Metal sensitivity test results, including lymphocyte transformation testing (LTT), are insufficient to diagnose knee replacement failure due to an immune reaction, according to a study published Feb. 6 in the Journal of Bone and Joint Surgery. The authors say the findings highlight the need to establish diagnostic criteria for total knee arthroplasty (TKA) failure due to an immune reaction. While TKA is usually successful, an estimated 20 percent of patients are dissatisfied due to chronic pain and/or stiffness, which can be a result of a local immune reaction to the metal. However. A hypersensitivity reaction can be considered in cases with low prosthetic wear and a high aseptic lymphocyte vasculitis-associated lesion (ALVAL) histopathology score, however, it remains a topic of debate for how to definitively diagnose metal sensitivity test as the cause of TKA failure. Previous research shows that while an estimated 10 to 15 percent of the general population is reactive to skin patch testing for metal sensitivity—most commonly, nickel—skin patch testing is not useful for predicting clinical results with TKA. It is important to understand the role of metal sensitivity in necessitating TKA revision surgery, as the average cost of the hypoallergenic revision implants is $5,669, or 37 […]