A spondylolisthesis happens when one of the spine’s vertebrae (bones) slips forward over the vertebra beneath it. Spondylolisthesis occurs most often in the lumbar spine (low back).
Symptoms of Spondylolisthesis
Most patients with spondylolisthesis have no symptoms. When symptoms do occur, they may include the following:
- Pain in the low back, thighs, and/or legs – especially after exercise – that radiates into the buttocks
- Muscle spasms
- Leg pain or weakness
- Tight hamstring muscles
- Irregular gait (walking pattern)
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Types of Spondylolisthesis
- Isthmic spondylolisthesis (51%) is the most common type (Fig. 2). It occurs as the result ofspondylolysis, a condition that leads to small stress fractures (breaks) in the part of the spinal bone called the pars interarticularis. Most cases actually develop before age 9 and are asymptomatic (no pain)
- Degenerative spondylolisthesis (25%) is the second most common form of the disorder. From age and activity, degererative changes occur to the spinal structures, especially the discs. When the discs and joints of the spine wear down, they are less able to resist movement by the vertebrae.
- Traumatic spondylolisthesis (<3%) which an injury leads to a spinal fracture or slippage.
- Pathological spondylolisthesis (<3%) results when the spine is weakened by disease — such as osteoporosis, an infection, or tumor
- Dysplastic (Congenital) spondylolisthesis (21%) results from abnormal bone formation in utero. In this case, the abnormal arrangement of the vertebrae puts the vertebrae at greater risk for slipping
- Post-surgical spondylolisthesis
Grading of Spondylolisthesis
Most spine physicians use the Meyerding Grading System to classify slips. This is a relatively easy system to understand. Slips are graded on the basis of the percentage that one vertebral body has slipped forward over the vertebral body below.
- Grade I: 1-24% of the vertebral body has slipped forward over the body below
- Grade II: 25-49% slip
- Grade III: 50-74% slip
- Grade IV: 75%-99% slip
- Grade V: If the body completely slips off the body below it is classified as a Grade V slip, known as spondyloptosis.
Generally, Grade I and Grade II slips do not require surgical treatment and are treated non-operatively. Grade III and Grade IV slips may require surgery if the spine is unstable and pain is unrelenting.
Imaging is necessary to diagnose spondylolisthesis. Simple x-rays of the lower back are usually adequate to show a vertebra out of place. However, computed tomography (CT) or magnetic resonance imaging (MRI) provides detailed images and may be needed to more clearly see the spinal structures involved.
Non-surgical Treatment. Non-surgical treatment for mild spondylolisthesis is successful in about 75% of cases. Non-surgical treatment may combine the following:
- Relative rest: The patient may be advised to temporarily avoid aggressive activities such as sports.
- Anti-inflammatory medication
- Analgesic medication
- Spinal injections (see transforaminal epidural steroid injection). Under x-ray guidance, strong anti-inflammatory medication (such as corticosteroids) are injected into and around affected spinal nerves. Spinal injections can help reduce inflammation and pain.
- A brace or back support may be prescribed to help stabilize the lower back and reduce pain.
- Physical Therapy: A program of passive therapy and active exercise to help increase range of motion, improve flexibility, and muscle strength.
Surgery. Surgery may be necessary if the vertebra continues to slip, or if pain is not relieved with non-operative treatment and interferes with daily activities. Surgery is successful in relieving symptoms in 85-90% of people with severe symptomatic spondylolisthesis.
Laminectomy and fusion. The most common surgical procedure used to treat spondylolisthesis is called alaminectomy and fusion. In this procedure, the compressed spinal canal is widened by removing or trimming the laminae (roof) of the vertebrae. This is done to create more space for the nerves and relieve pressure on the spinal cord. The surgeon may also need to remove all or part of the vertebral disc (discectomy) and then also fuse vertebrae together. If fusion is done, various devices (like screws or interbody cages) may be implanted to enhance fusion and to support the unstable spine.