Novel Titanium Tolerance Testing Before Adult Idiopathic Scoliosis Surgery: An Illustrative Case Report

Abstract

Metal hypersensitivity affects up to 10 to 15% of the general population, most commonly to nickel, cobalt, and chromium. Although cutaneous metal allergies are relatively common, clinically significant hypersensitivity reactions to spinal implants are rare but can lead to pain, implant failure, and revision surgery. Patch testing may identify metal sensitivities; however, its predictive value for deep-tissue reactions remains limited. Determining metal tolerance is particularly important in adult spinal deformity surgery, where extensive instrumentation is required.

A 29-year-old woman with adult idiopathic scoliosis, a 45° 1/NS/aligned curve, and chronic axial pain was evaluated for posterior spinal fusion after failure of conservative management. Patch testing demonstrated strong hypersensitivity to cobalt and chromium and equivocal reactivity to titanium. To assess in vivo titanium tolerance, a temporary titanium compatibility-test screw was placed into the T10 spinous process under cone-beam computed tomography guidance. The patient exhibited no local or systemic hypersensitivity reaction over 3 months. She subsequently underwent T4–L2 posterior spinal fusion using titanium-only instrumentation without complications or evidence of allergic reaction.

This proof-of-concept case demonstrates the feasibility of temporary in vivo titanium tolerance testing prior to complex spinal reconstruction. Prolonged asymptomatic observation may guide implant selection and reduce revision risk in metal-sensitive patients.