Block vertebrae

Congenital anomalies of spine
Classification and external resources
ICD-10	Q67.5, Q76.0-.4
ICD-9-CM	756.1
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Congenital vertebral anomalies are a collection of malformations of the spine. Most around 85% are not clinically significant, but they can cause compression of the spinal cord by deforming the vertebral canal or causing instability. This condition occurs in the womb. Congenital vertebral anomalies include alterations of the shape and number of vertebrae.

Lumbarization is an anomaly in the spine. It is defined by the nonfusion of the first and second segments of the sacrum. The lumbar spine subsequently appears to have six vertebrae or segments, not five. This sixth lumbar vertebra is known as a transitional vertebra. Conversely the sacrum appears to have only four segments instead of its designated five segments. Lumbosacral transitional vertebrae consist of the process of the last lumbar vertebra fusing with the first sacral segment. While only around 10 percent of adults have a spinal abnormality due to genetics, a sixth lumbar vertebra is one of the more common abnormalities.

Sacralization of the fifth lumbar vertebra (or sacralization) is a congenital anomaly, in which the transverse process of the last lumbar vertebra (L5) fuses to the sacrum on one side or both, or to ilium, or both. These anomalies are observed at about 3.5 percent of people, and it is usually bilateral but can be unilateral or incomplete (ipsilateral or contralateral rudimentary facets) as well. Although sacralization may be a cause of low back pain, it is asymptomatic in many cases (especially bilateral type). Low back pain in these cases most likely occurs due to chronic faulty biomechanics. In sacralization, the L5-S1 intervertebral disc may be thin and narrow. This abnormality is found by X-ray.

Sacralization of L6 means L6 attaches to S1 via a rudimentary joint. This L6-S1 joint creates additional motion, increasing the potential for motion-related stress and lower back pain/conditions. This condition can usually be treated without surgery, injecting steroid medication at the pseudoarticulation instead. Additionally, if L6 fuses to another vertebra this is increasingly likely to cause lower back pain. The presence of a sixth vertebra in the space where five vertebrae normally reside also decreases the flexibility of the spine and increases the likelihood of injury.

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