Finite Element Analysis of Head-Neck Kinematics in Rear-End Impact Conditions with Headrest

Area of Science:

• Biomechanics
• Computational modeling
• Spinal injury research

Background:

• Cervical spine injuries, particularly whiplash, are common in vehicular accidents.
• Understanding the complex kinematics of the head-neck complex is crucial for injury prevention.
• Finite element (FE) models offer a powerful tool for simulating these dynamics.

Purpose of the Study:

• To develop and validate a 3D finite element (FE) model of the human head-neck (C0-C7) complex.
• To analyze cervical spinal segment motion under static physiological loads and dynamic rear-end impact simulations.
• To investigate the influence of impact acceleration and headrest parameters on head-neck kinematics.

Main Methods:

• Development of a detailed three-dimensional (3D) finite element (FE) model (C0-C7).
• Application of static physiological loads (1.0 Nm flexion/extension) and dynamic rear-end impact pulses (4.5 G, 8.5 G at C7).
• Comparison of predicted segmental motions and head displacements with published data.

Main Results:

• Model predictions aligned with existing data for static physiological loads.
• Rear-end impact simulations revealed distinct kinematic responses within the first 200 ms, influenced by acceleration and headrest angle.
• Peak extension rotation varied based on acceleration (G) and headrest angle; higher C7 acceleration increased lower segment extension, but headrest distance was a limiting factor.
• Adjusting headrest angle from 45° to 30° shifted lower segment (C5-C6) rotation from extension to flexion, highlighting the importance of headrest positioning.

Conclusions:

• The C0-C7 FE model effectively simulates cervical spine responses to static and dynamic loading conditions.
• Rapid rotational changes in cervical segments during impacts may exceed tissue tolerance limits.
• Proper headrest location and angle are critical for mitigating cervical spine injury risk in vehicular accidents.