Analysis of Vertebral Stress and BMD During +Gz Impact Accelerations

摘要

The U.S. Air Force pilot population includes both males and females with an expanded range of anthropometric measurements. To address concerns that females and/or small and large individuals may be more at risk during ejections, a series of tests were conducted at the Air Force Research Laboratory (AFRL) to identify the effects of gender and size on vertebral stress and BMD. Twenty-two males and twenty-four females were tested at acceleration levels up to 10G on a vertical deceleration tower. The subjects' bone mineral density (BMD) and vertebral size at C2, C5, T12, L1, and L2 were measured by quantitative computed tomography (QCT). Vertebral loads and stresses were calculated at the five selected vertebrae for all subjects. As expected, vertebral sizes were significantly smaller for the female subjects when compared to the male subjects. No significant gender differences were found for BMD values except C2 which was 10% lower in females. Females have significantly higher vertebral stresses in the cervical vertebrae while no significant gender differences were found in the thoracic and lumbar vertebrae. Relationships between stress and weight, height, and sitting height were investigated for the five vertebrae. Correlations were found between stress and weight at T12, L1, and L2.