Metal sensitivity in total joint arthroplasty: None of the current diagnostic tests are reliable, sensitive and specific enough to guide treatment decisions!

Purpose: This systematic review was conducted to evaluate the current literature on metal hypersensitivity in patients undergoing joint arthroplasty. The aims of the study were to report diagnostic tools used to assess metal hypersensitivity and to report complications arising in patients who are hypersensitive to nickel or other metals performing joint arthroplasty. Given the potential impact on implant longevity and patient outcomes, understanding the clinical relevance of metal hypersensitivity is crucial for optimising surgical decision-making.

Methods: This systematic review adheres to PRISMA guidelines and evaluates the variability in diagnostic approaches and the challenges in clinical management. Included in this review were studies involving patients sensitive to nickel or other metals undergoing joint arthroplasty. Eligibility criteria focused on commonly employed diagnostic tools and associated complications. A comprehensive literature search was conducted across Medline, EMBASE, Scopus, CINAHL, and CENTRAL databases. The methodological quality of the included studies was assessed using the Joanna Briggs Institute Critical Appraisal tool for case series and the ROBINS-I tool for case-control studies.

Results: Twenty-four articles met the inclusion criteria and were included in this systematic review. A total of 4865 patients undergoing joint arthroplasty were selected. Diagnostic tools included patch testing, lymphocyte transformation test (LTT), and medical history assessment. Variability in time point of testing and diagnostic protocols was noted. Complications including joint pain, swelling, reduced range of motion, and implant failure were reported in 12 studies. Clinical outcomes varied widely: some studies showing no significant differences between hypersensitive and non-hypersensitive patients, while others reported increased pain and reduced joint function.

Conclusion: There is a lack of a standardised protocol for diagnosing metal hypersensitivity, leading to uncertainty regarding test selection and timing. This inconsistency leads to variability in reported outcomes, with limited studies focusing on post-surgical hypersensitivity in patients.

Level of evidence: Level III, systematic review.