Instability (2) can occur in individuals between the ages of 35 to 70 years old. During this stage, radial and circumferential tears can occur in the annulus accompanied by facet joint localized synovitis. Dysfunction occurs between the ages of 15 to 45 years old. The degenerative process of the cervical spine classifies into three distinct stages: (1) dysfunction, (2) instability, and (3) stabilization. Furthermore, NP fragments can be separated from the extruded disc material, yielding disc sequestration. However, the NP can also penetrate through injured annular fibers, and NP contents can extrude through a defect in the annulus, referred to as a disc extrusion. If the NP herniates but remains contained by the annulus, it is referred to as a disc protrusion. There are different types of NP herniations. Over time, the IVD not only begins to lose its water content but its proteoglycan supply as well, leading to a more fibrotic consistency of the NP and subsequent fissuring As those vertebral endplates calcify with aging. Most of the nutrition delivery is via metabolite diffusion from the vertebral endplates. A critical proteoglycan in the NP is aggrecan, which, when bound to hyaluronic acid, helps to keep water within the NP, allowing for load resistance.Īfter the first years of life, the IVD becomes the largest avascular structure in the body. The NP has a gel-like consistency composed mainly of water, which decreases with age (~90% at birth and 70% by the age of 60). The remaining minority of the NP contents then consists of type II collagen and proteoglycans. The AF of the intervertebral discs is mostly of type I collagen in layers (lamellae), proteoglycans, glycoproteins, elastic fibers, and extracellular matrix (ECM) secreting cells. These collagen layers are uniquely positioned to form a strong shell for the inner contents, the NP. The anterior and posterior longitudinal ligaments reinforce the IVD. The IVD is an intricate structure composed mainly of two parts, the peripherally located annulus fibrosus (AF) and the centrally located nucleus pulpous (NP) which are responsible for its’ load distribution function. This joint helps to reinforce the IVD and provides additional stability and motion. In contrast to the thoracic and lumbar vertebrae, the cervical vertebrae have a unique bony prominence called the uncinate process, which articulates with the adjacent level to form the joint of Luschka or uncovertebral joint. The intervertebral disc (IVD) is found from the C2-C3 level down, aids in cervical spine mobility and stabilization. Structures adjacent to the cervical vertebrae include the spinal cord and nerve roots, blood vessels as well as the trachea and esophagus. The upper cervical spine, C1 (the atlas, which articulates with the occiput), and C2 (the axis) are highly specialized, allowing for significant ranges of motion (rotation, flexion, extension, and side-bending) related to facet orientation allowing for more rotation. The cervical spine, C1 to C7, provide exceptional function and range of motion. This chapter will examine the anatomy, natural history, etiology, pathophysiology, evaluation, and treatment options. Treatment options range from nonoperative measures to decompression, instrumented fusion, or a combination of both laminoplasty or instrumentation or a combination of both. Pain, or in combination with other neurological symptoms, may require surgical intervention. Patients most commonly present with pain. Degenerative disc disease of the cervical spine typically develops in the aging population equally in terms of patient sex.
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