Craniovertebral junction degenerative arthritis- evolving understanding

The report analyzes the outcome of atlantoaxial stabilization in patients presenting with clinical symptoms and with radiological features that were attributed to atlantoaxial instability related degenerative alterations at craniovertebral junction.

During the period January 2009 to December 2024, 95 patients presented with clinical symptoms that indicated mild to severe myelopathy and on imaging were identified to have degenerative alterations at the craniovertebral junction. Apart from validated parameters of abnormal alterations in atlantodental interval, atlantoaxial instability was diagnosed based on high level of clinical suspicion and physical alterations in the region of craniovertebral junction that included abnormal bone and osteophyte formation or soft tissue alterations in the vicinity of the odontoid process and atlantoaxial articulation, joint space reduction and alterations in alignment of facets of atlas and axis. The height of occipital condyle- atlas facet- axis facet complex was assessed and compared with a 'normal' cohort of individuals between ages of 30-50 years. All patients underwent atlantoaxial stabilization using the described techniques. No bone or soft tissue decompression was done. The clinical outcome was assessed on the standard parameters of VAS, Goel's clinical grade and JOA score. Additionally, patient self-assessment questionnaire was used to evaluate the result of surgery.

On dynamic head flexion-extension imaging, 47 patients had completely reducible and 26 patients partially reducible) atlantoaxial instability, 30 patients had fixed or irreducible atlantoaxial instability and 16 patients had no abnormal alteration in the atlantodental interval. Two patients had vertical mobile and partially reducible atlantoaxial dislocation. Twenty-four patients had varying degree of basilar invagination. Fifty-one patients had osteophytes in the paraodontoid region that included apical region (46 patients), lateral to odontoid process (14 patients), retroodontoid region (34 cases) and around the facets (57 cases). The height of occipital condyle- atlas facet- axis facet complex ranged from 20 mm to 32 mm (average 27 mm) when compared to 30 mm to 43 mm (average 39 mm) in the control group. During the average follow-up period of 26 months, all patients improved in their clinical symptoms following surgery. No patient needed any additional surgery to the craniovertebral junction or to the cervical spine.

Chronic weakness of the muscles of the nape forms the basis of atlantoaxial instability that leads to secondary degenerative 'alterations'. Atlantoaxial stabilization can lead to gratifying clinical outcome.