Spondylolysis and spondylolisthesis in child and adolescent athletes: Clinical presentation, imaging, and diagnosis

INTRODUCTION — Among child and adolescent athletes, spondylolysis typically represents a fracture of the posterior arch in the lower lumbar spine due to overuse and is a relatively common cause of low back pain. Spondylolisthesis involves anterior displacement of a vertebral body due to bilateral defects of the posterior arch and is less common than spondylolysis.

The clinical presentation, approach to imaging, and diagnosis of spondylolysis and spondylolisthesis in children and adolescents are reviewed here. The treatment of spondylolysis and spondylolisthesis, as well as other causes of low back pain in children, are discussed separately. (See "Spondylolysis and spondylolisthesis in child and adolescent athletes: Management" and "Back pain in children and adolescents: Causes" and "Back pain in children and adolescents: Evaluation".)

DEFINITIONS, PATHOGENESIS, AND LOCATION — Spondylolysis is a unilateral or bilateral defect (fracture or separation) in the vertebral pars interarticularis, usually in the lower lumbar vertebrae (figure 1 and figure 2 and figure 3). In young athletes, spondylolysis usually represents a fatigue fracture in the posterior arch of the spine, specifically the bony area of the pars interarticularis (pars) between the zygapophyseal (facet) joints. Although usually an overuse injury, spondylolysis may present following an acute overload. Several observations suggest spondylolysis is primarily a fatigue fracture. First, it has never been reported in a fetus or non-ambulatory person [1,2]. Second, it occurs most frequently in athletes whose sport involves repetitive increased spinal loads. (See 'Epidemiology and risk factors' below.)

Spondylolysis occurs at the fifth lumbar vertebra (L5) approximately 85 to 95 percent of the time, with an L4 locus in 5 to 15 percent of cases. Most injuries occur at L5 because the pars interarticularis at this level is subject to a direct pincer-like effect from the inferior articular process of L4 above and the superior articular process of S1 below. Rarely, the injury develops at levels above L4, but it has been reported as high as L1 [3]. Multilevel involvement occurs approximately 4 percent of the time [4], and bilateral involvement occurs in approximately 80 percent of cases [5]. When bilateral defects develop, the vertebral body may slip anteriorly relative to the subadjacent vertebra and this is termed spondylolisthesis (figure 4).

CLASSIFICATION — The Wiltse Classification is typically used to categorize spondylolisthesis. This system is based on the etiology of vertebral slippage:

●Type I is dysplastic: The fundamental factor in Type I spondylolisthesis is congenital rounding of the first sacral vertebrae on the superior ventral surface. This configuration does not adequately prevent the L5 vertebrae above from slipping anteriorly. The more severe the sacral rounding, the greater the risk for significant slippage.

●Type II is isthmic: Type II is the most common type of spondylolisthesis seen in athletes. Most often, it presents with a stress fracture and separation of the pars interarticularis, which is referred to as Type II A. Occasionally, repetitive fracture and healing may lead to an elongated pars interarticularis, which is called Type II B. Rarely, acute trauma causes a Type II fracture of the pars interarticularis.

●Type III is degenerative: Type III spondylolisthesis involves vertebral slippage that is not due to a fracture or insufficiency of the pars interarticularis but rather segmental instability, usually at the L4-5 level. Segmental instability arises from arthritis generally and this type is more common in older patients, typically females above 40 years. Arthritis destroys the contour of the facet joint and the architecture no longer prevents movement. The resulting instability and chronic stress gradually break down the ligamentum flavum, other ligaments, and the capsule of the facet joint. The result is ligamentous instability of the facet joint permitting forward slippage of the vertebral body.

●Type IV is traumatic: Type IV spondylolisthesis is typically caused by high-impact trauma causing injury to bony and ligamentous structures of the lumbar segment other than the pars interarticularis.

●Type V is pathologic: Type V spondylolisthesis may be related to generalized bone disease. Its appearance in radiographs may resemble sclerosis, as occurs with osteopetrosis. Alternately, a lytic tumor in the pars pedicle region may cause Type V lesions.

Type I has the highest risk of progression at 32 percent, while the common, sports-related isthmic type demonstrates progression in only 4 percent of cases [6].

The degree of slippage in spondylolisthesis is most commonly classified using the Meyerding classification (picture 1) [7]. It refers to the percentage of the cephalad vertebral body that extends beyond the anterior border of the caudal vertebrae:

●Grade I is 25 percent or less

●Grade II is 26 to 50 percent

●Grade III is 51 to 75 percent

●Grade IV is 76 to 100 percent

●Grade V is over 100 percent, or spondyloptosis

EPIDEMIOLOGY AND RISK FACTORS

●General epidemiology – The prevalence of back pain from early life to adulthood demonstrates a progressive increase from a negligible level below the age of 7 to about 18 percent by the age of 16 [8,9]. However, the incidence is higher in competitive athletes, among whom the incidence of back pain has been reported to be as high as 36 percent [10-12]. Spondylolysis is the most frequent identifiable source of back pain in the young athlete [12]. In one study comparing adult and adolescent athletes with back pain, spondylolysis was identified in 47 percent of young athletes, while 48 percent of adult back pain was disc-related [13]. A retrospective chart review of 1142 adolescent athletes with low back pain reported that 30 percent went on to be diagnosed with a spondylolytic lesion [14]. In a 45-year prospective study involving 500 subjects, spondylolysis was found in 4.4 percent of first-graders and 6 percent of adults [15]. Overall, a higher incidence of spondylolysis is reported among participants in sports requiring extreme spinal motion (eg, gymnastics) [16].

●Incidence by sport – Spondylolysis is most common in athletes who engage in sports involving extreme spinal motion, particularly lumbar extension (table 1). These include dancers, gymnasts, figure skaters, American football linemen, wrestlers, and divers [17,18]. Weight lifting, such as Olympic lifts and overhead presses, cause an extension moment at the lumbar spine. When a rotational component is added to extension, this can be particularly problematic. Such motion occurs during the layback part of the rowing stroke, which involves asymmetric extension and rotation. The incidence among divers is reported to be as high as 40 percent and among ballet dancers as high as 32 percent [19].

In a retrospective review of 1142 adolescent athletes, baseball, soccer, and hockey were reported to pose the highest risk for spondylolysis among adolescent males, while gymnastics, marching band, and softball were associated with the highest risk among adolescent females [14]. A similar study of 267 child and adolescent athletes reported that multilevel and bilateral spondylolysis lesions were more common among soccer players (n = 33), while baseball players experienced more lesions on the side opposite their dominant pitching or hitting hand [20].

Incidence varies by region, reflecting the relative emphasis on different sports. In a review of Japanese athletes, approximately 20 percent of rugby and judo players developed spondylolysis, while the incidence was 30 percent among professional soccer and baseball players [16]. However, the incidence varied from 8 to 12 percent among adolescents participating in the same sports.

●Growth – The fatigue fractures of spondylolysis commonly develop during the adolescent growth spurt. This relatively high incidence may be explained by several factors. First, growth increases lumbar lordosis, which puts greater compressive stress on the posterior elements of the spine (posterior elements include the bony neural arch, including the facet joints; anterior elements refer to the disc and vertebral body). Secondly, according to an observational study of over 2000 subjects, increased cumulative time spent in sports activity is associated with greater lumbar lordosis in children and adolescents [21]. Finally, bone mineralization lags behind growth [22]. Non-ossified (or immature) bone is less capable of withstanding compressive and tensile loads.

●Genetics – Genetics appears to play a significant role in the development of spondylolysis and spondylolisthesis [23,24]. The overall incidence of spondylolysis is about 6 percent, but there is some variation among ethnicities. In a large cadaver study, the incidence was as follows: White men 6.4 percent, African American men 2.8 percent, White women 2.3 percent, and African-American women 1.1 percent [25]. This may reflect the higher bone density of African American individuals compared with the White population.

Among Canadian Inuits reported rates are as high as 50 percent [26,27]. However, this phenomenon may not be related to bone density as the pars interarticularis is often elongated (Type II B spondylolisthesis) in Inuits with spondylolysis. Studies of Asian populations show variable rates. A Korean study using CT scans reported an incidence of 9 percent and several Japanese studies report comparable rates [16,28]. Genetic factors are likely involved in the risk for spondylolisthesis as well. In a radiologic survey of 47 patients with spondylolisthesis, 19 percent of first-degree relatives were also treated for the condition [23].

●Gender – Previously, spondylolysis was thought to be two to three times more common in males than females [29]. Such data reflected a time when more males participated in sports than females. However, increased participation in female-dominated sports such as ballet, gymnastics, and figure skating has led to near-equal prevalence rates for spondylolysis among male and female athletes. Nevertheless, some studies report persistent gender differences. An observational study of the Japanese population using CT for diagnosis reported a 2:1 male to female ratio [30].

●Muscle weakness and inflexibility – Weakness and inflexibility are common during the adolescent growth period, during which bone growth exceeds musculotendinous development. Gluteal and lumbar extensor weakness are risk factors for back pain in adolescent athletes [31,32]. As discussed above, the increased lordosis that develops during the adolescent growth spurt is associated with back pain in adolescents [33]. Factors that contribute to lordosis include tight hip flexor muscles (eg, psoas) and weak abdominal muscles. Observational studies suggest that a high BMI is not associated with an increased risk of spondylolysis, although it is associated with low back pain and facet arthrosis.

●Spinal deformity – Some spinal deformities, including kyphosis and spina bifida occulta (SBO), have been associated with spondylolysis. The incidence of spondylolysis in patients with Scheuermann’s kyphosis is reported to be between 30 and 50 percent [34,35]. This is likely related to the concurrent increase in lumbar lordosis in these cases. According to a retrospective review, patients with SBO have a 3.7-fold increase in the incidence of spondylolysis [30]. As SBO does not weaken the posterior arch of the lower lumbar spine, this increase is likely due to genetic factors [36]. In an observational study of 122 adolescent athletes with low back pain, a ratio of the interfacet distance of L1 to L5 (L1:L5 ratio) greater than 65 percent was associated with spondylolysis identified on magnetic resonance imaging (MRI) [37].

●Sport-specific biomechanics – The mechanisms involved in developing spondylolysis include spinal (particularly lumbar) flexion, extension, and rotation, and shear forces exerted at the lumbar spine [38]. During sport, great stress occurs at the pars interarticularis during spinal extension and rotation, and the combination of these two motions results in the highest recorded stresses [39]. A tensile force exerted on the ventral surface of the pars interarticularis can also initiate a fracture at the pars [40,41].

Such movements occur commonly in sport. One example is the kick serve in tennis. During this serve, spinal extension is combined with asymmetric rotation, which places great stress on the spine. In an attempt to generate greater shot velocity, tennis players often hit their forehand using a more direct approach to the ball, which increases the rotational forces exerted on the spine compared to previous methods involving a more lateral approach. The layback portion of the rowing stroke also involves asymmetric spinal extension and rotation.

Athletic movements involving repetitive flexion and extension exert great stress across the pars region of the lumbar spine. As an example, during the butterfly stroke swimmers generate compressive forces during lumbar spine extension and tensile forces during flexion. Dancers and gymnasts perform spine extension repeatedly when moving into the layback position.

CLINICAL ANATOMY — The spine may be visualized as a triple joint with the two facet joints posteriorly and the intervertebral disc anteriorly (figure 5 and figure 6 and figure 7 and figure 8 and figure 9). This complex allows a large range of motion and the transfer of forces from the lower to the upper extremities. Forward flexion places more stress on the disc, and extension imparts more stress across the facet joints. As noted above, extension with rotation will amplify this stress, leading to stress fractures. There are multiple ligamentous attachments that also stabilize the spine. The anterior and posterior longitudinal ligaments run on the front and back of the vertebral body with attachments to the ligamentous annulus of the intervertebral disc.

Posteriorly, the interspinous and intraspinous ligaments stabilize one vertebra from slipping forward on the caudal vertebrae along with the bony prominences of the facet joints. The facets maintain this stability as the inferior facet above hooks onto the superior articular process of the caudal facet. When a spondylolytic fracture occurs, bony stability is lost but usually the ligaments, provided they are intact, compensate adequately. The bony arch anterior to the pars is the pedicle that connects to the vertebrae. Posteriorly, the pars expands into the lamina. Sometimes, fractures extend into the pedicle or lamina.

The pars forms the posterior roof of the neural foramina for the exiting nerve root. While not common, occasionally a spondylolysis will exhibit clinical signs of irritation of the exiting nerve root [42].

CLINICAL PRESENTATION AND EXAMINATION

Common presentations

Spondylolysis — Children who develop a spondylolysis in early life usually have no symptoms. The condition is found incidentally while imaging the spine for other reasons. Such a presentation generally does not lead to complications and is not concerning. (See "Spondylolysis and spondylolisthesis in child and adolescent athletes: Management", section on 'Prognosis and complications'.)

Adolescent athletes with an acute or subacute spondylolysis often develop symptoms insidiously. The primary symptom is low back pain during activities, particularly those involving lumbar extension [17,43]. Sometimes the adolescent recalls a particular moment when the pain began, but usually activity-related pain increases gradually and is not associated with an acute episode. The pain may be central or off to one side of the low back and may radiate to the buttocks or posterior thigh. Initially, pain usually resolves when the athlete stops practicing or playing, but if left untreated, pain may worsen and persist after activity. When subacute spondylolysis symptoms worsen significantly, the concern is that the condition has progressed to true spondylolisthesis. Neurologic signs are more common with a higher-grade spondylolisthesis and may include paraesthesias and/or pain radiating to the buttocks or thigh.

Night pain is uncommon and should prompt the clinician to consider other causes. Pain while sitting usually indicates pathology involving an intervertebral disc or the sacroiliac joint. However, occasionally a spondylolysis extends into the pedicle (pediculolysis) causing discomfort with sitting [44]. In more progressive cases of spondylolysis (and with more chronic spondylolistheses), pain often does not resolve completely with rest. More chronic cases often involve a loss of intervertebral disc height and associated neurologic symptoms. (See 'Differential diagnosis' below.)

Spondylolisthesis — Spondylolisthesis patients often develop pain that spreads across their lumbar region and radiates into their buttocks or posterior legs. The pain can be associated with radicular symptoms, including paresthesias, numbness, or a feeling of weakness in the extremities. Athletes may experience acute, sharp pains during particular activities, such as kicking a soccer ball, spiking a volleyball, or serving a tennis ball, all of which involve some degree of back extension. If these symptoms are ignored, patients may begin to complain of progressive back stiffness and may alter their standing posture to be more kyphotic in order to avoid any back extension. In chronic cases, patients may develop a compensatory gait involving a forward lean and reduced hip extension, reflecting pain or weakness in the gluteal and hamstring muscles.

Physical examination — While no single examination finding or combination of findings has been proven to be highly sensitive or specific for spondylolysis, pain with lumbar extension is the most commonly reported finding [45]. In our experience, most athletes with spondylolysis or acute spondylolisthesis develop pain with lumbar extension; pain is often further increased by hyperextension performed while standing on one leg. These provocative maneuvers are important but are usually performed following observation and palpation, as described below.

Examination of the adolescent athlete with possible spondylolysis or spondylolisthesis begins with an assessment of their gait. Begin by watching the patient walk into the exam room. Gait is usually normal unless there is severe pain or a significant spondylolisthesis. With high grade spondylolisthesis, the athlete may demonstrate an exaggerated posterior pelvic tilt with the buttocks appearing “tucked in” (ie, loss of normal gluteal contour) (figure 10). Severe pain from spondylolysis may cause an antalgic gait with kyphotic posture and reduced hip extension.

Next, the clinician observes the standing patient. The patient should be assessed from behind and then from the sides and front. Hyperlordosis with an anterior pelvic tilt (figure 10) may contribute to the development of spondylolysis. Loss of lumbar lordosis with a posterior pelvic tilt may stem from pain and muscle spasm or a high grade spondylolisthesis [43].

Palpation follows observation. The lumbar spine and sacroiliac ligaments should be palpated. Typically, there is minimal tenderness in athletes with spondylolysis, unless there is associated muscle spasm. In patients with more unilateral symptoms, muscle spasm on palpation or some tendency toward a scoliotic posture, concave on the affected side, may be observed. In the athlete with spondylolisthesis, clinicians may palpate a step-off in the lumbar spine, but this is unlikely unless the slip is advanced. The examiner should palpate each lumbar vertebra to detect tenderness at that specific level. If deep palpation elicits pain, it is consistent with a spondylolysis. Conversely, tenderness to light palpation often reflects a more superficial cause, such as spinous process abutment. .

Following palpation, spinal motion is assessed. This may elicit pain, particularly during lumbar hyperextension; spinal flexion usually does not cause pain. The single-leg hyperextension test may cause greater pain on the affected side. We typically use this test, which is performed by having the patient stand on one leg with the knee straight and the other leg flexed at the knee and hip (picture 2). Pain on the weight-bearing side during lumbar extension suggests a fracture [46]. However, the sensitivity and specificity of this test have been questioned [47].

An alternative approach is to test repeated lumbar extension. According to a prospective observational study of 100 adolescent athletes with low back pain, 42 of whom were ultimately diagnosed by radiograph or CT with spondylolysis, pain elicited by repeated lumbar extension within a physiologic range (ie, not hyperextension) has a sensitivity of 81 percent and a specificity of 39 percent for detecting spondylolysis [48]. While range-of-motion testing may reveal limitations in some athletes, gymnasts and dancers often have excessive spine mobility at baseline and loss of motion may not be appreciated.

Pain elicited by manual resistance to back extension with the patient lying prone and supporting their weight on their forearms is suggestive, particularly if a symptomatic athlete experiences focal pain on the affected side. Another helpful examination technique is to have an athlete identify the location of pain while they perform a provocative sport-specific movement (eg, asking a tennis player to demonstrate their serving motion).

Once spine motion testing is completed, the patient is asked to assume a supine position, from which most of the strength and flexibility assessments are performed. Tight hamstring muscles are common in the setting of spondylolysis and spondylolisthesis. This is tested with a straight leg raise or by measuring the popliteal angle (figure 11). Clinicians continue to debate the importance of hamstring tightness in diagnosing spondylolysis or acute spondylolisthesis, and the angle measurements used for this purpose. We believe that a popliteal angle greater than 50 degrees is of greater clinical significance and is consistent with these diagnoses. Inflexibility of the thoracolumbar fascia and psoas muscle increases lumbar lordosis and may be present with spondylolysis or acute spondylolisthesis. Psoas tightness is assessed with the Thomas Test (picture 3).

The combination of weak lower abdominal and weak gluteal muscles contributes to a more anteriorly rotated pelvis with increased lordosis [49]. Abdominal strength may be assessed with the abdominal flexor endurance test in which the athlete is asked to hold a 45 degree trunk flexion angle for 30 seconds while supine with the knees bent to 90 degrees. Gluteal strength may be assessed by having the patient perform a single leg squat (picture 4). Lumbar extensor weakness may contribute to secondary sacroiliac instability and pain. Lumbar extensor strength can be assessed by having the athlete hold a single leg bridge position (picture 5) for one minute. Pain often prevents patients with an acute spondylolysis from completing this test. In addition to their role in diagnosis, these strength and flexibility tests help to determine the biomechanical factors that must be addressed during rehabilitation.

A careful neurologic examination is important to rule out alternative pathology. In most patients with spondylolysis, the neurologic examination is normal. Typically, there are no signs of dural tension. However, in advanced spondylolisthesis both neurologic signs and dural tension may be evident during a straight leg-raise test, causing radiating pain or paresthesias. Rarely, a high-grade spondylolisthesis causes lumbosacral radiculopathy, usually from impingement of the nerve root in the neural foramina. As an example, at L4/5 the L4 nerve root is most often affected. In such cases, the motor examination should include careful testing of ankle dorsiflexion (predominantly L4), large toe extension (predominantly L5), and ankle plantar flexion and eversion (S1). Appropriate testing for cauda equina syndrome should be performed in any patient with signs of radiculopathy or a high grade spondylolisthesis identified by imaging study. (See "Acute lumbosacral radiculopathy: Etiology, clinical features, and diagnosis" and "The detailed neurologic examination in adults".)

DIAGNOSTIC IMAGING

Approach to imaging for spondylolysis — A clear and well-conceived approach to imaging is necessary to maximize outcomes and minimize risks in the adolescent athlete. Injury to the posterior elements of the spine (eg, pars interarticularis) must be ruled out in any adolescent athlete presenting with back pain, particularly those whose sports involve lumbar extension. For patients without concerning constitutional signs or complicating factors (eg, fevers, night pain, neurologic or genitourinary complaints, or immunosuppressant medication [eg, glucocorticoid] use), whose pain is of recent onset, rest from all exacerbating activity and early follow-up is reasonable. However, if the pain has persisted for more than a few weeks, imaging is typically necessary.

A plain anteroposterior (AP) and lateral radiograph of the lumbar spine are generally the first studies obtained [50]. Oblique views are not obtained, nor are views of the thoracic spine unless a problem in the thoracic spine is suggested by the history and examination. If the plain radiographs of the lumbar spine are unrevealing but clinical suspicion for spondylolysis remains high after two to three weeks of rest, advanced imaging is performed, unless the athlete continues to improve with conservative management and refrains from participating in any sports (figure 9).

However, often the adolescent athlete wants to return to sports, in which case advanced imaging can be used to determine whether spondylolysis is present. The studies used most often are magnetic resonance imaging (MRI) or a single-photon emission computed tomography (SPECT) bone scan. However, SPECT scanning has a higher false positive rate due to facet joint irritation. Particularly in children and adolescents, MRI is preferred due to the lack of radiation exposure. If MRI demonstrates a high signal in the pedicle, spondylolysis is assumed and treatment initiated. Alternatively, a SPECT study may be obtained if there is concern for other pathology based primarily on the appearance of the initial plain radiographs. Such pathology may include osteoid osteoma (a benign focal tumor seen in the posterior elements), transitional vertebrae (an L5 vertebrae with incomplete segmentation), or spinous process impingement.

A CT scan is typically not helpful as an initial study even if a fracture is identified on plain radiographs because the CT image encompasses only the level where spondylolysis is suspected in order to limit radiation exposure. These focused CT studies define fractures at the level in question but miss any fracture or bony changes at adjacent levels unless a full lumbar CT is performed, which entails a large dose of radiation.

A common problem when performing the radiologic workup of these patients is that many radiology departments outside pediatric hospitals use MRI sequences that are designed to detect adult disc disease. It is important for the clinician to ensure that their local radiologists use MRI sequences appropriate for identifying spondylolysis in children and adolescents (see 'Magnetic resonance imaging' below). In the event this is not possible, a SPECT bone scan may be most useful. In resource-limited settings with minimal access to advanced imaging, plain AP and lateral radiographs alone may provide some assistance. If initial studies are normal, it is reasonable to repeat the radiographs in six weeks to see if there is any progression in those athletes with persistent pain.

Plain radiographs — The radiographic workup for suspected spondylolysis or acute spondylolisthesis typically begins with an anteroposterior (AP) and lateral radiograph. Many of the original studies describing the prevalence of spondylolysis used plain radiographs, although subsequent studies using more advanced imaging techniques have raised questions about these early reports. Nevertheless, a plain AP and lateral radiograph may demonstrate a fracture (figure 9 and image 1). The injury, including any significant slippage from a spondylolisthesis, is best seen on the lateral view, while other abnormalities (eg, transitional vertebrae) may be seen on the AP view. Once considered important for diagnosing spondylolysis, the oblique view (or "Scotty dog" view) (figure 2) is no longer recommended due to its limited sensitivity and greater radiation exposure [51,52]. With many oblique views, the fracture line falls out of the plane of the x-ray beam [52].

A two-view series (AP and lateral) is used in most cases of suspected spondylolysis and exposes the patient to less than one mSv of radiation exposure, while a four view series doubles the radiation exposure but generally provides little additional information [50,53,54]. It is important to recognize that plain radiographs typically provide little information about the acuity or chronicity of the lesion. Thus, in cases that are not responding to conservative care, advanced imaging is obtained.

Magnetic resonance imaging — When advanced imaging to diagnose spondylolysis, magnetic resonance imaging (MRI) is the preferred technique. The approach to imaging patients suspected of the diagnosis is discussed above. (See 'Approach to imaging for spondylolysis' above.)

MRI is useful for detecting bone marrow edema in the pedicle and pars region, an early sign of injury, and the increased metabolic activity associated with acute injury and bone healing [55]. Early detection of a bone stress reaction with MRI followed by appropriate treatment may prevent the development of pars defects and provides insight into the healing potential of the injury [50,56,57].

The effectiveness of MRI is supported by multiple, small observational studies, although the precise sensitivity and specificity are unknown. In a cohort study of 200 consecutive adolescent athletes, MRI revealed signs of pedicle edema consistent with spondylolysis in 97 patients whose plain radiographs did not reveal a fracture, and all but 10 of these injuries were found to be early fractures on CT [45]. In a study of 23 consecutive children with spondylolysis diagnosed by CT, the presence of high signal on MRI consistent with early lesions was associated with far higher healing rates compared to late lesions without a high signal [57].

Appropriate MRI imaging to identify signs consistent with spondylolysis involves precise sequencing that is different from standard adult techniques designed to identify vertebral disc pathology. Four MRI sequencing characteristics are important for detecting a spondylolytic lesion. First, there should be an edema sensitive sequence with a STIR or fat saturated T2 image. This is roughly equivalent to a bone scan image showing increased metabolic activity. Second, there should be a cortex sensitive image with a T1 or non-fat saturated T2 sequence. This provides information about the presence of a fracture. Third, the sequences should include axial, sagittal, and coronal views. Fourth, thin cuts (ie, less than 3 mm) should be used.

One advantage of MRI is the absence of radiation exposure. In addition, MRI detects soft tissue abnormalities such as disc pathology, apophysitis, and discitis. However, MRI has limitations. Some studies suggest that MRI is less sensitive than SPECT [19]. Furthermore, MRI cannot delineate the stage of a fracture and may reveal bone stress reactions in asymptomatic athletes, who typically do not require treatment [58]. The 3 Tesla MRI may provide greater sensitivity and specificity. Initial studies using the 3 Tesla MRI and a thin-slice 3D T1 VIBE sequence suggest that this technology provides images with greater fracture detail than CT scan and allows radiologists to determine the presence or absence of fibrous union [59].

SPECT bone scan — Single-photon emission computed tomography (SPECT) is a sensitive test for detecting spondylolysis, but its specificity is limited [47,60]. There are several spinal pathologies other than spondylolysis that show up on SPECT scan, including osteoid osteoma, infection (eg, osteomyelitis), and facet joint arthrosis. In a retrospective review involving 162 adolescent athletes with symptoms of spondylolysis, SPECT bone scan detected 24 percent more spondylolytic lesions than plain bone scan [60]. SPECT may provide information about osseous healing, as its signal reflects the metabolic activity of bone [61,62]. The main drawback of SPECT is the substantial radiation exposure involved, which is reported to be as high as 5.4 to 6.7 mSv [53].

Computed tomography — Computed tomography (CT) is the most accurate imaging technique for detecting osseous abnormalities, and offers higher specificity than a SPECT scan for identifying spondylolysis (image 2), although the exact sensitivity and specificity of CT are not known [63]. According to one study of 40 patients with spondylolysis not apparent on plain radiographs, CT revealed a fracture in 34 patients, while SPECT scans revealed findings suggestive of fracture in 40, but six of these were false positive results [63].

CT is useful for distinguishing between acute and chronic lesions, which can help to determine prognosis and treatment. In an observational study of 346 spondylolysis lesions in 185 adolescents, researchers classified the stage of each injury and found that healing occurred in 73 percent of early fractures, 39 percent of progressive fractures, and none of the terminal or bilateral fractures [4]. In another study, the stage of the fracture as determined by a combination of CT and MRI findings helped to predict healing, and thereby to determine how long athletes should be kept from participating in sport and treated with bracing [64]. The mean healing time for each injury type was as follows: 94 percent of early lesions healed in 3.2 months; 64 percent of injuries with a progressive designation by CT and high signal on MRI healed in 5.4 months; 27 percent of progressive lesions by CT without a high signal on MRI healed in 5.7 months.

However, the use of CT in children and adolescents remains controversial primarily because of the high radiation exposure involved. Thus, many clinicians prefer MRI and use CT only if problems arise during the course of management. The radiation exposure of a full lumbar CT is approximately 6 mSv. However, CT scans limited to the two or three vertebrae of interest when spondylolysis is suspected involve only about 1.5 mSv, which is about the same as a two view lumbar series using plain radiographs. Some clinicians use CT in this manner to determine prognosis.

DIAGNOSIS — The approach to diagnosing spondylolysis and spondylolisthesis varies by patient age. For this purpose, patients may be divided into children (ie, prepubescents), adolescents in puberty, and late adolescents/young adults.

Children — Among prepubescent athletes, especially children as young as six or seven years, the prevalence of back pain is much lower than among adolescent athletes. When significant back pain occurs in this age group potentially dangerous causes of back pain may exist. This may include infection and tumor, which are relatively more common (although dangerous causes remain uncommon overall), while spondylolysis and spondylolisthesis are relatively rare. Thus, a more thorough workup is often indicated in children with persistent low back pain. The evaluation of these patients is discussed in detail separately. (See "Back pain in children and adolescents: Evaluation" and "Back pain in children and adolescents: Causes".)

Younger adolescents — Younger adolescents in the midst of puberty, particularly those experiencing their adolescent growth spurt, are at higher risk of developing spondylolysis or spondylolisthesis. In such athletes, the diagnosis is made on the basis of a history of low back pain made worse by activities involving lumbar extension. As an example, a young gymnast may present with back pain made worse by activities such as back hand springs and an examination that reveals focal lumbar pain with lumbar extension. In such cases, a presumptive diagnosis is made and the athlete is made to rest for a week or two to see if symptoms resolve.

If pain persists for longer than a few weeks despite rest from inciting activities, plain radiographs are obtained. If a spondylolysis or spondylolisthesis is detected the diagnosis is established. If the radiographs are unremarkable and there are no signs suggesting other serious disease, such as night pain or neurologic symptoms, obtaining advanced imaging to establish a definitive diagnosis may be deferred while the patient continues resting from inciting activities. If symptoms persist, advanced diagnostic imaging, preferably MRI, is performed to confirm the diagnosis and assist in determining the acuity of the fracture. In the athlete unable or unwilling to rest due to competition, advanced imaging is sometimes obtained earlier.

Older adolescents/young adults — Among older adolescents and young adults, the diagnosis of spondylolysis or spondylolisthesis is suspected in patients who complain of low back pain of more than three weeks duration that is made worse by activities involving lumbar extension. On physical examination, most patients demonstrate pain on lumbar hyperextension. In such cases, plain radiographs are obtained and if a spondylolysis or spondylolisthesis is detected the diagnosis is established. If the radiographs are unremarkable and there are no signs suggesting other serious disease, such as night pain or neurologic symptoms, obtaining advanced imaging to establish a definitive diagnosis may be deferred while the patient rests from inciting activities. If symptoms persist, advanced diagnostic imaging, preferably MRI, is performed to make the diagnosis.

INDICATIONS FOR SURGICAL REFERRAL

Emergent referral — Although rare, any patient with a motor deficit or evidence of cauda equina syndrome (eg, urinary incontinence, saddle anesthesia) requires immediate surgical consultation. In addition, any concern for an infectious cause of low back pain, such as discitis or an abscess, warrants immediate evaluation and surgical consultation. Immediate consultation is also required if diagnostic imaging reveals another pathologic cause of back pain (eg, bone tumor). (See "Acute lumbosacral radiculopathy: Etiology, clinical features, and diagnosis" and "Clinical features and diagnosis of neoplastic epidural spinal cord compression" and "Spinal epidural abscess" and "Vertebral osteomyelitis and discitis in adults".)

Non-urgent consultation — Patients with refractory pain from spondylolysis despite appropriate conservative management are appropriately referred to an adult or pediatric spine surgeon. The referring clinician should ensure that the patient has been compliant with conservative care, including rest from sport, bracing if prescribed, and physical therapy.

Spine surgery consultation for spondylolisthesis is appropriate in the following circumstances:

●Progression of spondylolisthesis to Grade II or higher (picture 1). (See 'Classification' above.)

●Persistent pain despite appropriate conservative management of a Grade I spondylolisthesis without evidence of progression.

DIFFERENTIAL DIAGNOSIS — As described in the diagnosis section, spondylolysis and spondylolisthesis are relatively rare in prepubescent children and a more thorough workup is often indicated in children with persistent low back pain. The evaluation of these patients is discussed in detail separately (see "Back pain in children and adolescents: Evaluation" and "Back pain in children and adolescents: Causes"). The following diagnoses are of particular relevance when considering the diagnosis of spondylolysis in adolescents in particular and should be entertained prior to obtaining imaging studies.

Lumbar disc — Lumbar disc-related pathology is uncommon in children and young adolescents. However, such pathology may occur in young athletes. In contrast to spondylolysis, pain secondary to lumbar disc protrusion more often increases with lumbar flexion (rather than extension) and with sitting. However, central protrusion may elicit pain on extension, causing some clinical confusion. True radiculopathy involving neurologic deficits can occur from protruding discs but is uncommon with spondylolysis. High grade spondylolisthesis can cause neurologic findings (eg, cauda equina syndrome) but is readily diagnosed by plain radiograph. If necessary, MRI is obtained to distinguish disc-related pathology and establish the diagnosis. (See "Back pain in children and adolescents: Causes", section on 'Intervertebral disc herniation'.)

Scheuermann’s (juvenile) kyphosis of lumbar spine — Scheuermann’s kyphosis involves pathologic changes in the vertebral endplate. Most often these changes occur in the thoracic or thoracolumbar spine, but in some instances, the upper lumbar spine is affected. The condition presents with activity-related pain in the mid-back region, and pain is typically worse with extension and flexion. The back often has a flat appearance when the patient is not bending. Plain lateral radiographs of the spine reveal anterior wedging of three adjacent vertebrae, which is diagnostic and distinguishes the condition from spondylolysis. (See "Back pain in children and adolescents: Causes", section on 'Scheuermann (juvenile) kyphosis'.)

Sacroiliac instability — Athletes with any lumbar injury may develop atrophy of the lumbar extensor musculature due to pain inhibition and disuse. This may result in some degree of sacroiliac instability, which typically presents with pain at the superior buttocks adjacent to the L5 region. Pain often increases with lumbar flexion as well as extension. Sacroiliac provocation maneuvers are often helpful for distinguishing between sacroiliac instability and spondylolysis. One such maneuver is the thigh thrust or thigh compression. This maneuver involves having the supine patient flex both their hip and knee to 90 degrees, followed by the clinician pushing the thigh posteriorly into the pelvis. Pain at the posterior superior iliac spine marks a positive test.

Other maneuvers include a direct thrust on the sacrum while the patient is prone and focal tenderness over the sacroiliac ligaments. Limited motion on one side with a FABERE test (figure 12) or asymmetric motion of one sacroiliac joint when the pelvis is rocked also suggest sacroiliac dysfunction. Pain due to sacroiliac instability is more likely to develop directly over the sacroiliac joint during a crossover (or "pretzel") stretch (a supine patient rotates a shoulder towards the opposite wall while rotating the leg on the opposite side across their body toward the floor). While all these rotational maneuvers tend to exacerbate pain due to sacroiliac instability, they typically do not cause pain in patients with spondylolysis.

Lordotic low-back pain — Lordotic low back pain generally presents with diffuse, multilevel back pain and significant lordosis. Palpation may reveal tender posterior elements along the entire lumbar spine, including the facet joints and spinous processes. Most commonly, this diagnosis is made after spondylolysis has been ruled out.

Apophysitis — Tenderness along the spinous processes to light palpation suggests apophysitis in a growing adolescent athlete with back pain whose diagnostic workup is otherwise negative. Apophysitis may also occur at the superior and inferior endplates of vertebral bodies (ring apophysitis) and at the iliac crest. These can present with pain during activity or when sitting. If obtained, careful review of an MRI or bone scan of the area may reveal inflammation.

Vertebral segmentation abnormalities — Abnormalities of segmentation of the lower lumbar spine are common. These may include lumbar super-segmentation with a lumbarized S1 (ie, “L6” not incorporated into the sacrum), which is not commonly associated with back pain. Conversely, incomplete segmentation of L5 is associated with a unilateral bony bridge from L5 that remains in continuity with the sacrum and creates a pseudoarthrosis. This pseudoarthrosis is a common cause of back pain in the athlete and often presents in a similar fashion to spondylolysis or sacroiliac pain with pain on hyperextension. It is identified by plain radiograph and the pain often correlates with the area of pseudoarthrosis.

Discitis and osteomyelitis — Discitis is a bacterial infection involving the disc. The disease is most common in young children and typically presents with gradual onset of irritability and increasingly severe pain along with refusal to bear weight, crawl, or walk. The older adolescent or young adult may have a more indolent course without fever or chills. This is more difficult to diagnose and often requires an MRI. Osteomyelitis involving vertebral bodies and discs also causes progressive back pain. It is most common among adolescents but may occur in younger children. In comparison to discitis, those with vertebral osteomyelitis are more likely to be febrile and ill appearing. (See "Back pain in children and adolescents: Causes", section on 'Discitis' and "Back pain in children and adolescents: Causes", section on 'Intervertebral disc herniation'.)

Osteoid osteoma — Osteoid osteoma is a benign tumor that often localizes to the spine in children and commonly presents as back pain in such cases. It is characterized by night pain relieved by nonsteroidal antiinflammatory drugs. Diagnosis is made by imaging study, although spine lesions may be missed on plain radiograph. (See "Nonmalignant bone lesions in children and adolescents", section on 'Osteoid osteoma'.)

Other tumors — A number of other tumors can localize to the spine, including leukemia, lymphoma, Ewing sarcoma, neuroblastoma, osteoblastoma, osteosarcoma, and neurofibroma. Nocturnal pain and constant pain unaffected by activity suggest the possibility of a tumor and the need for imaging studies. (See appropriate topic reviews.)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Spondylolysis and spondylolisthesis".)

SUMMARY AND RECOMMENDATIONS

●Terminology – Spondylolysis is a unilateral or bilateral defect (fracture or separation) in the vertebral pars interarticularis, usually in a lower lumbar vertebrae, most often L5 (figure 1 and figure 3 and figure 2). In young athletes, spondylolysis usually represents a fatigue fracture, but it may also be caused by acute overload.

Spondylolisthesis involves anterior displacement of a vertebral body due to bilateral defects of the posterior arch and is less common than spondylolysis. Spondylolistheses are classified by etiology and the extent to which the cephalad vertebral body extends beyond the anterior border of the caudal vertebrae (picture 1). (See 'Definitions, pathogenesis, and location' above and 'Classification' above.)

●Epidemiology and risk factors – Spondylolysis is the most frequent clearly identifiable source of back pain in the young athlete. Spondylolysis is most common in athletes who engage in sports involving extreme spinal motion, particularly lumbar extension (table 1). The fatigue fractures of spondylolysis commonly develop during the adolescent growth spurt. Genetics and relative muscle weakness or inflexibility (eg, lumbar extensor weakness) can contribute to the development of spondylolysis and acute spondylolisthesis. (See 'Epidemiology and risk factors' above.)

●Children often asymptomatic – Children who develop a spondylolysis in early life usually have no symptoms; the condition is found incidentally while imaging the spine for other reasons. Such a presentation generally does not lead to complications and is not concerning. (See 'Common presentations' above.)

●Presentation in adolescents – Adolescent athletes with an acute or subacute spondylolysis often develop symptoms insidiously. The primary symptom is low back pain during activities, particularly those involving lumbar extension. Initially, pain usually resolves when the athlete stops practicing or playing, but if left untreated, pain may worsen and persist after activity ceases. Night pain is uncommon and should prompt the clinician to consider other causes. Spondylolisthesis patients often develop pain that spreads across their lumbar region and radiates into their buttocks or posterior legs. The pain can be associated with radicular symptoms, including paresthesias, numbness, or a feeling of weakness in the extremities.

●Examination findings – Most adolescent athletes with spondylolysis or acute spondylolisthesis develop pain with lumbar extension; pain is often further increased by hyperextension performed while standing on one leg. Typically there is minimal tenderness in athletes with spondylolysis, unless there is associated muscle spasm. (See 'Physical examination' above.)

●Diagnostic imaging – Imaging studies may not be necessary for patients without concerning constitutional signs or complicating factors (eg, fevers, night pain, neurologic or genitourinary complaints, or immunosuppressant medication [eg, glucocorticoid] use), whose pain is of recent onset and who are willing to abstain from all exacerbating activity. If pain has persisted for more than a few weeks, plain anteroposterior (AP) and lateral radiographs of the lumbar spine are generally the first studies obtained. If the plain radiographs of the lumbar spine are unrevealing but clinical suspicion for spondylolysis persists, advanced imaging (typically MRI) is usually performed. (See 'Diagnostic imaging' above.)

●Approach to back pain in children – The approach to diagnosing spondylolysis and spondylolisthesis varies by patient age. Among prepubescent athletes, especially children as young as six or seven years, the prevalence of back pain is much lower than among adolescent athletes. When significant back pain occurs in this age group potentially dangerous causes of back pain may exist (although they are uncommon) and a more thorough workup is often indicated. The evaluation of these patients is discussed in detail separately. (See "Back pain in children and adolescents: Evaluation" and "Back pain in children and adolescents: Causes".)

●Diagnostic approach – Younger adolescents in the midst of puberty, particularly those experiencing their adolescent growth spurt, are at higher risk of developing spondylolysis or spondylolisthesis. In such patients, the diagnosis may be made on the basis of a history of low back pain made worse by activities involving lumbar extension. If pain is severe or persists for longer than a few weeks despite rest from inciting activities, plain radiographs are obtained. If the radiographs are unremarkable and there are no signs suggesting other serious disease (eg, night pain, neurologic symptoms), advanced imaging to establish a definitive diagnosis may be deferred while the patient rests from inciting activities. If symptoms persist, advanced diagnostic imaging, preferably MRI, is performed to establish the diagnosis. A similar approach is used with older adolescents and young adults. (See 'Diagnosis' above.)

●Indications for surgical referral – Indications for immediate consultation with a spine surgeon include: presence of a motor deficit or evidence of cauda equina syndrome (eg, urinary incontinence, saddle anesthesia); concern for an infectious cause of low back pain, such as discitis or an abscess; and, imaging that reveals another pathologic cause of back pain (eg, bone tumor).

Non-emergency indications for surgical consultation include: refractory pain from spondylolysis despite appropriate conservative management; progression of spondylolisthesis to Grade II or higher (picture 1); and, persistent pain despite appropriate conservative management of a Grade I spondylolisthesis without evidence of progression. (See 'Indications for surgical referral' above.)

●Differential diagnosis – Alternative diagnoses that may be present in a manner similar to spondylolysis or acute spondylolisthesis include lumbar disc herniation, sacroiliac instability, and other spine pathology (eg, infection, tumors). (See 'Differential diagnosis' above.)