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Lumbar Spondylolisthesis


Summary of Key Points

  • Isthmic and degenerative lumbar spondylolisthesis are common lumbar deformities associated with a significant impact on the health status of affected patients.

  • Surgery for symptomatic lumbar spondylolisthesis is supported by clinical trial evidence.

  • Published guidelines support a surgical approach to symptomatic lumbar spondylolisthesis.

  • There are a number of surgical approaches that are appropriate for the treatment of lumbar spondylolisthesis.

  • Studies are being done to evaluate the cost effectiveness of lumbar fusion for patients with lumbar spondylolisthesis.

  • Medical treatments for osteoporosis are important to consider when recommending surgery, especially for the elderly.

Isthmic and degenerative lumbar spondylolisthesis represent an important component of any spine practice. There is considerable evidence to guide care for these conditions, and ultimately the individual condition and symptoms of the patient determine what treatment option is optimal. In this chapter, we define these conditions, explore their classification and natural history, and carefully review treatment options. There have been significant efforts to generate high-quality evidence to guide practice. We will place these studies in context to permit the reader to understand the priorities to consider when selecting from various treatment options.

Definitions

Isthmic Spondylolisthesis

Isthmic spondylolisthesis is defined as the anterior translation of one vertebral body over the next caudal one with an associated defect of the pars interarticularis (spondylolysis). It is more common in males and develops in 40% to 60% of patients who have bilateral pars defects, or spondylolysis. The pathophysiology of acquired isthmic spondylolisthesis involves repetitive stress at the lumbar sacral junction in patients with low sacral slope with a low pelvic incidence (nutcracker mechanism). Isthmic spondylolisthesis may also be developmental, and related to dysplasia of the posterior elements and shear forces in patients with a high sacral slope and high pelvic incidence. Some patients might be predisposed genetically to developing pars defects. Some patients (3.7%–11.5%) reach adulthood without symptoms. ,

Degenerative Lumbar Spondylolisthesis

Degenerative lumbar spondylolisthesis is characterized by anterior translation of one vertebral body over the next caudal one and is usually associated with a combination of disc and ligamentous compression of the thecal sac (spinal stenosis). The condition is common, occurring in 11.5% of the U.S. population. The degree of spondylolisthesis is typically classified using the Meyerding scale, which is based upon the percentage of slippage relative to the length of the caudal vertebral body (I up to 25%, II 25%–50%, III 50%–75%, and IV >75%). High-grade spondylolisthesis is generally considered to be different from grades I and II, and its management will be discussed separately.

Degenerative spondylolisthesis is sometimes characterized by whether or not it is stable. Translational movement (measured on standing flexion and extension radiographs) greater than 3 mm is often used to designate instability of the listhesis. Not all patients with instability will have translational movement. In some cases, a change in angular rotation measured on flexion-extension images can also be used to predict instability ( Fig. 34.1 ). Finally, some patients with instability of the listhesis have a characteristic mechanical low back pain that is brought on by axial loading of the spine and relieved by unloading the spine. Because there are multiple factors that influence stability, clinical judgment is necessary when evaluating patients with degenerative spondylolisthesis to determine whether the listhesis is stable or not.

Fig. 34.1, Extension ( A ) and flexion ( B ) plain radiographs for a patient with grade I lumbar spondylolisthesis are depicted. The images demonstrate angular rotation at the L4‒L5 spondylolisthesis.

Natural History

The vast majority of patients with isthmic spondylolisthesis are asymptomatic. It is often diagnosed as an incidental finding on plain radiographs. It is estimated that 25% of patients will develop back pain with radiating pain into one or both legs. , Although spondylolysis can often be diagnosed from plain radiographs, lumbar computed tomography often will depict the anatomy more clearly and can therefore demonstrate the pars defect more clearly. It is generally believed that spondylolisthesis will gradually progress over time.

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