Whiplash injuries and the potential for mechanical instability

Area of Science:

• Biomechanics
• Orthopedic Surgery
• Trauma Research

Background:

• Whiplash-associated disorders (WAD) present diagnostic challenges due to poor correlation between symptoms and clinical findings.
• The underlying cause of chronic WAD symptoms is hypothesized to be mechanical derangement of the cervical spine from trauma.
• Quantifying soft tissue injuries is crucial for validating this hypothesis.

Purpose of the Study:

• To quantify the mechanical changes in human cadaveric cervical spine specimens subjected to experimental whiplash trauma.
• To identify the threshold acceleration and specific spinal levels affected by whiplash injury.
• To provide data that can assist clinicians in diagnosing whiplash trauma patients more accurately.

Main Methods:

• Human cadaveric cervical spine specimens (C0-T1 or C0-C7) were subjected to a whiplash trauma model with increasing acceleration.
• Flexibility tests measured changes in range of motion (ROM) and neutral zone (NZ) at each intervertebral level.
• A 1.0 Nm pure flexion-extension moment was applied before and after trauma to assess spinal motion parameters.

Main Results:

• Significant increases in flexibility, specifically extension ROM and NZ at C5-C6, were observed after 4.5-g rear-end acceleration.
• Extension ROM at C5-C6 increased by 98% and NZ by 160% (P < 0.05) at this acceleration.
• Tendencies for increased extension NZ were noted at C0-C1 and C6-C7 after 6.5-g acceleration, but ROM changes were not significant.

Conclusions:

• The study identified specific acceleration thresholds and spinal levels vulnerable to whiplash injury.
• Lower cervical spine (C5-C6) demonstrated significant flexibility changes at lower acceleration magnitudes.
• Findings provide objective data to improve the diagnosis and understanding of whiplash-related cervical spine injuries.