Metal allergy in total-joint arthroplasty: Case report and literature review

RATIONALE: Due to the low incidence and lack of effective diagnostic measures for the diagnosis of metal allergy in patients undergoing total joint arthroplasty (TJA), diagnosis relies mainly on the exclusion of other causes, in particular infection. It remains a relatively unpredictable and poorly understood cause of implant failure. At present, skin patch testing, leukocyte migration inhibition test (LMIT) and lymphocyte transformation tests (LTT) are being commonly used to assess metal hypersensitivity. This report presents both a case and literature review. PATIENT CONCERNS: A 61-year-old female patient experienced continuous swelling and pain in the right knee joint for 9 months after a right-side total knee arthroplasty (TKA). DIAGNOSES: We believe this is the case report of metal allergy in TKA. The following were the reasons for this. First, no definite symptoms of infection during revision arthroplasty were observed, but with obvious hyperplasia of synovium. Furthermore, a frozen biopsy revealed an extremely low neutrophil count, which was considered to be caused by chronic inflammation. Second, the results of repeated post-operation reexaminations indicate a clear increase in the number of eosinophils, while no bacteria were found in the tissue bacterial smear performed during the operation. Third, improvements were clearly observed in the patient following synovectomy, revision of the polyethylene insert and anti-anaphylactic treatment. INTERVENTIONS: The patient underwent synovectomy, revision of the polyethylene insert and anti-anaphylactic treatment. OUTCOMES: The patient's right knee remained mildly swollen; however, the pain has been relieved significantly. The range of motion could achieve 0 degrees of extension and 90 degrees of flexion. LESSONS: No consensus has been reached about the best diagnostic criteria for this disease, and most physicians would consider it to be a possibility when other diseases including periprosthetic joint infection (PJI) have been excluded. Although this case followed the same course, the outcome following synovectomy and anti-anaphylactic treatment further confirmed our hypothesis.