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Spinal canal narrowing during simulated whiplash
Shigeki Ito1, Manohar M Panjabi, Paul C Ivancic
1Biomechanics Research Laboratory, Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, New Haven, CT 06520-8071, USA.
Spine
|June 10, 2004
Summary
Whiplash simulations showed that spinal canal pinch diameter (CPD) narrowed significantly during the event, especially at higher accelerations. However, post-whiplash CPD did not remain significantly narrower, suggesting cord compression is unlikely in average canals.
Area of Science:
- Biomechanics of injury
- Spinal cord injury research
- Automotive safety
Background:
- Whiplash injuries are common, but spinal cord injuries are rare.
- Existing hypotheses suggest increased cerebrospinal fluid pressure may cause neural tissue damage.
- Patients with pre-existing narrow spinal canals may be at higher risk.
Purpose of the Study:
- Quantify spinal canal pinch diameter (CPD) narrowing during simulated whiplash.
- Determine if whiplash events lead to a narrower post-whiplash CPD.
Main Methods:
- Utilized a biofidelic whole cervical spine model with muscle force replication.
- Simulated whiplash using a bench-top apparatus at varying g-force accelerations (3.5-8 g).
- Measured CPD in neutral, pre-whiplash, dynamic whiplash, and post-whiplash states.
Main Results:
- Dynamic whiplash CPD was significantly narrower than pre-whiplash CPD at 3.5 g and above (P < 0.05).
- The narrowest CPD (3.5 mm less than neutral) occurred at C5-C6 during a 6.5 g simulation.
- Post-whiplash CPD measurements were not significantly narrower than pre-whiplash values.
Conclusions:
- Simulated whiplash does not likely cause cord compression in individuals with average spinal canal diameters.
- The findings do not exclude the risk of injury for patients with pre-existing narrow spinal canals.
- Physiologic extension loading during whiplash is unlikely to cause sustained cord compression.