Cervical spine joint loading with neck flexion

Area of Science:

• Biomechanics
• Spine Research
• Ergonomics

Background:

• Cervical spine flexion, common with digital device use ('text neck'), is a risk factor for chronic neck pain.
• Limited research quantifies cervical spine joint loads during flexion, considering muscle activation.

Purpose of the Study:

• To quantify compression and anteroposterior (AP) shear forces in the cervical spine during 45-degree flexion compared to a neutral posture.
• To investigate the mechanical basis for neck pain associated with prolonged flexion postures.

Main Methods:

• Eight healthy males performed 45-degree cervical spine flexion tasks.
• 3D head-trunk angles and surface electromyography of 10 neck muscles were recorded.
• An inverse dynamics model computed intervertebral joint forces (compression and AP shear).

Main Results:

• Cervical spine flexion increased compression twofold and anterior shear fourfold in the upper spine compared to neutral posture.
• Compression increased from cranial to caudal, leveling off at C5-C6.
• Anterior shear dramatically decreased in the lower cervical spine during flexion.

Conclusions:

• Significant changes in cervical spine joint kinetics during flexion provide mechanical evidence linking posture to neck pain.
• Findings support the hypothesis of increased loading in 'text neck' postures.
• Results emphasize the need for ergonomic interventions, such as optimal workstation and monitor setup.