What Is Spondylolisthesis?

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Spondylolisthesis is a condition in which a vertebra in the lumbar (lower) spine slips out of normal position, sliding forward (or sometimes backward) relative to the vertebra beneath it. It can be the result of an injury, lower back stress associated with sports such as gymnastics or football, or age-related changes in the spine. Whatever the cause, depending on the extent of movement of the vertebra involved, symptoms can range from none at all to severe pain caused by pressure on a nerve.

Spondylolisthesis usually is diagnosed with an X-ray. Low-grade spondylolisthesis may be relieved with non-invasive measures, while more severe cases may require a surgical procedure.
Types of Spondylolisthesis
Types of spondyloisthesis include:

Isthmic spondylolisthesis: This is a result of spondylolysis, a condition that leads to small stress fractures (breaks) in the vertebrae. In some cases, the fractures weaken the bone so much that it slips out of place.
Degenerative spondylolisthesis: Degenerative spondylolisthesis is related to changes that tend to occur in the spine with age. For example, the discs can start to dry up and become brittle; as this occurs, they shrink and may bulge. Degenerative changes that affect the disc may give rise to spinal arthritis. Another common condition in degenerative spondylolisthesis is spinal stenosis, in which the bones narrow and put pressure on the spinal cord.
Congenital spondylolisthesis: Congenital spondylolisthesis, identified at birth, is the result of abnormal bone formation, leaving the vertebrae vulnerable to slippage.
Less common forms of the condition include:


Traumatic spondylolisthesis: With this, a spinal fracture or slippage occurs as a result of injury.
Pathological spondylolisthesis: In this case, spondylolisthesis is secondary to another disease, such as osteoporosis, a tumor, or an infection.
Post-surgical spondylolisthesis: When spine surgery results in slippage of the vertebrae, it is known as post-surgical spondylolisthesis.

Symptoms
Many people with spondylolisthesis have no obvious symptoms. The condition may not even be discovered until an X-ray is taken for an unrelated injury or condition.

When symptoms occur, the most common one is lower back pain that can radiate to the buttocks and down the backs of the thighs. The symptoms may get worse during active and subside during rest. Specifically, you may find that symptoms disappear when you bend forward or sit and get worse when you stand or walk. This is because sitting and bending open up the space where nerves are located, thereby relieving pressure. Other potential symptoms include:


Muscle spasms
Tight hamstrings (muscles in the back of the thigh)
Bent knees when walking (as a result of tight hamstrings)
Changes in gait

Severe or high-grade slips may result in pressure on the spinal nerve root close to the fracture, causing tingling, numbness, or weakness in one or both legs.

Spinal Fractures or Degenerating Discs in the Elderly

Causes
Children involved in sports such as gymnastics, football, and diving tend to be at an increased risk for isthmic spondylolisthesis.1 These sports require repeated spinal hyperextension, which can weaken the pars interarticularis, L5-S1, the fifth lumbar vertebra and first segment of the sacrum. This leads to spondylolysis, the precursor to the slippage of the vertebra that is characteristic of spondylolisthesis. Slippage occurs in about 30% of patients with spondylolysis.

Another theory is that genetics plays a role in the development of the pars defects and spondylolisthesis. Certain racial groups, such as Inuit Eskimos, have a much greater overall incidence (approximately 40%) of spondylolysis, suggesting an inherent genetic weakness of the pars.2

Degenerative spondylolisthesis tends to mainly occur in non-athletic adults after the age of 40. Older age, female gender, larger body mass index (i.e., being overweight or obese), and certain anatomical variations that cause a bent-over posture are thought to be factors that elevate the risk for this condition.3

Diagnosis
Your doctor will first talk to you and/or your child)about your medical history, your general health, and any sports or physical activities you do. Then they will examine your spine in order to locate areas of tenderness and identify muscle spasms or problems with gait or posture.

Next, your doctor will perform imaging studies, including:

X-rays to help distinguish between spondylolysis—characterized by a fracture in the pars interarticularis portion of the fourth or fifth lumbar vertebra—and spondylolisthesis, in which the pars interarticularis has widened and the vertebra has shifted forward. An X-ray taken from the side is also used to assign a grade between I and IV, based on the severity of the slippage.
Computerized tomography (CT) scans: These provide greater detail than X-rays and help your doctor prescribe the most appropriate treatment.
Magnetic resonance imaging (MRI) scans: An MRI focuses on the body's soft tissues and can reveal damage to the intervertebral disks between the vertebrae or if a slipped vertebra is pressing on spinal nerve roots.
There are four grades, each representing 25% of slippage in the vertebra.4

Spondylolisthesis grade Degree of slippage
Grade I 0%—25%
Grade II 25%—50%
Grade III 51%—75%
Grade IV 76%—100%
Treatment
Spondylolisthesis is treated according to the grade. For grades I and II, conservative treatment, including nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, physical therapy, home exercises, stretching, and the use of a brace are often sufficient. In physical therapy, core strengthening and stabilization exercises are emphasized.

Over the course of treatment, periodic X-rays will be taken to determine whether the vertebra is changing position.

For spondylolisthesis patients who have high grades of slippage, slippage that is progressively worsening, or persistent back pain, spinal fusion surgery may be recommended.1 In this procedure, the affected vertebrae are fused together so that they heal into a single, solid bone. The theory is that if the painful spine segment does not move it should not hurt.

Approximately 10% to 15% of younger patients with low-grade spondylolisthesis will ultimately require surgical treatment.3

During the procedure, the doctor will first realign the vertebrae in the lumbar spine. Small pieces of bone—called a bone graft—are then placed into the spaces between the vertebrae to be fused. Over time, the bones grow together, much like when a broken bone heals. Metal screws and rods may be installed to further stabilize the spine and improve the chances of successful fusion.

In some cases, patients with high-grade slippage also have compression of the spinal nerve roots. If this is the case, a procedure to open up the spinal canal and relieve pressure on the nerves may be done prior to spinal fusion.

A Word From Verywell
With nonsurgical and surgical treatments available, having spondylolisthesis that is causing symptoms does not mean you have to live in pain. In most cases, it is possible to resume activities, including sports, once the condition has been treated.