Low Speed Rear-End Collisions Mechanism of Injury © Copyright 2002, James Publishing, Inc.
<ul><li>&quot;Institute researchers evaluated head restraint geometry in more than 200 passenger vehicles, all 1997 models...
<ul><li>Viano and Gargan documented the head restraint position of 1,915 vehicles at an intersection. They found that only...
The Phases of a Rear-End Collision 1.  Normal Position 2.  Spine Straightens 3.  Head Extension 4.  Rebound
<ul><li>Car seat begins to move forward </li></ul><ul><li>Occupant remains stationary, due to inertia </li></ul><ul><li>No...
<ul><li>Car seat pushes into occupant’s torso </li></ul><ul><li>Torso is accelerated forward with the seat </li></ul><ul><...
<ul><li>Torso fully accelerated by the car seat </li></ul><ul><li>Lower neck is pulled forward by the rapidly moving torso...
<ul><li>Head is still moving backwards </li></ul><ul><li>Car seat begins to spring forward </li></ul><ul><li>Torso is agai...
<ul><li>Head and torso are accelerated forward ahead of the car seat, resulting in flexion of the spine </li></ul>300 mill...
Normal Cervical Spine
<ul><li>Normal, smooth curvature of the spine </li></ul><ul><li>Each intervertebral joint contributes evenly to the motion...
Motion During a Collision 0 milliseconds At the moment of impact, the car seat just begins to move and the occupant has no...
Motion During a Collision 50 milliseconds As the car seatback pushes the torso forward, the spine moves forward, resulting...
Motion During a Collision This difference in motion between the neck and torso results in an S-shaped curve, where nearly ...
75 milliseconds 50 milliseconds Spine Straightens S-Shaped Curve
Motion During a Collision 150 milliseconds At about 150 milliseconds, the torso has pulled so far forward on the lower nec...
Motion During a Collision 200 milliseconds Finally, the head and torso are thrown forward by the force of the car seat. He...
The Cervical Facet Joints Vertebral Body Facet Joints Intervertebral Disc Spinous Process Facets Normal Gliding Motion
Abnormal Facet Motion Pinching of facet Torso movement forward Torso moving forward Stretching of ligaments and disc Facet...
Areas of Injury The rapid motion of the neck during a crash can result in a number of injuries - many of which are impossi...
Nerves of the Facet Joint The pain from inflamed facet joints is transmitted by the medial branch of the dorsal ramus. Sti...
Referred Pain Patterns &quot;... the prevalence of cervical zygapophysial joint pain was 60%.&quot; The most common facets...
Bibliography <ul><li>Barnsley L, Lord SM, Wallis BJ, Bogduk N. The prevalence of chronic cervical zygapophysial joint pain...
<ul><li>Fukui S, Ohseto K, Shiotani M et al. Referred pain distribution of the cervical zygapophysial joints and cervical ...
<ul><li>Lord SM, Barnsley L, Wallis BJ, et al. Percutaneous radio-frequency neurotomy for chronic cervical zygapophysial j...
<ul><li>Szabo TJ, Welcher JB. Human subject kinematics and electromyographic activity during low speed rear impacts. 40th ...
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Low Speed Rear End Collisions

  1. 1. Low Speed Rear-End Collisions Mechanism of Injury © Copyright 2002, James Publishing, Inc.
  2. 2. <ul><li>&quot;Institute researchers evaluated head restraint geometry in more than 200 passenger vehicles, all 1997 models. Measuring the geometry of all seat options in each vehicle model they could find in dealer showrooms, the researchers found fewer than 3 percent with good geometry.“ Insurance Institute for Highway Safety, Status Report, April 12, 1997;32(4):4. </li></ul><ul><li>&quot;The head restraints in about a third of all 1999 passenger vehicles are poorly designed. Only 1 in 20 of the 1999 cars, pickups, and utility vehicles earns a good rating for head restraint design. Disappointing as these findings are, they represent an improvement since 1997 models were evaluated. Then more than half of all passenger vehicles were equipped with head restraints rated poor.“ Insurance Institute for Highway Safety, News Release, June 3, 1999. </li></ul><ul><li>&quot;Most people don't adjust their head restraints, leaving them in the 'down' position. In most cases, this means the restraints provide little or no protection from whiplash injuries. But even in the unadjusted position, the head restraints still meet the federal requirements that have been in effect for 30+ years.“ Insurance Institute for Highway Safety, Status Report, April 8, 2001;36(4):4-6. </li></ul>
  3. 3. <ul><li>Viano and Gargan documented the head restraint position of 1,915 vehicles at an intersection. They found that only 10% of the occupants had the head restraint in the proper position to avoid hyperextension. Only ¼ of the adjustable head restraints were in the “up” position. </li></ul><ul><ul><ul><li>Viano DC, Gargan MF. Headrest position during normal driving: implication to neck injury risk in rear crashes. Accident Analysis and Prevention 1996;28(6):665-674. </li></ul></ul></ul>Proper Head Restraint Positioning Improper Head Restraint Positioning
  4. 4. The Phases of a Rear-End Collision 1. Normal Position 2. Spine Straightens 3. Head Extension 4. Rebound
  5. 5. <ul><li>Car seat begins to move forward </li></ul><ul><li>Occupant remains stationary, due to inertia </li></ul><ul><li>No occupant forces </li></ul>0 milliseconds
  6. 6. <ul><li>Car seat pushes into occupant’s torso </li></ul><ul><li>Torso is accelerated forward with the seat </li></ul><ul><li>Head is still stationary, due to inertia </li></ul>100 milliseconds
  7. 7. <ul><li>Torso fully accelerated by the car seat </li></ul><ul><li>Lower neck is pulled forward by the rapidly moving torso </li></ul><ul><li>Causing the head to rotate backward over the head restraint </li></ul>150 milliseconds
  8. 8. <ul><li>Head is still moving backwards </li></ul><ul><li>Car seat begins to spring forward </li></ul><ul><li>Torso is again accelerated forward </li></ul>175 milliseconds
  9. 9. <ul><li>Head and torso are accelerated forward ahead of the car seat, resulting in flexion of the spine </li></ul>300 milliseconds
  10. 10. Normal Cervical Spine
  11. 11. <ul><li>Normal, smooth curvature of the spine </li></ul><ul><li>Each intervertebral joint contributes evenly to the motion </li></ul>Normal Cervical Spine Extension
  12. 12. Motion During a Collision 0 milliseconds At the moment of impact, the car seat just begins to move and the occupant has not yet been accelerated forward.
  13. 13. Motion During a Collision 50 milliseconds As the car seatback pushes the torso forward, the spine moves forward, resulting in a straightening of the thoracic and cervical spine. Head remains stationary Seatback pushes torso forward
  14. 14. Motion During a Collision This difference in motion between the neck and torso results in an S-shaped curve, where nearly all of the bending in the cervical spine takes place in the lower cervical spine. This rapid bending in just a few joints can result in ligament damage in the lower spine. 75 milliseconds At this point in the collision, the car seat is rapidly pushing the occupant's torso forward, while the head remains stationary due to inertia. Head remains stationary Seatback pushes torso forward
  15. 15. 75 milliseconds 50 milliseconds Spine Straightens S-Shaped Curve
  16. 16. Motion During a Collision 150 milliseconds At about 150 milliseconds, the torso has pulled so far forward on the lower neck that the head is forced backwards over the head restraint. Depending on the severity of the collision, the ligaments in the front portion of the spine can be injured during this phase of the collision. Head rotates back Seatback pushes torso forward
  17. 17. Motion During a Collision 200 milliseconds Finally, the head and torso are thrown forward by the force of the car seat. Head thrown forward Force from car seat
  18. 18. The Cervical Facet Joints Vertebral Body Facet Joints Intervertebral Disc Spinous Process Facets Normal Gliding Motion
  19. 19. Abnormal Facet Motion Pinching of facet Torso movement forward Torso moving forward Stretching of ligaments and disc Facet Joint Reflectors Stretch of facet capsule
  20. 20. Areas of Injury The rapid motion of the neck during a crash can result in a number of injuries - many of which are impossible to see on x-rays or MRI. Here are some of the injuries that have been shown after whiplash crashes. <ul><li>Rim Lesions </li></ul><ul><li>Endplate avulsions </li></ul><ul><li>Tears of the anterior longitudinal ligament </li></ul><ul><li>Uncinate process </li></ul><ul><li>Articular subchondral fractures </li></ul><ul><li>Articular pillar </li></ul><ul><li>Articular process </li></ul><ul><li>Ligament Tear </li></ul>
  21. 21. Nerves of the Facet Joint The pain from inflamed facet joints is transmitted by the medial branch of the dorsal ramus. Stimulation of the facet nerves often results in referred pain. Facet Joints Medial Branch Dorsal Ramus Spinous Process Spinal Cord
  22. 22. Referred Pain Patterns &quot;... the prevalence of cervical zygapophysial joint pain was 60%.&quot; The most common facets to be injured were at C2/C3 and C5/C6. Wallis BJ, Lord SM, Bogduk N. Resolution of psychological distress of whiplash patients following treatment by radiofrequency neurotomy: a randomised, double-blind, placebo-controlled trial. Pain 1997;73:15-22. C2/3, C3 C3/4, C4/5, C4 C6/7, C6, C7 C2/3, C3/4, C3 C4/5, C5/6, C4, C5 C4/5, C5/6, C4 C7/T1, C7
  23. 23. Bibliography <ul><li>Barnsley L, Lord SM, Wallis BJ, Bogduk N. The prevalence of chronic cervical zygapophysial joint pain after whiplash. Spine 1995;20:20-25. </li></ul><ul><li>Bogduk N. Post whiplash syndrome. Australian Family Physician 1994;23:2303-2307. </li></ul><ul><li>Brault JR, Wheeler JB, Siegmund GP, Brault EJ. Clinical response of human subjects to rear-end automobile collisions. Archives of Physical Medicine and Rehabilitation 1998;79:72-80. </li></ul><ul><li>Eichberger A, Darok M, Steffan H, Leinzinger PE, et al. Pressure measurements in the spinal canal of post-mortem human subjects during rear-end impact and correlation of results to the Neck Injury Criterion (NIC). Traffic Safety and Auto Engineering Stream of the World Congress on Whiplash-Associated Disorders, 1999:345-359. </li></ul><ul><li>Farmer CM, Wells JK, Werner JV. Relationship of head restraint positioning to driver neck injury in rear-end crashes. Traffic Safety and Auto Engineering Stream of the World Congress on Whiplash-Associated Disorders, 1999:70-89. </li></ul>Continued…
  24. 24. <ul><li>Fukui S, Ohseto K, Shiotani M et al. Referred pain distribution of the cervical zygapophysial joints and cervical dorsal rami. Pain 1996;68:79-83. </li></ul><ul><li>Grauer JN, Panjabi MM, Cholewicki J, Nibu K, Dvorak J. Whiplash produces an s-shaped curvature of the neck with hyperextension at lower levels. Spine 1997;22:2489-2494. </li></ul><ul><li>Insurance Institute for Highway Safety, Press Release, April 7, 1998. </li></ul><ul><li>Insurance Institute for Highway Safety, Status Report, 1997. 32(4). </li></ul><ul><li>Insurance Institute for Highway Safety, Status Report, 1999. 34(5). </li></ul><ul><li>Kaneoka K, Ono K, Inami S, Hayashi K. Motion analysis of cervical vertebrae during simulated whiplash loading. Traffic Safety and Auto Engineering Stream of the World Congress on Whiplash-Associated Disorders 1999:152-160. </li></ul><ul><li>Kornhauser M. Delta-V thresholds for cervical spine injury. 1996, SAE 960093. </li></ul><ul><li>Kumar S, Narayan Y, Amell T. Role of awareness in head-neck acceleration in low velocity rearend impacts. Compendium of papers presented at the Traffic Safety and Auto Engineering Stream, World Congress on Whiplash-Associated Disorders 1999;276-296. </li></ul><ul><li>Lord SM, Barnsley L, Wallis BJ, Bogduk N. Chronic cervical zygapophysial joint pain after whiplash: a placebo-controlled prevalence study. Spine 1996;21(15):1737-1745. </li></ul>Continued…
  25. 25. <ul><li>Lord SM, Barnsley L, Wallis BJ, et al. Percutaneous radio-frequency neurotomy for chronic cervical zygapophysial joint pain. New England Journal of Medicine 1996;335(23):1721-1726. </li></ul><ul><li>Matsushita T, Sato TB, Hirabayashi K, et al. X-ray study of the human neck motion due to head inertia loading. 38th Stapp Car Crash Conference 1994; SAE 942208. </li></ul><ul><li>Ono K, Kaneoka K, Wittek A, Kajzer J. Cervical injury mechanism based on the analysis of human cervical vertebral motion and head-neck-torso kinematics during low speed rear impacts. Society of Automotive Engineers, 41 st STAPP Car Crash Conference Proceedings 1997; SAE 973340. </li></ul><ul><li>Ortengren T, Hansson HA, Lovsund P, et al. Membrane leakage in spinal ganglion nerve cells induced by experimental whiplash extension motion: a study in pigs. Journal of Neurotrauma 1996;13(3):171-180. </li></ul><ul><li>Robbins MC. Lack of relationship between vehicle damage and occupant injury. SAE 970494. </li></ul><ul><li>Siegmund GP, Brault JR, Wheeler JB. The relationship between clinical and kinematic responses from human subject testing in rear-end automobile collisions. Traffic Safety and Auto Engineering Stream of the World Congress on Whiplash-Associated Disorders, 1999:181-207. </li></ul><ul><li>Siegmund GP, King DJ, Lawrence, JM, et al. Head/neck kinematic response of human subjects in low-speed rear-end collisions. Society of Automotive Engineers, 41 st STAPP Car Crash Conference Proceedings 1997; SAE 973341. </li></ul>Continued…
  26. 26. <ul><li>Szabo TJ, Welcher JB. Human subject kinematics and electromyographic activity during low speed rear impacts. 40th Stapp Car Crash Conference, SAE 962432. </li></ul><ul><li>van den Kroonenberg A, Philippens M, Cappon H, et al. Human head-neck response during low-speed rear end impacts. 42 nd Stapp Car Crash Conference Proceedings (P-227), 1998. SAE 983158. </li></ul><ul><li>Viano DC, Gargan MF. Headrest position during normal driving: implication to neck injury risk in rear crashes. Accident Analysis and Prevention 1996;28(6):665-674. </li></ul><ul><li>Wallis BJ, Bogduk N. Faking a profile: can naïve subjects simulate whiplash responses? Pain 1996;66:223-227. </li></ul><ul><li>Wallis BJ, Lord SM, Barnsley L, Bogduk N. Pain and psychologic symptoms of Australian patients with whiplash. Spine 1996;21(7):804-810. </li></ul><ul><li>Wallis BJ, Lord SM, Barnsley L, Bogduk N.The psychological profiles of patients with whiplash-associated headache. Cephalgia 1998;18:101-105. </li></ul><ul><li>Wallis BJ, Lord SM, Bogduk N. Resolution of psychological distress of whiplash patients following treatment by radiofrequency neurotomy: a randomised, double-blind, placebo-controlled trial. Pain 1997;73:15-22. </li></ul><ul><li>Yoganandan N, Pintar FA, Cusick JF. Biomechanical analyses of whiplash injuries using experimental model. Traffic Safety and Auto Engineering Stream of the World Congress on Whiplash-Associated Disorders 1999:325-343. </li></ul>

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