Stabilizing effect of precontracted neck musculature in whiplash.
METHODS
This study investigated the effect of neck muscle precontraction in aware occupants in whiplash. Head angulation relative to T1 and facet joint capsular ligament distractions were compared between aware and unaware occupants.


OBJECTIVE
To quantify changes in facet joint capsular ligament distractions between aware occupants with precontracted neck muscles and unaware occupants with reflex muscle contraction.


BACKGROUND
Clinical studies have reported that patients aware of the impending impact had decreased symptom intensity and faster recovery after whiplash. To date, no study has investigated the effects of precontracted neck musculature on localized spinal soft tissue distortions in whiplash.


METHODS
Aware occupants with precontracted neck muscles and unaware occupants with reflex muscle contraction in whiplash were simulated using a validated computational model. Muscle contraction attained maximum levels before impact in the aware occupant and implemented reflex delay, electromechanical delay, and finite muscle rise time in the unaware occupant.


RESULTS
Precontraction of neck muscles in aware occupants resulted in 63% decreased maximum head angles, elimination of cervical S-curvature, and up to 75% decrease in maximum facet joint capsular ligament distractions.


CONCLUSIONS
Occupants aware of an impending whiplash impact with precontracted neck muscles can markedly reduce overall head-neck and spinal motions. It is our theory that this would reduce whiplash injury likelihood.
Stemper
Brian D
BD
Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, WI 53226, USA. stemps@mcw.edu
Yoganandan
Narayan
N
Cusick
Joseph F
JF
Pintar
Frank A
FA
D000063:Accidents, Traffic; D001364:Awareness / Q000502:physiology; D001696:Biomechanical Phenomena; D002574:Cervical Vertebrae / Q000503:physiopathology; D003198:Computer Simulation; D006257:Head / Q000503:physiopathology; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology*; D008954:Models, Biological; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009333:Neck / Q000503:physiopathology*; D012026:Reflex, Stretch; D014911:Whiplash Injuries / Q000503:physiopathology*