An indirect reduction technique for ventral stabilization of atlantoaxial instability in miniature breed dogs

Objective: To describe an indirect reduction method for ventral fixation of atlantoaxial instability. Study: Retrospective study. Animals: Miniature dogs (n = 5) with atlantoaxial instability. Materials and methods: For surgery, the anaesthetized dogs were positioned in dorsal recumbency. A standard ventral midline cranial cervical approach was used. The median part of the cervical (C) vertebral bodies of C1, C2 and C3 were exposed. After excision of the atlantoaxial joint capsule, a fenestration was performed at the C2-C3 intervertebral disc with a narrow slot in the ventral cranial end-plate of C3. A midline incision of the atlanto-occipital membrane at the intercondyloid incisure was made to provide access to the spinal canal. Longitudinal distraction and realignment of C1-C2 were obtained by placing the tips of a Gelpi retractor in the two openings created. Overdistraction allowed removal of articular cartilage between C1-C2. Closing of the C1-C2 articular gap was finally achieved by applying lateral distraction with a second Gelpi retractor placed between the paired longus colli muscles. Fixation could then be performed without further stabilization. Results: No intraoperative complications were observed. Recovery was uneventful. Conclusions: The described technique offered good surgical visibility and permitted safe reduction of atlantoaxial subluxation. Clinical relevance: By reducing manipulation and instrumentation necessary for reduction of atlantoaxial instability, the described technique may be advantageous in toy-breed dogs.