Lumbar Spondylolysis and Spondylolisthesis

Abstract

Background: Spondylolysis, or stress fracture of the pars interarticularis of a lumbar vertebra, is a common cause of back pain in children and adolescents, especially in athletes. It can be accompanied by a slippage of the vertebra, called spondylolisthesis. This chapter reviews the epidemiology, etiology, classification, clinical presentations, prognosis, and treatments for this disorder.

Methods: Information was extracted from extensive searches of medical literature on Medline.

Results: By the end of skeletal growth, 6% to 11% of people have spondylolysis in the lumbar spine. Most are asymptomatic. In late childhood and teenage years, many athletes presenting with recent onset back pain have spondylolysis as the likely cause of symptoms. Conservative treatment including activity modification, bracing, and gradual return to exercise and sports leads to improvement of symptoms and may foster healing of fracture. Spondylolytic spondylolisthesis is usually asymptomatic in adults. A small number of adults with spondylolytic spondylolisthesis may develop radiculopathy symptoms that may require treatment.

Conclusion: It is important to recognize spondylolysis in children as a cause of back pain, as conservative treatment may lead to fracture healing. Otherwise, spondylolysis and spondylolisthesis are generally benign conditions that only rarely produce symptoms.

Keywords

Spondylolysis, spondylolisthesis, isthmic spondylolisthesis, back pain, radiculopathy, children, adolescent

Synonyms
Isthmic spondylolisthesis
ICD-10 Codes
M43.07		Spondylolysis (lumbosacral)
Q76.2		Spondylolisthesis (congenital)
M43.10		Spondylolisthesis (acquired)
S33.100		Lumbar vertebral slippage (subluxation)
Add seventh character to S33 for the episode of care (A—initial encounter, D—subsequent encounter, S—sequela)
Q67.5	Congenital spine defect
S32.009	Unspecified fracture of unspecified lumbar vertebra
Add seventh character to S32 for the episode of care (A—initial encounter closed fracture, B—initial encounter open fracture, D—subsequent encounter fracture with routine healing, G—subsequent encounter fracture with delayed healing, K—subsequent encounter fracture with nonunion, S—sequelae)
M53.2X7	Spinal instability, lumbar region

Definition

Spondylolysis refers to a bony defect or pseudoarthrosis from prior fracture(s) of one or both pars interarticularis. Pars interarticularis translates to “bridge between the joints” and as such is the isthmus or bone bridge between the inferior and superior articular processes of the neural arch of a single vertebra ( Fig. 49.1 ). When bilateral spondylolysis is present, the inferior articular processes along with the posterior aspect of the neural arch are no longer connected by bone to the rest of the vertebra.

Spondylolysis results from nonunion of stress fractures of the pars interarticularis that are acquired during childhood and adolescence. Spondylolysis has never been found in newborns. Further supporting an acquired stress fracture as the cause is the lack of spondylolysis in the lumbar spines of individuals who have never walked. Surprisingly, most cases of spondylolysis are acquired in early childhood, resulting in a prevalence of 4.4% of children 5 to 7 years of age. Specific events or activities associated with early childhood spondylolysis are not known. Throughout adolescence, many new cases of spondylolysis occur, with a higher incidence in males and in those who consistently participate in sports requiring repetitive flexion-extension and twisting of the trunk, such as gymnastics, soccer, football, lacrosse, wrestling, rugby, judo, dance, baseball, volleyball and swimming breast and butterfly strokes. The frequency of spondylolysis may increase with intense and prolonged sports, with one study of professional volleyball players revealing a 21% incidence of spondylolysis. Spondylolysis is present in 6% to 11% of the population by adulthood, and this percentage remains stable throughout adulthood, suggesting that new cases are rare after skeletal maturity.

Spondylolysis most commonly occurs at the L5 vertebrae, where 70% to 90% of the cases are found, with decreasing frequency at progressively higher lumbar levels. Spondylolysis is rare in the cervical and thoracic spine. It is more common in males than in females, with roughly a 2:1 ratio (7.7% to 9% vs. 3.1% to 4.6%), can be unilateral (less common) or bilateral (more common), and has a suspected genetic predisposition.

Spondylolisthesis refers to displacement of a vertebral body in relation to the vertebral body below it. Spondylolisthesis is always an abnormal finding, and is pathognomonic of structural and functional failure of the neural arch and facet joints, which are responsible for maintaining normal vertebral alignment. Spondylolisthesis is characterized according to three factors: etiology, direction of slippage, and grade of slippage.

There are five etiologies for spondylolisthesis. The most common etiology of spondylolisthesis in adults is degenerative spondylolisthesis resulting from age-related degeneration of the facet joints and intervertebral discs. The second most common etiology is bilateral spondylolysis causing spondylolytic spondylolisthesis (sometime referred to as isthmic spondylolisthesis). The remainder of this chapter will be limited to the discussion of spondylolytic (isthmic) spondylolisthesis. The other three etiologies are rarely encountered, and include dysplastic spondylolisthesis resulting from congenital malformation of one or more facet joints, traumatic spondylolisthesis resulting from fractures of facet joints, laminae, or pedicles, and pathologic spondylolisthesis resulting from destruction of posterior elements by neoplasm, infection, or primary bone disease.

Spondylolisthesis associated with spondylolysis and dysplasia can only result in an anterior slippage or anterolisthesis . Degenerative, traumatic, and pathologic etiologies most often cause anterolisthesis, but can also result in posterior slippage or retrolisthesis and lateral slippage or laterolisthesis .

The grades of anterolisthesis are determined by the percentage of slippage of the inferior-posterior corner of the vertebral body above over the superior surface of the vertebral body below ( Fig. 49.2 ). At least 5% slippage must be present for a diagnosis of spondylolisthesis to be established. Grade I reflects a slippage of 5% to 25%; grade II—26% to 50%; grade III—51% to 75%; grade IV—more than 75%; and grade V is complete dislocation of adjacent vertebrae, also called spondyloptosis. Most cases (60% to 75%) are classified as grade I; 20% to 38% are classified as grade II; and less than 2% of all cases are graded III, IV, and V.

In children and adolescents with bilateral spondylolysis, spondylolisthesis is already present in 50% to 75% at the time of initial diagnosis, and is more common in females. For parents of adolescents and children recently diagnosed with these conditions, concern about the progression of spondylolisthesis is common. Unilateral spondylolysis almost never progresses to spondylolisthesis. Typically, progression of spondylolisthesis occurs before and during the early teenage years, and only minor progression occurs in young adults. Unfortunately, prognostic factors for progression of spondylolisthesis are lacking. Of importance, participation in competitive sports has not been found to influence the progression of spondylolisthesis. Throughout adulthood, advancing age often leads to slight progression of spondylolytic spondylolisthesis, which is attributable to progressive degeneration of the disc and facet joints.

Symptoms

Acute back pain in children and adolescents can be a sign of developing or worsening spondylolysis. Extensive evaluations of children and adolescents with mechanical low back pain found an incidence of spondylolysis of 8%. Of great importance, spondylolysis rates of 32% to 49% have been reported for young athletes presenting with persistent back pain by specialty clinics, making it essential to consider spondylolysis as the cause of back pain in this population.

Signs and symptoms of symptomatic spondylolysis in children and adolescents are nonspecific. Low back pain can range from mild to severe and is frequently described as a dull, aching pain in the back, buttocks, and posterior thigh. Difficulty falling asleep, waking up because of back pain, and pain induced by standing, walking, and physical activities are equally common in spondylolysis and other diagnoses. However, those with spondylolysis reported less severe pain with standing and sitting than those with nonspecific back pain.

Over the long run, spondylolysis and spondylolisthesis are relatively benign conditions. Most children and adults with spondylolysis and spondylolisthesis are asymptomatic. Less than 5% of children diagnosed through radiographic screening with spondylolysis reported problematic back pain before the age of 18 years. For adults with spondylolysis, it is impossible to attribute back pain to this abnormality, as their incidence of back pain is similar to those without spondylolysis. Furthermore, the degree of spondylolytic spondylolisthesis is not associated with the prevalence of back pain, and no study has linked progression of spondylolisthesis with new onset or worsening back pain symptoms. Disability because of back pain is no more prevalent in the population with spondylolysis and spondylolisthesis than in the general public.

For some adults, spondylolysis with spondylolisthesis combined with disc degeneration may result in significant narrowing of the neural foramina at the affected level. This can cause irritation of the exiting spinal nerve, resulting in radiating pain and neurologic sequelae in the lower limb, often in dermatomal or myotomal distribution. Because spondylolytic spondylolisthesis most commonly involves the L5-S1 level, the L5 nerve is most often affected by this problem. For most adults with this problem, radicular signs and symptoms are transient.

Physical Examination

The physical examination in spondylolysis and spondylolisthesis has few unique signs. Painful and limited trunk range of motion is often noted with children and adolescents with symptoms from acute spondylolysis, though these findings are equally common in those with other diagnoses. It has been postulated that pain with trunk extension may be common in acute spondylolysis, as this motion shifts load to the posterior vertebral elements and thus through the region of the pars. However, painful trunk extension is no more common in spondylolysis than back pain from other conditions. Palpation of the back may reveal local tenderness at the lumbosacral junction, but this again is common in back pain from other causes.

Detection of spondylolisthesis on physical examination is possible when a “step-off” of the spinous processes can be seen or palpated at the level of the spondylolisthesis.

Neurologic deficits and positive results of straight-leg raising tests are rarely found in cases of spondylolytic spondylolisthesis, including cases with sciatica. When neurologic deficits are noted, they usually involve the L5 roots with findings of weakness of the extensor hallucis longus and hip abductors as well as sensory loss on the dorsum of the great toe.

Diagnostic Studies

In the past, but not currently, anteroposterior, lateral and right and left oblique lumbar spine radiographs were a standard part of the evaluation of children who are suspected of having spondylolysis. The lateral radiograph reveals the presence and grade of spondylolisthesis. The oblique radiograph may reveal the classic “collar on the Scottie dog” finding of spondylolysis that represents the bone defect between the inferior and superior articulating processes ( Fig. 49.3 ). The sensitivity of oblique views only approaches 33% because the plane of the pars defect must be close to the plane of the radiographic image to be clearly visualized, and recent studies suggest that oblique views add little or nothing to the diagnostic accuracy of anteroposterior and lateral views only.

Because of its ability to image bone, computed tomography (CT) is considered the best test for direct visualization of bony defects of the pars interarticularis ( Fig. 49.4 ). When spondylolysis is suspected, CT scanning can be done with thin sections or reverse gantry angle to ensure optimum axial visualization of the pars. On axial views, it is useful to identify an intact ring of cortical bone for each vertebra that includes the vertebral body, the pedicles, the pars and the posterior neural arch. If the intact ring is not found in any of the cuts through the levels of the pedicles, spondylolysis is suggested. Spondylolysis can usually be differentiated from adjacent facet joints, as they lack the smooth cortical surface. Sagittal reconstruction CT images are useful for visualizing spondylolysis as a linear bony gap between the superior and inferior articular process of the vertebra (see Fig. 49.4 ).

Bone scintigraphy uses radioisotopes that accumulate in metabolically hyperactive bone such as with active stress reaction or recent fracture. In recent spondylolysis, this test is always positive.

In developing spondylolysis, bone scintigraphy will reveal stress reaction in the bone before the actual fracture occurs. Long-standing spondylolysis with an established nonunion reveals no such activity. Single-photon emission computed tomography (SPECT) improves the localizing ability of bone scintigraphy ( Fig. 49.5 ). SPECT creates a series of slices through the target structure, permitting spatial separation of overlapping bone. In one study, SPECT identified stress reaction in pars interarticularis in 20% of children with new onset back pain in whom CT imaging was normal. Because of these abilities, SPECT imaging has established its place for the evaluation of adolescent athletes with back pain.