Lower+Back+Pain

toc = Low Back Pain = Low back pain, a nonspecific term, refers to pain centered over the lumbosacral junction

=** Pathophysiology **= The basic functional unit of the spine is the //functional spinal unit// and comprises two adjacent vertebral bodies with two posterior facet joints, an intervertebral disk, and the surrounding ligamentous structures. The intervertebral disk absorbs energy and distributes weight evenly from one spinal segment to the next while allowing movement of the protective bony elements.

Lifting, bending, twisting, or whole body vibration can damage elements of the spine. With injury and aging, progressive degenerative changes appear in each element of the functional spinal unit, along with the onset of characteristic symptoms. The earliest change in the lumbar facet joints is synovitis, which progresses to degradation of the articular surfaces, capsular laxity and subluxation, and finally enlargement of the articular processes (facet hypertrophy).

Progressive degeneration also occurs within the intervertebral disks, starting with loss of hydration of the nucleus pulposus followed by the appearance of circumferential or radial tears within the annulus fibrosis (internal disk disruption).

Lumbosacral pain can arise from the facet joints or the annulus fibrosis.[|[5]] With internal disruption of the annulus, some of the gelatinous central nucleus pulposus can extend beyond the disk margin, as a disk herniation (herniated nucleus pulposus, or HNP). When HNP extends to the region adjacent to the spinal nerve, it incites an intense inflammatory reaction.

Patients with HNP typically present with acute radicular pain. Hypertrophy of the facet joints and calcification of the ligamentous structures can reduce the size of the intervertebral foramina and central spinal canal (spinal stenosis), with onset of radicular pain and neurogenic claudication.

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