What is Spondylolisthesis?

Spondylolisthesis is a condition in which one of the bones of the spine (vertebrae) slips out of place onto the vertebra below it. If it slips too much, the bone might press on a nerve, causing pain. Usually, the bones of the lower back are affected.

The more common types of Spondylolisthesis include :

  • Congenital Spondylolisthesis — Present at birth, congenital spondylolisthesis is the result of abnormal bone formation. This abnormal arrangement of the vertebrae puts them at greater risk for slipping.
  • Isthmic Spondylolisthesis — Occurs as the result of spondylolysis, a condition that leads to small stress fractures (breaks) in the vertebrae that weaken the bone so much that it slips out of place.
  • Degenerative Spondylolisthesis — The most common form of the disorder caused when aging discs (the cushions between the vertebral bones) lose water and become less spongy and flexible.

Less common forms of spondylolisthesis include:

  • Traumatic Spondylolisthesis – Caused when an injury leads to a spinal fracture or slippage
  • Pathological Spondylolisthesis – Occurs when the spine is weakened by disease such as osteoporosis, infection, or tumor
  • Post-surgical Spondylolisthesis – slippage that occurs or becomes worse after spinal surgery

How common is spondylolisthesis?

Spondylolisthesis is the most common cause of back pain in teens who often begin showing symptoms during the teen-age growth spurt. Degenerative spondylolisthesis occurs most often after age 40.

What are the symptoms of spondylolisthesis?

Oftentimes people with spondylolisthesis are asymptomatic and don’t even know they have the condition. When symptoms do occur, the most common one is low back pain which often spreads across the lower back, and might feel like a muscle strain.

Spondylolisthesis can also cause muscle spasms in the hamstring muscles in the back of the thighs. Tight hamstrings can cause the person to walk with short strides and with the knees slightly bent. If the slipped vertebra is pressing on a nerve, pain might spread down the leg to the foot. The foot might also tingle and/or feel numb.

How is spondylolisthesis graded?

By viewing the results of specialized X-rays, a radiologist is able to determine the degree of slippage. Slippage is graded I through IV:

  • Grade I — 1 percent to 25 percent slip
  • Grade II — 26 percent to 50 percent slip
  • Grade III — 51 percent to 75 percent slip
  • Grade IV — 76 percent to 100 percent slip

Generally, Grade I and Grade II slippage does not require surgical treatment and are treated medically. Grade III and Grade IV slippage might require surgery if the patient experiences persistent pain or discomfort.

How is spondylolisthesis diagnosed?

An X-ray of the lower back can show a vertebra out of place. However, the more detailed images of a computed tomography (CT) scan, or a magnetic resonance imaging (MRI) scan may be needed to more clearly see the bones and nerves involved.

How is spondylolisthesis treated?

Treatment for spondylolisthesis depends on several factors, including the age and overall health of the person, the extent of the slippage, and the severity of the symptoms. Most often, treatment is conservative (see below). More severe spondylolisthesis might require surgery.

  • Conservative treatment — This involves rest, medication and moderate exercise. Taking a break from sports and other activities until the pain subsides is recommended. An over-the-counter non-steroidal anti-inflammatory drug (NSAID), such as ibuprofen (Motrin®) or naproxen (Aleve® or Naprosyn®), might also be recommended to help reduce pain and inflammation. Stronger medications might be prescribed if the NSAIDs do not provide relief. Epidural steroid injections, in which medication is placed directly in the space surrounding the spine, might also help reduce inflammation and ease pain.

    Additionally a brace or back support might be used to help stabilize the lower back and reduce pain. An exercise program and/or physical therapy will help increase pain-free movement, and improve flexibility and muscle strength. We periodically take X-rays to determine if bone slippage persists.

  • Physical therapy — Exercise strengthens the abdominal and/or back muscles thus minimizing bony movement of the spine. We generally recommend eight to 12 weeks of aggressive daily stabilization exercises to achieve clinical improvement.
  • Surgery — May be necessary if the vertebra continues to slip or if the pain is not relieved by conservative treatment. Through surgery, we are able to stabilize the spine where the vertebra has slipped out of place and relieve the pain associated with an irritated nerve, all of which increases the person’s ability to function.

Two surgical procedures are used to treat spondylolisthesis:

  • Decompressive laminectomy – a procedure in which involves removing the part of the bone that is pressing on the nerves. Although this procedure can reduce pain, removing a piece of bone can leave the spine unstable.
  • Spinal fusion – Performed to provide stability of the spine. In a fusion, a piece of bone is transplanted to the back of the spine. As the bone heals, it fuses with the spine and creates a solid mass of bone. This keeps the spine from moving. In some cases, instruments such as rods or screws are used to hold the vertebra firm as the fusion heals.

What complications are associated with spondylolisthesis?

The persistent pain cause by spondylolisthesis often leads to inactivity which can result in weight gain as well as loss of bone density, muscle strength and  bone density. Permanent nerve damage can occur if a slipped vertebra is pressing on a spinal nerve root.

What is the outlook for people with spondylolisthesis?

The outlook depends on the severity of the spondylolisthesis. In the case of minor slippage, where the bone is not pressing on any nerves, the person might never have a recurrence of back pain related to spondylolisthesis.

Conservative treatment for mild cases of spondylolisthesis is successful in about 80 percent of cases. Surgery is successful in relieving symptoms in 85 percent to 90 percent of people with severe spondylolisthesis.

Can spondylolisthesis be prevented?

While not entirely preventable, we’ve listed some steps you can take to reduce risk:

  • Maintain a healthy weight. Excess weight puts added stress on your lower back.
  • Keep your back and abdominal muscles strong to help support and stabilize the lower back.
  • Choose activities and sports that do not place your lower back at risk for injury.
  • Keep your bones well nourished and strong by eating a well-balanced diet.

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