Evaluating Atlantoaxial Dislocation Based on Cartesian Coordinates: Proposing a New Definition and Its Impact on Assessment of Congenital Torticollis.

Background: Conventional 2-dimensional (2-D) definition of atlantoaxial dislocation (AAD) is inadequate for coexisting 3-D displacements.

Objective: To prospectively classify AAD and its related abnormalities along 3 Cartesian coordinates and assess their association with torticollis.

Methods: One hundred and fifty-four patients with congenital AAD were prospectively classified according to their C1-2 displacement along 3 Cartesian coordinates utilizing 3-D multiplanar CT.

Knock and Drill Technique: A Simple Tips for the Instrumentation in Complex Craniovertebral Junction Anomalies without using Fluoroscopy.

Context: Existence of complex variable bony and vertebral artery (VA) anomalies at craniovertebral junction (CVJ) in subset of complex CVJ anomalies demands individualized instrumentation policy and placing screws in each bone requires strategic preoperative planning and intraoperative skills.

Aim: To evaluate the clinical accuracy of knock and drill (K and D) technique for the screw placement in complex CVJ anomalies.

Settings And Design: Prospective study and operative technical note.

Craniovertebral junction anomalies: When is resurgery required?

Background: Craniovertebral junction (CVJ) abnormalities, such as atlantoaxial dislocation (AAD) with or without basilar invagination (BI), with or without associated Chiari malformation (CM), may cause a high cervical myelopathy. Occasionally, mechanical factors such as inadequate canal decompression, torticollis, and/or scoliosis may lead to lack of improvement following the primary surgery. Furthermore, implant-related factors, requiring implant revision/removal, or the presence of surgical site infections may cause the patient to undergo resurgery.

Congenital Spondylolytic Spondylolisthesis of C2 Vertebra Associated With Atlanto-Axial Dislocation, Chiari Type I Malformation, and Anomalous Vertebral Artery: Case Report With Review Literature.

Background: Congenital spondylolytic spondylolisthesis of C2 vertebra resulting from deficient posterior element of the axis is rarely described in the literature.

Case Description: We describe a unique case of agenesis of posterior elements of C2 with craniovertebral junction anomalies consisting of osseous, vascular, and soft tissue anomalies. A 26-year-old man presented with symptoms of upper cervical myelopathy of 12 months' duration.