Lower Back Issues

Lumbar Spondylolisthesis

Causes
Spondylolisthesis may very rarely be congenital, which means it is present at birth. It can also occur in childhood as a result of injury. In older adults, degeneration of the disc and facet (spinal) joints can lead to spondylolisthesis.

Spondylolisthesis from degeneration usually affects people over 50 years old. This condition occurs in African Americans more often than in whites. Women are affected more often than men. The effect of the female hormone estrogen on ligaments and joints is to cause laxity or looseness. The higher levels of estrogen in women may account for the greater incidence of spondylolisthesis. Degenerative spondylolis-thesis mainly involves slippage of L4 over L5.

In younger patients (under 20 years old), spondylolisthesis usually involves slippage of the fifth lumbar vertebra over the top of the sacrum. There are several reasons for this. First, the connection of L5 and the sacrum forms an angle that is tilted slightly forward, mainly because the top of the sacrum slopes forward. Second, the slight inward curve of the lumbar spine creates an additional forward tilt where L5 meets the sacrum. Finally, gravity attempts to pull L5 in a forward direction.

Facet joints are small joints that connect the back of the spine together. Normally, the facet joints connecting L5 to the sacrum create a solid buttress to prevent L5 from slipping over the top of the sacrum. However, when problems exist in the disc, facet joints, or bony ring of L5, the buttress becomes ineffective. As a result, the L5 vertebra can slip forward over the top of the sacrum.

A condition called spondylolysis can lead to the slippage that happens with spondylolisthesis. Spondylolysisis a defect in the bony ring of the spinal column. It affects the pars interarticularis, mentioned earlier. This defect is most commonly thought to be a stress fracture that happens from repeated strains on the bony ring. Participants in gymnastics and football commonly suffer these strains. Spondylolysis can lead to the spine slippage when a fracture occurs on both sides of the bony ring. This slippage is called spondylolisthesis. The slippage is graded from I through IV, one being mild, IV often causing neurological symptoms. The back section of the bony ring separates from the main vertebral body, so the injured vertebra is no longer connected by bone to the one below it. In this situation, the facet joints can’t provide their normal support. The vertebra on top is then free to slip forward over the one below.

A traumatic fracture in the bony ring can lead to slippage when the fracture goes completely through both sides of the bony ring. The facet joints are no longer able to provide a buttress, allowing the vertebra with the crack in it to slip forward. This is similar to what happens when spondylolysis (mentioned earlier) occurs on both sides of the bony ring, but in this case it happens all at once.

Degenerative changes in the spine (those from wear and tear) can also lead to spondylolisthesis. The spineages and wears over time, much like hair turns gray. These changes affect the structures that normally support healthy spine alignment. Degeneration in the disc and facet joints of a spinal segment causes the vertebrae to move more than they should. The segment becomes loose, and the added movement takes an additional toll on the structures of the spine. The disc weakens, pressing the facet joints together. Eventually, the support from the facet joints becomes ineffective, and the top vertebra slides forward.

Symptoms
An ache in the low back and buttock areas is the most common complaint in patients with spondylolisthesis. Pain is usually worse when standing, walking, or bending backward and may be eased by resting or bending the spine forward. Leaning on a counter top, piece of furniture, or shopping cart are common ways to alleviate (reduce) the symptoms.

Spasm is also common in the low back muscles. The hamstring muscles on the back of the thighs may become tight.

The pain can be from mechanical causes. Mechanical pain is caused by wear and tear on the parts of the spine. When the vertebra slips forward, it puts a painful strain on the disc and facet joints.

Slippage can also cause nerve compression. Nerve compression is a result ofpressure on a nerve. As the spine slips forward, the nerves may be squeezed where they exit the spine. This condition also reduces space in the spinal canal where the vertebra has slipped. This can put extra pressure on the nerve tissues inside the canal. Nerve compression can cause symptoms where the nerve travels and may include numbness, tingling, slowed reflexes, and muscle weakness in the legs.

Nerve pressure on the cauda equina (mentioned earlier), the bundle of nerve roots within the lumbar spinal canal, can affect the nerves that go to the bladder and rectum. When this happens, bowel and/or bladder function can be affected. The pressure may cause low back pain, pain running down the back of both legs, and numbness or tingling between the legs in the area you would contact if you were seated on a saddle.