Acquired Degenerative Changes Of The Intervertebral Segments At And Suprajacent To The Lumbosacral Junction A Radioanatomic An

Spine-related pain and disability are some of the greatest preoccupations of clinicians and patients. Beyond`normal' aging of the elements of the spine, absolute degeneration of these spinal substructures eventually occurs. This at some point entails a superoinferior narrowing and eventual collapse of the intervertebral disk. Preceding or accompanying these diskal alterations, significant degenerative changes also occur in the nondiskal structures of the spinal column and related tissues, including the posterior spinal facet joints, the spinal ligaments, the underlying bone of the posterior bony elements of the spine and the perispinal muscles. This article outlines the clinically relevant spinal and perispinal consequences of and phenomena contributing to acquired degenerative changes of the nondiskal structures of the intervertebral segments at and immediately suprajacent to the lumbosacral junction (i.e., L5-S1, L4-5, and L3-4 levels) and illustrates how these pathoanatomic findings relate to the normal and variant anatomy and dysfunction of this region of the spine. The nondiskal structures of the spine that may undergo degenerative changes include the posterior spinal facet (e.g., zygapophyseal) joints; the spinous processes; the intraspinal ligaments; the spinal nerves and spinal innervation; and the perispinal (intraspinal) muscles (Figs. 1-4). Normal gross anatomic variations in these structures include those of lumbosacral spinal curvature (e.g., straight spine: hypolordosis; exaggerated spinal curvature: hyperlodorsosis [Fig. 5] ; and lateral and rotational scoliosis); central spinal canal diameter (e.g., developmental spinal stenosis); vertebral morphology (e.g., normal anterior wedge shape of L2-L5 vertebral bodies); diskal morphology (e.g., normal anterior wedge shape of L2-3 through L5-S1 intervertebral disks); spinous process morphology (e.g., normal hypoplasia of L5 spinous process); and facet joint angulation in the axial plane (e.g., sagittal or coronal orientation; facet joint tropism or lateral asymmetry of angulation). These variations may predispose or accelerate degenerative changes in predictable ways. In turn, these degenerative alterations may in some cases result in signs and symptoms including low back pain and lower-extremity referred pain, both of which may respond to therapies specific to the underlying problem. * The anatomic foundation for these signs and symptoms is clear and is found within the innervation of these spinal and perispinal structures and in the central nervous system pathways serving the peripheral nervous system. Figure 1. Normal osseous and ligamentous anatomy of the lumbosacral spine. A, Midline sagittal section of the lumbosacral spinal ligaments and related spaces. B, Coronal section through the midportions of the lower lumbar vertebrae and intervertebral disks with …