Lumbosacral Spondylolysis and Spondylolisthesis

Novel Predictive Scoring System for Bone Union Rate After Conservative Management of Lumbar Spondylolysis

STUDY DESIGN

A single-center retrospective cohort study.

OBJECTIVES

To develop a predictive scoring system for bone union after conservative treatment of lumbar spondylolysis and assess its internal validity.

SUMMARY OF BACKGROUND DATA

Lumbar spondylolysis, a common stress fracture in young athletes, is typically treated conservatively. Predicting bone union rates remains a challenge.

METHODS

This study included patients aged 18 years or younger with lumbar spondylolysis undergoing conservative treatment. A multivariable logistic regression analysis was used to develop a scoring system containing 6 factors: sex, age, lesion level, main side stage of the lesion, contralateral side stage of the lesion, and spina bifida occulta. The predictive scoring system was internally validated from the receiver operating characteristic (ROC) curve using bootstrap methods.

RESULTS

The final analysis included 301 patients with 416 lesions, with an overall bone union rate of 80%. On multivariable analysis, the main and contralateral stages were identified as factors associated with bone union. The predictive scoring system was developed from the main side stage score (prelysis, early=0, progressive stage=1) and the contralateral side stage score (none=0, prelysis, early, progressive stage=1, terminal stage=3). The area under the curve was 0.855 (95% confidence interval, 0.811-0.896) for the ROC curve, showing good internal validity. The predicted bone union rates were generally consistent with the actual rates.

CONCLUSIONS

A simple predictive scoring system was developed for bone union after conservative treatment of lumbar spondylolysis, based on the stage of the lesion on the main and contralateral sides. The predicted bone union rate was ~90% for a total score of 0-1 and ≤30% for a score of 3-4. This system demonstrated good internal validity, suggesting its potential as a useful tool in clinical decision-making for the management of spondylolysis.

Risk Factors and Successful Interventions for Cricket-Related Low Back Pain: An Updated Systematic Review

Lower back pain (LBP) poses a significant challenge for cricketers of all standards, often leading to rehabilitation periods exceeding eight months and potential termination of the playing season. Despite the identification of modifiable risk factors and interventions in previous studies, a comprehensive review of the past decade is absent. With the introduction of shorter formats like Twenty20 (T20) and the rise of franchise cricket, an updated evaluation of risk factors and interventions for preventing and treating LBP in cricketers is needed. This study critically assesses and summarises current understanding in this area, incorporating previous recommendations and considering the evolving cricket landscape. A systematic review was conducted using databases such as SportsDiscus, MEDLINE, CINAHL, ISI Web of Knowledge, and Cochrane Library. Key terms related to LBP in cricketers were utilised. The Down and Black quality assessment tool, in addition to van Tulder's criteria for levels of evidence, was applied. The quantitative analysis involved meta-analyses conducted using IBM SPSS Statistics for Windows, Version 29 (Released 2023; IBM Corp., Armonk, New York). Sixteen studies, of which 15 were of high quality, investigated risk factors associated with LBP. One low-quality randomised controlled trial examined LBP treatment. The meta-analysis revealed significant associations between LBP and increased workload, decreased bone mineral density, and poor lumbo-pelvic control through increased side flexion during the bowling action. Strong evidence supported the association between the presence of bone marrow oedema (BMO) and LBP. Bone marrow oedema on magnetic resonance imaging (MRI) provides an early indicator before the development of stress fractures, serving as a valid and reliable screening tool. Workload monitoring plays a crucial role in identifying high-risk bowlers. However, further research is needed to establish causal relationships among several other risk factors outlined. Additionally, addressing the scarcity of high-quality interventional studies is of utmost importance.

Treatment of lumbar spondylolysis in young adults using modified intravertebral screw-rod fixation system for single vertebral body combined with autologous cancellous bone graft: a technical note and preliminary report

BACKGROUND

There is currently no consensus on the surgical treatment of lumbar spondylolysis in young adults, and the nonunion rate remains relatively high even after surgery. Therefore, in this study, we proposed a modified intravertebral screw-rod fixation technique within a single vertebral segment and investigated the clinical efficacy of this modified fixation system combined with autologous cancellous bone grafting in the treatment of lumbar spondylolysis in young adults.

METHODS

This study included 28 young adults with lumbar spondylolysis who were treated at our center between 2021 and 2023. All patients underwent modified intravertebral screw-rod fixation within a single vertebral segment combined with autologous cancellous bone grafting. We performed postoperative follow-ups regularly to assess the patient's pain status using the visual analog scale (VAS), Oswestry Disability Index (ODI), and radiological findings.

RESULTS

All 28 patients successfully underwent the surgery with an average operation time and blood loss volume of 96.01 ± 21.3 min and 186.78 ± 63.43 mL, respectively. Postoperatively, patients experienced significant symptom relief, with notable decreases in VAS scores and ODI indices at 1, 3, 6, and 12 months compared with preoperative conditions. These differences were statistically significant (P < 0.05). Radiological findings revealed a healing rate of 92.86% for the 56 fractured pars interarticularis among the 28 patients. No implant-related complications, such as fracture, loosening, or pseudarthrosis, were observed.

CONCLUSIONS

The modified intravertebral screw-rod fixation system within a single vertebral segment combined with autologous cancellous bone grafting is a safe and effective treatment for lumbar spondylolysis in young adults. It significantly improves pain and functional disability as it promotes bone healing.

Evaluation of V-type titanium cable internal fixation for the treatment of young adult fifth lumbar spondylolysis: technical notes and a retrospective clinical study

BACKGROUND

Various strategies, each with its own set of limitations, are available for managing lumbar spondylolysis. In response, our department has developed an innovative solution: a V-shaped titanium cable integrated with a pedicle screw internal fixation system specifically designed for lumbar spondylolysis in young adults.

AIM

The objective of this study was to thoroughly investigate the long-term efficacy of V-type titanium cable internal fixation for the management of spondylolysis, especially in young adults.

METHODS

Twenty-one patients with fifth lumbar spondylolysis were treated using V-shaped titanium cables and pedicle screw internal fixation at the General Hospital Xinjiang Military Command. The duration of low back pain before surgery was 6 ~ 48 (15.85 ± 11.57) months. The Medtronic (S7) navigation system was used during surgery to guide the placement of pedicle screws, aiming to avoid damaging the L4-5 facet joint by positioning the screws lower and further to the side. Intraoperative indices (operative time and intraoperative blood loss) were recorded. The visual analog scale (VAS), Oswestry Disability Index (ODI), pelvic incidence (PI), and intraoperative imaging measurements of screw accuracy were meticulously recorded and assessed in a comprehensive manner. This thorough evaluation was conducted both intraoperatively and throughout the follow-up period, which lasted for at least one year.The Macnab efficacy criteria were used to assess postoperative outcomes during the final follow-up period.

RESULTS

All patients successfully completed the 1-year follow-up on time. Two patients experienced postoperative wound liquefaction and successfully recovered after undergoing dressing changes. The average duration of the surgical procedure was 113.09 ± 6.97 min, and an intraoperative blood loss of 50.47 ± 21.32 millilitres was observed. Significant differences were noted in visual analog scale (VAS) scores before and after surgery at various time intervals, indicating improvement with the progression of rehabilitation exercises. No significant changes were found in the pelvic incidence (PI), and there were no notable differences between the preoperative and postoperative periods. No loosening, breakage, or failure of the internal fixation was found during the long-term follow-up. Furthermore, there were no serious complications, such as infection or vascular or nerve injuries. occurred during the procedure. A patient who presented with a considerable cryptic fissure of sacrum 1 experienced dural injury during the surgical procedure. Intraoperatively, dural sutures were skillfully applied, and the adjacent muscles were fortified. Remarkably, the patient achieved successful healing in a single stage. On the first day postsurgery, a gradual improvement in mobility was noted.

CONCLUSIONS

The use of a V-shaped titanium cable in conjunction with a pedicle screw internal fixation system for the management of fifth lumbar spondylolysis in young individuals is characterized by its ease of execution and ability to yield favorable outcomes. This approach relies on the prerequisite that patients with minimal intervertebral disc injury or mild lumbar spondylolisthesis demonstrate high overall success rates but experience low failure rates associated with internal fixation. Most significantly, this technique involves segmental internal fixation, which safeguards the functional spinal unit (FSU).

Swimming Anatomy and Lower Back Injuries in Competitive Swimmers: A Narrative Review

CONTEXT

Competitive swimmers are at high risk of overuse musculoskeletal injuries due to their high training volumes. Spine injuries are the second most common musculoskeletal injury in swimmers and are often a result of the combination of improper technique, high loads on the spine in strokes that require hyperextension, and repetitive overuse leading to fatigue of the supporting trunk muscles. The purpose of this review is to summarize the current evidence regarding swimming biomechanics, stroke techniques, and common injuries in the lumbar spine to promote a discussion on the prevention and rehabilitation of lower back injuries in competitive swimmers.

EVIDENCE ACQUISITION

From a PUBMED/MEDLINE search, 16 articles were identified for inclusion using the search terms "swimming," "low back" or "lumbar," and "injury" or "injuries."

STUDY DESIGN

Narrative review.

LEVEL OF EVIDENCE

Levels 4 and 5.

RESULTS

The trunk muscles are integral to swimming stroke biomechanics. In freestyle and backstroke, the body roll generated by the paraspinal and abdominal muscles is integral to efficient stroke mechanics by allowing synergistic movements of the upper and lower extremities. In butterfly and breaststroke, the undulating wave like motion of the dolphin kick requires dynamic engagement of the core to generate repetitive flexion and extension of the spine and is a common mechanism for hyperextension injuries. The most common lower back injuries in swimming were determined to be lumbar strain, spondylolysis and spondylolisthesis, facet joint pain, and disc disease. Most overuse swimming injuries can be treated conservatively with physical therapy and training adjustments.

CONCLUSION

Managing swimmers with low back pain requires a basic knowledge of swimming technique and a focus on prevention-based care. Since most swimming injuries are secondary to overuse, it is important for providers to understand the mechanisms underlying the swimming injury, including an understanding of the biomechanics involved in swimming and the role of spine involvement in the 4 strokes that assist in stabilization and force generation in the water. Knowledge of the biomechanics involved in swimming and the significant demands placed on the spinal musculoskeletal system will aid the clinician in the diagnosis and management of injuries and assist in the development of a proper rehabilitation program aimed at correction of any abnormal swimming mechanics, treatment of pain, and future injury prevention.

STRENGTH OF RECOMMENDATIONS

B. Recommendation based on limited quality or inconsistent patient-oriented evidence.

Correlation of Radiographic Healing on Advanced Imaging in Young Adults and Adolescents With Symptomatic Spondylolysis Before and After Treatment: A Retrospective Study

STUDY DESIGN

Retrospective chart review.

OBJECTIVE

To determine the effect of conservative measures on radiographic outcomes in those with isolated spondylolysis.

SUMMARY OF BACKGROUND DATA

Spondylolysis is a common cause of low back pain in pediatric patients, affecting between 4.4% and 4.7% of all pediatric patients. This rate is even higher in high-level athletes, with recent studies suggesting a rate of 47% in this population. Conservative measures are recommended for treating symptomatic spondylolysis and are effective in controlling symptoms, but there is little evidence regarding their effect on radiographic outcomes.

METHODS

A retrospective review was conducted of patients diagnosed with spondylolysis who were treated at a single academic institution between January 1, 2012, and January 1, 2022. Data collected included demographics, presentation characteristics, pretreatment and post-treatment radiologic findings, types of treatments employed, and final symptomatic status at follow-up. The Student t test and the Wilcoxon rank sum test were used to compare continuous variables. The χ 2 test was used to compare categorical variables.

RESULTS

A total of 119 patients were included in the study. There was an 81.5% rate of healing on advanced imaging for those treated with conservative measures. When comparing those with healing on advanced imaging to those without, those with healing were more likely to have an acute fracture ( P= 0.04), have symptomatic improvement ( P <0.01), and return-to-play ( P= 0.02) compared with those without. Those with healing also had an odds ratio of 6.9 ( P <0.01) and 4.5 ( P =0.02) to achieve symptomatic improvement and return to their sport, respectively, compared with those who did not.

CONCLUSION

Our study found those with isolated spondylolysis who were treated with conservative measures had a high healing rate on advanced imaging and those with healing had significantly higher odds of having symptomatic improvement and returning to play compared with those without.

LEVEL OF EVIDENCE

4.

Transforaminal Endoscopic Lumbar Foraminotomy for the Treatment of L5-S1 Isthmic Lumbar Spondylolisthesis with Foraminal Stenosis: A 1-Year Follow-Up

BACKGROUND

Isthmic lumbar spondylolisthesis (ILS) is a prevalent spinal pathology. Radicular pain in patients is often attributed to L5-S1 ILS combined with foraminal stenosis (FS), making such patients prime candidates for surgical intervention. We herein aimed to elucidate the surgical technique and clinical outcomes of transforaminal endoscopic lumbar foraminotomy (TELF) in the treatment of L5-S1 ILS with FS.

METHODS

From September 2021 to December 2022, 20 consecutive patients were diagnosed with L5-S1 ILS with FS and underwent TELF. All patients were followed up for at least 12 months. The clinical outcomes were evaluated using the visual analog scale (VAS), Oswestry Disability Index, and modified MacNab criteria.

RESULTS

The mean age of the patients was 62.4 ± 10.9 years. The mean preoperative VAS score for low back, VAS score of the leg, and Oswestry Disability Index score was 5.1 ± 1.7, 7.4 ± 0.7, and 58.0 ± 8.4, respectively. These scores significantly improved to 1.8 ± 0.7, 1.5 ± 0.6, and 15.3 ± 7.1 at 12 months postoperatively, respectively (P < 0.01). Evaluation based on the modified MacNab criteria revealed that 95.0% of patients achieved a good-to-excellent outcome. One patient underwent revision surgery.

CONCLUSIONS

TELF emerges as a potentially safe and effective surgical option for alleviating radicular pain in patients with L5-S1 stable ILS combined with FS. While our short-term clinical results are satisfactory, it is necessary to expand the sample size and extend the follow-up time to validate the effectiveness and long-term efficacy of TELF.

Buck technique supplemented by temporary intersegmental pedicle screw fixation to repair lumbar spondylolysis in youth

BACKGROUND

Lumbar spondylolysis is a bone defect in the pars interarticularis of the lumbar vertebral, which is a common cause of low back pain in youth. Although non-surgical treatment is a mainstream option, surgery is necessary for patients with persistent symptoms. Buck technique is widely used as a classical direct repair technique, but it cannot achieve reduction of low-grade spondylolisthesis and reconstruction of lumbosacral sagittal balance. We have described a novel surgical procedure based on Buck technique with temporary intersegmental pedicle screw fixation, and report a series of clinical outcomes in 5 patients to provide a reference for the clinical treatment of young lumbar spondylolysis.

METHODS

Five young patients with symptomatic lumbar spondylolysis with a mean age of 19.20 ± 5.41 years underwent surgical treatment after an average of 7.60 ± 1.52 months of failure to respond to conservative treatment, using a new surgical procedure based on Buck technique combined with temporary intersegmental pedicle screw fixation.

RESULTS

Five patients were successfully operated without serious complications such as nerve and vascular injury. The average operation time was 109.00 ± 7.42 min, the interpretative average blood loss was 148.00 ± 31.14 ml, and the average fusion time was 11.20 ± 1.64 months. All patients were followed up for 2 years after surgery, and the visual analogue score (VAS) of low back pain and Oswestry disability index (ODI) scores were significantly improved compared with those before surgery, and the Henderson's evaluation were rated excellent or good. After the removal of the internal fixation, it was observed that temporary intersegmental fixation could repair the isthmus, reduce lumbar spondylolisthesis, and reconstruct the sagittal balance of the lumbosacral vertebrae while preserving lumbar motion and preventing intervertebral disc degeneration. Postoperative MRI indicated the Pfirrmann classification of the affected discs: 1 case from grade III to grade II, 3 cases from grade II to grade I, and 1 case remained grade II.

CONCLUSIONS

Buck technique supplemented by temporary intersegmental pedicle screw fixation is a highly applicable and effective method for the treatment of adolescent lumbar spondylolysis. The isthmic fusion is accurate, and temporary intersegmental fixation can effectively prevent disc degeneration and reconstruct the sagittal balance of lumbosacral vertebra.

Fusion Surgery for Lumbar Spondylolisthesis: A Systematic Review with Network Meta-Analysis of Randomized Controlled Trials

OBJECTIVE

This study aimed to systematically evaluate the optimal surgical fusion approach for lumbar spondylolisthesis, to provide the latest and most reliable evidence for future clinical practice.

METHODS

A comprehensive search of the PubMed, Ovid-Embase, Web of Science, Cochrane, and Scopus databases was conducted from inception to September 1, 2023, to identify relevant records. Two independent reviewers performed the literature screening, data extraction, and assessment of study quality.

RESULTS

Fifteen randomized controlled trials involving 892 patients met the inclusion criteria. The network evidence plot showed that posterolateral fusion and posterior lumbar interbody fusion (PLIF) were the most used fusion techniques. The network meta-analysis results revealed that minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) had a significantly greater improvement in the Oswestry Disability Index (ODI) compared to endoscopic-TLIF, while PLIF had a significantly better fusion effect than posterolateral fusion. Furthermore, no statistically significant differences were observed between other fusion surgeries in terms of improving ODI, fusion rate, complications, or the improvement of visual analog scale-low back pain. The surface under the cumulative ranking curve results indicated that MIS-TLIF had the greatest potential for improving ODI, visual analog scale-low back pain, and complications, while PLIF had the greatest potential for increasing fusion rates. However, the existing selection bias, measurement bias, reporting bias, and publication bias may have reduced the reliability of the meta-analysis results.

CONCLUSIONS

Among the various fusion surgeries for lumbar spondylolisthesis, MIS-TLIF appears to provide the greatest benefit to patients. However, more high-quality, large-scale studies are needed to further investigate the treatment efficacy of different fusion surgeries for lumbar spondylolisthesis.

T1-VIBE and STIR MRI of lumbar pars interarticularis injuries in elite athletes: fracture characterisation and potential prognostic indicators

OBJECTIVES

To assess how pars interarticularis fracture characteristics on T1-VIBE and STIR MRI relate to healing and identify anatomical parameters that may impact healing.

MATERIALS AND METHODS

A retrospective review of an MRI series of lumbar pars interarticularis injuries in elite athletes over a 3-year period. Fracture configurations, signal intensities and anatomical parameters were recorded by two radiologists. Statistical analysis employed multilevel mixed-effects linear regressions, adjusted for repeated measures and baseline covariates.

RESULTS

Forty-seven lumbar pars interarticularis injuries among 31 athletes were assessed. On final scans for each athlete, 15% (7/47) injuries had worsened, 23% (11/47) remained stable, 43% (20/47) partially healed and 19% (9/47) healed completely. Healing times varied, quickest was 49 days for a chronic fracture in a footballer. Bone marrow oedema signal was highest in worsened fractures, followed by improved, and lowest in stable fractures. As healing progressed, T1-VIBE signal at the fracture line decreased. Bone marrow oedema and fracture line signal peaked at 90-120 days before decreasing until 210-240 days. Fractures with smaller dimensions, more vertical orientation and a longer superior articular facet beneath were significantly associated with better healing (p < 0.05).

CONCLUSION

Most diagnosed athletic pars interarticularis injuries improve. Normalising T1-VIBE signal at the fracture line is a novel measurable indicator of bony healing. Contrastingly, bone marrow oedema signal is higher in active fractures irrespective of healing or deterioration. Injuries initially perceived as worsening may be exhibiting the normal osteoclastic phase of healing. Better outcomes favour smaller, vertical fractures with a longer superior articular facet beneath.

Spondylolysis and Spondylolisthesis in Athletes

This article is an update on spondylolysis and spondylolisthesis in athletes, from diagnosis to treatment, based on our service experience and a literature review.

Pars Interarticularis Fractures Treated with Minimally Invasive Surgery: A Literature Review

Recurrent stress on the isthmic pars interarticularis often leads to profound injury and symptom burden. When conservative and medical management fail, there are various operative interventions that can be used. The current review details the common clinical presentation and treatment of pars injury, with a special focus on the emerging minimally invasive procedures used in isthmic pars interarticularis repair. PubMed and Google Scholar database literature reviews were conducted. The keywords and phrases that were searched include but were not limited to; "history of spondylolysis", "pars interarticularis", "pars defect", "conventional surgical repair of pars", and "minimally invasive repair of pars". The natural history, conventional presentation, etiology, risk factors, and management of pars interarticularis injury are discussed by the authors. The surgical interventions described include the Buck's repair, Morscher Screw-Hook repair, Scott's Wiring technique, and additional pedicle screw-based repairs. Minimally invasive techniques are also reviewed, including the Levi technique. Surgical intervention has been proven to be safe and effective in managing pars interarticularis fractures. However, minimally invasive techniques often provide additional benefit to patients such as reducing damage of surrounding structures, decreasing postoperative pain, and limiting the time away from sports and other activities.

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.

Incidence of lumbar spondylolysis in athletes with low back pain: A systematic evaluation and single-arm meta-analysis

BACKGROUND

Low back pain (LBP) is a common chief complaint from athletes. Lumbar spondylolysis (LS) is a common sport injury. Severe LS is likely to cause spinal instability, resulting in lumbar spondylolisthesis or lumbar disc herniation, and even damage to the spinal nerve roots. The incidence of LS is approximately 5% in the adult population, and nearly half of young athletes with LBP are diagnosed with LS. This meta-analysis analyzed the incidence of LS in athletes with LBP.

METHODS

PubMed, Embase, Cochrane (Cochrane Central Register of Controlled Trials), and Web of Science databases were systematically searched for published case report and retrospective analyses related to the topic from the date of database creation to January 1,2023. Relevant literature was screened and information extracted, and risk of bias was assessed for included studies using the methodological index for non-randomized-studies scale. Single-arm Meta-analysis was performed using R4.04 software. Heterogeneity was quantified by Cochran Q test and Higgins I2. Funnel plots were used to visualize publication bias, and Egger test and Begg test were used to statistical tests.

RESULTS

A total of 9 studies (835 patients) were included in this study. Meta-analysis revealed that the prevalence of LS in athletes with LBP was estimated at 41.7%, [95% CI = (0.28-0.55)], but this prevalence varied considerably with the gender and age of the athletes.

CONCLUSION

The estimated prevalence of LS in athletes with LBP is 41.7%, and future correlations between the prevalence of LS in adolescent athletes worldwide need to be assessed from different perspectives, including biomechanical, hormonal, anatomical, behavioral, and gender differences.

Diagnostic Performance of the Darth Vader Sign for the Diagnosis of Lumbar Spondylolysis in Routinely Acquired Abdominal CT

Spondylolysis is underdiagnosed and often missed in non-musculoskeletal abdominal CT imaging. Our aim was to assess the inter-reader agreement and diagnostic performance of a novel "Darth Vader sign" for the detection of spondylolysis in routine axial images. We performed a retrospective search in the institutional report archives through keyword strings for lumbar spondylolysis and spondylolisthesis. Abdominal CTs from 53 spondylolysis cases (41% female) and from controls (n = 6) without spine abnormalities were identified. A total of 139 single axial slices covering the lumbar spine (86 normal images, 40 with spondylolysis, 13 with degenerative spondylolisthesis without spondylolysis) were exported. Two radiology residents rated all images for the presence or absence of the "Darth Vader sign". The diagnostic accuracy for both readers, as well as the inter-reader agreement, was calculated. The "Darth Vader sign" showed an inter-reader agreement of 0.77. Using the "Darth Vader sign", spondylolysis was detected with a sensitivity and specificity of 65.0-88.2% and 96.2-99.0%, respectively. The "Darth Vader sign" shows excellent diagnostic performance at a substantial inter-reader agreement for the detection of spondylolysis. Using the "Darth Vader sign" in the CT reading routine may be an easy yet effective tool to improve the detection rate of spondylolysis in non-musculoskeletal cases and hence improve patient care.

Main and contralateral side stages of lesion affected bone union in the conservative treatment of adolescent lumbar spondylolysis: a multivariable analysis of 217 patients and 298 lesions in a retrospective cohort study

BACKGROUND

Factors affecting bone union in the conservative treatment of adolescent lumbar spondylolysis remain controversial. We aimed to examine these factors along with advances in diagnostic imaging using multivariable analysis of a sufficient number of patients and lesions.

METHODS

In this retrospective study, high-school-aged patients or younger (n = 514) who were diagnosed with lumbar spondylolysis from 2014 to 2021 were investigated. We included patients with acute fractures who showed signal changes around the pedicle on magnetic resonance imaging and who completed conservative treatment. The following factors were investigated at the initial visit: age, sex, level of lesion, main side stage, presence and stage of contralateral side lesion, and presence of spina bifida occulta. The association of each factor with bone union was evaluated through a multivariable analysis.

RESULTS

Altogether, 298 lesions in 217 patients (174 boys and 43 girls; mean age: 14.3 years) were included in this study. Multivariable logistic regression analysis of all factors showed that the main side progressive stage was more likely associated with nonunion as compared to the pre-lysis (OR: 5.86; 95% confidence interval [CI]: 2.00-18.8; p = 0.0011) and early stages (OR: 3.77; 95% CI: 1.72-8.46; p = 0.0009). Regarding the contralateral side stage, the terminal stage was more likely to be associated with nonunion.

CONCLUSION

In the conservative treatment of lumbar spondylolysis, the factors affecting bone union were the main and contralateral side stages. Sex, age, level of lesion, or spina bifida occulta had no significant effects on bone union. The main, progressive, and contralateral side terminal stages were negative predictors of bone union. Trial registration This study was retrospectively registered.

Experimental Rat Model of Bony Defects in the Facet Joint Maintained with Bone Wax for the Study of Spinal Pain

Purpose

Studies using experimental rat models for low back pain due to facet-joint defects are scarce. This study used a novel experimental rat model to determine whether bony defects induced by facetectomy could be maintained by bone wax, thus mimicking spondylolysis, and to analyze the effect of the facetectomy on rat behavior.

Patients and Methods

Twelve 10-week-old male Wistar rats weighing 300–350 g were divided into group A (n = 6) that underwent unilateral facetectomy of the right L5-6 facet joint and group B (n = 6) that additionally applied water-soluble bone wax at the facetectomy site. The difference in the left and right stride length, detected by the footprint test, and change in the left and right facet joint area were compared before and 4 weeks after the experiment.

Results

Even though the difference between the left and right stride lengths of groups A and B was not statistically significant, in contrast to group A, group B showed a shorter stride length on the right side (p = 0.22 and 0.46, in group A and group B, respectively). The right facet joint area, where the facetectomy was performed, was significantly smaller in group B 4 weeks after surgery, but not in group A (p = 0.50 and < 0.01, in group A and group B, respectively).

Conclusion

Based on the results, we concluded that the bony defects, induced by facetectomy at the L5-6 facet joint, were maintained with bone wax. This study will provide an experimental model for bony defects in the facet joint.