C2 translaminar screw as the optimal choice for atlantoaxial dislocation with C2–C3 congenital fusion

Abstract

The entry point and trajectory are very important for transarticular screw (TAS) and C2 pedicle screw (PDS) plantation. When the physical size is not large enough for the screw passing through, an accurate entry point is the most important point for successful screw insertion without vertebral artery (VA) injury and spinal cord injury. Once the laminas of C2 and C3 are fused, the normal anatomic mark might disappear and the insertion point would be hard to find. As a result, the complication of TAS or PDS implantation increases rapidly. We used C2 translaminar screws (TLSs) with C1 lateral mass screws as the optimal fixation for atlantoaxial dislocation in order to reduce the risk of VA injury and spinal cord injury. A 37-year-old woman with atlantoaxial dislocation due to obsolete odontoid fracture complained of neck pain and myelopathy. Preoperative CT reconstruction showed C2-C3 fusion and small size of C2 isthmus. The patient underwent posterior atlantoaxial fusion using C1 lateral mass screws and C2 TLSs. The posterior arch of atlas was removed for decompression and fusion was done at C1-C2 joints by grafting bone fragments from the posterior iliac crest. TLSs combined with C1 lateral mass screws might be a useful technique for patients with atlantoaxial dislocation and C2-C3 fusion, especially with small size of C2 isthmus. Also, the fusion of posterior elements between C2 and C3 might be a relative contraindication for TAS fixation.