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What is a Compression/Wedge Fracture?
A compression fracture is a common fracture
of the spine. It implies that the vertebral body has suffered a crush or wedging
injury. The vertebral body is the block of bone that makes up the spinal column.
Each vertebral body is separated from the other with a disc. When an external
force is applied to the spine, such as from a fall or carrying of a sudden heavy
weight, the forces may exceed the ability of the bone within the vertebral body
to support the load. This may cause the front part of the vertebral body to crush
forming a wedge shape. This is known as a compression fracture. If the entire
vertebral body breaks, this is considered a burst fracture and is discussed elsewhere.
The compression fracture may range from mild to severe in terms of severity. A
mild compression fracture causes minimal pain, minimal deformity and is often
treated with time and activity modification. Severe Pain
A severe compression
fracture may be such that the spinal cord or nerve roots are involved, as they
are draped over the sudden angulation of the spine. This may cause severe pain,
a hunched forward deformity (kyphosis) and rarely neurologic deficit from spinal
cord compression. Risks - Osteoporosis - Trauma
The risk for spinal compression
fracture increases with age. Osteoporosis is the most common risk factor for
compression fractures. Osteoporosis is a condition in which there is thinning
of the bones, weakening them. This may be due to a lack of calcium in the diet,
certain medications, old age, inactivity or genetic factors. In general, some
trauma occurs with each compression fracture. In cases of severe osteoporosis,
the trauma may be minimal, such as, stepping out of a bathtub or lifting a heavy
object. Moderate trauma is usually required to create a fracture in patients with
mild to moderated osteoporosis. This may range from falling off a chair to an
automobile accident. A normal spine may also suffer from a compression fracture
when there is a severe forward bending injury. This most commonly occurs from
a fall from a height or an automobile accident. Nerve Injury
Neurologic injury
is rare with compression fractures. The degree of neurologic injury is usually
due to the amount of force present at the time of injury. If there is severe angulation
of the spine secondary to a wedge fracture, this may stretch the spinal cord and
create injury. This would then lead to loss of strength and sensation, as well
as reflexes. In most patients with osteoporotic compression fractures, there is
no neurologic injury but only pain from the fracture. However, if left untreated
the fracture angulation may worsen and lead to late paralogic injury. Diagnosis
A compression fracture is usually diagnosed by the history, physical exam and
x-rays. In any patient over the age of 60 with the acute onset of sudden low back
pain, a compression fracture should be suspected. Physical exam will usually note
tenderness directly over the area of pain as well as mild kyphotic deformity (e.g.,
a sudden angulation forward or hunched over appearance). Plain x-rays will demonstrate
the wedge shape of the vertebral body on a lateral view. A CAT scan is occasionally
needed to help differentiate a compression fracture from a burst fracture.
Occasionally
an MRI scan is obtained to rule out disc herniation along with a compression fracture.
MRI scan may also help differentiate pathologic compression fractures, that is,
those that involve a tumor, from a typical osteoporotic compression fracture.
In any patient with a known history of cancer, a compression fracture should tip
off the physician to look for evidence of a metastatic lesion and pathologic fracture.
If osteoporosis is suspected, a Bone Mineral Density (BMD) test may be ordered.
This test helps determine the severity of the bone thinning. In addition, laboratory
tests to look at blood count and thyroid function may be indicated as well. A
decision as to whether to treat osteoporosis should be made by the patients' primary
physician.
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