|Year : 2021 | Volume
| Issue : 1 | Page : 29-39
Spondylolysis and pars repair technique: A comprehensive literature review of the current concepts
KS Sri Vijay Anand, Naresh Kumar Eamani, Ajoy Prasad Shetty, S Rajasekaran
Department of Spine Surgery, Ganga Hospital, 313, Mettupalayam Road, Coimbatore, Tamil Nadu, India
|Date of Submission||10-Aug-2020|
|Date of Acceptance||17-Dec-2020|
|Date of Web Publication||28-Jan-2021|
Ajoy Prasad Shetty
Department of Spine Surgery, Ganga Hospital, 313, Mettupalayam Road, Coimbatore, Tamil Nadu.
Source of Support: None, Conflict of Interest: None
Spondylolysis is an important cause of low back pain in children and adolescents, especially in those involved in athletic activities. Spondylolysis is caused either by a fracture or by a defect in the pars inter-articularis and can be unilateral or bilateral. Among the various hypotheses regarding the etiopathogenesis of pars lysis, the occurrence of chronic micro-fractures secondary to repetitive extension and rotational stresses across pars remains the most convincing explanation to date. The majority of these patients remain asymptomatic. Imaging contributes to the staging and prognostication of the lesions, planning the line of management, and monitoring the response to treatment. Nonoperative treatment with activity restriction, braces, graded physiotherapy, and rehabilitation forms the cornerstone of management. Surgery is indicated in a specific cohort of patients whose symptoms persist despite an adequate conservative trial and includes spinal fusion and pars defect repair techniques. Patients who demonstrate good pain relief after diagnostic pars infiltration can be considered for pars repair. Patients aged ≤25 years, those with an athletic background, unilateral pathologies, and those without associated spondylolisthesis, instability, or disc degeneration are ideal candidates for pars repair. The overall outcome in spondylolysis is good, and 85% to 90% of athletes return to sports at 6 months following conservative or surgical line of treatment. In this current narrative review, we comprehensively discuss the etiology, patho-anatomy, natural history, clinical features, diagnostic modalities, and management of spondylolysis with special emphasis on direct repair techniques of pars.
Keywords: Etiopathogenesis, imaging, natural history, pars repair, spondylolysis
|How to cite this article:|
Sri Vijay Anand K S, Eamani NK, Shetty AP, Rajasekaran S. Spondylolysis and pars repair technique: A comprehensive literature review of the current concepts. Indian Spine J 2021;4:29-39
|How to cite this URL:|
Sri Vijay Anand K S, Eamani NK, Shetty AP, Rajasekaran S. Spondylolysis and pars repair technique: A comprehensive literature review of the current concepts. Indian Spine J [serial online] 2021 [cited 2021 Feb 28];4:29-39. Available from: https://www.isjonline.com/text.asp?2021/4/1/29/308205
| Introduction|| |
Spondylolysis is a developmental or acquired defect of pars inter-articularis resulting from repetitive microtrauma to a healthy or defective neural arch. The population incidence of spondylolysis is reported to be around 6%, with considerable variation across different ethnicities. Spondylolysis commonly occurs at the L5 vertebra (85–95%), followed by the L4 vertebra (5–15%), and can be either unilateral or bilateral., These levels are subjected to the highest degrees of static and dynamic stresses during physiological lumbar motions., Factors including upright posture, bipedal gait, and the presence of lumbar lordosis have been implicated as major reasons underlying the unique occurrence of spondylolysis in hominids. Although most patients remain asymptomatic, it is a well-acknowledged cause for low back pain (LBP) in young athletic individuals. Although various imaging modalities like plain radiograph, magnetic resonance imaging (MRI), computed tomography (CT), and bone scintigraphy have been demonstrated to be useful, there is still considerable ambiguity regarding the relative significance of each modality in the evaluation of spondylolysis. Currently, there is no consensus on the ideal diagnostic and treatment algorithms for patients presenting with pars lysis. Because a significant proportion of patients are young, there has been a considerable emphasis on nonfusion surgeries like direct pars repair in a certain proportion of patients who are eligible for this option. The current narrative review comprehensively discusses etiology, patho-anatomy, natural history, clinical features, diagnostic modalities, and management of spondylolysis, with special emphasis on direct repair techniques of pars.
| Materials and Methods|| |
A comprehensive search was done in PubMed database and Google Scholar using the following terms as MeSH headings and keywords: “spondylolysis,” “pars defect,” “pars repair,” “spondylolysis nonoperative treatment” on 24 May 2020. Only full-text articles with no restriction of language were included. The search resulted in a total of 5761 articles initially. Articles not pertaining to spondylolysis, articles with details not related to the current topic of interest, and duplicates were excluded. All original articles pertaining to the subject of interest were included. Furthermore, additional articles from recent reviews were handpicked and included in this review, resulting in a total of 232 studies.
Ever since the initial description by Sir Robert of Coblenz in 1855, the etiopathogenesis of spondylolysis has been extensively debated in the literature.,, It is now well established that spondylolysis is a developmental anomaly and is absent at birth. This has been confirmed by cadaveric and radiographic studies on stillborn/newborn babies, which showed no evidence of pars lysis at this age.,,, In a prospective study, Fredrickson noted that the first-degree relatives of patients with spondylolysis had a higher incidence (23%) than the general population. The contribution of the genetic component in the etiology has also been reported by Wiltse,, Wynne-Davies, and Albanese.
It is now well accepted that spondylolysis occurs due to repetitive stress to the pars inter-articularis primarily due to hyperextension. Wiltse et al. were the first to propose that spondylolysis results from fatigue fracture of the pars inter-articularis. This hypothesis was supported by a 47% incidence of lysis in young athletes, who presented with LBP. Particularly sports like gymnastics, diving, weight lifting, swimming, rowing, football, and volleyball that involve repetitive lumbar extension activities have a higher reported incidence of pars lysis., The effect of mechanical factors on lysis development is also supported by the 0% incidence in a group of 143 patients who never walked. Using a 3-D finite element model (FEM), Sairyo et al. analyzed stress lines at pars inter-articularis of a lumbar motion segment (L3-S1) in various modes. They found that stresses were high during extension and rotational movements and were the highest when the lumbar spine was subjected to combined extension and rotational forces. These stresses result in microcellular injury to the bone, and when the rate of injury far exceeds the rate of repair, fracture ensues.
There is a progressive increase in the strength of the neural arch from childhood to 50 years of age, following which it decreases. The elastic intervertebral discs and weaker pars in children cause increased stress to be placed on the pars inter-articularis on repeated extension during sporting events. The increased incidence of spondylolysis has been reported in athletes,, osteopetrosis,, athetoid cerebral palsy,, Scheuermann kyphosis.,
Anatomical factors pertaining to pars inter-articularis
The “lateral buttress,” which is the bony bridge across the superolateral edge of the inferior facet to pedicle/transverse process (TP) junction, grows progressively thinner, smaller, and structurally weaker as we caudally move from L1 to L5. The medial angulation of the isthmus is also significantly greater at L5 than proximal levels, which makes the L5 pars most vulnerable for failure under stresses.
Peleg et al. postulated that a horizontal sacral orientation puts L5 pars under significant stress due to the “pincer effect” exerted between the L4 inferior articular process and the S1 superior articular process during repetitive activities. It has also been shown that the pincer effect is significantly enhanced in increased lordosis between lower lumbar levels (L4-S1 levels). The fractures typically originate from the infero-medial margin and propagate in a superolateral direction.,
Natural history of spondylolysis
Fredrickson, in his landmark prospective study, reported that the prevalence of spondylolysis at birth was zero and increased progressively to 4.4%, 5.2%, and 6% by the ages 6 years, 12 years, and adulthood, respectively. Sairyo et al. reported that a majority of acute pars fractures have excellent healing potential in the early stages and heal with early immobilization and activity restriction. Nevertheless, if abnormal stresses persist, the fracture can progress to chronic pseudoarthrosis. The development of spondylolisthesis and slip progression has always remained major topics for debate in spondylolysis.,
The slippage in spondylolysis has been reported to be most prevalent during growth, particularly around growth spurt, and rarely progresses during adulthood., In a longitudinal study with a mean follow-up of 6 years, Sairyo et al. classified the children into three categories based on skeletal age: (a) cartilaginous (absent secondary ossification center), apophyseal (the apophyseal ring is present but not fused), and epiphyseal stages (fused apophysis). Overall, the majority of slippage (80%) occurred between the cartilaginous and apophyseal stages. Slip progression in spondylolysis is relatively uncommon and is extremely rare beyond the age of 16. Based on a 20-year follow-up study, Saraste reported a mean slip progression of 4 mm in spondylolysis, with only 11% and 5% of adolescents and adults progressing to greater than 10 mm, respectively. Beutler et al. performed a 45-year follow-up of the patients from the Fredrickson et al. study and noted spondylolysis in 6% of the patients. He also observed that unilateral spondylolysis did not show any slip progression, and only 22 patients with bilateral lysis had developed spondylolisthesis.
Another important point of discussion in spondylolysis is its role in contributing to degeneration at the involved and adjacent levels. While it is well acknowledged that degeneration is accelerated at the disc level just caudal to the level of lysis, studies have also demonstrated enhanced degenerative changes at the segment cranial to bilateral pars lysis.
A majority of patients with spondylolysis are asymptomatic. The most common complaint in symptomatic patients is focal, predominantly axial LBP. Spondylolysis must always be one of the differential diagnoses to be considered in a highly athletic adolescent patient who presents with exertional LBP. Some common physical findings include antalgic gait, exaggerated lumbar lordosis, paraspinal spasm, and hamstring tightness. The only reported pathognomonic finding is the reproduction of pain with a single-leg hyperextension test (patient stands on ipsilateral leg and hyperextends his lumbar spine; sensitivity 81%, specificity 39.7%).,,
Imaging modalities are of immense benefit not only in diagnosing but also in staging, prognosticating, treatment planning, and monitoring treatment response.
The current recommendation is to use anteroposterior (AP) and lateral views as the initial investigation. Dynamic X-rays (flexion and extension) may help to assess instability., In comparison with CT and bone scan, plain radiograph only has a sensitivity of 74% in detecting spondylolysis and therefore has a limited role in confirming the diagnosis and treatment planning. Indirect signs of spondylolysis on AP radiographs include spinous process deviation and “pedicle anisocory” (pedicle asymmetry)., On lateral radiographs, spondylolysis appears as pars lucency. While acute injuries have narrow and irregular edges, chronic lesions have smooth and rounded edges. Oblique views are useful in suspected cases and the typical description for pars defect is a “collared Scottie dog,” where collar denotes the defect.,
The presence of a discontinuity in the neural arch (incomplete ring sign) at the level of pedicle on axial CT is pathognomonic.,, It is extremely valuable in differentiating incomplete fractures from complete ones, as well as in identifying contralateral pedicle sclerosis in unilateral spondylolysis. The overall sensitivity of CT is around 85% (as compared with SPECT).
Morita et al. classified spondylolysis based on CT into three stages, namely early, progressive, and terminal stages [Table 1]. Defects with narrow, noncorticated margins have a good potential for healing with conservative management. On the other hand, lesions with a wide defect and sclerotic margins have low healing potential., CT is also the most sensitive investigation to confirm bony union, and typically the healing proceeds from the superior to the inferior cortex.
|Table 1: Morita classification of lytic lesions of pars inter-articularis|
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CT’s major limitations include relatively high radiation exposure, inability to diagnose early stress reactions, and difficulty in reliably distinguishing fresh fractures from nonunion.
Magnetic resonance imaging
MRI is the most useful investigation during the early stages of spondylolysis. Hyperintense signal changes on T2WI and short tau inversion and recovery sequences, at the level of pars, are indicative of edema secondary to active inflammation due to stress reaction or acute fracture. More chronic defects are characterized by focal hypo-intense regions on T1- and T2WI sagittal sequences [Figure 1]. Similarly, MRI also clearly depicts the tissue contained within the defect. While fibro-cartilaginous tissues appear hypointense on T1- and hypo- to isointense on T2WI, osseo-fibrous tissues appear as hypointense signals on both T1- and T2WI. High-intensity signals on T2WI represent inflammatory tissues or fluid. MRI is also useful in assessing Pfirrmann’s grading of degeneration of the disc, evaluating neural compression, and ruling out other pathologies.
|Figure 1: T1-weighted (A) and T2-weighted (B) sagittal MRI images of pars lysis|
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When compared with CT, MRI has 80% sensitivity in diagnosing spondylolysis, and is now recommended as the preferred investigation over CT and SPECT in the evaluation of spondylolysis. CT and MRI scans are corroborative and guide the management of lysis.,, Single photon emission tomography (SPECT) and hybrid SPECT-CT are preferred over the Tc99m bone scan but should be interpreted cautiously. SPECT is not recommended as an initial investigation in pars lysis. The current indications only include (a) detecting early stress reaction in patients with high suspicion when MRI is negative, (b) to differentiate acute lesions from pseudoarthrosis, (c) in determining the stage of healing and monitoring the response to conservative management.,
Tofte et al. have recommended an imaging approach for patients with suspected spondylolysis [Figure 2]. Similarly, Cheung et al. has recommended an approach for imaging in athletic patients with suspected spondylolysis. The classification put forth by Tatsamura et al., which uses both CT and MRI scans, guides the treatment and also predicts healing. The classification has two components, namely axial slice and sagittal slice classifications [Table 2]. On the basis of the imaging features, patients are divided into (a) curable stage—pre-lysis, early, and progressive—axial and sagittal stages of 0 to 2. (b) Pseudoarthrosis stage—terminal axial and sagittal stage 3.
|Figure 2: Diagnostic algorithm in a young patient suspected with spondylolysis [Tofte et al.]|
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Fluoroscopy-guided pars injection is an invasive procedure described as a therapeutic and diagnostic tool in symptomatic spondylolysis. Patients with ≥80% symptomatic pain relief for at least 60min after diagnostic pars block are reported to have a good prognostic outcome following pars repair., Pars injection has also been used therapeutically, using a combination of steroid and local anesthetic.,
The overall aim of treatment in active children with spondylolysis is to enable a return to regular activity or competitive sports without LBP. The goal of treating curable lesions with bone marrow edema is to achieve fusion through conservative measures. In patients with pseudo-arthritic lesions, aggressive physical rehabilitation should be performed to have relief from pain. Pars repair may be indicated in a small group of patients who have persistent pain despite conservative treatment.
Activity restriction, including timely cessation of sports in young athletes, is often the first step in the management of patients with symptomatic spondylolysis; this should be supplemented with a semi-hard lumbosacral brace to prevent lumbar extension and rotation. A full-time (≥20h/day) brace wear for at least 3 months has been demonstrated to result in complete osseous healing in ≥90% of patients. Physiotherapy protocol involving core strengthening and hamstring stretching exercises can be helpful after the completion of brace treatment., Sakai et al., based on their study involving 60 patients, reported 100% healing in the very early stage, 93.8% healing in the early stage, and 80% healing in the progressive stage. They did not try conservative treatment in the terminal group.
Low-intensity pulsed ultrasound therapy (LIPUS therapy)
The rationale underlying LIPUS is the stimulation of cellular production of cyclo-oxygenase 2 and consequent mineralization., LIPUS therapy, involving the use of ultrasound carriers at a frequency of 1.5 MHz, output intensity of 60 mW/cm2, and exposure time of 20min/day, has been demonstrated to significantly enhance healing rates. Busse et al. performed a meta-analysis and reported an average decrease in the healing time of 64 days in the LIPUS group when compared with the control. Though the initial results are promising, larger studies are necessary to assess the effectiveness.
Predictors of union
Overall, 87.5% of athletes returned to sports at a mean of 5.4 months following conservative treatment. Patients with a stress reaction on MRI and absent fracture line on CT show the best healing rates (almost 100%). Although unilateral spondylolysis has traditionally been considered to have high healing rates (around 70%), recent studies have also revealed that such lesions are not entirely benign and can potentially exert enormous amounts of stresses across the contralateral neural arches resulting in lysis of contralateral pars, pedicle, or lamina.,, The various predictive factors for a good outcome after conservative treatment of spondylolysis have been enumerated in [Table 3].
|Table 3: Positive predictors for pars defect union with conservative management|
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Surgery in spondylolysis has been recommended in symptomatic patients with pseudoarthrosis (terminal stage) following failed conservative management (≥6 months). The surgical options for these patients are either direct pars repair or lumbar fusion. Direct pars repair is preferred, as spinal fusion causes a decreased range of motion and may result in adjacent segment degeneration.,,
Candidates likely to have good outcomes after Pars repair
Patients ≤25 years of age, those with an athletic background, unilateral pathologies, and those without associated spondylolisthesis or instability or disc degeneration (Pfirmann grade 1–3) are ideal candidates for pars repair [Table 4].,, Suh et al. advocated that good pain relief after pars infiltration is also a good predictor for a successful outcome following pars repair. Patients with spina bifida occulta with hypoplastic posterior elements are poor candidates for pars repair.
Surgical techniques of pars repair
The surgical techniques can be classified as open and minimally invasive approaches. The basic principles underlying pars repair include debridement of pseudoarthrosis, placement of the bone graft, and achieving compression across the defect. Kimura was the first to perform a direct, noninstrumented pars repair. The various surgical techniques of pars repair have been discussed below.
Buck’s single lag screw fixation—
This technique involves direct internal fixation of pars defect with a lag screw (4.0 mm or 4.5 mm cortical screw) and autologous cancellous bone graft. The entry point is prepared by creating a notch in the inferior margin of the lamina, 10 mm lateral to the base of the spinous process. The screw trajectory is made across the defect with a 3.2 drill bit, in an upward, forward, and lateral direction (towards ipsilateral pedicle) [Figure 3]. Multiple studies have reported good results following Buck’s repair in 82%–100% of patients.,,,, It offers stable low-profile fixation, making it an excellent option in minimally invasive repairs. Disadvantages include difficult screw placement in the presence of narrow lamina and decreased amount of bone graft due to the screw.,,,
|Figure 3: Buck’s repair. A preoperative lateral radiograph (A), CT scan (B), and postoperative radiographs of a patient who underwent Buck’s repair|
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In 1986, Nicol and Scott described this technique of pars repair using stainless steel (SS) cerclage wire and bone grafting. In this technique, a 20-gauge SS wire is looped around the TPs bilaterally, and the four-wire ends are passed caudally to the spinous process of the affected segment. After bone grafting, the wires are tightened to achieve compression. Satisfactory results varying between 80% and 100% have been reported.,, Although technically more straightforward, this technique has many disadvantages, including significant muscle stripping, nerve root injury around TP, weak anchor points, implant failure, fatigue fracture of the spinous process, and need for postoperative bracing., A modification of the Scott technique is popular, and it involves the passage of wire around the pedicle screws passed into the pedicle of the affected vertebrae.
Cable-pedicle screw construct—
This technique described by Songer and Rovin involved the use of a special cable-screw construct. A double cable is passed under the lamina and threaded through a hole in the pedicle screw. It is then wrapped around the superior border of the spinous process before passing through a loop on the opposite end of the cable. Both cables are then tensioned simultaneously to achieve compression.
Morscher’s hook-screw technique—
Morscher designed a special hook-screw in which a spring-loaded screw holds the lamina snuggly and provides compression across the defect. Overall, studies have reported satisfactory results in 56%–83% of patients.,,, The major criticism against this technique is the high possibility of inaccurate screw placement, potentially leading to implant failure.
Pedicle screw hook fixation—
Tokuhashi and Matsuzaki described this modification of Morscher’s screw hook technique, wherein compression across the defect is achieved with the help of a proximal pedicle screw and a distal, infra-laminar hook connected by a 3/16 inch rod [Figure 4]. The implant failure rates are significantly less with this technique, and the overall good outcome has been reported in 79%–100% of patients.,,, The main advantages are the availability of a large area for bone grafting and the absence of a need for postoperative bracing.
|Figure 4: Pedicle screw-hook fixation. A preoperative lateral radiograph (A), CT scan (B), and postoperative radiographs of a patient who underwent Buck’s repair on the right side and pedicle screw-hook construct on the left side|
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Butterfly plate fixation technique—
Louis, in 1988, reported a 93.5% success rate using his construct of a specially designed butterfly plate and screws.
Rod-screw construct/V-rod technique—
Gillet and Petit in 1999 described a technique of repairing pars defect with a V-shaped rod and pedicle screw construct. In a patient with L5 spondylolysis, pedicle screws are inserted into the L5 vertebra bilaterally, and a V-shaped 6 mm rod is passed through the L5-S1 interspinous ligament. Both limbs of the rods are fixed to the pedicle screws with compression across the defect. A similar technique was described by Noordeen, where the V-shaped rod is replaced by a U shaped modular link, popularly described as the “Smiley face technique” [Figure 5]. The overall success rates with this technique have been reported to be around 80%.
|Figure 5: Smiley face technique. A preoperative lateral radiograph (A), postoperative radiographs (B), and clinical photos (C) of a patient who underwent pars repair by smiley face technique (screw-rod technique). Image courtesy: Dr. Subbaiah M, Madurai|
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Temporary short segment fixation—
Huang et al. described a “temporary short segment fixation” technique using pedicle screws and transverse connecting rod, wherein the implant removal is performed after the complete bony union. He reported 100% success rates with this technique. Although it is a safe and stable construct, it is more invasive and necessitates a second surgery for implant removal.
Fan et al. studied the biomechanical effects of various surgical techniques on calf cadaveric spines. They found no significant difference between Modified Scott, screw-rod-hook, screw-rod, and Buck’s techniques with regard to rotational and lateral flexion stresses. The screw-rod-hook and Buck’s techniques demonstrated more excellent stability in flexion and extension. In a prospective study, Lee et al. compared 87 conservatively treated patients to another group of 62 patients treated by Buck’s repair. The surgically treated group had significant pain relief at a 1-month follow-up. However, there was no statistically significant difference in the functional and radiological outcome between the two groups at 1-year follow-up.
Based on a systematic review, Drazin et al. reported that 84% of patients were able to return to sports after pars repair, and no significant difference was observed between the outcomes following different pars repair procedures.
Recent advances in pars repair
Minimally invasive surgery
With the significant advancements in present-day technology, it is possible to perform pars repair by minimally invasive techniques using fluoroscopic, microscopic (with tubular retractors), endoscopic, robotic, or navigation-assisted approaches.,, The techniques utilize tubular retractors or endoscopy to access the pseudoarthrosis and perform debridement and add bone graft, while the screws, as in Buck’s repair, are placed accurately by image or navigation guidance.
Studies have shown that microscopy/endoscopy-assisted pseudoarthrosis debridement and navigation-assisted lag screw placement can significantly enhance the accuracy and outcome following pars repair by Buck’s technique. Recent literature suggests that the healing rates are significantly enhanced by using such advanced modalities, with reported success rates ranging between 81.3% and 91.7%.,,
In a recent systematic review, Kolcun et al. concluded that minimally invasive approaches were associated with significantly higher pain resolution, shorter recovery, and better clinical outcomes. Nevertheless, MIS techniques are still evolving, and large-scale prospective studies in the future are necessary to throw more light on their benefits over conventional techniques.
Postoperative rehabilitation and follow-up
There is no standard recommendation for the postoperative rehabilitative protocol following pars repair. The protocol must be tailor-made based on the patient profile, surgeon’s preference, and technique employed. [Figure 6] describes a postoperative rehabilitative protocol (based on the suggestions by Radcliff) for patients undergoing pars repair.
|Figure 6: Flowchart showing postoperative rehabilitative protocol after pars repair (Radcliff)|
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| Conclusion|| |
Spondylolysis is an important differential diagnosis to be considered in all children, adolescents, and young sportspersons presenting with LBP. Treatment decisions and prognosis depend on staging and, therefore, an early diagnosis is crucial for better outcomes. Imaging modalities must be used with discretion to aid in diagnosis and treatment planning. Most symptomatic patients respond well to conservative treatment, and high success has been reported in early and progressive lesions. In a specific subset of patients with persistent symptoms, pars repair provides good relief of symptoms. Recently, technological advancements have paved the way for minimally invasive approaches to repair the pars defects. Such approaches can potentially enhance the healing rates and ameliorate the clinical outcome in these children.
The authors thank Dr. Vibhukrishnan Vishwanathan for his valuable help in editing the manuscript.
Financial support and sponsorship
Conflict of interest
None of the authors has any conflict of interest.
| References|| |
Simper LB Spondylolysis in Eskimo skeletons. Acta Orthop Scand 1986;57:78-80.
Rothman SL, Glenn WV Jr. CT multiplanar reconstruction in 253 cases of lumbar spondylolysis. AJNR Am J Neuroradiol 1984;5:81-90.
Fredrickson BE, Baker D, McHolick WJ, Yuan HA, Lubicky JP The natural history of spondylolysis and spondylolisthesis. J Bone Joint Surg Am 1984;66:699-707.
Chosa E, Totoribe K, Tajima N A biomechanical study of lumbar spondylolysis based on a three-dimensional finite element method. J Orthop Res 2004;22:158-63.
Dietrich M, Kurowski P The importance of mechanical factors in the etiology of spondylolysis. A model analysis of loads and stresses in human lumbar spine. Spine (Phila Pa 1976) 1985;10:532-42.
Merbs CF Spondylolysis and spondylolisthesis: A cost of being an erect biped or a clever adaptation? Am J Phys Anthropol 1996;101(S23):201-28.
Cheung KK, Dhawan RT, Wilson LF, Peirce NS, Rajeswaran G Pars interarticularis injury in elite athletes [The role of imaging in diagnosis and management]. Eur J Radiol 2018;108:28-42.
Rowe GG, Roche MB The etiology of separate neural arch. J Bone Joint Surg Am 1953;35-A:102-10.
Batts MJ The etiology of spondylolisthesis. J Bone Joint Surg 1939;21:879-84.
Friberg S Studies on spondylolisthesis. Acta Chir Scand1939;82:1-140.
Wiltse LL Etiology of spondylolisthesis. Clin Orthop 1957;10:48-60.
Wiltse LL The etiology of spondylolisthesis. J Bone Joint Surg Am 1962;44-A:539-60.
Wynne-Davies R, Scott JH Inheritance and spondylolisthesis: A radiographic family survey. J Bone Joint Surg Br 1979;61-B:301-5.
Albanese M, Pizzutillo PD Family study of spondylolysis and spondylolisthesis. J Pediatr Orthop 1982;2:496-9.
Wiltse LL, Widell EH Jr, Jackson DW Fatigue fracture: The basic lesion is inthmic spondylolisthesis. J Bone Joint Surg Am 1975;57:17-22.
Micheli LJ, Wood R Back pain in young athletes. Significant differences from adults in causes and patterns. Arch Pediatr Adolesc Med 1995;149:15-8.
Zetaruk M Lumbar spine injuries. In: Micheli LJ, Purcell L, editors. The Adolescent Athlete: A Practical Approach. New York, NY: Springer; 2007. pp. 109-40.
Tawfik S, Phan K, Mobbs RJ, Rao PJ The incidence of pars interarticularis defects in athletes. Global Spine J 2020;10:89-101.
Rosenberg NJ, Bargar WL, Friedman B The incidence of spondylolysis and spondylolisthesis in nonambulatory patients. Spine (Phila Pa 1976) 1981;6:35-8.
Sairyo K, Katoh S, Komatsubara S, Terai T, Yasui N, Goel VK, et al
. Spondylolysis fracture angle in children and adolescents on CT indicates the fracture producing force vector: A biomechanical rationale. Int J Spine Surg2005;1(2).
Cyron BM, Hutton WC The fatigue strength of the lumbar neural arch in spondylolysis. J Bone Joint Surg Br 1978;60-B:234-8.
Martin RP, Deane RH, Collett V Spondylolysis in children who have osteopetrosis. J Bone Joint Surg Am 1997;79:1685-9.
Szappanos L, Szepesi K, Thomázy V Spondylolysis in osteopetrosis. J Bone Joint Surg Br 1988;70:428-30.
Sakai T, Yamada H, Nakamura T, Nanamori K, Kawasaki Y, Hanaoka N, et al
. Lumbar spinal disorders in patients with athetoid cerebral palsy: A clinical and biomechanical study. Spine (Phila Pa 1976) 2006;31:E66-70.
Takada S The incidence of spondylolysis in cerebral palsied patients (children and adults). Chubu Nihon Seikeigeka Saigaigeka Gakkai Zasshi (Cent Jpn J Orthop Traumatol) 1985;28:476-8.
Ogilvie JW, Sherman J Spondylolysis in Scheuermann’s disease. Spine (Phila Pa 1976) 1987;12:251-3.
Greene TL, Hensinger RN, Hunter LY Back pain and vertebral changes simulating Scheuermann's disease. J Pediatr Orthop 1985;5:1-7.
Weiner BK, Walker M, Wiley W, McCulloch JA The lateral buttress: An anatomic feature of the lumbar pars interarticularis. Spine (Phila Pa 1976) 2002;27:E385-7.
Ebraheim NA, Lu J, Hao Y, Biyani A, Yeasting RA Anatomic considerations of the lumbar isthmus. Spine (Phila Pa 1976) 1997;22:941-5.
Peleg S, Dar G, Steinberg N, Masharawi Y, Been E, Abbas J, et al
. Sacral orientation and spondylolysis. Spine (Phila Pa 1976) 2009;34:E906-10.
Dunn AJ, Campbell RSD, Mayor PE, Rees D Radiological findings and healing patterns of incomplete stress fractures of the pars interarticularis. Skeletal Radiol 2008;37:443-50.
Sairyo K, Sakai T, Yasui N Conservative treatment of lumbar spondylolysis in childhood and adolescence: The radiological signs which predict healing. J Bone Joint Surg Br 2009;91:206-9.
Kajiura K, Katoh S, Sairyo K, Ikata T, Goel VK, Murakami RI Slippage mechanism of pediatric spondylolysis: Biomechanical study using immature calf spines. Spine (Phila Pa 1976) 2001;26:2208-12; discussion 2212-3.
Konz RJ, Goel VK, Grobler LJ, Grosland NM, Spratt KF, Scifert JL, et al
. The pathomechanism of spondylolytic spondylolisthesis in immature primate lumbar spines in vitro and finite element assessments. Spine (Phila Pa 1976) 2001;26:E38-49.
Seitsalo S, Osterman K, Hyvãrinen H, Tallroth K, Schlenzka D, Poussa M Progression of spondylolisthesis in children and adolescents. A long-term follow-up of 272 patients. Spine (Phila Pa 1976) 1991;16:417-21.
Sairyo K, Katoh S, Ikata T, Fujii K, Kajiura K, Goel VK Development of spondylolytic olisthesis in adolescents. Spine J 2001;1:171-5.
Saraste H Long-term clinical and radiological follow-up of spondylolysis and spondylolisthesis. J Pediatr Orthop 1987;7:631-8.
Beutler WJ, Fredrickson BE, Murtland A, Sweeney CA, Grant WD, Baker D The natural history of spondylolysis and spondylolisthesis: 45-year follow-up evaluation. Spine (Phila Pa 1976) 2003;28:1027-35; discussion 1035.
Sairyo K, Goel VK, Faizan A, Vadapalli S, Biyani S, Ebraheim N Buck’s direct repair of lumbar spondylolysis restores disc stresses at the involved and adjacent levels. Clin Biomech (Bristol, Avon) 2006;21:1020-6.
Porter RW, Hibbert CS Symptoms associated with lysis of the pars interarticularis. Spine (Phila Pa 1976) 1984;9:755-8.
Stanitski CL Pediatric and adolescent sports injuries. Clin Sports Med 1997;16:613-33.
d’Hemecourt PA, Zurakowski D, Kriemler S, Micheli LJ Spondylolysis: Returning the athlete to sports participation with brace treatment. Orthopedics 2002;25:653-7.
Masci L, Pike J, Malara F, Phillips B, Bennell K, Brukner P Use of the one-legged hyperextension test and magnetic resonance imaging in the diagnosis of active spondylolysis. Br J Sports Med 2006;40:940-6; discussion 946.
Jackson DW, Wiltse LL, Dingeman RD, Hayes M Stress reactions involving the pars interarticularis in young athletes. Am J Sports Med 1981;9:304-12.
Hirano A, Takebayashi T, Yoshimoto M, Ida K, Yamashita T. Characteristics of clinical and imaging findings in adolescent lumbar spondylolysis associated with sports activities. J Spine2012;1:2.
Tofte JN, CarlLee TL, Holte AJ, Sitton SE, Weinstein SL Imaging pediatric spondylolysis: A systematic review. Spine (Phila Pa 1976) 2017;42:777-82.
Miller R, Beck NA, Sampson NR, Zhu X, Flynn JM, Drummond D Imaging modalities for low back pain in children: A review of spondylolysis and undiagnosed mechanical back pain. J Pediatr Orthop 2013;33:282-8.
Ravichandran G A radiologic sign in spondylolisthesis. AJR Am J Roentgenol 1980;134:113-7.
Maldague BE, Malghem JJ Unilateral arch hypertrophy with spinous process tilt: A sign of arch deficiency. Radiology 1976;121: 567-74.
Standaert CJ, Herring SA Spondylolysis: A critical review. Br J Sports Med 2000;34:415-22.
Jarvik JG, Deyo RA Diagnostic evaluation of low back pain with emphasis on imaging. Ann Intern Med 2002;137:586-97.
Gregory PL, Batt ME, Kerslake RW, Webb JK Single photon emission computerized tomography and reverse gantry computerized tomography findings in patients with back pain investigated for spondylolysis. Clin J Sport Med 2005;15:79-86.
Yang J, Servaes S, Edwards K, Zhuang H Prevalence of stress reaction in the pars interarticularis in pediatric patients with new-onset lower back pain. Clin Nucl Med 2013;38:110-4.
Ozturk ES, Ozturk K, Parlak M Imaging principles of spondylolysis. Eur Congress Radiol2017.
Leone A, Cianfoni A, Cerase A, Magarelli N, Bonomo L Lumbar spondylolysis: A review. Skeletal Radiol 2011;40:683-700.
Morita T, Ikata T, Katoh S, Miyake R Lumbar spondylolysis in children and adolescents. J Bone Joint Surg Br 1995;77:620-5.
Pizzutillo PD, Hummer CD III. Nonoperative treatment for painful adolescent spondylolysis or spondylolisthesis. J Pediatr Orthop 1989;9:538-40.
Johnson DW, Farnum GN, Latchaw RE, Erba SM MR imaging of the pars interarticularis. AJR Am J Roentgenol 1989;152:327-32.
Campbell RS, Grainger AJ, Hide IG, Papastefanou S, Greenough CG Juvenile spondylolysis: A comparative analysis of CT, SPECT and MRI. Skeletal Radiol 2005;34:63-73.
Yamaguchi KT Jr, Skaggs DL, Acevedo DC, Myung KS, Choi P, Andras L Spondylolysis is frequently missed by MRI in adolescents with back pain. J Child Orthop 2012;6:237-40.
Matesan M, Behnia F, Bermo M, Vesselle H SPECT/CT bone scintigraphy to evaluate low back pain in young athletes: Common and uncommon etiologies. J Orthop Surg Res 2016;11:76.
Papanicolaou N, Wilkinson RH, Emans JB, Treves S, Micheli LJ Bone scintigraphy and radiography in young athletes with low back pain. AJR Am J Roentgenol 1985;145:1039-44.
Tatsumura M, Gamada H, Ishimoto R, Okuwaki S, Eto F, Ogawa T, et al
. Prevalence of curable and pseudoarthrosis stages of adolescent lumbar spondylolysis. J Rural Med 2018;13:105-9.
Sarazin L, Chevrot A, Pessis E, Minoui A, Drape JL, Chemla N, et al
. Lumbar facet joint arthrography with the posterior approach. Radiographics 1999;19:93-104.
Suh PB, Esses SI, Kostuik JP Repair of pars interarticularis defect. The prognostic value of pars infiltration. Spine (Phila Pa 1976) 1991;16:S445-8.
Wu SS, Lee CH, Chen PQ Operative repair of symptomatic spondylolysis following a positive response to diagnostic pars injection. J Spinal Disord 1999;12:10-6.
Kershen LM, Nacey NC, Patrie JT, Fox MG Accuracy and efficacy of fluoroscopy-guided pars interarticularis injections on immediate and short-term pain relief. Skeletal Radiol 2016;45:1329-35.
Kang WY, Lee JW, Lee E, Kang Y, Ahn JM, Kang HS Efficacy and outcome predictors of fluoroscopy-guided facet joint injection for spondylolysis. Skeletal Radiol 2018;47:1137-44.
Klein G, Mehlman CT, McCarty M Nonoperative treatment of spondylolysis and grade I spondylolisthesis in children and young adults: A meta-analysis of observational studies. J Pediatr Orthop 2009;29:146-56.
Sairyo K, Sakai T, Yasui N, Dezawa A Conservative treatment for pediatric lumbar spondylolysis to achieve bone healing using a hard brace: What type and how long?: Clinical article. J Neurosurg Spine 2012;16:610-4.
El Rassi G, Takemitsu M, Glutting J, Shah SA Effect of sports modification on clinical outcome in children and adolescent athletes with symptomatic lumbar spondylolysis. Am J Phys Med Rehabil 2013;92:1070-4.
Sakai T, Tezuka F, Yamashita K, Takata Y, Higashino K, Nagamachi A, et al
. Conservative treatment for bony healing in pediatric lumbar spondylolysis. Spine (Phila Pa 1976) 2017;42:E716-20.
Tang CH, Yang RS, Huang TH, Lu DY, Chuang WJ, Huang TF, et al
. Ultrasound stimulates cyclooxygenase-2 expression and increases bone formation through integrin, focal adhesion kinase, phosphatidylinositol 3-kinase, and akt pathway in osteoblasts. Mol Pharmacol 2006;69:2047-57.
Leung KS, Cheung WH, Zhang C, Lee KM, Lo HK Low intensity pulsed ultrasound stimulates osteogenic activity of human periosteal cells. Clin Orthop Relat Res 2004;418:253-9.
Arima H, Suzuki Y, Togawa D, Mihara Y, Murata H, Matsuyama Y Low-intensity pulsed ultrasound is effective for progressive-stage lumbar spondylolysis with MRI high-signal change. Eur Spine J 2017;26:3122-8.
Busse JW, Bhandari M, Kulkarni AV, Tunks E The effect of low-intensity pulsed ultrasound therapy on time to fracture healing: A meta-analysis. Cmaj 2002;166:437-41.
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 2004;14:346-51.
Porter RW, Park W Unilateral spondylolysis. J Bone Joint Surg Br 1982;64:344-8.
Sairyo K, Katoh S, Takata Y, Terai T, Yasui N, Goel VK, et al
. MRI signal changes of the pedicle as an indicator for early diagnosis of spondylolysis in children and adolescents: A clinical and biomechanical study. Spine (Phila Pa 1976) 2006;31:206-11.
Fujii K, Katoh S, Sairyo K, Ikata T, Yasui N Union of defects in the pars interarticularis of the lumbar spine in children and adolescents. The radiological outcome after conservative treatment. J Bone Joint Surg Br 2004;86:225-31.
Ivanic GM, Pink TP, Achatz W, Ward JC, Homann NC, May M Direct stabilization of lumbar spondylolysis with a hook screw: Mean 11-year follow-up period for 113 patients. Spine (Phila Pa 1976) 2003;28:255-9.
Debnath UK, Scammell BE, Freeman BJC, McConnell JR Predictive factors for the outcome of surgical treatment of lumbar spondylolysis in young sporting individuals. Global Spine J 2018;8:121-8.
Debusscher F, Troussel S Direct repair of defects in lumbar spondylolysis with a new pedicle screw hook fixation: Clinical, functional and CT-assessed study. Eur Spine J 2007;16:1650-8.
Kimura M [My method of filing the lesion with spongy bone in spondylolysis and spondylolistesis]. Seikei Geka 1968;19:285-96.
Buck JE Direct repair of the defect in spondylolisthesis. Preliminary report. J Bone Joint Surg Br 1970;52:432-7.
Menga EN, Jain A, Kebaish KM, Zimmerman SL, Sponseller PD Anatomic parameters: Direct intralaminar screw repair of spondylolysis. Spine (Phila Pa 1976) 2014;39:E153-8.
Pedersen AK, Hagen R Spondylolysis and spondylolisthesis. Treatment by internal fixation and bone-grafting of the defect. J Bone Joint Surg Am 1988;70:15-24.
Hardcastle PH Repair of spondylolysis in young fast bowlers. J Bone Joint Surg Br 1993;75:398-402.
Bonnici AV, Koka SR, Richards DJ Results of buck screw fusion in grade I spondylolisthesis. J R Soc Med 1991;84:270-3.
Roca J, Moretta D, Fuster S, Roca A Direct repair of spondylolysis. Clin Orthop Relat Res 1989;246:86-91.
Rajasekaran S, Subbiah M, Shetty AP Direct repair of lumbar spondylolysis by buck’s technique. Indian J Orthop 2011;45:136-40.
Beckers L Buck’s operation for treatment of spondylolysis and spondylolisthesis. Acta Orthop Belg 1986;52:819-23.
Deguchi M, Rapoff AJ, Zdeblick TA Biomechanical comparison of spondylolysis fixation techniques. Spine (Phila Pa 1976) 1999;24:328-33.
Ulibarri JA, Anderson PA, Escarcega T, Mann D, Noonan KJ Biomechanical and clinical evaluation of a novel technique for surgical repair of spondylolysis in adolescents. Spine (Phila Pa 1976) 2006;31:2067-72.
Altaf F, Osei NA, Garrido E, Al-Mukhtar M, Natali C, Sivaraman A, et al
. Repair of spondylolysis using compression with a modular link and screws. J Bone Joint Surg Br 2011;93:73-7.
Nicol RO, Scott JH Lytic spondylolysis. Repair by wiring. Spine (Phila Pa 1976) 1986;11:1027-30.
Jeanneret B Direct repair of spondylolysis. Acta Orthop Scand Suppl 1993;251:111-5.
Songer MN, Rovin R Repair of the pars interarticularis defect with a cable-screw construct. A preliminary report. Spine (Phila Pa 1976) 1998;23:263-9.
Sales de Gauzy J, Vadier F, Cahuzac JP Repair of lumbar spondylolysis using Morscher material: 14 children followed for 1–5 years. Acta Orthop Scand 2000;71:292-6.
Pavlovcic V Surgical treatment of spondylolysis and spondylolisthesis with a hook screw. Int Orthop 1994;18:6-9.
Albassir A, Samson I, Hendrickx L [Treatment of painful spondylolysis using Morscher’s hook]. Acta Orthop Belg 1990;56:489-95.
Hefti F, Seelig W, Morscher E Repair of lumbar spondylolysis with a hook-screw. Int Orthop 1992;16:81-5.
Tokuhashi Y, Matsuzaki H Repair of defects in spondylolysis by segmental pedicular screw hook fixation. A preliminary report. Spine (Phila Pa 1976) 1996;21:2041-5.
Kakiuchi M Repair of the defect in spondylolysis. Durable fixation with pedicle screws and laminar hooks. J Bone Joint Surg Am 1997;79:818-25.
Louis R [Pars interarticularis reconstruction of spondylolysis using plates and screws with grafting without arthrodesis. Apropos of 78 cases]. Rev Chir Orthop Reparatrice Appar Mot 1988;74:549-57.
Gillet P, Petit M Direct repair of spondylolysis without spondylolisthesis, using a rod-screw construct and bone grafting of the pars defect. Spine (Phila Pa 1976) 1999;24:1252-6.
Huang Y, Liu J, Guo L, Meng Y, Hao D, Du J “Temporary” short segment fixation in treating adolescent lumbar spondylolysis. World Neurosurg 2019;123:e77-84.
Fan J, Yu GR, Liu F, Zhao J, Zhao WD A biomechanical study on the direct repair of spondylolysis by different techniques of fixation. Orthop Surg 2010;2:46-51.
Lee GW, Lee SM, Ahn MW, Kim HJ, Yeom JS Comparison of surgical treatment with direct repair versus conservative treatment in young patients with spondylolysis: A prospective, comparative, clinical trial. Spine J 2015;15:1545-53.
Drazin D, Shirzadi A, Jeswani S, Ching H, Rosner J, Rasouli A, et al
. Direct surgical repair of spondylolysis in athletes: Indications, techniques, and outcomes. Neurosurg Focus 2011;31:E9.
Brennan RP, Smucker PY, Horn EM Minimally invasive image-guided direct repair of bilateral L-5 pars interarticularis defects. Neurosurg Focus 2008;25:E13.
Widi GA, Williams SK, Levi AD Minimally invasive direct repair of bilateral lumbar spine pars defects in athletes. Case Rep Med 2013;2013:659078.
Min J, Wang J, Zhang Z, Zheng W, Zhou Y Direct repair of lumbar pars interarticularis defects by utilizing intraoperative O-arm-based navigation and microendoscopic techniques. Spine2016;41:B6-13.
Zhu X, Wang J, Zhou Y, Zhang Z, Li C, Zheng W [Minimally invasive surgery for direct repair of lumbar spondylolysis by utilizing intraoperative navigation and microendoscopic techniques]. Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi 2015;29: 1244-8.
Goncalves-Ramírez FJ, Serrano MT, Lee SH, Dominguez CJ, Manuel-Rimbau J Headless compression screw in the neuronavigation-guided and microscope-assisted treatment of spondylolysis. Neurocirugia (Astur) 2017;29:122-30.
Kolcun JPG, Chieng LO, Madhavan K, Wang MY Minimally-invasive versus conventional repair of spondylolysis in athletes: A review of outcomes and return to play. Asian Spine J 2017;11:832-42.
Radcliff KE, Kalantar SB, Reitman CA Surgical management of spondylolysis and spondylolisthesis in athletes: Indications and return to play. Curr Sports Med Rep 2009;8:35-40.
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
[Table 1], [Table 2], [Table 3], [Table 4]