Multimodal sensor-based weight drop spinal cord impact system for large animals

Abstract

Background context: A conventional weight drop spinal cord (SC) impact system for large animals is composed of a high-speed video camera, a vision system, and other things. However, a camera with high speed at over 5,000 frames per second (FPS) is very expensive. In addition, the use of the vision system involves complex pattern recognition algorithms and accurate arrangement of the camera and the target.

Purpose: The purpose of this study was to develop a large animal spinal cord injury (SCI) modeling system using a multimodal sensor instead of a high-speed video camera and vision system. Another objective of this study was to demonstrate the possibility of the developed system to measure the impact parameters in the experiments using different stiffness materials and an in vivo porcine SC.

Study design: A multimodal sensor-based SCI impact system was developed for large animals. The experiments to measure SC impact parameters were then performed using three different stiffness materials and a Yucatan miniature pig to verify the performance of system developed.

Methods: A comparative experiment was performed using three different stiffness materials such as high-density (HD) sponge, rubber, and clay to demonstrate the system and perform measurement for impact parameters such as impact velocity, impulsive force, and maximally compressed displacement reflecting physical properties of materials. In the animal experiment, a female Yucatan miniature pig of 60-kg weight was used. Impact conditions for all experiments were fixed at freefalling object mass of 50 g and height of 20 cm.

Results: In the impact test, measured impact velocities were almost the same for the three different stiffness materials at 1.84±0.0153 m/s. Impulsive forces for the three materials of rubber, HD sponge, and clay were 50.88 N, 32.35 N, and 6.68 N, respectively. Maximally compressed displacements for rubber, HD sponge, and clay were 1.93 mm, 3.35 mm, and 15.01 mm, respectively. In the pig experiment, impact velocity, impulsive force, and maximally compressed dural displacement were measured at 1.84 m/s, 13.35 N, and 3.04 mm, respectively. After 3 days from the experiment, paralysis was confirmed for the lower half body of the experimental pig.

Conclusions: Through experiments, it was verified that our proposed system could be used to measure the SC impact parameters and induce SCI for large animals.

Keywords: Contusional impact; Impact parameters; Multimodal sensor; Spinal cord impactor; Spinal cord injury; Weight drop impact.