Atlantoaxial arthrodesis in the presence of posterior spondyloschisis (bifid arch) of the atlas. A report of three cases and an evaluation of alternative wiring techniques by computerized tomography.

The presence of a bifid posterior arch of the atlas has been regarded as a contraindication to the wiring of C1-2 for atlantoaxial arthrodesis. Three cases with C1 posterior spondyloschisis are presented with successful atlantoaxial arthrodesis using laterally placed wires to avoid the midline defect of the atlas. An experimental study of the efficacy of three different wiring constructs by computerized tomography showed that there is little difference between midline versus lateral wiring in restricting rotation of C1-2.