Outcome of a modified ventral surgical approach in 5 dogs with atlantoaxial (AA) subluxation was assessed by clinical examination and phone interviews with owners. Two approaches to AA joint stabilization have been described: Ventral stabilization allows reduction of the luxation, visualization, and inspection of the dens as well as good stability through bony fusion (ankylosis). The dorsal technique relies on soft tissue to maintain stability, which prevents bony arthrodesis of the joint. The modified approach described in this article is similar to the standard ventral approach, except that the division between the right sternocephalicus and the right sternothyroideus muscles is extended cranially (an adaptation of the Cechner approach to the atlantoaxial junction). When the sternothyroideus muscle is retracted medially, the larynx and its associated neural, vascular, and glandular structures are retracted with it and away from the surgical field. In the standard ventral approach to the AA junction, it is necessary to dissect around the larynx, thyroid, and carotid sheath, risking complications such as bleeding and tissue trauma and/or swelling. The modified approach proved effective in providing the surgeons the ability to adequately expose the AA joint, properly place threaded or nonthreaded Kirschner wires into the first and second cervical vertebrae, and place a cancellous bone graft obtained from the greater tubercle of the humerus. All dogs in this study recovered uneventfully from anesthesia and were kept in a padded neck brace for 6 weeks after the procedure. At the 6-week follow-up evaluation, all dogs had improved neurologic function.
COMMENTARY: Although this paper has a low number of reported cases, it very clearly describes a highly useful technique that minimizes tissue trauma while providing adequate exposure for stabilization with implants and for ankylosis with bone grafts. Since this surgery is complicated and fraught with potential complications, the positive outcome of these patients in light of the less-invasive technique may encourage more surgeons to provide this treatment. It is hoped that, as more surgeons use this technique nationwide, more data on intraoperative complications and long-term follow-up can be obtained.
A modified ventral approach to the atlantoaxial junction in the dog. Shores A, Tepper LC. VET SURG 36:765-777, 2007.