Pain Biomechanics

Abstract

Painful injury is a tremendous problem affecting a large proportion of the population during their lifetime. Pain most commonly results from trauma and/or injury, with the spine as the most common injury site for producing chronic pain. This chapter reviews relevant anatomy, mechanics and techniques used to study cervical spine pain in particular, since it is the region most prone to injury and because the largest body of research has been in this region. In vivo, many behavioral assessments exist to functionally measure painful outcomes, with hyperalgesia and allodynia as the two primary classes of behavioral responses. Both provide quantitative measures of pain that relate to the clinical presentation of symptoms. This chapter begins with a brief review of the anatomical tissues that are most at risk for injury and pain generation. This is followed by a review highlighting the cellular and molecular mechanisms of nociception and pain, addressing modifi cations in the periphery and in the central nervous system (CNS). The relationship between injury biomechanics and the local and spinal cellular responses are presented in the context of nociception and pain, with specifi c focus on injury to the facet capsule and nerve root because of their common involvement in cervical spine injury. Lastly, a brief review of experimental methodologies used to study pain biomechanics, ranging from the macroscopic to the cellular and molecular scales, is provided along with contextualization of the relative advantages and limitations of each. A brief summary integrates all of the sections to identify future areas of research that will defi ne a more detailed understanding of pain biomechanics.