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Trice v. Dorel Juvenile Group, Inc.,

Biomechanics Expert Paul Lewis Explains Impact of Crash on Toddler in Trial Against Booster Seat Maker

The Expert: Paul Lewis, a biomedical engineer and biomechanics expert based in Roswell, Georgia, testifies for the plaintiff concerning the child’s injuries suffered in the accident.

The Verdict: A confidential settlement during jury deliberations.

By Dr. Gary F. Gansar, MD, FACS
Senior Physician Medical Director, AMFS

Bioforensic consultant and biomedical engineer Paul Lewis testifies for the plaintiff in a 2022 Georgia trial, Trice v. Dorel Juvenile Group, Inc., a case involving a motor vehicle collision that resulted in the quadriplegia of a toddler. The plaintiff contended that the child’s injuries were caused by defects in a car booster seat manufactured by the defendant. The expert, a biomechanics expert based in Roswell, Georgia, addresses specific spinal cord injuries in this clip.

Mr. Lewis begins by describing the pattern of bruising around the victim’s right eye extending back along the right side of his head. There was also bleeding within the skull and around the foramen magnum where the spinal cord exits the skull. In the neck itself, the first and second vertebrae were subjected to distraction forces, and the posterior longitudinal ligament was thus disrupted by the momentum of the accident. This would result in a significant destabilization of the spine. The third and fourth vertebrae were also involved, becoming distracted posteriorly and “splaying” away from each other while compressing down anteriorly. This is referred to as a “combined load failure,” compressing and pulling apart at the same time. These are the specific injuries that actually caused the child’s paralysis.

The discussion is diverted for a moment so the expert can explain how the vertebrae of the spine are categorized. There are seven cervical, or neck vertebral bones, twelve thoracic vertebrae extending from the base of the neck to the top of the lower back, five lumbar vertebrae extend from below that level to the top of the pelvis, and five fused sacral vertebrae terminate the spinal column in the pelvis.

The expert then points out that there was a “chance fracture” of the third lumbar vertebra. This is an injury that happens when extreme flexion of a torso occurs around a lap seatbelt, fracturing the vertebra in its middle from front to back. That injury was accompanied by horizontal soft tissue bruising across the abdomen at the level of the third lumbar vertebra, just slightly higher than the usual position of the seat belt. This is a “soft seatbelt sign.” The vertical portion of the seat belt also caused a left lung contusion or bruise due to percussion of the left hemithorax by the stationary shoulder belt as the child’s chest moved quickly forward. This occurred without the ribs fracturing.

A confidential settlement was agreed to during jury deliberations.

About the Author Dr. Gary F. Gansar, MD, FACS

Gary Gansar, MD, is residency-trained in general surgery. He served as Chief of Surgery and Staff at Elmwood Medical Center and on the Medical Executive Committee at Touro Infirmary and Mercy Hospital in New Orleans, LA. Dr. Gansar was Board Certified in general surgery while in active practice. He joined AMFS in 2015 as a Physician Medical Director.

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