Advancing Biomechanical Research Through a Camelid Model of the Human Lumbar Spine.

摘要

The increasing incidence of disc degeneration and its correlation with lower back pain is an alarming trend in modern society. The research of intervertebral disc degeneration and low back pain would greatly benefit from additional methods to study its etiology and possible treatment methods. A large animal model that maintains the biological and mechanical environment that is most similar to the human lumbar spine could provide substantial improvements in understanding and resolving the problem of intervertebral disc related low back pain.;This dissertation presents my doctoral work of investigating the potential for the camelid cervical spine to serve as a suitable animal model for advancing biomechanical research of low back pain and intervertebral disc degeneration in the human lumbar spine. Specifically, this work identifies the cellular, morphological and biomechanical characteristics of the camelid cervical spine and intervertebral disc as compared to the human lumbar spine. My results demonstrate that there are remarkable similarities in all aspects. Many of the similarities with respect to the cellular environment of the intervertebral disc are a consequence of the camelid status as a large mammal. Additional testing of the cellular makeup of the camelid intervertebral disc cells revealed that many human qRT-PCR primers associated with disc degeneration are suitable for use in alpacas without modification. From a biomechanics standpoint, the camelid cervical spine also has a vertically oriented spinal posture and is unsupported near the end in an open kinetic chain, providing a mechanical parallel with the human lumbar spine. The camelid cervical intervertebral disc size is closer to the human lumbar intervertebral disc than all other currently used animal models available for comparison in the literature. Average flexibility (range of motion) of a camelid spinal motion segment showed similarities in all modes of loading. Based on magnetic resonance imaging and radiologic grading of the intervertebral disc, almost 90% of elderly camelids exhibited advanced degeneration (Pfirrmann grade 3 or higher) in their cervical spine, and about half of aged camelids have developed severe degeneration (Pfirrmann grade 4 or higher) in at least one or more of their cervical segments, most commonly within the two lowest cervical segments (e.g. c6c7 and/or c7t1). Thus, while there remain differences, the remarkable similarities between the camelid and human spine strengthen the case for using camelids as a model for human disc degeneration, normal and pathological biomechanics and fluid transport, and potentially as a pre-clinical model for investigating the efficacy of novel spinal devices.