Civil Engineering Reference
In-Depth Information
16
Mechanisms for
Pain and Injury in
Musculoskeletal
Disorders
16.1 Neurophysiologic Mechanisms of Pain . . . ......
16-2
Neural Anatomy Relevant to Pain
†
Tissue Injury, Central
Sensitization, and Pain
†
Biochemical Mediators of
Pain
†
Neuroimmunologic Responses in the CNS
16.2
Implications for MSD: Pain Mechanisms and
Injury Biomechanics . . .....................
16-8
16.3
Confounding Factors Affecting Pain ...........
16-9
16.4
Implications for MSD: Applications
and Future Research . . ..................... 16-11
Beth A. Winkelstein
University of Pennsylvania
16.5
Summary
. . . ............................ 16-12
Painful musculoskeletal disorders are a common problem in today's society, affecting an estimated one-
third of the population. The societal costs (including litigation, work-lost, treatment and disability) for
painful musculoskeletal disorders are staggering. Financially, considering all chronic pain syndromes
together, there is an annual cost of $90 billion.
2
For example, the cost of low back pain alone has
been estimated between $40-50 billion annually.
20,21
Until a better understanding of the pathomechan-
isms in chronic pain and the injuries which cause them is defined, the effective prevention and treatment
of these disorders and their symptoms will remain elusive. It is the intent of this chapter to review and
highlight traditional and more recently emerging theories explaining pain sensation, signaling and trans-
mission in the context of injury and musculoskeletal disorders.
This review offers an overview of the mechanistic pathways of persistent (chronic) pain associated with
musculoskeletal disorders (MSDs) and injuries. A discussion of the neurophysiology of pain addresses
concepts of injury and pain processing and describes more recent hypotheses of the central nervous
system's (CNS) neuroimmunologic involvement in persistent pain. These concepts, together with the
associated neurochemical nociceptive responses are addressed and discussed in the context of findings
from animal models of persistent pain with behavioral hypersensitivity. Physiologic responses in the
CNS are addressed as they pertain to the interplay of the electrophysiological and immune research
areas, and also as they relate to MSDs and biomechanics of injury. In particular, one such injury
16-1
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