If patients, whose transverse and alar ligaments are eroded, incline their cervical spine, the AADI broadens excessively (5.47 mm on average).
Table 1: Diameter of AADI and PADI measured in mm at neutral position, flexion, and extension: measurements were carried out in intact specimens and after the transverse and the alar ligaments were damaged.
 Also, the horizontally oriented facet joints and capsules between the atlas and axis can be affected by accentuated axial rotation, which can injure the alar ligaments
Scheithauer, "Lesions of the alar ligaments
in vivo and in vitro studies with magnetic resonance imaging," Spine, vol.
Analysis of MRI and MRI video findings in craniocervical instability pathology of 420 patients with clinical symptoms consistent with possible spinal instability Findings Patients n (%) Complete alar ligament
rupture [*] 20 (4.8) Incomplete alar ligament
rupture, [*] 52 (12.4) Alar signal-pattern variation; instability 81 (19.3) Alar signal-pattern variation; no instability 102 (24.3) Normal alar signal pattern; no instability 158 (37.6) Dens variation 4 (1.0) Elasticity syndromes 3 (0.7) Total 420 (100) (*.)These 72 patients (17.1%) were referred to a neurosurgeon.