Blood cobalt levels elevated with rod fracture following posterior spinal fusion in scoliosis: A report of two cases

Elevated blood metal ion levels and the accumulation of metal debris in peri-implant tissues have been reported after metal-on-metal total hip arthroplasty and total disc replacement. However, little is known about the relationship between blood metal ion levels and clinical adverse events in instrumented spinal fusion surgery. We report 2 cases of scoliosis with elevated blood cobalt levels following cobalt-chromium rod fracture. Following fractured rod removal and rod replacement, the blood cobalt levels decreased over time. At the final follow-up, both patients presented without symptoms, correction loss, or rod fractures on radiographs. Our results suggest that repeated macro-motion may result in metal ion release due to mechanical wear and corrosion of the fracture surfaces. In patients with rod fracture, it may be worthwhile to measure blood cobalt levels and consider revision surgery if necessary.