Metal Hypersensitivity Following Total Ankle Arthroplasty: Case Series and Literature Review.

Metal hypersensitivity following total ankle arthroplasty (TAA) is an underreported complication that can manifest as dermal, systematic, and orthopaedic-specific symptoms. It is critical to recognize that metal hypersensitivity is a diagnosis of exclusion; only after all other potential sources of failure, such as loosening or infection are ruled out, can this diagnosis be considered. Aside from imaging and common laboratory analysis, skin patch testing, leukocyte migration inhibition test (LMIT), and lymphocyte transformation test (LTT) are the testing options available for metal allergy. With regards to management of metal hypersensitivity, nonoperative modalities involving topical dermatological management are generally preferred. Severe cases of metal allergy may necessitate operative management consisting of explantation of the implant and either revision TAA with a custom hypoallergenic implant or conversion to an ankle fusion. We present 3 cases of presumed metal hypersensitivity following TAA. In all 3 cases, other forms of TAA failure were carefully ruled out. One patient underwent explantation and conversion to hypoallergenic implant, 1 patient underwent explantation and ankle arthrodesis with hypoallergenic hardware, and 1 patient elected for conservative care. In patients who underwent explantation and conversion to hypoallergenic hardware, no further symptoms associated with metal allergy were noted. Additional research is necessary to improve diagnostic accuracy of metal allergy and make treatment options more effective and accessible.Level of Evidence: Retrospective case series, IV.