The Dynamic Biomechanical Nature of Spinal Fractures and Articular Facet Derangement.
AEROSPACE MEDICAL RESEARCH LAB WRIGHT-PATTERSON AFB OHIO
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The application of appropriate scaling laws, animal experiments, particularly on primates, have been shown to be of value to explain hard tissue injury mechanisms and individual organ injury potential in man exposed to impact forces. In support of this approach rhesus monkeys were anesthetized, radiographed, positioned in an impact carriage, restrained by lap belt, torso harness, and limb retention straps, and exposed to Gz seated rectangular acceleration time histories from predetermined drop heights. Shortly following impact all primates were radiographed, killed, and a necropsy performed. Attempts were made by means of an injury classification system to determine injury potential as a function of plateau acceleration and pulse duration for the spinal column. Type, frequency, and severity of vertebral body centrum fractures along with injury to the vertebral appendages were classified. Vertebral articular facets-apophyseal joints disorders and derangements proved difficult to identify radiographically due to poor x-ray film resolution, overlying soft tissue, and bony margin shadows. Necropsy demonstrated a large percentage of primates exhibited this type of lesion. Injury probabilities for the vertebral column established by radiographic and gross necropsy examination supplement and explain available knowledge on spinal injury mechanisms observed in the rhesus monkey. Applicability of these data to man will be discussed. Author
- Medicine and Medical Research