Carbon Coated Implants as a New Solution for Metal Allergy in Early-Onset Scoliosis: A Case Report and Review of the Literature

Study DesignRetrospective case report.ObjectiveTo report the first known case of immunological camouflage of a metal spinal implant with carbon coating.Summary of Background DataMetal sensitivity is common and is a consideration when choosing orthopedic implants in susceptible individuals. The sensitivity often is to nickel, cobalt, or chromium, and titanium is used as a safe alternative. However, when the allergy is also to titanium, solutions may be much more difficult. This case describes an innovative solution to a complex metal allergy that includes titanium in a child requiring spinal instrumentation for early-onset scoliosis.MethodsAt age 6 years 7 months, the patient underwent an uncomplicated placement of bilateral posterior Vertical Expandable Prosthetic Titanium Ribs (VEPTRs; Synthes, Inc., West Chester, PA). At that time, there were no known metal allergies. At 3 weeks, the right side had become erythematous and had serosanguineous drainage. It briefly improved after each of 2 surgical debridements and a course of intravenous antibiotics, but within 6 weeks of the index procedure, the pain was still worsening. A titanium allergy was suspected and blood was sent for allergy testing. A test confirmed hypersensitivity to titanium, niobium, molybdenum, iron, and aluminum, among others. The remaining rod was removed. An in vivo trial for tolerance to high-grade stainless-steel implants was done. The implant was removed after 2 weeks because of systemic symptoms that occurred.ResultsA plasma-spray, carbon-coated VEPTR rod was designed. A rod sample was inserted into the patient's forearm for trial. After 3 months, there was no appreciable reaction. Carbon-coated VEPTRs were placed without complications. The patient has undergone multiple lengthening using the carbon-coated VEPTRs.ConclusionsIn the rare patient with multiple allergies, choosing orthopedic implants can be challenging. An innovative carbon coating was applied by plasma spray to the VEPTR system, with good results.