Morphometric analyses of the cervical superior facets and implications for facet dislocation

Area of Science:

• Orthopedics
• Anatomy
• Radiology

Background:

• Cervical spine articular facets are crucial for stability.
• Limited data exists on superior facet morphology and traumatic cervical spine dislocation.
• Understanding facet anatomy is key to explaining injury mechanisms.

Purpose of the Study:

• To perform morphometric analysis of superior cervical spine facets (C3-C7).
• To compare facet morphology between upper (C3-5) and lower (C6-7) cervical levels.
• To investigate the in vivo orientation of superior facets relative to the transverse plane.

Main Methods:

• Morphometric analysis of superior facets from 30 dried cervical spines (C3-C7).
• Measurement of facet angle relative to the transverse plane using CT scans from 30 patients with neck injuries (no fracture/dislocation).
• Statistical comparison of morphometric parameters between cervical levels.

Main Results:

• Superior facets at C6-C7 levels showed significantly lower vertical and surface lengths (P < 0.01) compared to C3-5.
• Anteroposterior diameter was smaller at C6 and C7 compared to C3-5 (P < 0.05).
• In vivo, superior facets at lower cervical levels exhibit a more horizontal inclination relative to the transverse plane.

Conclusions:

• Morphological differences in superior facets exist between upper and lower cervical spine levels.
• The combination of reduced height, smaller diameter, and horizontal orientation of C6-C7 superior facets may predispose to translational injuries.
• Findings provide insights into the biomechanics of lower cervical spine instability and traumatic dislocation.