Metal hypersensitivity in spinal surgery: mechanisms, diagnosis, and management - a narrative review

Metal hypersensitivity in spinal surgery is an immune-mediated reaction to metal ions released from implants like pedicle screws and rods, presenting a notable clinical challenge. Common allergens such as nickel, cobalt, and chromium can trigger delayed-type IV hypersensitivity, resulting in pain, inflammation, implant loosening, and the need for revision surgery. Risk factors include prior metal exposure through jewelry or implants, as well as comorbidities like diabetes and behaviors like smoking. Diagnosis is complex, as symptoms often resemble infection or mechanical failure, necessitating the use of tools like patch testing, lymphocyte transformation testing, and histopathological analysis. Management strategies focus on preoperative risk assessment, selection of hypoallergenic materials like PEEK or titanium, and revision surgery when hypersensitivity is confirmed. Multidisciplinary collaboration involving spine surgeons, allergists, and dermatologists is crucial for accurate diagnosis, effective treatment, and improved patient outcomes, emphasizing the importance of tailored implant choices and vigilant postoperative care.