Congenital vertebral anomaly

These anomalies are observed in 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).

This L6-S1 joint creates additional motion, increasing the potential for motion-related stress and lower back pain/conditions.

[4] Hemivertebrae are wedge-shaped vertebrae and therefore can cause an angle in the spine (such as kyphosis, scoliosis, and lordosis).

Signs include rear limb weakness or paralysis, urinary or fecal incontinence, and spinal pain.

Severe cases may respond to surgical spinal cord decompression and vertebral stabilization.

[citation needed] Evidence for block vertebrae found in the fossil record is studied by paleopathologists, specialists in ancient disease and injury.

This suggests that the basic development pattern of vertebrae goes at least as far back as the most recent common ancestor of archosaurs and mammals.

It is caused by persistence of the notochord (which usually only remains as the center of the intervertebral disc) during vertebrae formation.

A transitional vertebra at the lumbosacral junction can cause arthritis, disk changes, or thecal sac compression.

One study found that male German Shepherd Dogs with a lumbosacral transitional vertebra are at greater risk for cauda equina syndrome, which can cause rear limb weakness and incontinence.

[5] In Manx it accompanies a condition known as sacrocaudal dysgenesis that gives these cats their characteristic tailless or stumpy tail appearance.