused on components such as cobalt and bone cement.

- read the release