Occipitoatlantoaxial Malformation in a Dog Treated with a Custom-Made Implant

Abstract

Background Occipitoatlantoaxial malformation (OAAM) is reported rarely in dogs and few treatment options are described. The congenital condition is thought to be associated with a proatlas re-segmentation failure resulting in malformation and malalignment of the craniovertebral junction which can result in C1 to 5 myelopathic signs. Methods Customized three-dimensional printed locking plate with trajectory screw implantation points for the stabilization of the atlantoaxial joint in a dog with OAAM. The dog was evaluated at time points 0, 2, 6 and 9 months to determine clinical outcome, degree of fusion, implant positioning and subsidence. Results New bone formation was noted 9 months after surgery, but complete fusion remained absent, although no implant failure occurred. Clinically, the dog made a good recovery and was able to exercise normally 9 months after surgery. The only residual deficit was a subtle left-sided cervical torticollis. Clinical Significance This report illustrates a management option and outcome of a dog treated with OAAM. Collaboration between clinicians and engineers provides a new dimension of care for patients with vertebral malformations.

Basilar Invagination in a Cat with Incomplete Ossification of the Atlas Treated by C1-C2 Arthrodesis

“…The use of customized three-dimensional printed locking plates could be an option in the treatment of these malformations. 20 However, complete stabilization was achieved by the method described, as evidenced by the satisfactory permanent clinical improvement, despite asymmetric implant placement.…”

C1 Facetectomy and Ventral Fixation of Occipitoatlantoaxial Complex for Concurrent Congenital Atlanto-Occipital Dislocation and Atlantoaxial Instability in a Toy Poodle

“…This condition, while rare in dogs and cats, emerges due to the failure of the inherent stability mechanisms at the cranio-cervical junction, while typically prevent such dislocations [4]. Since the occipital region of the skull and the first two cervical vertebrae develop together embryologically, AOD frequently manifests concomitantly with other cranio-cervical junction anomaly (CCJA) including atlanto-axial instability (AAI), atlantooccipital overlapping and Chiari-like malformation [5][6][7]. Traumatic events are the primary cause of Disclaimer/Publisher's Note: The statements, opinions, and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s).…”

C1 Facetectomy and Ventral Fixation of Occipitoatlantoaxial Complex for Concurrent Congenital Atlanto-Occipital Dislocation and Atlantoaxial Instability in a Toy Poodle

“…This association could be explained by embryology, as the occipital bone and the first Animals 2024, 14, 1886 2 of 12 two cervical vertebrae develop together, incorporating the sclerotomal occipital region into the skull and integrating the cranial part of the spinal cord into the brain. CCJAs include atlanto-axial instability (AAI), atlanto-occipital overlapping (AOO), and Chiari-like malformation [4][5][6][7]. In both veterinary and human medicine, traumatic events are the primary cause of AOD, resulting in significant dynamic instability between the atlanto-occipital (AO) joint.…”