Clinical Evaluation of a New Surgical Augmentation Technique for Transarticular Atlantoaxial Fixation for Treatment of Atlantoaxial Instability

Simple SummaryInstability between the two uppermost vertebrae (atlantoaxial instability) is a common problem, especially in toy breed dogs, resulting in a variety of neurologic symptoms. In most cases, surgical stabilization is indicated, but all of these procedures have some degree of complication, one of which is recurrent instability due to implant failure/loosening. To reduce this problem, a new augmentation technique involving additional wire/suture fixation through a bone tunnel in the second vertebra was evaluated, and the long-term clinical outcome was analyzed. Ten of the eleven dogs enrolled in the study had good to excellent clinical outcomes with no neurological symptoms. One dog died due to postoperative complications. In conclusion, the augmentation technique may be a valuable and technically feasible addition to the surgical stabilization of atlantoaxial instability in toy breed dogs, hopefully reducing the rate of recurrent postoperative instability.The feasibility of a newly developed augmentation of ventral fixation technique for surgical stabilization of atlantoaxial instability was clinically evaluated in a cohort of eleven dogs, and long-term clinical outcomes were retrospectively analyzed. The new technique combines wire/suture fixation through a transverse hole in the axis anchored by two screws placed in the alae atlantis or at the cranial end of plates used to bridge the atlantoaxial joint ventrally. A previous biomechanical study demonstrated good stability of this technique during shear loading, comparable to the stability achieved with other standard techniques. Ten dogs improved clinically after surgery and returned to a normal life within 3-6 months of surgery. One dog developed aphonia, dysphagia, and died of aspiration pneumonia three days after surgery. The augmentation of conventional ventral atlantoaxial fixation with the transverse bony corridor of the proximal axis body may be a valuable way to enhance stabilization of the atlantoaxial joint.