Salvage of a malpositioned anterior odontoid screw.

Abstract

Description of surgical technique with case correlation. This article presents an alternative approach to anterior odontoid screw salvage in a patient with established nonunion. Type II odontoid fractures are often treated surgically because of their risk of nonunion. Anterior odontoid screw fixation offers stable fixation without loss of atlantoaxial motion. Treatment failure may occur despite adequate screw placement but is more likely when fixation is inadequate. The traditional solution is a posterior fusion. In selected cases the surgeon may want to revise the anterior instrumentation with the hope of retaining as much C1-C2 motion as possible. A 43-year-old man presented 16 months after Type II odontoid fracture treated by anterior odontoid screw fixation. He had neck pain, instability, and a pseudarthrosis confirmed on radiographs. The screw was excessively long, piercing the C3 vertebral body and providing inadequate fixation. To avoid posterior fusion, a modified anterior approach was used. An entry point was selected 10 mm lateral to the midline, along the anterior rim of the C2 vertebral body. A large-diameter lag screw was then passed to the tip of the fragment. An angled curette was introduced into the fracture gap through the interval between the odontoid and the C1 ring. Autogenous bone was packed into the gap and along the old screw tract. At the 2-year follow-up the patient had a solid union with no neck pain, no headaches, no radicular symptoms, and excellent range of motion. The approach is described. In properly selected patients an anterior revision approach can provide a better outcome than posterior cervical fusion. This modified approach allows placement of an adequate fixation screw in a vertebra damaged by previous screw failure.