Metallosis in Spine: A Review of 2020-2025 Case Reports.

Background: Metallosis is a rare but serious post-surgical complication of metal implantation where metal corrodes and debris accumulates in periprosthetic tissue. The mechanism, effects, diagnosis, and risk factors that contribute to metallosis in spine surgery remain poorly understood. Given its rarity, much of what we know about metallosis in spinal surgery is translated from joint arthroplasty literature and derived from case reports. The purpose of this paper is to review recent case reports of metallosis in patients having previously undergone instrumented spinal fusion, with particular emphasis on clinical presentations. Methods: We searched PubMed/MEDLINE for studies that containing the terms "spine, "spinal", "lumbar", or "cervical" and "metallosis", "corrosion" or "metal hypersensitivity", and "fusion", "fixation", "stabilization", "diskectomy" or "discectomy" from January 2020 to December 2025 in accordance with PRISMA guidelines. Results: 17 articles were identified and 12 case reports were included in the final review. Conclusion: Metallosis following spinal instrumentation has unpredictable presentations, occurring over a wide range of time, recently observed between one month and 15 years post-operatively. Recently reported presentations included systemic signs including anorexia and hair loss, structural signs including pain and neurological deficits, and absence of symptoms, making it imperative that metallosis is considered in the differential for post-operative complaints. As more cases of metal-losis are reported on in the spinal implant patient population, contributing factors must be clarified. Future directions of study may include identifying biological markers for early risk stratification for metallosis and seeking less-invasive diagnostic methods. Surgeons should be aware of this potential complication in spinal implant surgery and consider this as a cause of varied symptoms in this patient population. Level of Evidence: IV.