New technique for posterior intra-articular arthrodesis using a single-block graft in cases of atlantoaxial instability. Case report of unstable atlantoaxial rotatory luxation in a 10-year-old girl.

A new method of posterior C1-2 arthrodesis, derived from the W.V. Cone and G. Bertrand, technique (Montreal, 1970) is described with two modifications: (1) the exact measurements of the ideal graft are determined preoperatively, using CT and a sterilized pasteboard horseshoe-shaped model; (2) in the sitting position, single occipital block graft was cut out microsurgically, using the preoperative model. After decortication of the graft, posterior arches of C1 and 2, and microsurgical excision of the cartilage of the C1-2 lateral joints, the graft was imbedded into the entire C1-2 space, fixed, and tightened using a braid of "nylacap" yarn. A case report of rotatory luxation and associated atlantoaxial instability in a 10-year-old girl illustrates the excellent functional results of this technique.