Biomechanical specialist says Rian Orr was not injured by shaking

Another key witness in David Paul’s defense took the witness stand on Monday. The 24-year old Paul is accused of abusing the baby of his girlfriend, four-month old Rian Orr, including shaking her so hard that she died from complications brought on by brain damage.

Dr. Toby Hayes testifies that shaking could not have caused Rian Orr’s injuries during the David J. Paul homicide trial on Monday. Photo by Matt Miller/KTOO News

Dr. Wilson ‘Toby’ Hayes is an Oregon specialist who said he went to the equivalent of medical school before earning a PhD in mechanical or biomedical engineering. He specializes in the combination of biology and mechanical engineering, or injury biomechanics.

“So, when we talk about injury biomechanics, and particularly injuries to the muscular skeletal system or to the neurological structures of the human body, the real question of injury biomechanics is ‘What kinds of forces are required in order to cause injuries to a particular part of the body?’”

Hayes is not a physician and does not treat patients, but he helps analyze the type of forces involved in various injuries. For example, one common equation is recognizable by any physicist or engineer: F = MA, or force equals mass times acceleration.

Hayes testified that it was unlikely that Rian Orr died because of injuries suffered from shaking. According to his calculations, it’s nearly impossible to create the necessary acceleration forces with shaking a baby that could create a brain injury.

“The shaking can’t cause the accelerations to cause brain injuries. Even if it could, you can’t get a brain injury without a neck injury from a biomechanical perspective.”

Hayes said that a four-month old baby like Rian would have a proportionally large head with a larger fraction of body weight, and a weak and undeveloped neck, ligament, and muscle structure. She was only barely able to hold her own head up by herself about a month before she died.

If the baby was shaken, then Hayes said she would’ve likely suffered from a nearly fatal neck and spinal cord injury long before the onset of any brain injuries.

“If you do the F is equal to MA calculations, you think about the forces that are necessary to cause an injury to the spinal cord of small infants from shaking, or from, in this instance, dropping and catching, (then the) neck injury would come first. It’s much, much weaker than the brain.”

Even with the baby being dropped and hitting the floor, Hayes said it would be unlikely that Rian would’ve suffered a brain injury without a scalp or an exterior skull impact injury like a contusion.

An autopsy of Rian Orr did not indicate such a head injury or any neck or spinal injuries.

One study long ago cited by Shaken Baby Syndrome proponents concerns monkeys used in the testing of shoulder seat belt straps at thirty miles per hour. But Hayes said even the original author of the study noted that the monkeys had no head rests and the collisions had produced injuries that were based on impact as well as shaking.

The 24-year old Paul is facing trial for murder in the second degree and the lesser included charge of manslaughter in connection with Rian Orr’s death nearly three years ago.