Spondylolysis originates in the ventral aspect of the pars interarticularis: a clinical and biomechanical study

Characteristics of lumbar spondylolysis: L5 versus non-L5

BACKGROUND

Fifth lumbar vertebra (L5) spondylolysis has a lower bone union rate than non-L5 spondylolysis, but the reason for this is unknown. This study aimed to evaluate the differences in patient and lesion characteristics between L5 and non-L5 spondylolysis.

METHODS

A total of 410 patients with lumbar spondylolysis aged 18 years or younger who were treated conservatively were enrolled. Patients and lesions were divided into L5 and non-L5 (L2-L4) spondylolysis. Factors, including sex, age, presence of spina bifida occulta, stage of the main side lesion, whether the lesion was unilateral or bilateral, presence and stage of the contralateral side lesion and treatment duration, were evaluated at the first visit and compared between the two groups.

RESULTS

A total of 250 patients with 349 lesions were included. The bone union rate of L5 lesions was lower than that of non-L5 lesions (75% vs. 86%, p = 0.015). Patients with L5 spondylolysis were more likely to be male (86% vs. 66%) and younger (14.0 vs. 14.6 years) than patients with non-L5 spondylolysis. Lesions of L5 spondylolysis were more likely to be in a progressive stage (28% vs. 15%), less likely to be in a pre-lysis stage (28% vs. 43%) and more likely to be in a contralateral terminal stage (14% vs. 5.3%, p = 0.013) compared with lesions of non-L5 spondylolysis.

CONCLUSIONS

L5 spondylolysis was characterised by a lower bone union rate, more males, younger age, more progressive stage and more contralateral pseudarthrosis than non-L5 spondylolysis.

Effect of lumbar lordosis angle on the development of lumbar spondylolysis in adolescent baseball players: A cross-sectional study

BACKGROUND

Lumbar spondylolysis (LS) is a lumbar vertebral arch stress fracture that often occurs in adolescent athletes, especially baseball players. An increase in lumbar lordosis angle (LLA) increases the compressive stress on the vertebral arch, influencing the development of LS. However, the effect of LLA on LS development in adolescent baseball players is unknown. Therefore, it is necessary to elucidate the risk factors that influence the development of LS. This cross-sectional study aimed investigate the effect of LLA on LS development in adolescent baseball players.

METHODS

Patients were male baseball players aged 11-18 years who visited an orthopedic clinic with a chief complaint of lumbar pain and underwent a magnetic resonance imaging (MRI) examination between January 1, 2018, and October 31, 2021. LLA was defined as the angle formed by the line parallel to the superior endplate of the L1 and S1. A person other than the data analyst measured LLA three times from the MRI, and the average value was used for data analysis. Logistic regression analysis was performed, with the presence or absence of LS as the objective variable and LLA, age, and previous pitching experience as explanatory variables.

RESULTS

Of the 112 subjects included, 79 were in the LS group and 33 in the non-LS group. The LLA was 45.42 ± 8.19° in the LS group and 36.68 ± 8.26° in the non-LS group, with significant differences between the groups. Logistic regression analysis showed that LLA significantly differed with an odds ratio of 1.140 (95% confidence interval: 1.070-1.21), even after adjusting for age and previous pitching experience.

CONCLUSIONS

LLA in adolescent baseball players was significantly greater in the LS group than in the non-LS group, which may influence the development of LS.

Biomechanical evaluation of lumbar spondylolysis repair with various fixation options: A finite element analysis

Objective: This study was designed to compare the biomechanical properties of lumbar spondylolysis repairs using different fixation methods by using three-dimensional finite element analysis.

Methods: Five finite element models (A, B, C, D, and E) of L4-S1 vertebral body were reconstructed by CT images of a male patient (A: intact model; B: spondylolysis model; C: spondylolysis model with intrasegmental direct fixation by Buck screw; D: spondylolysis model with intersegmental indirect fixation by pedicle screw system; E: spondylolysis model with hybrid internal fixation). L5-S1 level was defined as the operative level. After the intact model was verified, six physiological motion states were simulated by applying 500 N concentrated force and 10 Nm torque on the upper surface of L4. The biomechanical properties of the three different internal fixation methods were evaluated by comparing the range of motion (ROM), maximum stress, and maximum displacement.

Results: Compared with Model B, the ROM and maximum displacement of Model C, D, and E decreased. The maximum stress on L5/S1 disc in models A, B, and C was much higher than that in Model D and E under extension and lateral bending conditions. Under axial rotation and lateral bending conditions, the maximum stress of interarticular muscle and internal fixation system in Model B and Model C was significantly higher than that in Model D and Model E. In contrast to Model D, the stress in Model E was distributed in two internal fixation systems.

Conclusion: In several mechanical comparisons, hybrid fixation had better biomechanical properties than other fixation methods. The experimental results show that hybrid fixation can stabilize the isthmus and reduce intervertebral disc stress, which making it the preferred treatment for lumbar spondylolysis.

Spondylolysis

Spondylolysis is a bony defect of the pars interarticularis and most often results from repetitive stress. Although spondylolysis is usually asymptomatic, symptomatic spondylolysis is the most common cause of identifiable back pain in children and adolescent athletes. A thorough history and physical exam, as well as appropriate imaging studies are helpful in diagnosis. General first-ine therapy for spondylolysis is conservative and consists of rest from sports, core strengthening, as well as spinal bracing. Patients who have failed conservative therapy may consider surgical repair. This article aims to review the epidemiology, pathophysiology, presentation, and treatment options of spondylolysis.

Diagnosis and Management of Spondylolysis and Spondylolisthesis in Children

»

Spondylolysis is defined as a defect of the pars interarticularis, and spondylolisthesis is defined as a slippage of a vertebra relative to the immediately caudal vertebra.

»

Most cases of spondylolysis and low-grade spondylolisthesis can be treated nonoperatively. Depending on a patient's age, nonoperative treatment may include a thoracolumbosacral orthosis (TLSO), physical therapy, and activity modification. Bracing and physical therapy have been found to be more effective than activity modification alone.

»

Patients with dysplastic spondylolisthesis are at higher risk for progression and should be monitored with serial radiographs every 6 to 9 months.

»

Operative management is recommended for symptomatic patients with failure of at least 6 months of nonoperative management or patients with high-grade spondylolisthesis.

»

Surgical techniques include pars defect repair, reduction, and fusion, which may include posterior-only, anterior-only, or circumferential fusion.

Prevalence of Multiple-Level Spondylolysis and the Bone Union Rates among Growth-Stage Children with Lower Back Pain

Introduction

Lumbar spondylolysis is usually single level, and only a few multiple-level cases have been reported. We investigated the frequency of multiple-level spondylolysis and the bone union rates among growth-stage children with lower back pain (LBP).

Methods

The subjects were growth-stage children examined for LBP between April 2013 and December 2018. All patients with LBP persisting for at least 2 weeks and severe enough to make playing sports difficult underwent lumbar plain radiogram, computed tomography, and magnetic resonance imaging. The cases diagnosed as multiple-level spondylolysis and classified as early or progressive stage received conservative treatment to achieve bone union.

Results

A total of 782 growth-stage children were examined for LBP. Of them, 243 children (31.1%) were diagnosed with lumbar spondylolysis. Of these 243 children, 23 (9.5%) children had multiple-level spondylolysis. Of the children diagnosed with multiple-level spondylolysis, most children (87.0%) had pars defects in the early or progressive stage in which bone union could be expected. Most children (78.3%) had pars defects in the terminal stage and combined with these defects, had pars defects in the early or progressive stage at a different spinal level.

Twenty children diagnosed with multiple-level spondylolysis who also had pars defects in the early or progressive stage received conservative treatment for bone union, which was achieved in 31 of 39 sites (79.5%). The bone union rate by stage was 92.9% (26 of 28 sites) in the early stage and 45.5% (5 of 11 sites) in the progressive stage.

Conclusions

In cases of multiple-level spondylolysis, bone union is likely to be achieved with conservative treatment when the pars defects are in the early or progressive stage. Therefore, the first choice of treatment should be conservative treatment to achieve bone union, the same for single-level spondylolysis.

Repair of symptomatic bilateral L5 spondylolysis with autogenous iliac crest graft and temporary intersegmental pedicle screw fixation in youth

Background

When symptomatic spondylolysis fail to respond to nonoperative treatment, surgical management may be required. A number of techniques have been described for repair by intrasegmental fixation with good results; however, there are still some problems. We reported a repair technique with temporary intersegmental pedicle screw fixation and autogenous iliac crest graft. The aim of present study is to assess the clinical outcomes of L5 symptomatic spondylolysis with this technique.

Methods

A retrospective analysis of 128 patients with L5 spondylolysis treated with this method was performed. According to CT scan, the spondylolysis were classified into 3 categories: line, intermediate, and sclerosis type. The diagnostic block test of L5 bilateral pars defect was done in all patients preoperatively. The sagittal and axial CT images were used to determine the bone union. The healing time, complications, number of spina bifida occulta, Japanese Orthopedic Association (JOA) score, and VAS for back pain were recorded. After fixation removal, the rate of ROM preservation at L5S1 was calculated.

Results

There were 97 patients (194 pars) followed with mean follow-up of 23 months (range, 12–36 months). The union rate of pars was 82.0% at 12 months and 94.3% at 24 months postoperatively. Low back pain VAS significantly (P < 0.05) improved from preoperative mean value of 7.2 to 1.3 at the final follow-up postoperatively (P < 0.05). JOA score increased significantly postoperatively (P < 0.05) with average improvement rate of 79.3%. The rates of L5S1 ROM preservation were 79.8% and 64.0% after fixation removal at 1 and 2 years postoperatively. There were 3 patients of delayed incision healing without other complications.

Conclusions

Although sacrificing L5S1 segment motion temporarily, more stability was obtained with intersegmental fixation. This technique is reliable for spondylolysis repair which has satisfactory symptom relief, high healing rate, low incidence of complications, and preserve a large part of ROM for fixed segment.

Familial development of lumbar spondylolysis: a familial case report of 7- and 4-year-old brothers and their father

The incidence of lumbar spondylolysis is affected by sex, race, and congenital abnormalities. These differences suggest a genetic component to the etiology of spondylolysis. However, no definitive evidence has been presented regarding the inheritance of lumbar spondylolysis. We report familial cases of lumbar spondylolysis in 7- and 4-year-old brothers and their father, each of whom visited our clinic complaining of low back pain. Spondylolysis in the fifth lumbar vertebra (L5) was identified in both boys and their father from clinical, radiographic, computed tomographic, and magnetic resonance imaging examinations. Conservative treatment was provided for both boys. No bony union of any spondylolytic lesions was obtained, but they returned to sports activity without low back pain. Frequent development of spondylolysis, even at younger ages, in all male family members might indicate an underlying genetic etiology in lumbar spondylolysis, primarily in the form of autosomal dominant inheritance. However, information on patients and their parents should be considered carefully, as bony union with conservative therapy is not expected in such patients.

Presence of bone marrow oedema in asymptomatic elite fast bowlers: Implications for management

OBJECTIVES

1) Quantify the intensity of bone marrow oedema (BMO) present in the lumbar vertebrae of asymptomatic elite adult fast bowlers; 2) relate the intensity of BMO to bowling workload and lumbar bone stress injury (LBSI), and; 3) evaluate the utility of MRI screening to reduce the risk of LBSI.

METHODS

Thirty-eight elite Australian fast bowlers (21.6 ± 3.7 years) completed 48 screening MRI over 3 years. BMO intensity was quantified on MRI retrospectively. Standard practices for bowling workload monitoring and injury diagnosis were followed.

RESULTS

Clinically significant BMO (signal intensity ratio ≥ 2.0) was observed in 22 (46%, 95% CI 31-61) screening MRI. These bowlers had a total of 77 (IQR 45-115) days off between seasons, compared to 66 (IQR 41-94) days off for bowlers with a BMO intensity less than 2.0 (p = 0.510). Fifteen bowlers received follow up MRI as part of individualised management based on their screening MRI, of which less than five went on to develop LBSI in the subsequent season. There was no difference in days or balls bowled in the 12 months following screening MRI between those who sustained LBSI and those who did not.

CONCLUSIONS

BMO is common in asymptomatic bowlers. Identification of high-risk bowlers using screening MRI informs individualised management and may prevent progression to LBSI.

Trapezoidal Vertebral Body and Spine-Pelvis Sagittal Alignment in Patients with Lumber Spondylolisthesis

Background

Trapezoidal changes of the vertebral body are more common in patients with lumbar spondylolisthesis than in others. However, we lack an understanding of factors predisposing to the development of a marked trapezoidal deformity. Also, no associations between a trapezoidal vertebrae (TV) and spine-pelvis sagittal parameters have been previously reported.

Material/Methods

A total of 73 subjects with lumbar spondylolisthesis were enrolled and we collected their clinical data. Vertebral body parameters and spine-pelvis sagittal alignment parameters were measured via lumbar spine X-ray. Using the lumbar index (LI), patients were divided into a TV group (LI ≤0.8, n=24) and a control group (LI >0.8, n=49). The clinical data and spine-pelvic sagittal parameters of the 2 groups were compared using the t test or chi-squared test. Pearson’s correlation analysis and multiple linear regression were used to determine relationships among the parameters.

Results

The TV and control groups differed significantly in terms of the slipped segment, extent of slippage, intervertebral disc height (IDH), and sagittal parameters (all P<0.05). Pearson’s correlation analysis and multiple linear regression analysis showed that the slipped segment (r=−0.606), extent of slippage (r=−0.660), and IDH (r=0.698) were risk factors for the development of a TV body. Also, vertebral trapezoidal deformation was closely associated with sagittal parameters.

Conclusions

The vertebral body affected by lumbar spondylolisthesis exhibits a trapezoidal change closely associated with the slipped segment, the extent of slippage, and IDH. The TV group exhibited greater pelvic incidence values and lumbar lordosis, which may have caused wedging of the slipped vertebra.

Neural Arch Bone Marrow Edema and Spondylolysis in Adolescent Cheerleaders: A Case Series

Objective

Spondylolysis is 1 of the most common sources of low back pain in children and adolescents; however, there is still a great deal of confusion in regard to etiology, clinical presentation, and diagnostic imaging findings. It is imperative for clinicians to recognize that persistent low back pain is strongly indicative of spondylolysis, especially in high-performance athletes. This case series demonstrates a comprehensive diagnostic spectrum of spondylolysis and its treatment in 2 competitive adolescent cheerleaders.

Clinical Features

In case 1, a 12-year-old female competitive cheerleader presented with a gradual onset of subacute low back pain. Comprehensive clinical examination indicated imaging studies that identified bilateral L5 grade 1 stress reaction, consisting of neural arch bone marrow edema (BME). Treatment included spinal adjustments, rehabilitation, and myofascial therapy. In case 2, 15-year-old female competitive cheerleader presented with insidious chronic low back pain that was provocative with extension. Magnetic resonance imaging revealed a left L5 grade 1 pars interarticularis stress reaction. Computed tomography demonstrated right L5 pars grade 3 and left L5 healing spondylolysis. Treatment included spinal adjustments and rehabilitation exercises. She was also seen by a physical therapist who prescribed a lumbar spine flexion brace.

Intervention and Outcome

Diagnosis of BME and spondylolysis led to temporary cessation of cheerleading activities in cases 1 and 2. The individual in case 1 self-discharged with a list of rehabilitation exercises and was lost to follow-up. The individual in case 2 was able to return to sport pain free approximately 5 weeks after seeking treatment.

Conclusion

Spondylolysis is common in adolescent athletes, and the presence of BME precedes spondylolysis. Primary spine providers could consider this diagnosis in any adolescent, especially an athlete, who has persistent low back pain. Timely diagnosis will optimize treatment outcomes.

Stress Injuries of the Spine in Sports

Spine sports stress injuries account for a significant amount of time loss at play in athletes, particularly if left unrecognized and allowed to progress. Spondylolysis makes up most of these stress injuries. This article focuses on spondylolysis, bringing together discussion from the literature on its pathomechanics and the different imaging modalities used in its diagnosis. Radiologists should be aware of the limitations and more importantly the roles of different imaging modalities in guiding and dictating the management of spondylolysis. Other stress-related injuries in the spine are also discussed including but not limited to pedicle fracture and apophyseal ring injury.

Radiographic Outcomes of Immobilization using Boston Brace for Pediatric Spondylolysis

BACKGROUND AND AIMS

Spondylolysis is a common cause of lower back pain during youth. The aim of this study is to report the bony union rate and risk factors for non-union of the lumbar spondylolysis of pediatric patients treated with a rigid thoracolumbosacral orthosis (Boston brace).

MATERIALS AND METHODS

A retrospective review of 68 children (mean age = 13.9 years) treated for spondylolysis with a thoracolumbosacral orthosis. Patient charts and imaging studies were evaluated to identify the bony union rate of the spondylolysis after a minimum of 3 months of immobilization (mean = 4.2 months). Laterality, grade, level, and presence of high signal intensity in the magnetic resonance imaging were evaluated as prognostic factors.

RESULTS

Sixty-eight patients presented with 110 defects. Of them, 46 (42%) were incomplete fractures, 38 (35%) complete fractures, and 26 (24%) pseudoarthrosis. Of these defects, 38 (82.6%), 11 (28.9%), and 0 (0.0%) had bony union at the end of the treatment (p < 0.001). Unilateral defects healed significantly better than bilateral ones (relative risk = 1.71, 95% confidence interval = 1.16-2.54, 17/26 (65%) vs 32/84 (38%), p = 0.014). High signal intensity in the magnetic resonance images before the treatment predicted healing (relative risk = 13.24, 95% confidence interval = 1.93-91.01, 48/87 (55%) vs 1/24 (4.3%), p < 0.001). The level of the spondylolysis (L5 vs above L5) did not affect the healing rate.

CONCLUSION

The union rates of spondylolysis with a thoracolumbosacral orthosis were similar as compared to earlier studies done with a low thoracolumbosacral orthosis. The grade of the defect, laterality, and presence of high signal intensity increased the probability of bony union. A high thoracolumbosacral orthosis (underarm) does not seem to improve the healing rate of pediatric spondylolysis defects.

What Type of Orthosis is Optimal for Conservative Treatment of Lumbar Spondylolysis?: A Biomechanical Analysis

Introduction

To analyze the extent to which various types of orthoses can restrict motion of the lumbar spine and provide basic evidence regarding the optimal orthosis for conservative treatment of lumbar spondylolysis (LS), particularly. Although several orthoses have been developed and applied for LS with better outcomes for bony healing, basic data regarding which is optimal are still lacking.

Methods

Ten healthy voluntary participants were included in this study. Lumbar spine range of motion (ROM) was analyzed using a three-dimensional motion capture system (NEXUS 2.2, Vicon Motion Systems Ltd., UK) under five conditions wearing no orthosis (NB) and four types of lumbar-sacral orthoses (LSO): custom-made hard LSO (HO), soft LSO supported by four aluminum stays and a custom-molded back cast-panel named "Return to Sports" braces (RS), custom-made soft LSO known as Damen type elasticity corset (DC), and off-the-shelf soft LSO.

Results

HO showed the highest restriction of motion in all directions than the others. Especially, ROM of rotation and side bending were reduced to 58.3% and 63.6% compared with NB, respectively. The other three LSOs showed significantly higher restriction in extension, rotation, and side bending than NB. In flexion and side bending, DC showed significantly higher restriction than NB.

Conclusions

HO showed high restriction in all directions. RS showed higher restriction in extension than NB and less restriction in flexion and side bending than other custom-made LSOs. DC was the only soft LSO showing higher restriction than NB in flexion.

Sagittal Alignment With Downward Slope of the Lower Lumbar Motion Segment Influences Its Modes of Failure in Direct Compression: A Mechanical and Microstructural Investigation

STUDY DESIGN

Microstructural investigation of compression-induced herniation of ovine lumbar discs with and without added component of anterior-inferior slope.

OBJECTIVE

Does increased shear arising from a simulated component of motion segment slope imitating sacral slope weaken the lateral annulus and increase risk of overt herniation at this same region.

SUMMARY OF BACKGROUND DATA

An increase in sacral slope secondary to lordosis and pelvic incidence increases shear stresses at the lumbosacral junction and has been associated with an increase in spondylolisthetic disorders and back injury. The small component of forward shear induced when a segment is compressed in flexion is suggested to cause differential recruitment of the lateral annular fibers leading to its early disruption followed by intra-annular nuclear tracking to the posterolateral/posterior regions. However, the influence of even greater forward shear arising from the added component of slope seen where pelvic incidence and lumbar lordosis are increased in the lower lumbar spine is less understood.

METHODS

Ovine motion segments were compressed at 40 mm/min up to failure; 9 with a horizontal disc alignment and 26 with a segment slope of 15° and then analyzed structurally.

RESULTS

All the horizontal discs failed (11.8 ± 2.4 kN) via vertebral fracture without any evidence of soft tissue failure even in the lateral aspects of the discs. The increased forward shear resulting from the slope decreased the failure load (6.4 ± 1.6 kN). The sloping discs mostly suffered mid-span, noncontinuous disruption of the lateral annulus with some extruding nuclear material directly from these same lateral regions.

CONCLUSION

The increased level of forward shear generated in moderately sloping lumbar segments when compressed was abnormally damaging to the lateral regions of the disc annulus. This is consistent with the view that shear differentially loads the oblique-counter oblique fiber sets in the lateral annulus, increasing its vulnerability to early disruption and overt herniation.

LEVEL OF EVIDENCE

N/A.

Dash-Associated Spondylolysis Hypothesis

Introduction

In past biomechanical studies, repetitive motion of lumbar extension, rotation, or a combination of both, frequently seen in batting or pitching practice in baseball, shooting practice in soccer, and spiking practice in volleyball, have been considered important risk factors of lumbar spondylolysis. However, clinically, these have been identified in many athletes performing on a running track or on the field, which requires none of the practices described above. The purpose of this study was to verify how much impact running has on the pathologic mechanism of lumbar spondylolysis.

Methods

In study 1, 89 consecutive pediatric patients diagnosed with lumbar spondylolysis at a single outpatient clinic between January 2012 and February 2017 were retrospectively analyzed. In study 2, motion analysis was performed on 17 male volunteers who had played on a soccer team without experiencing low back pain or any type of musculoskeletal injury. A Vicon motion capture system was used to evaluate four movements: maximal effort sprint (Dash), comfortable running (Jog), instep kick (Shoot), and inside kick (Pass).

Results

In study 1, 13 of the 89 patients with lumbar spondylolysis were track and field athletes. In study 2, motion analysis revealed that the hip extension angle, spine rotation angle, and hip flexion moment were similar in Dash and Shoot during the maximum hip extension phase. The pelvic rotation angle was significantly greater in the kicking conditions than in the running conditions.

Conclusions

Kinematically and kinetically, the spinopelvic angles in Dash were considered similar to those in Shoot. Dash could cause mechanical stress at the pars interarticularis of the lumbar spine, similar to that caused by Shoot, thus leading to spondylolysis.

Bony Healing of Discontinuous Laminar Stress Fractures Due to Contralateral Pars Defect or Spina Bifida Occulta

Introduction

Although there has been a dramatic improvement in the outcomes of conservative treatment to achieve bony healing due to advances in diagnostic and therapeutic tools, in some patients, the results continue to be unfavorable. The purpose of this study was to investigate the outcomes of conservative treatment in pediatric patients with stress fractures occurring in the lamina that are discontinuous due to a contralateral pars defect or spina bifida occulta (SBO).

Methods

The medical records at our outpatient clinic for 103 consecutive patients (83 boys, 20 girls) with lumbar spondylolysis (LS) were reviewed to identify those who had presented with a stress fracture and a contralateral pars defect or with SBO at the affected lamina level.

Results

Twelve patients (11 boys, 1 girl) of mean age 12.3 (range 8-16) years were identified. Except for 1 stress structure that occurred at L4, all the stress fractures occurred at L5. Six patients had a pars defect, 5 had SBO, and 1 had both. Two of the 6 patients with a contralateral pars defect had early LS, 3 had progressive LS, and 1 had a pedicle fracture. The fracture healed in 1 (50%) of the 2 patients with early LS and in the patient with the pedicle fracture, but did not heal in any of the patients with progressive LS. Two of the 5 patients with SBO at the affected lamina level had early LS and 3 had progressive LS. The bony healing rate was 100% in the 2 patients with early LS and 66.7% in the 3 patients with progressive LS. The fracture healed in the patient with progressive LS and both a pars defect and SBO at the affected lamina.

Conclusions

Contralateral pars defect remains an unfavorable factor for bony healing discontinuous laminar stress fractures.

Biomechanical analysis of spino-pelvic postural configurations in spondylolysis subjected to various sport-related dynamic loading conditions

PURPOSE

To study the risks of spondylolysis due to extrinsic loading conditions related to sports activities and intrinsic spino-pelvic postural parameters [pelvic incidence (PI) and sacral slope (SS)].

METHODS

A comprehensive osseo-disco-ligamentous L4-S1 finite element model was built for three cases with spondylolysis representing three different spino-pelvic angular configurations (SS = 32°, 47°, 59° and PI = 49°, 58°, 72°, respectively). After simulating the standing posture, 16 dynamic loading conditions were computationally tested for each configuration by combining four sport-related loads (compression, sagittal and lateral bending and axial torque). For each simulation, the Von Mises stress, L5-S1 facet contact force and resultant internal loads at the sacral endplate were computed. Significant effects were determined with an ANOVA.

RESULTS

The maximal stress and volume of cancellous bone in the pars with stress higher than 75% of the ultimate stress were higher with 900 N simulated compression (2.2 MPa and 145 mm³) compared to only the body weight (1.36 MPa and 20.9 mm³) (p < 0.001). Combined compression with 10 Nm of flexion and an axial torque of 6 Nm generated the highest stress conditions (up to 2.7 MPa), and L5-S1 facet contact force (up to 430 N). The maximal stress was on average 17% higher for the case with the highest SS compared to the one with lowest SS for the 16 tested conditions (p = 0.0028).

CONCLUSIONS

Combined flexion and axial rotation with compression generated the highest stress conditions related to risks of spondylolysis. The stress conditions intensify in patients with higher PI and SS. These slides can be retrieved under Electronic Supplementary Material.

Conservative Treatment for Bony Healing in Pediatric Lumbar Spondylolysis

STUDY DESIGN

A retrospective review of prospectively collected data.

OBJECTIVE

The aim of this study was to investigate recent outcomes of conservative treatment for bony healing in pediatric patients with lumbar spondylolysis (LS) and to identify the problems that need to be resolved.

SUMMARY OF BACKGROUND DATA

Several diagnostic and therapeutic techniques for LS have been developed recently, leading to better outcomes for bony healing.

METHODS

Overall, 63 consecutive pediatric patients (53 boys and 10 girls) with LS (average age: 13.8 years; range: 6-17 years) were analyzed. Diagnosis and staging (very early, early, progressive, and terminal) were based on multidetector computed tomography (CT) scans and magnetic resonance imaging (MRI). For all patients except those with terminal-stage pars defect, conservative treatment included rest, avoidance of sports, and the use of a thoraco-lumbo-sacral-type trunk brace. Follow-up MRI was performed monthly. When the signal changes resolved, CT scans were obtained to assess bony healing.

RESULTS

Three patients dropped out during the study period. A total of 60 patients were included (50 boys and 10 girls) in this study (follow-up rate: 95.2%), with 86 instances of LS (very early: 36, early: 16, progressive: 15, terminal: 19) in 65 laminae. In the very early stage, the bony healing rate was 100%, and average treatment period was 2.5 months (range: 1-7 months). In the early stage, the bony healing rate was 93.8%, and the average treatment period was 2.6 months (range: 1-6 months). In the progressive stage, the bony healing rate was 80.0%, and the average treatment period was 3.6 months (range: 3-5 months). The average overall recurrence rate was 26.1%. All patients showing recurrence eventually achieved bony healing.

CONCLUSION

High bony healing rates and short treatment periods were observed with conservative treatment in pediatric patients with LS. However, the recurrence rates were relatively high. This issue should be targeted in future studies.

LEVEL OF EVIDENCE

2.

State-of-the-art management of low back pain in athletes: Instructional lecture

In this paper, we describe "state of the art" on the diagnosis and treatment for low back pain in athletes. Lumbar motion that induces specific pain would be a clue to the exact diagnosis. In the flexion pain group, lumbar herniated nucleus pulposus is the most common disorder. Discogenic pain and type 1 Modic endplate inflammation may also cause flexion pain; however, the diagnosis is sometimes difficult. In children and adolescents, apophyseal ring fracture is prevalent. In the extension pain group, lumbar spondylolysis is very common, especially in pediatric athletes. In adults, facet pain due to overloading would be the pathology, while low back pain with trunk rotation is not common. However, throwing athletes, such as pitchers and hammer throwers, may experience this kind of pain; facet arthritis contralateral to the throwing arm would be the origin of the pain. Low back pain on lumbar lateral bending is rare, but we experienced some cases in golfers in whom type 1 Modic change at the lateral corner was the source of pain. In this article, we explained strategies for state-of-the-art diagnosis and minimally invasive treatment.

Current Evidence Regarding the Etiology, Prevalence, Natural History, and Prognosis of Pediatric Lumbar Spondylolysis: A Report from the Scoliosis Research Society Evidence-Based Medicine Committee

STUDY DESIGN

Structured literature review.

OBJECTIVES

To assess the current state of evidence as a first step in the development of practice guidelines for pediatric spondylolysis.

SUMMARY OF BACKGROUND DATA

Progress in published medical knowledge, changes in societal expectations, and developments in health care economics have led medical organizations to develop evidence-based documents and products.

METHODS

A comprehensive literature search for pediatric spondylolysis was performed with the assistance of a medical librarian. The authors reviewed citations and abstracts. Abstracts were reviewed for exclusions and data from included studies were analyzed by committee. A total of 44 articles provided the best available evidence for the questions of etiology, prevalence, natural history, and prognosis: 9 were graded as level I evidence, 23 were level II, 3 were level III, and 9 were level IV. No level V studies were included in the final list.

RESULTS

There is good evidence that pediatric lumbar spondylolysis is an acquired fracture of the pars interarticularis that can occur unilaterally or bilaterally. Evidence shows that when chronic, bilateral pars defects develop, 43% to 74% of patients will progress to grade 1 or 2 spondylolisthesis. In addition, unilateral, incomplete, and early lesions can obtain bony union. With or without bony union or spondylolisthesis, short-term symptom resolution is the norm. Long-term prognosis is less clear, but there is fair evidence that most patients will have lumbar symptoms compared with the general population. There is also fair evidence that some patients will develop significant symptoms as adults and will undergo surgical treatment. There is insufficient knowledge to predict which patients will continue to do well in the long term with conservative or no treatment and which patients will develop symptoms significant enough to warrant early intervention.

CONCLUSIONS

The current medical literature provides fair to good evidence for clinically relevant questions regarding the etiology, prevalence, natural history, and prognosis of pediatric spondylolysis.

Lumbar spondylolysis and spondylolytic spondylolisthesis: who should be have surgery? An algorithmic approach

Lumbar spondylolysis and spondylolisthesis are common spinal disorders that most of the times are incidental findings or respond favorably to conservative treatment. In a small percentage of the patients, surgical intervention becomes necessary. Because too much attention has been paid to novel surgical techniques and new modern spinal implants, some of fundamental concepts have been forgotten. Identifying that small but important number of patients with lumbar spondylolysis or spondylolisthesis who would really benefit from lumbar surgery is one of those forgotten concepts. In this paper, we have developed an algorithmic approach to determine who is a good candidate for surgery due to lumbar spondylolysis or spondylolisthesis.

Lumbar spondylolysis in juveniles from the same family: a report of three cases and a review of the literature

Spondylolysis is reported as a stress fracture of the pars interarticularis with a strong hereditary basis. Three cases of lumbar spondylolysis in juveniles from the same family are reported, and the genetics of the condition are reviewed. The first boy, a 13-year-old soccer player, was diagnosed with terminal stage L5 bilateral spondylolysis with grade 1 slippage. The second boy, a 10-year-old baseball player, had terminal stage right side unilateral spondylolysis. The third boy, also a 10-year-old baseball player, was diagnosed with early stage bilateral L5 spondylolysis. The second and third boys are identical twins, and all three cases exhibited concomitant spina bifida occulta. Lumbar spondylolysis has a strong hereditary basis and is reported to be an autosomal dominant condition.

Development of an equation for calculating vertebral shear failure tolerance without destructive mechanical testing using iterative linear regression

Equations used to determine vertebral failure tolerances without the need for destructive testing are useful for scaling applied sub-maximal forces during in vitro repetitive loading studies. However, existing equations that use vertebral bone density and morphology for calculating compressive failure tolerance are unsuitable for calculating vertebral shear failure tolerance since the primary site of failure is the pars interarticularis and not the vertebral body. Therefore, this investigation developed new equations for non-destructively determining vertebral shear failure tolerance from morphological and/or bone density measures. Shear failure was induced in 40 porcine cervical vertebral joints (20 C3-C4 and 20 C5-C6) by applying a constant posterior displacement to the caudal vertebra at 0.15 mm/s. Prior to destructive testing, morphology and bone density of the posterior elements were made with digital calipers, X-rays, and peripheral quantitative computed tomography. Iterative linear regression identified mathematical relationships between shear failure tolerance, and morphological and bone density measurements. Along with vertebral level, pars interarticularis length and lamina height from the cranial vertebra, and inferior facet height from the caudal vertebra collectively explained 61.8% of shear failure tolerance variance. Accuracy for this relationship, estimated using the same group of specimens, was 211.9 N or 9.8% of the measured shear failure tolerance.

L5 spondylolysis/spondylolisthesis: a comprehensive review with an anatomic focus

INTRODUCTION

Spondylolysis is most commonly observed in the lumbar spine, particularly L5, and is associated with spondylolisthesis, or anterior "slippage" of a vertebra in relation to an adjacent vertebra. Isthmic spondylolisthesis is the result of a pars interarticularis defect and will be the only type of spondylolisthesis addressed in this review.

CONCLUSIONS

Spondylolysis and spondylolisthesis represent a relatively common cause of low back pain, especially in young athletes, and a less common cause of neurologic compromise. When discovered in a symptomatic patient with corroborating imaging findings, early intervention provides an excellent prognosis. Herein, we review the anatomy and pathology of spondylosis and spondylolisthesis of the L5 vertebra.

Synchronic multiple stress fractures of L5 left hemilamina: a case of an unusual type of lumbar spondylolysis

Lumbar spondylolysis is a stress fracture that commonly occurs in adolescent sports players. It is found in approximately 6% of the adult general population. The condition is usually detected as a defect in the pars interarticularis, sometimes in the pedicle (pediculolysis), and rarely in the lamina (laminolysis). Such fractures are typically seen as one defect in each side of the lamina: multiple stress fractures in the same side of the lamina rarely occur synchronically. Here, we report an unusual type of lumbar spondylolysis in the form of synchronic multiple stress fractures of the L5 left hemilamina in an adolescent baseball player. Conservative treatment was effective for bony healing. Although this type of spondylolysis is very rare, to avoid overlooking it, it is essential to examine reconstructed CT images and take the patient's history carefully. If an accurate diagnosis is made early, conservative treatment may be sufficient to achieve bony healing.

Painful lumbar spondylolysis among pediatric sports players: a pilot MRI study

INTRODUCTION

For children and adolescents who are very active athletes, fresh lumbar spondylolysis is the main pathologic cause of lower back pain (LBP). However, regarding the terminal-stage spondylolysis (pars defect), there have been few studies to clarify the pathomechanism of LBP. The purpose of this study is to clarify the cause of LBP associated with pars defects in athletes. This is the first report showing a possible pathomechanism of LBP in active athletes with painful pars defect.

METHOD

Six pediatric athletes (5 boys and 1 girl) below 18 years old with painful bilateral lumbar spondylolysis were evaluated. In all cases, spondylolysis was identified as terminal stage (pseudoarthrosis) on CT scan. To evaluate the inflammation around the pars defects, short time inversion recovery (STIR) MRI was performed along with the sagittal section. Fluid collection, which is an indicator of inflammatory events, was evaluated in 12 pars defects as well as in 12 cranial and caudal adjoining facet joints.

RESULTS

Inflammation (i.e., fluid collection) was observed in all 12 pars defects in six subjects at the pseudoarthrotic pars defects. In terms of facet joints, 7 of 12 (58%) pars defects showed fluid collection at the cranial and/or caudal adjoining joints on STIR MRI.

CONCLUSION

The present study showed that inflammation was always present at the pars defects and in some cases at the adjoining facet joints. Thus, it is not difficult to understand how, during sports activity, inflammation may first occur at the pseudoarthrotic site and then spread to the adjoining facet joints. This mechanism could cause LBP associated with terminal-stage (pseudoarthrotics) spondylolysis in athletes.