The porcine cervical spine as a model of the human lumbar spine: an anatomical, geometric, and functional comparison.

Animal models for analysis of spine injury and orthopaedic issues are common given concerns about bone integrity, disc degeneration, and controlled studies of identical specimens matched for age, weight, physical activity and genetic background. Given this asset, the question is asked: "Is the porcine cervical spine a reasonable model of the human lumbar spine?" Three porcine cervical spines (C2-C7) were assessed for geometric characteristics, with a larger cohort (N = 24) loaded to failure under compressive or shear loading. In addition, in vivo loading was estimated and compared between the human low back (biped) and the porcine neck (quadruped). Generally, the porcine vertebrae are smaller in all dimensions. The porcine vertebrae have anterior processes unlike humans; however, they possess similar ligamentous structure and facet joint orientation. Stiffness values (compression and shear) are similar, and comparable injuries resulted from applied compressive and shear loads. Given the scarcity of healthy, young human lumbar spines, porcine cervical spines may be a useful model for studying human lumbar injury because of the similarity of mechanical characteristics and the resulting injuries, particularly of the adolescent or young adult who has not experienced disc degeneration or calcified end-plates.