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In-Depth Information
radiography provides limited information about the posterior spinal structures and
the intervertebral disk pathology. Magnetic resonance imaging (MRI) and computer
tomography (CT), as three-dimensional imaging tests, provide superior structural
information and a better resolution. MRI is ideal for visualizing pathology of the
intervertebral disk, neural structures such as the spinal cord, and is often the spinal
imaging test of choice for patients with neurological symptoms. MRI is also useful to
depict in
ammatory changes in bones and soft tissues. Therefore it has gained
interest as a method to assess the treatment response in in
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ammatory spine diseases.
CT is most often used in patients who have contraindications to MRI. CT is also an
ideal imaging modality for bony structures. CT myelography remains the gold
standard for diagnosing the cause of nerve root compression, differentiating osteo-
phytes from disk pathology. Spinal CT is also used in research settings to assess the
progression of bony pathology in ankylosing spondylitis.
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2 Osteoarthritis
2.1 Cervical and Lumbar Spondylosis
2.1.1 De
nition and Occurrence
Spondylosis refers to degenerative arthritis of the spine, including osteoarthritis of
the discovertebral and facet joints, and degenerative changes of related soft tissues,
including surrounding ligaments and muscles.
The cause of spondylosis remains unclear. A widely cited hypothesis states that
degenerative changes begin with the loss of water content in the annulus
fibrosis
[
1
]. The annulus gradually becomes drier and weaker, and eventually the disk
content leaks out, resulting in intervertebral disk protrusion and narrowing of the
disk space. This subsequently leads to increased mechanical stress at the discov-
ertebral joints, the facet joints and the spinal ligaments, causing both bony over-
growth and ligament thickening. Bony growths at the front and side of the vertebral
bodies are commonly seen. These so-called marginal osteophytes originate from the
end plate of the vertebral body. At the microscopic level, the cartilage endplate
degenerates and is replaced by bony proliferation; over time, it becomes hard and
protrudes into the intervertebral disk and the edge of the vertebral body [
2
]. Similar
changes occur at the facet joints, with overgrowth of bone (osteophytes) and nar-
rowing of the joint spaces. The spinal ligaments, especially the ligamentum
avum,
become thickened and may eventually calcify. These degenerative changes are most
commonly found at the
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fifth cervical, eighth thoracic and third lumbar spinal levels,
possibly due to greater spinal
flexibility in these areas [
3
]. Progression of degen-
erative changes may lead to compression of the adjacent structures, particularly on
the spinal cord and/or the spinal nerve roots, causing spinal stenosis. This condition
is discussed in detail below.
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