Preliminary Study of the Effects of Prolonged Acceleration on Spinal Dynamics of Baboons. 1. Acceleration. 2. Biomechanical Analysis

Abstract

Abstract : To determine if repetitive exposures to acceleration have an effect on spinal dynamics, such as to cause bone strength variations or predisposition to spinal injuries, two baboons were exposed simultaneously to 10 plateaus of +4 Gz/30 seconds each separated by intervals of +1.5 Gz/45 seconds at the rate of two times per week for 26 weeks. This phase of the study covers the methodology and compares the results to control non-centrifuged baboons. Subsequently, the spinal columns of these baboons were subjected to extensive mechanical strength testing. Next each vertebra of the same two baboons was subjected to axial compressive loading at the rate of 8.89 X 10 to the minus third power meter/sec (21 in./min) on a material testing machine. The data, analyzed by PDP-11/34 computer, were compared with data obtained previously from four non-centrifuged baboons of the same age, weight and sex. Although none of the eight material property (strength tests) evaluated was conclusive, there was a consistent trend that this centrifugation stress has a weakening effect on baboon vertebrae. This preliminary study makes it feasible to repeat the experiment using more animals under better controlled conditions to determine if the spinal changes are significant.