Spondylolysis and Spondylolisthesis in Children and Adolescents: I

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Spondylolysis and Spondylolisthesis in Children and Adolescents: I. Diagnosis, Natural History, and Nonsurgical Management

Ralph Cavalier, MD Abstract Martin J. Herman, MD Spondylolysis and spondylolisthesis are often diagnosed in children Emilie V. Cheung, MD presenting with low back pain. Spondylolysis refers to a defect of Peter D. Pizzutillo, MD the vertebral pars interarticularis. Spondylolisthesis is the forward translation of one vertebral segment over the one beneath it. Isth- Dr. Cavalier is Attending Orthopaedic mic spondylolysis, isthmic spondylolisthesis, and stress reactions Surgeon, Summit Sports Medicine and involving the pars interarticularis are the most common forms seen Orthopaedic Surgery, Brunswick, GA. Dr. Herman is Associate Professor, in children. Typical presentation is characterized by a history of Department of Orthopaedic Surgery, activity-related low back pain and the presence of painful spinal Drexel University College of Medicine, mobility and hamstring tightness without radiculopathy. Plain ra- St. Christopher’s Hospital for Children, Philadelphia, PA. Dr. Cheung is Fellow, diography, computed tomography, and single-photon emission Department of Orthopaedic Surgery, computed tomography are useful for establishing the diagnosis. Mayo Clinic, Rochester, MN. Dr. Symptomatic stress reactions of the pars interarticularis or adjacent Pizzutillo is Professor, Department of vertebral structures are best treated with immobilization of the Orthopaedic Surgery, Drexel University College of Medicine, St. Christopher’s spine and activity restriction. Spondylolysis often responds to brief Hospital for Children. periods of activity restriction, immobilization, and physiotherapy. None of the following authors or the Low-grade spondylolisthesis (≤50% translation) is treated similarly. departments with which they are The less common dysplastic spondylolisthesis with intact posterior affiliated has received anything of value elements requires greater caution. Symptomatic high-grade spondy- from or owns stock in a commercial company or institution related directly or lolisthesis (>50% translation) responds much less reliably to non- indirectly to the subject of this article: surgical treatment. The growing child may need to be followed Dr. Cavalier, Dr. Herman, Dr. Cheung, clinically and radiographically through skeletal maturity. When and Dr. Pizzutillo. pain persists despite nonsurgical interventions, when progressive Reprint requests: Dr. Herman, St. vertebral displacement increases, or in the presence of progressive Christopher’s Hospital for Children, Department of Orthopaedic Surgery, neurologic deficits, surgical intervention is appropriate. Front Street at Erie Avenue, Philadelphia, PA 19134-1095. pondylolysis and spondylolisthe- conditions; there are no reported cas- J Am Acad Orthop Surg 2006;14:417- sis are common causes of low es in nonambulators.1 Spondylolysis 424 S back pain in children and adoles- has been rarely reported in infancy, Copyright 2006 by the American cents. Upright posture and ambula- but by age 6 years, the reported inci- Academy of Orthopaedic Surgeons. tion appear to be contributing fac- dence of 5% approximates that of tors to the development of these the adult population.2-5 Most chil-

Volume 14, Number 7, July 2006 417 Spondylolysis and Spondylolisthesis: I. Diagnosis, Natural History, and Nonsurgical Management

Table 1 olescent. Type I, the dysplastic type, defines spondylolisthesis secondary Classification Systems for Spondylolisthesis to congenital abnormalities of the Wiltse-Newman Marchetti-Bartolozzi lumbosacral articulation, including maloriented or hypoplastic facets I. Dysplastic Developmental and sacral deficiency. The pars is II. Isthmic High dysplastic poorly developed, which allows for IIA, Disruption of pars as a With lysis elongation or eventual separation result of stress fracture With elongation IIB, Elongation of pars without Low dysplastic and forward slippage of L5 on the disruption related to repeated, With lysis sacrum with repetitive loading over healed microfractures With elongation time. This type is less common, IIC, Acute fracture through pars Acquired comprising 14% to 21% of cases in III. Degenerative Traumatic large series.12,13 IV. Traumatic Acute fracture Type II, the isthmic type, defines V. Pathologic Stress fracture spondylolisthesis that results from Postsurgery defects of the pars interarticularis. Direct surgery This group is subdivided into three Indirect surgery subtypes. Type IIA, the most com- Pathologic mon subtype, is caused by fatigue Local pathology Systemic pathology failure of the pars from repetitive Degenerative loading, resulting in a complete ra- Primary diolucent defect. Type IIB is caused Secondary by an elongated pars secondary to repeated microfractures that heal. This type can be difficult to distin- dren are asymptomatic. Hereditary the pars, adjacent lamina, or pedicle, guish radiographically from the dys- factors appear to predispose some in- the term stress reaction is most ap- plastic type. Type IIC refers to a pars dividuals to the development of propriately applied. Magnetic reso- fracture that results from an acute spondylolysis and spondylolisthe- nance imaging (MRI) will demon- injury. Wiltse hypothesized that sis.6,7 Specific sporting activities strate intraosseous edema in the isthmic defects are the result of with repetitive hyperextension and affected areas in these patients. chronic loading of a pars interarticu- rotational loads applied to the lum- When the defect is characterized by laris that is genetically predisposed bar spine may result in the develop- a radiolucent gap with sclerosis of to fatigue failure.14 ment of spondylolysis and spondy- the adjacent bone edges, it is termed Marchetti and Bartolozzi15 pro- lolisthesis in the young athlete. The a spondylolytic or isthmic defect. posed an alternative classification incidence of spondylolysis is as high Spondylolisthesis describes the system with two broad categories— as 47% in elite athletes who partic- forward translation of one vertebra developmental and acquired. The de- ipate in high-risk sports such as div- relative to the next caudal vertebral velopmental category defines spondy- ing and gymnastics.8,9 segment. Spondylolysis occurs most lolisthesis resulting from an inherited Spondylolisthesis may be associ- commonly in the fifth lumbar verte- dysplasia of the pars, lumbar facets, ated with neurologic dysfunction in bra but may occur at more cephalad disks, and vertebral endplates, com- patients with congenital dysplasia of lumbar levels. Patients with L4 bining the dysplastic and isthmic cat- the lumbosacral facets and sacrum. spondylolysis are more frequently egories of Wiltse-Newman. Acquired These congenital changes allow an- symptomatic.10 In children and ado- spondylolysis and spondylolisthesis terior translation of the L5 vertebral lescents, however, spondylolisthesis define failure of the pars secondary to body with intact posterior elements most commonly occurs at the L5-S1 repetitive spinal loading related to that can compress the L5 and sacral motion segment. specific activities. An expanded ver- nerve roots. sion of this classification was later proposed15 ( Table 1). Although some Spondylolysis is the term used to Classification describe an anatomic defect of the aspects of this detailed classification pars interarticularis without dis- The Wiltse-Newman classification are more easily applied to the child placement of the vertebral body. (Table 1) is the most widely used and adolescent than is the Wiltse- When plain radiographs or comput- classification of spondylolisthesis.11 Newman scheme, the Marchetti- ed tomography (CT) reveal sclerosis Of the five types, only types I and II Bartolozzi classification has not yet with incomplete bone disruption at apply commonly to the child and ad- achieved universal acceptance. De-

418 Journal of the American Academy of Orthopaedic Surgeons Ralph Cavalier, MD, et al scriptive terms such as dysplastic, ysis and spondylolisthesis, Wiltse6 Form scores between the study pop- congenital, sclerotic, spondylolytic, and Albanese and Pizzutillo7 noted ulation and the age-matched general developmental, acquired, traumatic, that 26% and 22%, respectively, of population. stress fracture, and stress reaction first-degree relatives demonstrated In most studies, no distinction have resulted in substantial confusion radiographically similar changes. has been made between the dysplas- in taxonomy. Most affected individuals were un- tic and isthmic types of spondylolis- aware of the existing spinal changes thesis. Also, most of the reported Natural History and were asymptomatic. Although studies are retrospective. In addition, most patients with an isthmic patients with spondylolysis and Stress reactions of the pars, lamina, spondylolysis present with some de- spondylolisthesis have often been and pedicle have been documented gree of slip, <4% of children and ad- considered together in natural histo- in athletes who participate in high- olescents demonstrate slip progres- ry studies. risk sports such as gymnastics, div- sion through skeletal maturity and 9 16,17 ing, football, and rowing. These in- into adulthood. Children who are Clinical Assessment juries are the result of repetitive diagnosed before their adolescent loading of the lumbar spine in exten- growth spurt, girls, and those pre- History and Physical sion and rotation, may be unilateral senting with >50% slip are most Examination or bilateral, and occur most com- likely to progress.12 Hamstring The child or adolescent typically monly at L5. With immobilization, spasm is the most frequently associ- presents with low back pain or, occa- stress injuries may heal, particularly ated neurologic abnormality. Lum- sionally, pain that radiates to the when the stress reaction is unilater- bar radiculopathy and bowel or blad- buttock or posterior thigh. Although al and has not yet resulted in cortical der symptoms are rare but may acute injury may precipitate the on- disruption.16 When left untreated, occur in individuals with severe set of pain, insidious onset is more healing becomes less predictable, isthmic spondylolisthesis. common. In addition to document- and well-defined lucent defects may Harris and Weinstein20 studied ing a detailed history of the patient’s develop. the long-term outcome in patients complaints and their relation to ac- In dysplastic spondylolisthesis with Meyerding grades III or IV tivity, a record of specific physical (Wiltse-Newman type I), the L5 ver- spondylolisthesis (≥51% slip) and activities and sports participation is tebra, with intact posterior elements, found that 36% of the patients treat- helpful. Radicular symptoms and slips forward on the sacrum. The re- ed nonsurgically were asymptomat- disturbance of bowel or bladder sulting lumbar stenosis may cause ic, 55% had occasional back pain, function rarely occur with spondy- L5 nerve radiculopathy as well as and 45% had neurologic symptoms; lolysis or low-grade spondylolisthe- bowel and bladder dysfunction from none of the patients was inconti- sis, but they may be reported by pa- compression of sacral nerve roots. nent. At an average follow-up of 18 tients with high-grade (Meyerding Children and adolescents with dys- years, all patients were leading ac- grade III or IV) slip. A history of night plastic spondylolisthesis are more tive lives with only minor adjust- pain is not typical; when present, it like to develop neurologic injury and ments in lifestyle. may suggest the presence of an oc- carry greater risk of progressive Beutler et al21 reported on the nat- cult neoplasm. deformity than do patients with ural history of spondylolysis and A thorough orthopaedic and neu- isthmic spondylolisthesis (Wiltse- spondylolisthesis with a 45-year rologic evaluation is mandatory for Newman type II). McPhee et al17 re- follow-up. No patients with unilat- all children and adolescents present- ported a markedly higher frequency eral defects progressed to slippage ing with back pain. Gait should be of progression in the dysplastic type over the course of the study. Patients observed with the patient wearing (32%) than in the isthmic type (4%). with bilateral L5 pars defects and underwear or a bathing suit. A short- Furthermore, patients with dysplas- low-grade (Meyerding grade I or II, ened stride length with flexion at the tic spondylolisthesis are notably ≤50%) slips followed a clinical hips and knees secondary to ham- more likely to require surgical treat- course similar to that of the general string contracture may be seen in pa- ment.18,19 population. Marked slowing of slip tients with advanced degrees of Isthmic spondylolysis and progression was observed with each spondylolisthesis (Figure 1). spondylolisthesis, the most com- decade, and no patient reached a Coronal spinal alignment is ob- monly occurring form in children 40% slip. No correlation was found served for scoliosis, but more defin- and adolescents, has an incidence of between slip progression and low itive evaluation of scoliosis is de- 4.4% at age 6 years, increasing to 6% back pain. Furthermore, there was ferred until pain and muscle spasm by age 18 years.3 In family studies of no significant difference in Medical have resolved. A flattened lumbar individuals with isthmic spondylol- Outcomes Study 36-Item Short lordosis is commonly observed in

Volume 14, Number 7, July 2006 419 Spondylolysis and Spondylolisthesis: I. Diagnosis, Natural History, and Nonsurgical Management

Figure 1 The standard posteroanterior radiographic view allows evaluation of coexisting scoliosis that may be secondary to paraspinal spasm, wheth- er idiopathic or olisthetic (ie, the result of asymmetric forward vertebral translation at the level of the spondylolisthesis). The standing lateral view is useful for identifying spondylolytic defects and document- ing the degree of spondylolisthesis. Supine oblique and spot lateral radiographic views of the lumbosacral junction improve the likelihood of diagnosing stress reactions and spondylolytic defects (Figure 2). The Meyerding classification quantifies the amount of forward translation based on the standing lateral radiograph22 (Figure 3, A). Measurement of the slip angle quantifies the degree of lumbosacral kyphosis that has occurred in associa- tion with this anterior translation. The slip angle is the angle subtend- ed by the intersection of a line drawn along the superior endplate of L5 and the perpendicular of a line drawn along the posterior cortex of the sacrum (Figure 3, B). In the past, the inferior limb of the angle was con- A, A 9-year-old girl with grade IV dysplastic (Wiltse type I) spondylolisthesis of L5- structed by drawing a line parallel to S1. Note the position of flexion of her hips and knees. B, Popliteal angle the superior border of S1. This has measurement of 55° secondary to contracture of hamstring muscles. C, Standing proved to be unreliable because of lateral radiograph of the lumbosacral spine of the same patient, illustrating high- the rounding of the superior sacrum grade dysplastic spondylolisthesis with severe lumbosacral kyphosis (arrows). that occurs secondary to the slip. A slip angle >50° is associated with patients with painful spondylolysis. es. A rectal examination is indicated greater risk of slip progression, insta- The sacrum appears vertically ori- in patients with bowel or bladder bility, and development of postoper- ented, and a visible or palpable step- dysfunction to assess anal sphincter ative pseudarthrosis.12 off at the spinous processes of the in- tone and reflex contraction. Straight Single-photon emission CT volved levels may be observed in leg–raise testing to assess nerve root (SPECT) of the lumbosacral spine is patients with advanced slip. The irritation and popliteal angle mea- the most effective method for de- spinous processes and lumbodorsal surements to assess hamstring tecting spondylolysis when plain ra- fascia, paraspinal muscles, and sa- spasm and contracture complete the diographs are normal and the patient croiliac joints are palpated for ten- examination. history and physical examination derness. Lumbar flexion and exten- are suggestive of the diagnosis.23-25 sion are often limited, and lumbar Diagnostic Studies Increased radionuclide uptake in an hyperextension frequently will Standing posteroanterior and lat- intact pars, lamina, or pedicle is con- elicit pain. eral radiographs of the thoracolum- sistent with a stress reaction (Fig- Neurologic examination should bar spine, with supine oblique views ure 4). A relative decrease in tracer include lumbar sensory and motor of the lumbosacral spine, are most uptake on serial SPECT scans has root testing as well as evaluation of useful to assess the child or adoles- been correlated with improvement deep tendon reflexes at the knees cent with back pain and potential of clinical symptoms and signs in pa- and ankles and of abdominal reflex- spondylolysis or spondylolisthesis. tients treated for symptomatic

420 Journal of the American Academy of Orthopaedic Surgeons Ralph Cavalier, MD, et al

Figure 2

Standing lateral (A) and supine oblique (B) radiographs demonstrating spondylolytic defect of the pars interarticularis of L5 (circle, arrow). C, Axial CT image through the L5 vertebra of the same patient, demonstrating the bilateral spondylolytic defects of the pars interarticularis. Note the sclerotic margins.

Figure 3

A, The Meyerding classification is used to quantify the degree of spondylolisthesis. Grade I is 0% to 25% slip, grade II is 26% to 50% slip, grade III is 51% to 75% slip, and grade IV is 75% to 99% slip.A=width of the superior endplate of S1, a = distance between the posterior edge of the inferior endplate of L5 and the posterior edge of the superior endplate of S1. B, Slip angle A quantifies the degree of lumbosacral kyphosis. A value >50° correlates with a significantly increased risk of progression of spondylolisthesis. (Adapted with permission from Herman MJ, Pizzutillo PD, Cavalier R: Spondylolysis and spondylolisthesis in the child and adolescent athlete. Orthop Clin North Am 2003;34:461-467.)

Volume 14, Number 7, July 2006 421 Spondylolysis and Spondylolisthesis: I. Diagnosis, Natural History, and Nonsurgical Management

Figure 4 Figure 5

Axial image of a SPECT scan of the lumbar spine of a 13-year-old boy with a 2-month history of activity-related low back pain. Increased tracer uptake is seen in both pars regions (arrows). Plain radiographs appeared normal. A 15-year-old diver presented with upper lumbar back pain of several months’ spondylolysis.26 duration. A, Anteroposterior radiograph of the lumbar spine showing sclerosis of the L2 pedicle (arrows). B, Axial CT image through the L2 vertebra demonstrating Thin-section CT, performed with dense sclerosis in the area of the left pedicle, which is indicative of stress reaction. a reverse gantry angle, is the best mo- After 8 weeks of restricted activities and full-time bracing, the patient’s symptoms dality for defining the bony anatomy resolved and he returned to diving after a short course of physical therapy. of spondylolysis and spondylolisthesis.27 Stress reactions, diagnosed by SPECT scan, and spondylolytic de- diagnostic tool in young patients ly detection may improve clinical fects may be definitively evaluated with stress reactions or symptomat- outcome.16 Early treatment with by thin-section CT scan for the de- ic spondylolytic defects is not well brace immobilization has achieved gree of cortical disruption, lysis, and defined. A high rate of false-positive results superior to those of activity sclerosis at the pars, lamina, or pedi- studies and a low positive predictive cle (Figure 5). Progressive healing of restriction alone. Early brace treat- value suggest that other modalities stress reactions may be documented ment also has been shown to be may be more effective in diagnosing by serial CT scan evaluation. CT is more effective than bracing after an these entities.28 also useful for identification of the initial trial period of activity restriction.26,29 nidus of an osteoid osteoma, which Nonsurgical Full-time immobilization in a may cause back pain and is associ- Management ated with focal increased uptake on thoracolumbosacral orthosis (TLSO), SPECT. Two- and three-dimensional Stress Reaction with or without a thigh extension, or CT reconstruction of the spine in pa- Spondylotic stress fractures of the in a one-legged pantaloon spica cast tients with severe spondylolisthesis pars interarticularis without cortical for a period of 6 to 12 weeks is indi- is useful to clarify the pathoanatomy disruption were reported in 47% of cated for the child or adolescent with of the region for preoperative plan- 100 adolescent athletes assessed by a stress reaction of the pars. Immobi- ning. Micheli and Wood.9 This sympto- lization may be discontinued once MRI is indicated when neurolog- matic stress reaction of the pars has pain-free lumbar extension and rota- ic symptoms and signs are present in the potential to heal.9 Lesions may tion can be demonstrated and conjunction with spondylolysis and present with unilateral or bilateral follow-up evaluation with repeat CT spondylolisthesis. Nerve root com- involvement of the pars, adjacent documents progressive bony healing. pression, lumbar disk abnormalities, lamina, or pedicle; in the presence of After discontinuation of immobiliza- spinal cord anomalies, and neoplasm normal radiographs, these lesions tion and a period of physiotherapy, of the spinal cord or vertebral spinal are diagnosed by SPECT and CT. Os- activities are gradually reintroduced. column are other sources of low seous healing potential is greater in If bony healing is absent on back pain that are best assessed with unilateral than bilateral lesions, and follow-up CT but symptoms have re- MRI. The role of MRI as a primary prompt treatment as a result of ear- solved, a fibrous union has occurred.

422 Journal of the American Academy of Orthopaedic Surgeons Ralph Cavalier, MD, et al

Fibrous union of a pars defect does dominal muscles (internal oblique serial physical examination and ra- not indicate instability, and it often and transversus abdominus) and the diographs for the asymptomatic leads to a good clinical result with lumbar multifidus (proximal to the child with low-grade dysplastic resumption of sporting activities.16,26 pars defect). These muscles sur- spondylolisthesis at 6- to 9-month Surgery is indicated when patients rounding the lumbar spine have the intervals through skeletal maturity. do not respond clinically despite a primary role of contributing to dy- Children and adolescents with minimum of 6 months of nonsurgi- namic segmental stability. At 30- symptomatic high-grade spondy- cal treatment. month follow-up, patients in the lolisthesis, regardless of type, re- specific exercise group demonstrated spond less reliably to nonsurgical Spondylolysis With a marked reduction in pain and dis- measures. Symptomatic relief can Spondylolytic Defect ability compared with the control be expected in <10% of cases. Con- (Isthmic Spondylolysis) group, who underwent more general sequently, surgical management is The goals of treatment of the physiotherapy treatment. Also rou- recommended for children and ado- young patient with a symptomatic tinely prescribed was stretching of lescents with symptomatic high- spondylolytic defect are alleviation tight lumbodorsal fascia and ham- grade spondylolisthesis.32 There is of pain and improvement of spinal string muscles. no evidence to support prophylactic mobility—not bony healing.16 In this Serial examination and radio- fusion for asymptomatic high-grade clinical scenario, a thorough search graphs are indicated for children who isthmic spondylolisthesis, nor is it for other sources of pain must be have recurrence of symptoms or un- indicated on the basis of long-term conducted because many of these ra- dergo change in clinical appearance. evaluation of individuals with high- diographic lesions are asymptomat- grade spondylolisthesis.20 ic. For most symptomatic children Spondylolisthesis and adolescents, a period of restrict- In two studies of children and ad- Indications for Surgical ed activity and physiotherapy will olescents with symptomatic low- Management relieve symptoms and allow a safe grade spondylolisthesis, two thirds return to activities. The need for in one study32 and all patients in the Surgical treatment is indicated for the brace treatment is infrequent and is second study34 responded to nonsur- child with persistent pain resulting reserved for patients who do not re- gical measures, including activity re- from a nonhealing stress fracture of spond to rest and physical therapy. striction, physiotherapy, and brace the pars, a spondylolytic defect, or An antilordotic TLSO or soft spinal treatment. When pain, spinal mobil- low-grade spondylolisthesis despite a corset, which limits the extremes of ity, and hamstring spasm are im- minimum of 6 months of nonsurgi- spinal motion, is effective in reduc- proved, the patient may return to cal treatment. A careful diagnostic ing pain and facilitating progression full activities. Low-grade isthmic search for discogenic, abdominal, or to physiotherapy.30-32 In this popula- spondylolisthesis rarely progresses, pelvic sources of low back pain is tion, the duration of brace treatment regardless of patient age or activity mandatory because a spondylolytic rarely exceeds 6 to 8 weeks. Clinical level, and it has a benign clinical defect may be an incidental radio- observation of diminished pain, im- course in the majority of patients. In graphic finding. Surgery is also in- proved spinal mobility, and de- their report on the natural history of dicated in young patients with creased hamstring spasm confirm symptomatic low-grade spondylolis- progressive dysplastic spondylolisthe- the efficacy of treatment. Activities thesis, Frennered et al35 found that sis, those presenting with neurologic may be resumed once symptoms only 2 of 47 patients demonstrated deficit, and symptomatic children have resolved after an appropriate progression of slip. Accordingly, we presenting with a high-grade slip. period of physiotherapy. routinely advise parents to maintain Physical therapy incorporating a awareness of the spondylolisthesis; Summary “specific exercise” treatment ap- they should not, however, restrict proach has been found to be more ef- the child’s activity, expect an in- Spondylolysis and spondylolisthesis fective than other commonly pre- crease in any deformity, or antici- are common causes of back pain in scribed general therapy programs. pate a higher likelihood of develop- the child or adolescent. The inci- O’Sullivan et al33 evaluated 44 pa- ment of incapacitating pain. dence of spondylolysis and spondy- tients with radiographic diagnosis of In contrast, children and adoles- lolisthesis is particularly high in ath- spondylolysis or spondylolisthesis; cents with low-grade dysplastic letes who participate in sports that patients were assigned randomly to spondylolisthesis are at greater risk place excessive stress on the lumbar two treatment groups. Those in one for progression, development of neu- spine. Careful clinical and diagnostic group were taught specific strength- rologic deficit, and need for surgical evaluation is important to properly ening exercises to target the deep ab- intervention. Thus, we recommend diagnose and effectively treat pa-

Volume 14, Number 7, July 2006 423 Spondylolysis and Spondylolisthesis: I. Diagnosis, Natural History, and Nonsurgical Management tients with specific types of spondy- ural progression in athletes. Am J ST, Micheli LJ: Low-back pain in ado- lolysis and spondylolisthesis. Most Sports Med 1997;25:248-253. lescent athletes: Detection of stress children and adolescents with 9. Micheli LJ, Wood R: Back pain in injury to the pars interarticularis with young athletes. Arch Pediatr Adolesc SPECT. Radiology 1991;180:509-512. spondylolysis and low-grade spondy- Med 1995;149:15-18. 24. Bodner RJ, Heyman S, Drummond lolisthesis may be successfully 10. Saraste H: Long-term clinical and ra- DS, Gregg JR: The use of single photon treated by nonsurgical methods with diological follow-up of spondylolysis emission computed tomography expected return to full activity. Sur- and spondylolisthesis. 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424 Journal of the American Academy of Orthopaedic Surgeons