Intervertebral motion between flexion and extension in asymptomatic individuals.

Area of Science:

• Biomechanics of the spine
• Radiographic analysis of spinal motion
• Quantitative assessment of intervertebral dynamics

Background:

• Existing literature reports wide variations in normal cervical spine flexion-extension motion.
• The underlying causes of these intervertebral motion variations remain poorly understood.

Purpose of the Study:

• To investigate intervertebral motion during cervical spine flexion and extension in asymptomatic individuals.
• To identify factors contributing to variations in intervertebral motion.
• To establish a quantitative database of cervical spine motion using a practical imaging tool.

Main Methods:

• Fluoroscopic images of the cervical spine in maximum flexion and extension were analyzed in 140 asymptomatic volunteers.
• A validated, clinically applicable image analysis system was used to measure sagittal plane rotation and translation between vertebrae.
• Independent variables were analyzed for their contribution to motion variation.

Main Results:

• Significant variation in measured intervertebral motion was observed.
• Intervertebral level and overall rotation (C2-C6) significantly impacted all motion measures.
• Intervertebral levels and displacement measures explained nearly 90% of the variation in sagittal plane intervertebral rotations.

Conclusions:

• A comprehensive database of intervertebral motion in asymptomatic subjects was created, aiding patient interpretation.
• Analysis of various intervertebral motion aspects can enhance the clinical utility of radiographic flexion-extension studies.