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Updated: Jun 21, 2026
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A Test Bed to Examine Helmet Fit and Retention and Biomechanical Measures of Head and Neck Injury in Simulated Impact
Published on: September 21, 2017
Whiplash injury prevention with active head restraint
Paul C Ivancic1, Daohang Sha, Manohar M Panjabi
1Biomechanics Research Laboratory, Department of Orthopaedics and Rehabilitation, Yale University, School of Medicine, New Haven, CT 06520-8071, USA. paul.ivancic@yale.edu
Clinical Biomechanics (Bristol, Avon)
|August 12, 2009
Summary
A new human neck model shows active head restraints reduce spinal motion during rear impacts. However, excessive head restraint backset can still lead to hyperextension injuries, indicating limitations in current protective measures.
Area of Science:
- Biomechanics
- Injury Prevention
- Automotive Safety
Background:
- Epidemiological studies link head restraint backset >10 cm to increased neck injury risk.
- Persistent symptoms following neck injuries are a significant concern.
Purpose of the Study:
- Investigate the relationship between active head restraint position and peak neck motion.
- Utilize a novel human neck model for detailed biomechanical analysis.
Main Methods:
- Simulated rear impacts (7.1 and 11.1g) on an osteoligamentous neck model with and without active head restraint.
- Measured physiologic rotation and peak spinal motions.
- Employed linear regression to analyze correlations between head restraint backset and spinal rotations.
Main Results:
- Active head restraint significantly reduced peak spinal rotations.
- Despite reductions, peak motions exceeded physiologic ranges in flexion (head/C1) and extension (C4/5-C7/T1).
- Observed correlation between head restraint backset and extension peaks at C4/5 and C5/6.
Conclusions:
- Head restraint backset exceeding 8.0 cm may cause hyperextension injuries in the mid-lower cervical spine.
- Active head restraint's protective effect may be limited if not fully activated during peak spinal motion events.
