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

Abstract Study Design Retrospective case report. Objective To report the first known case of immunological camouflage of a metal spinal implant with carbon coating. Summary of Background Data Metal 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. Methods At 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. Results A 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. Conclusions In 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.