Radiographic Lucency around Pedicle Screws with Cobalt Chromium Rod Constructs in the Setting of Lumbar Fusion

Background Context: Hybrid spinal implants that combine cobalt-chrome rods with titanium screws have been introduced with the goal of reducing the profile of implants used for lumbar fusion. 4.5mm and 4.75mm cobalt-chrome rods have been reported by the manufacturers as having similar results in biomechanical testing to conventional 5.5mm titanium rods, however little is known about the long-term clinical performance of these implants. This report discusses an interesting radiographic finding routinely encountered in our practice following use of these implants.