The term, spondylolisthesis, is used to describe forward displacement of one vertebral body on another. Such a displacement frequently occurs at the lumbosacral junction in association with a defect, called spondylolysis. in the fifth lumbar (L5) isthmus (pars interarticularis) on each side. Spondylolisthesis may also develop secondary to degenerative changes of the facet joints and intervertebral disc between adjacent spinal segments; this frequently occurs between the L4 and L5 vertebral segments. Most patients with spondylolisthesis present with low back pain, and plain radiographs are usually sufficient for diagnosis. Although the majority of patients will obtain pain relief from conservative measures, some will require neural decompression, bony fusion, or spinal instrumentation.

Presentation

Symptoms and signs in patients depend on the severity of the condition. Pain is the most common symptom of spondylolysis and spondylolisthesis. Pain may originate in the area of lysis or may arise from other structures that have been affected by secondary changes of lysis or spondylolisthesis, such as degenerative change in the disk, facet-joint arthropathy, and ligamentous sprain or strain. In addition, pain may arise from neural involvement, which may be from the spinal canal stenosis that can occur in high grades of spondylolisthesis. In this situation, an intact neural arch slides forward, narrowing the spinal canal and compressing the cauda equina. Clinical features of spinal claudication may ensue. Alternatively, as the neural arch slides forward, the inferior articular process of the slipping vertebra can impinge on the nerve roots in the lateral recess of the spinal canal and cause clinical findings of radiculopathy. Typically, this may involve the L5 or S1 nerve roots. These pain mechanisms are common to all etiologies of spondylolisthesis. However, studies show that patients with spondylolysis are relatively asymptomatic. When a symptomatic adolescent is evaluated, other causes of pain should be considered; these include infection, neoplasm, osteoid osteoma, and disk herniation. Indeed, the same findings may hold true for mild grades of spondylolisthesis.