Patients who have a previously unrecognized allergy to metal and undergo a Nuss repair with a stainless steel bar can present with a picture of wound infection after bar placement. Although not as detrimental as a wound infection, metal allergies are not to be taken lightly.
Contact dermatitis from the Nuss bar is a type IV delayed hypersensitivity reaction that occurs in response to one of the components of stainless steel, usually Zinc or Chromium. The reaction can range from mild with localized dermatitis, to a more systemic inflammatory response. Patients occasionally simply present with chronic fatigue.
Preoperative screening for metal allergies should include inquiry about personal or family history of metal allergies (specifically ask for problems with metal touches the skin, not just "does anyone in the family have metal allergies"). Even in the absence of a history of atopy, some recommend screening all patients with a patch test that identifies such allergies (T.R.U.E test or AllergEAZE).
In a recent study by Shah et al, the authors recommended testing all patients preoperatively, regardless of family or personal history of allergy, as they recognized a higher incidence of metal allergy (6.4%) than previously reported (2.2%).
Once metal allergy is identified, patients can be treated with a course of steroids, and removal of the bar can be avoided in most cases.