A healthy intervertebral disc maintains a certain level of pressure, which is called the intradiscal pressure. The chondrocytes provide a constant balanced turnover within the nucleous pulposus: they synthesise and break down the proteoglycans for the nucleous pulposus matrix that holds the water and collagen for the annulus fibrosus. A normal nucleous pulposus is a gelatinous structure with high viscosity and elasticity, comprised of proteoglycans and intermolecular water (up to 80%). In the majority of cases, the degenerative process starts with the nucleous pulposus. Advanced degeneration may eventually involve distant structures and lead to facet joint osteoarthritis, ligamentum flavum hypertrophy and spinal canal stenosis ( C-changes) (Fig. On imaging the degenerative process usually starts within the nucleolus pulposus ( A-changes) and extend to the disc, annulus fibrosus, end plates and bone marrow of the adjacent vertebral bodies ( B-changes). We propose a simple mnemonic and classification to facilitate description of spinal degenerative changes by dividing them into three categories of A, B and C changes, based on the location and sequence of progression. No degenerative change should be considered an isolated event or reported as a random finding.Ĭommonly, the degenerative process may include other elements of the involved functional spinal unit, which we term horizontal or segmental degeneration, or change the entire biomechanics of the spine, including the adjacent functional spinal units, know as an adjacent segment disease (Fig. The pathophysiology-based approach in assessing imaging findings in the degenerative spine can: (1) accurately characterise the process in the involved segment (2) identify the sequence of degenerative changes and predict further abnormalities (3) identify hidden or subtle abnormalities based on indirect signs (4) assist clinicians in finding the source of pain or neurological symptoms (5) identify the best treatment options for patients. Therefore, understanding the pathophysiology of these biomechanical changes in the spine is essential for radiologists to characterise radiological abnormalities. The pathogenesis of these changes in the spine is a biomechanically related continuum of alterations that evolve over time. All elements of the spine, including the intervertebral discs, joints, ligaments and bony structures, may undergo morphological changes that can be classified as degenerative.Īccurate and comprehensive interpretation of imaging findings relating to the degenerative spine can be challenging and sometimes even confusing because the word “degeneration” means different things to radiologists, neurologists, neurosurgeons and pathologists. The aetiology of the degenerative changes may be mechanical micro-insults or damage secondary to macro-insults, such as spinal fractures, spinal surgery not related to degenerative disc disease or significant metabolic processes, such as ochondrosis or mucoplysaccharidoses. Spine degeneration is a biomechanically related continuum of alterations evolving over time.ĭegenerative change is considered a response to insults, such as mechanical or metabolic injury, rather than a disease.Degenerative change is a response to insults, such as mechanical or metabolic injury.The adjacent vertebrae, intervertebral disc, ligaments and facet joints constitute a spinal unit.The article provides an illustrated review on the topic for radiology residents.
Findings are described in association with the clinical symptoms they may cause, with a brief review of the possible treatment options. The aim of this article is to review radiological findings involving the intervertebral discs, end plates, bone marrow changes, facet joints and the spinal canal in relation to the pathogenesis of degenerative changes in the spine. The pathogenesis of this degenerative process represents a biomechanically related continuum of alterations, which can be identified with different imaging modalities. Imaging of the degenerative spine is a frequent challenge in radiology. Degenerative changes in the spine have high medical and socioeconomic significance.
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