The Spine Journal 11 (2011) 1157–1163

Case Report

The imaging and management of nonconsecutive pars interarticularisdefects: a case report and review of literature

Mohammed Nayeemuddin, MBBS, MRCS, FRCR, Paula J. Richards, BSc, MBBS, FRCR*,Elnasri B. Ahmed, FRCS (Orth)

X-ray Department, University Hospital of North Staffordshire NHS Trust, Royal Infirmary, Princes Rd, Hartshill, Stoke-On-Trent,

Staffordshire ST4 7LN, United Kingdom

Received 1 April 2011; revised 1 October 2011; accepted 15 November 2011

Abstract BACKGROUND CONTEXT: Lumbar spond

FDA device/drug

Author disclosures

EBA: Nothing to disc

* Corresponding a

Staffordshire NHS Tru

Trent, Staffordshire ST

E-mail address: p

1529-9430/$ - see fro

doi:10.1016/j.spinee.2

ylolysis is a well-recognized condition occurring inadolescents because of repetitive overuse in sports. Multiple-level spondylolysis involving consec-utive lower lumbar segments are rare. Several authors have reported failure of conservative treat-ment in the management of multiple-level pars fractures.STUDY DESIGN: A case report and review of previous literature is presented.OBJECTIVE: The objectives of this case report were to present a rare case of pars fracture involv-ing nonconsecutive segments and discuss image findings and treatment.METHODS: The patent’s history, clinical examination, computed tomography (CT), magneticresonance imaging (MRI) findings, and treatment are reported. We also discuss the pathogenesis,various treatment options, and review the literature.RESULTS: We present the fourth case of bilateral pars fractures involving nonconsecutive lowerlumbar spine segments of L3 and L5, in a 16-year-old young adolescent footballer who presentedwith 4-month history of constant low back pain. After 1 year of conservative management, the moreacute fractures at L3 showed complete bony union, symptomatic pain relief, and return to full sport-ing activity.CONCLUSION: We report a rare case of bilateral pars fractures involving nonconsecutive seg-ments. Multiplane reconstruction of CT images and MRI are very useful in planning treatmentand follow-up. Conservative management may be used to treat multilevel nonconsecutive pars frac-tures. � 2011 Elsevier Inc. All rights reserved.

Keywords: Spondylolysis; Spondylolisthesis; Pars interarticularis fracture

Introduction

Spondylolysis is the most common overuse sports injuryof the low back with an incidence of 13% to 47% in ado-lescent athletes [1] but has a prevalence of 6% in theasymptomatic general population [2]. There is an inheritedpredisposition to hypoplastic pars that may manifest afterrepetitive loading, leading to a stress reaction and subse-quent failure [1]. Exaggerated lumbar lordosis and a morevertical sacral alignment may place increased stress on

status: Not applicable.

:MN:Nothing to disclose. PJR:Nothing to disclose.

lose.

uthor. X-ray Department, University Hospital of North

st, Royal Infirmary, Princes Rd, Hartshill, Stoke-On-

4 7LN, United Kingdom. Tel.: 01782 555246.

aula.richards@uhns.nhs.uk (P.J. Richards)

nt matter � 2011 Elsevier Inc. All rights reserved.

011.11.011

the arch [3]. It is also associated with an increased fre-quency of congenital defects in the adjacent vertebrae, suchas the transitional vertebrae and spina bifida [4] that canpredispose to stress fractures. Spondylolytic pars lesionsthat are reported to occur in 27% of fast bowlers [5],16% gymnasts [6], 23% weight lifters [6], and 27% to48% track and field throwers [6]. It is more common inmen [4], affects Caucasians two to three times more thanAfrican Americans [4], and occurs 85% to 95% at L5 and5% to 15% at L4 [7]. A higher incidence is seen in youngathletes involved in sports that require repetitive loading,extreme hyperextension, and/or rotation of the lumbarspine, which together amplifies traumatic stress to the pos-terior arch. Pars lesions are usually seen as a continuumwith stress reaction at one end and fracture nonunion withspondylolisthesis at the other [8]. Multilevel lumbar spon-dylolysis is rare, and only a few articles have been reported

1158 M. Nayeemuddin et al. / The Spine Journal 11 (2011) 1157–1163

in literature [9–13]. Many authors [10,11,14] have reportedfailure of conservative treatment in multilevel pars frac-tures. We present the fourth [15,16] case of bilateral parsinterarticularis defects affecting nonconsecutive lower lum-bar levels of L3 and L5, which showed bony union of theacute bilateral L3 pars fractures after successful conserva-tive management.

Materials and methods

A 16-year-old previously fit and healthy teenager, in-volved in regular academy football training, presented witha 4-month history of insidious onset of constant low backpain. At times, the pain was severe preventing him fromwalking, and it was associated with bilateral buttock pain.Pain was partially relieved with rest and physiotherapy,but he was unable to return to football. There was no his-tory of trauma. On examination, there was discomfort inlower lumbar spine. He had normal forward flexion, butlumbar spine extension was limited with reproduction ofhis pain. The neurologic examination was normal.

Fig. 1. Anteroposterior lumbar spine X-ray showing pars interarticularis

defect (black arrow) and spina bifida occulta (white arrow) at L5.

Results

The X-rays (Figs. 1 and 2) showed spina bifida occultaand spondylolysis at L5 with associated Grade I spondylo-listhesis at L5/S1. There was also a spondylolysis at L3level. A computed tomography (CT) scan (Figs. 3–5) andmagnetic resonance imaging (MRI) of lumbosacral spinedemonstrated a normal spinal cord, marked L5/S1 disc nar-rowing and bilateral foraminal narrowing, abutting both L5nerve roots. There was edema on the short tau inversion re-covery sequences (Fig. 6) within both pedicles of L3, whichwas tracking into the adjacent soft tissues consistent withacute bilateral pars interarticularis fractures at L3. Noedema was noted at pars interarticularis defects at L5 sug-gesting bilateral chronic nonunion of pars interarticularis.

The patient was managed conservatively with rest, lum-bosacral bracing, and physiotherapy exercises. The physio-therapy regimen included activity restriction and avoidanceof overhead activities and lumbar extension movements.Therapeutic exercises included low-impact aerobic condi-tioning exercises (inclusive of abdominal strengthening,pelvic tilts, and hamstring stretching) and core stabilization.A CT scan of lumbar spine at 6 month and 1-year follow-upshowed complete healing of the bilateral acute fractures ofpars interarticularis at L3 level (Figs. 7 and 8), and the L5pars were unaltered. The patient was completely pain freeand was able to return to football training sessions.

Discussion

Spondylolysis at multiple levels is presumed to resultfrom fatigue fractures, similar to the etiology of single-

level pars fracture [14]. Most patients with single-levelspondylolysis respond to conservative treatment (whichincludes a period of rest, with or without bracing, rehabil-itation, and return to play when pain free), and only a smallpercentage require surgery. In contrast, multiple-level parsfractures often require surgery, and conservative measuresare rarely useful [10,14]. Developmental spondylolysis donot usually unite, but patients with chronic nonunion ofpars fracture can often return to normal physical activities[17].

Plain radiography (lateral/oblique radiograph) is diag-nostic for pars lesions; however, it cannot differentiateacute lesions from chronic [14,18]. In unilateral spondylol-ysis, there is reactive sclerosis of the contralateral pedicle,

Fig. 2. Lateral lumbar spine X-ray showing L3 and L5 pars interarticula-

ris fractures (arrows).Fig. 3. Sagittal computed tomography reconstruction showing more acute

L3 pars interarticularis fracture (long white arrow) with irregular hazy

edges and chronic well-corticated L5 pars interarticularis defect (small

white arrow).

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which should be differentiated from osteoid osteoma andcongenitally absent pedicle, lamina [19], or articular facet.In symptomatic spondylolisthesis patients (ie, back painwith or without leg pain), flexion/extension radiographscan be helpful to assess instability. Single-photon emissioncomputed tomography nuclear medicine scan detects earlystress reactions before radiographic changes and differenti-ates active spondylolysis from inactive. Chronic nonunionsand developmental lesions are often inactive on isotopestudies. Computed tomography shows bony anatomy, de-tects occult/incomplete fractures, and is also useful forfollow-up. Sagittal or a reverse gantry is used to imagethe pars defects [20]. Magnetic resonance imaging is the in-vestigation of choice to assess both anatomy and activity atthe pars but has a poor sensitivity (57%) and positive pre-dictive value (14%), as it requires thick slices, has problemswith partial voluming, and may miss incomplete fractures.It has a high negative predictive value (97%) [21], whennormal marrow is seen across the pars region.

Hollenberg et al. [22] graded pars interarticularis frac-tures on MRI into five grades: Grade 0: normal (normalmarrow and intact cortical margins; negative bone scan);

Grade 1: stress reaction (marrow edema with intact corticalmargins; positive bone scan); Grade 2: incomplete fracture(marrow edema with one cortical fracture; positive bonescan); Grade 3: acute complete fracture (marrow edemawith both cortical fracture; positive bone scan); and Grade4: chronic complete fracture (no marrow edema with bothcortical fracture; negative bone scan).

Fast bowlers undertake strenuous extension, axial rota-tion, and lateral flexion of lower lumbar spine during deliv-ery phase of fast bowling [23], which produces the forcesthat lead to pars fracture in these athletes. Ranawat et al.[15] described multiple lumbar pars defects in 18 profes-sional cricketers, diagnosed using plain radiographs andCT. The activity of the pars defect was not assessed. Of18 cricketers, 13 had pars defects on the side opposite tothe bowling arm. Eight cricketers responded to conservativetreatment, bowling analysis, and reeducation, and 10 nonre-sponders were treated operatively. All patients returned to

Fig. 6. Short tau inversion recovery sagittal magnetic resonance sequence

showing edema surrounding L3 pars fracture, which is tracking along the

adjacent soft tissues (thin arrows) and chronic L5 pars defect with fluid

within adjacent facet joint (thick arrow) but no surrounding edema.

Fig. 4. Axial computed tomography image through L3 showing bilateral

acute pars interarticularis fractures with hazy irregular edges.

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full sport after treatment. He described one unusual case ofskip pars fractures involving right L1 and L5 and also leftL3, for which the right L5 was surgically repaired. Fiveyears later, he suffered further injuries to left L4 and L5,which were conservatively managed.

Fig. 5. Axial computed tomography image through L5 showing bilateral

chronic pars interarticularis fracture (thin arrows) with well-corticated

edges and a spina bifida occulta (thick arrow).

Chung et al. [16] described six cases of multiple-levelspondylolysis treated by direct repair with pedicle screwlaminar hooks, after 6 months of failed conservative man-agement. Four had excellent result, and two had good re-sults based on Macnab [24] criteria. Macnab criteria havefour grades: excellent (no pain, full activity at work), good(occasional pain, not interfering with work), fair (occa-sional pain, interfering with work), and poor (persistentpain, frequently interfering with work). Plain radiographswere performed, and MRI was used to evaluate the discs,but there was no mention about edema in the pars fracture.He had two patients who were 20 years old with skip parslesions affecting bilateral L3 and L5 levels. Both had excel-lent results postoperatively, although left L5 pars fracture inone patient progressed to nonunion.

Eingorn et al. [11] published a case of multilevel lumbarspondylolysis affectingL2 toL4,where 4months of conserva-tive treatment with underarm body jacket was unsuccessful,and surgery (iliac bone grafting and wiring of transverse pro-cesses and spinous processes) was undertaken, which restoredspine stability and repaired pars defects.

Wiltse et al. [25] analyzed pars fractures in 424 young ath-letes and found that complete healing occurred in 29% of allunilateral pars fractures compared with only 6% of bilateralpars fractures [26]. Unilateral pars fractures are more likely

Fig. 7. Axial computed tomography scan of lumbar spine at 6-month

follow-up showing partial bony union of L3 par interarticularis.

Fig. 9. Preferred treatment algorithm.

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to heal than bilateral fractures because of intact contralateralpars providing stability and less stress across the healing frac-ture [27]. Dunn et al. [28] found 25 incomplete pars fractureson CT in 156 adolescents and showed that incomplete parsfractures progressed from inferior to superior and healing oc-curred in the reverse direction. On follow-up imaging, 92%showed partial or complete healing, and 8% progressed tocomplete fractures. It is essential to identify incomplete parsfractures, as failure to restrict or stop the sporting activity willlead to progression to complete pars fracture and ultimately tochronic nonunion [25]. With early detection, acute stress

Fig. 8. Axial computed tomography scan of lumbar spine at 1-year

follow-up showing complete bony union of L3 par interarticularis.

fractures of the pars may unite with conservative measuresalone [29,30].About 25%of all spondylolytic patients developlong-term complications, such as chronic persistent low backpain, spondylolisthesis, and sciatica [31]. Progressive spondy-lolisthesis associatedwith spondylolysis can occur at any timebut is often seen before 16 years of age and is asymptomatic[4]. Progressive spondylolisthesis is more commonly seenwith dysplastic type of spondylolysis than isthmic type [32].Histologic examination of the pars defect has been shown tohave fibrous union and pseudarthrosis. There may be commu-nication with the adjacent facet joints [33].

A widely referenced treatment protocol was proposed byd’Hemecourt et al. [34], Micheli and Curtis [35], and d’Hem-ecourt et al. [36]. In this protocol, the spondylolytic patientswere restricted from sporting activity and advised to wear allday a 0� extension Boston overlapping brace. Physiotherapyis initiated focusing on pelvic flexibility and antilordoticstrengthening but avoiding extension movements. After 4 to6 weeks, pain-free patient is allowed to return to sports withbracing and physical therapy. At 4-month follow-up CT, if

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there is bony healing and no pain, then weaning of brace isstarted. If CT shows nonunion and patient is symptomatic,electrical stimulation or bone stimulators are considered. Al-though, majority of lumbar spondylolysis responds to conser-vative measures, surgical treatment is reserved for patientswith persistent low back pain for greater than 6 months, pro-gressive spondylolisthesis, or neurologic symptoms. The twomain types of surgicalmethods are direct repair andposterolat-eral arthrodesis.Theadvantageofdirect repair over posterolat-eral fusion is that mobility of the lumbar segments ismaintained along with reduced risk of disc degeneration[37]. Preserving lumbarmotion is essential to athleteswho de-velop spondylolysis. Although in our case, to ascertain heal-ing, we performed CT scan at 6 months and at 1-yearfollow-up, we do not routinely recommend that if the patientis asymptomatic at 6-month follow-up and has returned backto sporting activity.

Our preferred treatment algorithm is as follows (Fig. 9):

1. For early detection, we recommend educating youngsports professionals (footballers, gymnasts, fast bow-lers, weightlifters, and track and field throwers) andschool children regarding the incidence and treatmentof acute spondylolysis. Educating the general practi-tioners and other clinicians is also important for earlydetection and referral.

2. Early detection is also facilitated by typical examina-tion findings and imaging investigations. We recom-mend plain radiography for diagnosis, CT scan toassess the nature and extent of the defect, and MRIto assess the discs and activity. Because there is goodcorrelation between single-photon emission com-puted tomography bone scan and MRI, a bone scanmay also be used in detecting activity.

3. Activity restriction, lumbosacral orthosis (for 3months),and physiotherapy exercises.

4. Clinical follow-up should be at 3 months with plainradiography.

5. After 6-month follow-up, asymptomatic patients canbe allowed to gradually return to sporting activities.In symptomatic patients, repeat imaging with CTand MRI to ascertain the potential for healing isrecommended.

� If there are signs of early healing, then continue con-servative management with follow-up at 12 months.

� If there are no signs of early healing, and the patientremains symptomatic, then consider surgicaltreatment.

Conclusion

Young athletes are prone to spondylolysis because of re-petitive involvement in vigorous training and strenuous ac-tivity. Early detection of acute or incomplete pars fracturesdramatically changes outcomes. We recommend at leasttwo modalities (CT, MRI, and bone scan) to carefully assess

the pars lesions. Skip multiple-level spondylolysis is veryrare and most respond to conservative measures. Surgicaltreatment is reserved for patients with persistent low backpain, progressive spondylolisthesis or neurologic symptoms.

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