الملخص
Atlato-axial instability is a serious condition that often requires operation. Atlanto-axial subluxation may cause severe symptoms; and threaten the intergrity of the spinal cord, leading to quadriplegia or sudden death. A techique of combining C1-C2 posterior screw fixation with a supplemental bone wire fusion has been advocated for the management of atlantoaxial instability. It was used in 9 patients with this disorder. Patients ages ranged from 20 years to 52 years; follow-up period ranged from 3 to 16 months with a mean of 9.8 months. All nine patients gained immediate rigid fixation of C1,2 with this technique. Of these 9 patients, instability occurred due to trauma in seven, os odotoideum in one and os odontoideum with trauma in another one. One patient was presented with nonunion and C1,2 instability after a Halovest applications a result of type II odontoid fracture. All 9 patients were placed in a philedelphia collar for 12weeks and all achieved solid fusion. Posterior atlantoaxial facet screw fixation provides immediate multidirectional rigid fixation of C1,2 and is mechanically superior to siring or clamp fixation. This technique maximizes success without the need for a supplemental rigid external orthosis.