Biomechanical Evaluation of Head Kinematics During Infant Shaking Versus Pediatric Activities of Daily Living
John D. Lloyd, Ph.D., M.Erg.S., CPE, CBIS
Board Certified Ergonomist | Certified Brain Injury Specialist
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Abusive shaking of infants has been asserted as a primary cause of subdural bleeding, cerebral edema, and retinal hemorrhages. Manual shaking of various biofidelic mannequins, however, has failed to generate the head kinematics believed necessary to cause these intracranial symptoms in the human infant. This study seeks to compare linear and angular accelerations between infant shaking and pediatric activities of daily living.
Using sensors attached to the heads and torsos of two infant surrogates, the investigators collected linear and angular motion data during resuscitative, aggressive and gravity-assisted shaking as well as during various non-abusive activities normally experienced by infants, such as burping, rough play, etc. The researchers also collected data from a 7-month old infant child spontaneously at play in a commercial jumping toy. Results were compared between the experimental conditions, against other biomechanical studies of shaking and in contrast to accepted biomechanical thresholds of injury.
In these experiments, the peak rotational acceleration generated, averaged across nine adult subjects, during aggressive shaking of the CRABI-12 biofidelic mannequin (1068.3rad/s2) were both consistent with the reports of prior biomechanical studies and, most interestingly, statistically undifferentiated from angular accelerations spontaneously generated and well tolerated by a normal 7-month-old infant at play in a commercially available jumping toy (954.4rad/s2).
Non-contact shaking appears to result in head kinematics that are well tolerated by normal infants, even if these rotational accelerations are repetitive, as experienced by the infant at play. Our data would indicate that intracranial injury in an infant is unlikely to be the direct result of the linear and/or angular accelerations generated during non-contact shaking.