Background: Joint distraction and manipulation surgeries to correct basilar invagination (BI) and atlanto-axial dislocation (AAD) are becoming standard procedures. However, current data are unable to aid in the understanding of normal and abnormal morphology of the C1/C2 joints.
Objective: To study various aspects of C1/C2 joint morphology to create normative and patient data on joint abnormalities that could provide the surgeon with objective data for surgical planning and approach.
Methods: Seventy (15-45 years old) patients were compared with an equal number of age- and sex-matched controls (21.9 +/- 8.2 years) with irreducible BI and AAD from a developmental etiology (May 2010 – July 2013). Joint anatomy was studied using thin slice CT scans. The joint parameters studied included sagittal joint inclination (SI), cranio-cervical tilt (CCT), coronal joint inclination (CI), surface area, joint overlap index, and joint reciprocity (JR). The severity of BI and AAD were compared.
Results: SI and CCT significantly correlated with both BI and AAD (p<0.01). CI correlated with BI (p=0.2). The mean SI value in controls was 87.15 +/- 5.65 degrees, and in patients with BI and AAD was 127.1 +/- 22.05 degrees. The mean CCT value in controls was 60.2 +/- 9.2 degrees, and in patients with BI and AAD was 84.0 +/- 15.1 degrees. The mean CI value in controls was 110.3 +/- 4.23 degrees, and in patients with BI and AAD was 121.15 +/- 14.6 degrees.
Conclusion: This study has demonstrated for the first time the important role of joint orientation and its correlation with the severity of BI and AAD, and has described new joint indices.
From: The Severity of Basilar Invagination and Atlanto-Axial Dislocation Correlates With Sagittal Joint Inclination, Coronal Joint Inclination and Cranio-cervical Tilt: A Description of New Indices for the Cranio Vertebral Junction by Chandra et al.