Application of Ventral Pins and Polymethylmethacrylate for the Management of Atlantoaxial Instability: Results in Nine Dogs

Objective — The purpose of this report was to determine the efficacy of the application of ventral pins and polymethylmethacrylate for the management of congenital and traumatic atlantoaxial instability (AAI) in dogs.
Study Design — Medical records and radiographs of nine dogs with AAI were reviewed for neurological deficits, clinical diagnosis, surgical technique, and long-term outcome.
Sample Population — Six toy breed dogs with congenital AAI and three medium or large breed dogs with traumatic AAI were identified for inclusion in the study.
Methods — The atlantoaxial joints of nine dogs with AAI were surgically stabilized using ventral application of pins and polymethylmethacrylate. Follow-up evaluation for resolution of clinical signs and possible complications of surgery was performed in all dogs. The median follow-up time for surviving dogs (8) was 11.5 months with a mean of 13 months.
Results — An excellent outcome was identified in five patients. Three dogs had a good outcome and one dog died of respiratory complications. Cervical pain was eliminated or significantly reduced in all dogs that survived and none of the dogs had major residual neurological deficits.
Conclusions — Arthrodesis could not be confirmed on follow-up radiographs due to the presence of the polymethylmethacrylate; however, adequate stabilization of C1-C2 appears to have been achieved based on the resolution of clinical signs.
Clinical Relevance — Application of ventral pins and polymethylmethacrylate is an effective means of surgical treatment for congenital and traumatic AAI.