Precision in Spinal Cord Injury Research: A Novel Electromagnetic Impactor for a Consistent Porcine Model

Purpose: Replicating spinal cord injury (SCI) in large animals is necessary for evaluating translational therapeutics, yet there is currently no commercial, standardized device for inducing SCI. We present the fabrication and testing of a custom impactor device for producing repeatable contusion SCI in porcine models. Methods: The device was built, and mechanical modeling was utilized for calibration. Benchtop verification measured impact force. Impact velocity and kinetic energy were calculated. The device was used to generate a contusion SCI model in 2 pigs and the results were compared to an uninjured pig. Ultrasound imaging and Hematoxylin-eosin (H&E) staining were used to confirm injury presence. The device was utilized in survival studies requiring a porcine SCI model and motor scores were collected at postoperative day 1 in 4 pigs. Results: Characterization revealed distinct impact velocities for each dial turn. This device further demonstrated repeatability and the potential for modulating injury severity on the benchtop. Impactor forces were demonstrated across a range from 12.8 to 67.6 N, with error between 0.2 and 0.7 N. Kinetic energy ranged from 0.045 to 0.338 J, with error between 0.0009 to 0.003 J. Intraoperative ultrasound imaging and histology of the spinal cord confirmed two injuries of different severity. The device produced a variety of injury severities through parameter modifications in survival studies assessed by the porcine neurological motor (PNM) score. Conclusion: This impactor device is a major advancement towards titratable contusions in large animal SCI models.