Back pain is a very common complaint of adults and young, active individuals. Many children and adolescent athletes are affected, and often seek care from physicians. In fact, 10% to 15% of young athletes experience back pain with their activities , making it one of the more common problems seen by sports medicine specialists and orthopedists.
In caring for these active children and adolescents, it is important to realize that the etiology of pain is often much different than in their adult counterparts. Micheli and Wood  found that the most common cause in young athletes is spondylolysis, which was diagnosed in 47% of patients complaining of low back pain. In contrast, discogenic back pain was most common in adults, with spondylolysis being rare. In addition, lumbosacral strains, which are frequently seen in adults, occurred in only 6% of young athletes. Thus, because back pain in young patients is much more likely to be a result of injury to bony structures rather than musculotendinous structures, a more complete evaluation is warranted. d'Hemecourt et al.  have recommended that any back pain in children and adolescents persisting more than 3 weeks be evaluated, and sooner if concerning symptoms such as fever and night pain are present. In this article we provide an update on spondylolysis, discussing the current ideas on diagnosis and treatment.
Spondylolysis is defined as a defect in the pars interarticularis of the neural arch. It occurs in about 6% of the general population , and is often asymptomatic. In athletes, the incidence is much higher, especially in those playing high-risk sports, and is commonly associated with significant symptoms. The extent of the defect can vary, with several classification schemes proposed, including that of Wiltse et al. . It is often viewed as a continuum with stress reaction lying on one extreme and nonunion fracture with spondylolisthesis at the other. In the middle of the continuum is a stress fracture to the pars interarticularis, which is a microfracture that may be very difficult to visualize radiographically.
Defects in the pars interarticularis result from repetitive mechanical stress, especially hyperextension and trunk rotation. Although any spinal level may be affected, 71% to 95% of lesions occur at L5 and 5% to 23% at L4 [5–8]. Many factors may contribute to the development of spondylolysis. In young athletes, the spine is undergoing growth and remodeling (full maturation of the bony pars does not occur until around the age of 25). The presence of numerous ossification centers leaves the posterior elements with points of weakness that are susceptible to injury with repeated stress. In addition, anatomic risk factors such as spina bifida occulta and severe scoliosis may place one at higher risk of injury . Biomechanically, increased lordosis is a known contributing factor, as are associated factors that contribute to increased lordosis, such as iliopsoas inflexibility, thoracolumbar fascia tightness, abdominal weakness, and thoracic kyphosis . Some of these characteristics, especially thoracolumbar fascia tightness, become more prominent during active growth spurts. This may explain the observation of some clinicians that spondylolysis is more common during periods of growth. In female athletes, Micheli and Curtis [10•] point out that nutrition may be a factor, as women are at risk for the female athlete triad of disordered eating, amenorrhea, and low bone density.
The contributing factors listed above may leave the young athlete more vulnerable to development of spondylolysis, but it is overload to the spine due to repetitive stress that leads to injury. In particular, it is the participation in sports and activities that involve frequent or extreme hyperextension of the back. Gymnastics, weightlifting, dance, and football are examples of sports that subject athletes to increased stresses on the pars interarticularis, and as a result have the highest rates of spondylolysis among athletes. In our clinic, we have also found that carrying a heavy backpack at school is an important risk factor for development of spondylolysis. Acute pars stress fractures are uncommon in adults, perhaps due to being skeletally mature and less likely to participate in activities involving trunk hyperextension .
Patients with symptomatic spondylolysis often present with insidious onset of localized low back pain. This pain may be quite severe and debilitating, and may extend into the buttocks, posterior thighs, or hamstrings. It may be severe enough to require hospitalization at times. The pain typically worsens with activity and improves with rest and lying down. Some patients may report a single traumatic event that led to onset of pain. However, most simply report a gradually worsening pain with no specific injury. The history should be negative for neurologic symptoms such as weakness or numbness into the lower extremities, so the presence of these signs may suggest another diagnosis. In addition, the presence of night pain or fever should alert the physician to pursue other diagnoses, such as discitis or tumors.
On physical examination, patients commonly have localized lumbosacral tenderness and muscle spasm. It is not uncommon for the spasm to be one-sided, and may even result in a list that resembles a scoliotic curve . Characteristic findings include pain and limited range of motion with back extension as well as with single-leg hyperextension (stork test). Other common physical findings include hamstring tightness and a flattened lumbar lordosis. The examination may be affected by an athlete's persistent nonsteroidal anti-inflammatory drug use, masking some findings. A vertically oriented sacrum and visible step-off suggests spondylolisthesis . Neurologic examination should be normal.
Congeni  describes three classic patient types that commonly characterize the patient presenting with s-pondylolysis. Type I is a hyperlordotic female athlete with increased range of motion and flexibility, such as a dancer or gymnast. Type II is a muscular male athlete with decreased flexibility who is undergoing a rapid growth spurt and has tight spinal erectors. These include football players and weightlifters. Type III is the reluctant male or female athlete who is new to his or her sport or activity and now undergoing vigorous routines to prepare for this new sport. They frequently have poor abdominal strength and trunk flexibility.
When spondylolysis is suspected based upon history and physical examination, diagnostic imaging is indicated. The role of imaging is to aid in diagnosis, direct therapy, and assess prognosis and return to play. If spondylolysis is present, one must also determine if it is the source of pain or merely an incidental finding. Traditionally, plain radiographs have been the best modality for initial diagnosis. They are now used in conjunction with newer technologies such as single-photon emission CT (SPECT), CT, and MRI.
Some controversy exists about the radiographic workup of spondylolysis. Most studies or reports relating to this condition start by ordering plain radiographs, including anteroposterior (AP), lateral, and lateral obliques. However, the sensitivity of plain radiographs are very low, especially early in the clinical course of spondylolysis.
Some centers view lateral oblique views as not being useful . In a study by Saifuddin et al. , only 32% of defects identified by CT were identified by lateral oblique views. Despite the limitations in demonstrating some defects, we at Akron Children's Sports Medicine have found oblique views to be helpful in identifying advanced lesions. To date, there is no consensus as to an ideal radiographic protocol. Radiographs are useful to rule out obvious pathology; however, further imaging may be necessary to better determine treatment and prognosis.
The development of bone scan and SPECT has provided clinicians with the ability to more reliably diagnose spondylolysis. These modalities have been found to be much more sensitive than plain radiographs in detecting pars defects . SPECT may also show evidence of stress reactions or subacute pars injuries before the development of radiographic changes , thus allowing for prompt intervention. Another advantage in the use of SPECT is its ability to differentiate symptomatic (“hot” scan) from silent spondylolysis (“cold” scan). Because spondylolysis is frequently asymptomatic, it is important to determine whether lesions are active. In a study by Raby and Mathews , patients diagnosed with spondylolysis by clinical evaluation, SPECT, and CT underwent spinal fusion. Those having had positive SPECT scans responded well to surgery, whereas those with negative results had persistent pain postoperatively.
An important limitation of SPECT is that it cannot reliably differentiate between spondylolysis and other pathology at the pars, such as osteoid osteomas, facet arthritis, infections, and neoplasms . SPECT is also an invasive procedure requiring an intravenous injection, radiation exposure, and requires several hours to complete the study. These inconveniences make it desirable to find reliable, noninvasive studies that achieve the sensitivity of SPECT.
CT has become a valuable tool in the diagnosis and management of spondylolysis. This is due in large part to its ability to visualize bony morphology and identify occult fractures by the use of multiple planes and thin cuts. When viewing the pars region, a reverse gantry angle is often employed in order to better visualize the defect . Many clinicians use CT to characterize a lesion at the time of diagnosis or later in the clinical course to determine if bony healing versus stable nonunion with fibrous tissue is occurring. The fact that SPECT is most sensitive to bone activity and CT is most specific with anatomy stresses the point that these tests should be thought of as complimentary to each other. Thus, it is often necessary to use SPECT in conjunction with CT in order to fully clarify the diagnosis.
Recently, investigators have studied the effectiveness of MRI in diagnosing spondylolysis. The advantages to the use of MRI would be a lack of radiation exposure and the use of one test to assess both anatomy and activity at the pars. Another advantage is that MRI would provide the added benefit of visualizing soft tissues, including intervertebral discs and neural structures, allowing for diagnosis of most entities in the differential diagnosis of low back pain. It would also allow for detailed visualization of lesions such as osteoid osteomas and neoplasms, which SPECT can identify but not characterize.
The effectiveness of MRI as a diagnostic tool has been the focus of several studies over the past few years. Saifuddin and Burnett  evaluated the ability of MRI to identify spondylolytic lesions. Sensitivity (57%) and positive predictive value (14%) were poor, but had a reliable negative predictive value (97%). Some factors may have contributed to the poor results, particularly the use of plain radiographs as a gold standard and the use of 5mm cuts on MRI. Sairyo et al.  showed that the use of T2-weighted MRI images can be valuable in diagnosing early spondylolytic lesions, especially ones that are amenable to bony healing. Several studies have been done using T1-weighted images looking for discontinuity of cortex and marrow as indicators of spondylolysis (15%).
Campbell et al. [20•] performed a comparative analysis to determine how well MRI correlates with CT and SPECT. MRI was reviewed blindly to study its ability to demonstrate the lesions, with only 29 of 40 (73%) lesions being correctly graded. The limitations of MRI were in its ability to diagnose stress reactions and incomplete defects. Nonetheless, MRI was shown to be very effective in demonstrating normal pars interarticularis, acute complete defects, and chronic established defects. The results of this study led the authors to devise a protocol using MRI as a first-line study [20•].
Gregory et al.  have proposed using SPECT as a first line study, followed by reverse gantry CT scans in those with positive results in order to further define the anatomy. They believe that negative SPECT scans should be followed with MRI rather than CT, as it is more likely to identify other pathology in the differential diagnosis of spondylolysis.
The Division of Sports Medicine at Children's Hospital Boston uses a very clear imaging protocol . Patients presenting with hyperextension pain receive AP and lateral radiographs as well as SPECT bone scan. If SPECT shows diffuse uptake, they are treated as a stress reaction. Those showing focal uptake receive a CT scan to further define the anatomy. CT scan is also repeated at 4 months to evaluate healing.
At our center, we begin our evaluation of young athletes with persistent hyperextension back pain for greater than 3 weeks with AP, lateral, and oblique radiographs. Negative findings are followed by SPECT bone scan. CT scan is performed at 12 weeks in patients with a positive SPECT to help answer questions about healing, bilaterality, extent of fracture, and prognosis . Recently, we have begun using MRI after initial negative radiographs rather than SPECT in cases where the athlete's symptoms have persisted for greater than 6 weeks. This is in agreement with information presented at the AAOS meeting in 2006 .
It is evident from reviewing the literature that opinions vary widely upon the appropriate diagnostic imaging protocol to be employed in evaluating spondylolysis. Nonetheless, most will agree that radiographs, though limited, are a reasonable screening tool due to cost effectiveness and ease of quickly obtaining the study. The combination of CT and SPECT provide the needed anatomic and physiologic information needed, and MRI has shown potential to demonstrate both aspects in certain clinical studies. More controlled trials need to be performed in order to put this debate to rest and provide a clear, detailed imaging protocol that is sensitive and specific for spondylolysis while being feasible in the clinical setting.
Although no randomized controlled trials have demonstrated the most effective treatment protocol [22•], several authors have published their preferences. Most clinicians agree that the treatment of spondylolysis should include a period of rest to allow for healing, with or without bracing, rehabilitation, and return to play when asymptomatic. However, the duration of treatment and degree of rest are often debated, as are the issues of bracing (including the type of brace) and the duration and type of physical therapy. Clearly, this problem usually takes months rather than days or weeks.
Steiner and Micheli  reported that 78% of patients had good or excellent results after wearing the modified Boston brace full time for 6 months then weaning from it over the next 6 months. Alternatively, Jackson and Wiltse  treated patients with activity restriction only, and was able to return 100% of patients with unilateral lesions and 50% of those with bilateral lesions to their sport. Thus, it is unclear as to what degree of intervention is required to achieve desired results.
The most widely referenced treatment protocol for spondylolysis is that of d'Hemecourt et al. , Micheli and Curtis [10•], and d'Hemecourt et al. . In this protocol, patients diagnosed with spondylolysis are removed from sporting activities and given a 0° extension Boston overlapping brace to be worn 23 of 24 hours per day. In addition, they may begin physical therapy, targeting pelvic flexibility and antilordotic strengthening while avoiding extension. The patient is returned to sports at 4 to 6 weeks with bracing if pain free and in physical therapy with spinal stabilization. If there is evidence of bony healing or pain-free nonunion on CT at 4 months, weaning of the brace is begun. If there is no healing and the patient is symptomatic, electrical stimulation is considered. Persistent pain and nonunion at 9 to 12 months are indications for surgical fixation.
At our institution, we use a similar approach. Initial treatment consists of relative rest from sports and hyperextension activities. We use a Boston brace for acute stress fractures and a nonrigid corset-type brace with a rigid molded piece for stability in subacute stress reactions or cold fractures. Physical therapy is begun within a few weeks to improve core strength and pelvic flexibility. Return to play is allowed in the brace if pain-free with extension at 4 to 6 weeks. For those sports where use of the brace is not feasible (eg, diving), a gradual return to play is implemented, beginning with impact conditioning, followed by sport-specific drills, and finally return to sporting activities [22•].
Recently, external electrical bone stimulation has been investigated as a possible adjunct to treatment. Bone stimulators have been used with spinal fusions, nonunions, and fractures in hard-to-heal areas. However, there is no current indication for its use in spondylolysis. Nonetheless, a few authors have published case reports using electrical bone stimulation to treat spondylolysis . At this point, it is unclear what role bone stimulators will have in treatment, and more research needs to be done in this area.
Surgical treatment of spondylolysis is viewed by most clinicians as a last resort when conservative treatment has failed. Indications for surgery include continued pain despite at least 9 to 12 months of conservative treatment, progression of spondylolisthesis to grade III or IV, or persistent neurologic symptoms . When indicated, surgical treatment usually involves posterolateral fusion of the transverse processes of the affected level.
Spondylolisthesis is a relatively common complication of spondylolysis. There is often some degree of slippage at the time of diagnosis of bilateral lesions, but this complication may develop later on or progress during the clinical course. Spondylolisthesis is graded I–IV based upon the percentage of slip of one vertebral body over the one below it . Thus, grade I slips have 0% to 25% forward displacement, grade II have 25% to 50%, and so on. Grades I and II are treated like spondylolysis, with surgery being reserved for slips greater than 50% (grades III and IV). Fortunately, spondylolisthesis rarely progresses in athletes. Blackburne and Velikas  followed patients with spondylolisthesis for 1 year and found that those with less than 30% slip at presentation were unlikely to progress past 30%.
Anatomic outcomes of spondylolysis include complete bony healing, healing with fibrous tissue, or nonunion. Painful nonunions may be problematic and may necessitate surgical fixation. Miller et al.  followed patients over an average of 9 years, with radiographic evaluation showing that none of the bilateral lesions showed bony healing. In contrast, all of the unilateral defects healed with bone. Shipley and Beukes  proposed that many cases of spondylolysis requiring surgery fail to heal due to the formation of a communicating synovial pseudoarthrosis at the pars interarticularis, thus creating a physical barrier that prevents healing. Whatever the cause, nonunion is a problem only if symptomatic. Many athletes are pain-free and able to return to their sport despite the absence of radiographic healing.
The most concerning complication of spondylolysis, especially from the patient's perspective, is chronic, persistent pain that limits the athlete's ability to participate in sports. Miller et al.  found that at an average of 9 years after diagnosis, 91% of patients had a good to excellent outcome, and 22% said their back influenced choices of recreational activity. However, these were ideal patients that presented with negative radiographs and positive bone scans, indicating early recognition.
Spondylolysis is a relatively common problem seen in young athletes with percentages in the range of 12% to 15%. Physicians, athletic trainers, and physical therapists caring for young athletes need to be aware of the typical clinical presentation and course. We must push for early diagnosis and intervention to help these athletes achieve optimal outcomes.
References and Recommended Reading
Papers of particular interest, published recently, have been highlighted as: • Of importance •• Of major importance
1. d'Hemecourt P, Gerbino P, Micheli L: Back Injuries in the young athlete.Clin Sports Med
2. Micheli L, Wood R: Back pain in young athletes: significant differences from adults in causes and patterns.Arch Pediatr Adolesc Med
3. Beutler W, Fredrickson B, Murtland A, et al.
: The natural history of spondylolysis and spondylolisthesis.Spine
4. Wiltse L, Newman P, Macnab I: Classification of spondylolysis and spondylolisthesis.Clin Orthop Relat Res
5. Congeni J, McCulloch J, Swanson K: Lumbar spondylolysis: a study of natural progression in athletes.Am J Sports Med
6. Iwamoto J, Takeda T, Wakano K: Returning athletes with severe low back pain and spondylolysis to original sporting activities with conservative treatment.Scand J Med Sci Sports
7. Morita T, Ikata T, Katoh S, Miyake R: Lumbar spondylolysis in children and adolescents.J Bone Joint Surg (Br)
8. Amato M, Totty W, Gilula L: Spondylolysis of the lumbar spine: demonstration of defects and laminal fragmentation.Radiology
9. Wiltse L: The etiology of spondylolisthesis.J Bone Joint Surg
10.• Micheli L, Curtis C: Stress fractures in the spine and sacrum.Clin Sports Med
Good discussion of spondylolysis, including risk factors and diagnosis. A very detailed treatment protocol is outlined.
11. Congeni J: Evaluating spondylolysis in adolescent athletes.J Musculoskel Med
12. Herman M, Pizzutillo P: Spondylolysis and spondylolisthesis in the child and adolescent: a new classification.Clin Orthop Relat Res
13. Herman M, Pizzutillo P: Spondylolysis and spondylolisthesis in the child and adolescent athlete.Orthop Clin N Am
14. Saifuddin A, White J, Tucker S, Taylor B: Orientation of lumbar pars defects: implications for radiological detection and surgical management.J Bone Joint Surg (Br)
15. Harvey C, Richenberg J, Saifuddin A, Wolman R: Pictoral review: the radiological investigation of lumbar spondylolysis.Clin Radiology
16. Gregory P, Batt M, Kerslake R, et al.
: The value of combining single photon emission computerised tomography and computerised tomography in the investigation of spondylolysis.Eur Spine J
17. Raby N, Mathews S: Symptomatic spondylolysis: correlation of ct and spect with clinical outcome.Clin Radiology
18. Saifuddin A, Burnett S: The value of lumbar spine mri in the assessment of the pars interarticularis.Clin Radiology
19. Sairyo K, Katoh S, Takata Y, et al.
: MRI signal changes of the pedicle as an indicator for early diagnosis of spondylolysis in children and adolescents.Spine
20.• Campbell RS, Grainger AJ, Hide IG, et al.
: Juvenile spondylolysis: a comparative analysis of CT, SPECT, and MRI.Skeletal Radiol
Radiologic study comparing the reliability of MRI with CT and SPECT. The authors recommend an imaging protocol based upon the results.
21. DiMarcantonio T: SPECT more effective than MRI at detecting mechanical back pain in the short term. When symptoms last over 6 weeks, however, MRI may be the most efficient test.Orthopedics Today
22.• Eddy D, Congeni J, Loud K: A review of spine injuries and return to play.Clin J Sport Med
Good review of spondylolysis and other entities in the differential diagnosis, citing important evidence from the literature.
23. Steiner M, Micheli L: Treatment of symptomatic spondylolysis and spondylolisthesis with modified Boston brace.Spine
24. Jackson D, Wiltse L: Stress reaction involving the pars interarticularis in young athletes.Am J Sport Med
25. d'Hemecourt P, Zurakowski D, Kriemler S, Micheli L: Spondylolysis: returning the athlete to sports participation with brace treatment.Orthopedics
26. Stasinopoulos D: Treatment of spondylolysis with external electrical stimulation in young athletes: a critical literature review.Br J Sports Med
27. Myerding H: Low backache and sciatic pain associated with spondylolisthesis and protruded intervertebral disc.J Bone Joint Surg Am
28. Blackburne J, Velikas E: Spondylolisthesis in children and adolescents.J Bone Joint Surg
29. Miller S, Congeni J, Swanson K: Long-term functional and anatomical follow-up of early detected spondylolysis in young athletes.Am J Sports Med
30. Shipley J, Beukes C: The nature of the spondylolytic defect: demonstration of a communicating synovial pseudoarthrosis in the pars interarticularis.J Bone Joint Surg (Br)