Intraspinal metallosis causing delayed neurologic symptoms after spinal instrumentation surgery

Study Design. Two cases of intraspinal metallosis causing delayed neurologic symptoms secondary to spinal instrumentation surgery are reported. Objective. To present an unusual delayed neurologic complication after spinal instrumentation surgery. Summary of Background Data. Metal-related complications caused by orthopedic implants have long been a concern in the field of arthroplasty or internal fixation of fractures, but no such complications have been reported for spinal instrumentation. Methods. Retrospective case report of two patients with degenerative scoliosis who presented with delayed neurologic symptoms months to years after uneventful, but without secondary degenerative changes or dislodgement of the implants. Results. In both reported cases, a granulation-tissue mass characterized by marked metallosis had been formed in the spinal canal adjacent to a loosened laminar hook. Conclusions. Intraspinal metallosis should be kept in mind as a rare cause of delayed neurologic symptoms after spinal instrumentation surgery. With the metal implants in place, myelography was the sole informative examination for diagnosis.