Stretch along the craniocaudal axis improves shape recoverability of the spinal cord.

The spinal cord is physiologically stretched along the craniocaudal axis, and is subjected to tensile stress. The purpose of this study was to examine the effect of the tensile stress on morphological plasticity of the spinal cord under compression and decompression condition. The C1-T2 spinal column was excised from 4 rabbits. The laminae and lateral masses were removed. After excision of surrounding structures, a small rod was placed on the spinal cord. The rod was connected with a pan of the scale balance. Varying the weight between 0 and 20g on the other scalepan, the indentation of the rod was measured. Then, the spinal cord was cut transversely to remove longitudinal tensile stress. The samples were measured again with the same protocol at point 10mm caudal to each pre-measured point on the spinal cord. The shape recovery rate was calculated. The length of the spinal cord decreased by 9.7% after the separation. The maximum indentation was 2.1mm (mean) at 20g, and did not differ between the separated and un-separated cords. The recovery rate was not significantly different between the separated and un-separated cords until 3g. At the load under 3g, the recovery rate after the separation was significantly lower than that before the separation. The tensile stress along the craniocaudal axis in the spinal cord did not affect the spinal cord deformation in response to the compression, but it did affect the shape recoverability after the decompression.