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.

Factors associated with non-fusion after direct pars repair of lumbar spondylolysis with pedicle screw and lamina hook: a clinical and CT-assessed study.

BACKGROUND: Pedicle screw and lamina hook (PSLH) technique is an effective and popular method for direct pars repair of lumbar spondylolysis. There is a lack of studies to explore factors that may influence the healing of spondylolysis after direct pars repair surgery. The present study aimed to investigate the factors associated with non-fusion after direct pars repair of lumbar spondylolysis with PSLH technique. METHODS: A total of 55 subjects (average age 21.1 ± 6.3 years, a total of 120 pars defects) diagnosed with symptomatic spondylolysis and underwent pars repair surgery with PSLH were followed up and their clinical data were analyzed. Subjects were divided into a non-fusion group and fusion group according to whether the pars defect had bony fusion at last follow-up assessed by CT. Radiographic data, data related to spondylolysis and clinical outcomes were collected and compared between groups. RESULTS: The mean follow-up time of the 55 patients was 24.8 ± 12.0 (12-64) months. Among the 120 pars defects, 101 defects were successfully fused and 19 were not fused according to CT. The fusion rate was 84.2%. Multivariable logistic regression analysis showed the factors correlated with non-fusion after pars repair surgery: whether the spondylolysis segment was associated with spina bifida occulta (SBO) (P = 0.001), stage of the defect (P = 0.047), width of the defect (P = 0.002), and disc degeneration (P = 0.014). CONCLUSION: Direct pars repair by PSHL is a reliable treatment for lumbar spondylolysis with a fusion rate of 84.2%. Association with SBO of the spondylolysis segment, a terminal stage of the defect, a wider defect gap, and grade III disc degeneration may be factors associated with non-fusion after direct pars repair of lumbar spondylolysis with PLSH. Non-fusion patients after pars repair appear to have worse clinical results compared to fusion patients.

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.

Biportal endoscopic bone graft repair and percutaneous screw fixation for lumbar spondylolysis-technical note and clinical outcomes.

BACKGROUND: Lumbar spondylolysis involves a bony defect in the vertebral pars interarticularis, predominantly affecting the lower lumbar spine. This condition is a significant etiological factor in lumbar instability and recurrent lower back pain, particularly in young individuals. While conservative treatments are the primary intervention, they often fail to provide relief, necessitating surgical approaches. Notwithstanding, executing bone grafting and fixation in the pars interarticularis defect simultaneously through minimally invasive surgery remains challenging. METHOD: This study elucidates the biportal endoscopic spinal surgery (BESS) technique, innovatively applied for bone graft repair and percutaneous cannulated screw fixation in a patient with lumbar spondylolysis. We offer a detailed walkthrough of the technical procedures supplemented with follow-up radiographic evidence. RESULTS: The BESS technique facilitated meticulous clearance of the defect site, coupled with bone grafting and cannulated screw fixation, effectively addressing lumbar spondylolysis through a minimally invasive approach. This method holds promise for achieving substantial osseous fusion at the vertebral pars interarticularis defect site. CONCLUSION: The BESS procedure for lumbar spondylolysis ensures a clean and prepared defect site for grafting and encourages successful osseous fusion, spotlighting its potential as a viable surgical strategy in managing this condition.

L5 spondylolysis: Anatomical study comparing healed and unhealed lesions.

The anatomy and pathogenesis of spondylolysis has been widely studied; however, the microanatomy of spondylolysis of the lumbar vertebra has not been well described. Therefore, we aim to better elucidate this anatomy. Twenty dry bone specimens of healed and unhealed spondylolysis of the L5 vertebra were collected from human skeletal remains. Twelve L5 vertebrae were examples of unhealed spondylolysis and eight specimens exhibited a healed (i.e., bony fusion of the lesion) spondylolysis lesion. The specimens underwent macro and microanatomical analysis followed by CT and microCT imaging. Finally, selected healed and unhealed lesions were submitted for histological analysis using Mason Trichrome staining. The pars interarticularis of two L5 vertebrae without signs of healed/unhealed spondylolysis were evaluated histologically as controls. Of the 12 unhealed L5 pars defects, three were unilateral on left side. Of the eight healed pars defects, all were unilateral and seven of these were on left sides. One unilateral pars defect also had spina bifida occulta. Both on imaging and histological analysis, healed pars defects were only so superficially and not at deeper levels. Histologically, unhealed edges were made up of dense cortical bone while healed edges were made up primarily of trabecular bone. Based on our anatomical findings, the so-called healed spondylolysis lesions, although externally fused, are not thoroughly fused internally. Moreover, the anterior and posterior edges of the unhealed spondylosysis lesions are irregular and show signs of long-term disarticulation. Taken together, these data suggest that such 'healed' lesions might not be as stable as the normal L5 pars interarticularis.

Epidemiological differences between the sexes in adolescent patients with lumbar spondylolysis: a single-institution experience in Japan.

BACKGROUND: Lumbar spondylolysis, a common identifiable cause of low back pain in young athletes, reportedly has a higher incidence rate in males. However, the reason for its higher incidence in males is not clear. This study aimed to investigate the epidemiological differences between the sexes in adolescent patients with lumbar spondylolysis. METHODS: A retrospective study was conducted in 197 males and 64 females diagnosed with lumbar spondylolysis. These patients visited our institution from April 2014 to March 2020 with their main complaint being low back pain, and they were followed-up until the end of their treatment. We investigated associations between lumbar spondylosis, their background factors, and characteristics of the lesions and analyzed their treatment results. RESULTS: Males had a higher prevalence of spina bifida occulta (SBO) (p = 0.0026), more lesions with bone marrow edema (p = 0.0097), and more lesions in the L5 vertebrae (p = 0.021) than females. The popular sports disciplines were baseball, soccer, and track and field in males, and volleyball, basketball, softball in females. The dropout rate, age at diagnosis, bone union rate, and treatment period did not differ between the sexes. CONCLUSION: Lumbar spondylolysis was more common in males than in females. SBO, bone marrow edema, and L5 lesions were more frequent in males, and sports discipline varied between the sexes.

Bilateral spondylolysis of inferior articular processes of lumbar vertebra with no active sports history: Case report and review of literature.

Lumbar spondylosis, though mostly occurs at pars interarticularis of vertebrae, it rarely occurs at articular processes. Like the ones in pars interarticularis, articular process fractures are stress fractures that are usually seen in people participated in active sprts activity. Most of the time, nonoperative treatment is adequate. When conservative treatment fails, removal of fragments accomplishes pain relief. In this report, we present a case with bilateral spondylolysis of inferior articular processes at 3rd lumbar vertebrae and discuss with regards to the literature.

Deep-Learning-Aided Evaluation of Spondylolysis Imaged with Ultrashort Echo Time Magnetic Resonance Imaging.

Isthmic spondylolysis results in fracture of pars interarticularis of the lumbar spine, found in as many as half of adolescent athletes with persistent low back pain. While computed tomography (CT) is the gold standard for the diagnosis of spondylolysis, the use of ionizing radiation near reproductive organs in young subjects is undesirable. While magnetic resonance imaging (MRI) is preferable, it has lowered sensitivity for detecting the condition. Recently, it has been shown that ultrashort echo time (UTE) MRI can provide markedly improved bone contrast compared to conventional MRI. To take UTE MRI further, we developed supervised deep learning tools to generate (1) CT-like images and (2) saliency maps of fracture probability from UTE MRI, using ex vivo preparation of cadaveric spines. We further compared quantitative metrics of the contrast-to-noise ratio (CNR), mean squared error (MSE), peak signal-to-noise ratio (PSNR), and structural similarity index (SSIM) between UTE MRI (inverted to make the appearance similar to CT) and CT and between CT-like images and CT. Qualitative results demonstrated the feasibility of successfully generating CT-like images from UTE MRI to provide easier interpretability for bone fractures thanks to improved image contrast and CNR. Quantitatively, the mean CNR of bone against defect-filled tissue was 35, 97, and 146 for UTE MRI, CT-like, and CT images, respectively, being significantly higher for CT-like than UTE MRI images. For the image similarity metrics using the CT image as the reference, CT-like images provided a significantly lower mean MSE (0.038 vs. 0.0528), higher mean PSNR (28.6 vs. 16.5), and higher SSIM (0.73 vs. 0.68) compared to UTE MRI images. Additionally, the saliency maps enabled quick detection of the location with probable pars fracture by providing visual cues to the reader. This proof-of-concept study is limited to the data from ex vivo samples, and additional work in human subjects with spondylolysis would be necessary to refine the models for clinical use. Nonetheless, this study shows that the utilization of UTE MRI and deep learning tools could be highly useful for the evaluation of isthmic spondylolysis.

Utility of ultrasonography in the diagnosis of lumbar spondylolysis in adolescent patients.

BACKGROUND: This study aims to investigate the utility of the Doppler effect on ultrasonography for the diagnosis of very early- and early-stage lumbar spondylolysis in adolescent patients. METHODS: In total, 76 adolescent patients with acute and subacute low back pain were prospectively enrolled, with 46 having lumbar spondylolysis and the remaining 30 having low back pain without spondylolysis. MRI and/or computed tomograms scans revealed very early- and early-stage lumbar spondylolysis. Furthermore, positive Doppler findings in ultrasonography around the area from the facet joint to the laminae were investigated. RESULTS: There were no significant differences in age (p > 0.99) and body mass index (p = 0.11) between cases with and without spondylolysis. Very early- and early-stage spondylolysis were observed in 27.6% and 72.4% of patients, respectively. Positive power Doppler was 91.3% and 33.3% in cases with and without spondylolysis, respectively, which was significantly higher in spondylolysis (p < 0.001). The sensitivity and specificity of this positive power Doppler were 91.4% and 66.7%, respectively. Furthermore, the rate of positive power Doppler was significantly higher in early-stage spondylolysis (p = 0.02), with 75.0% and 97.6% sensitivity in very early- and early-stage spondylolysis, respectively. CONCLUSIONS: A positive Doppler effect on ultrasonography is effective for screening very early- and early-stage spondylolysis in adolescent patients in an outpatient clinic.

Association of spinal anomalies with spondylolysis and spina bifida occulta.

PURPOSE: To investigate the association of spinal anomalies with lumbar spondylolysis and spina bifida occulta (SBO). METHODS: A total of 1190 patients with thoracic, abdominal, and pelvic computed tomography scans available were categorized according to the number of presacral (thoracic and lumbar) mobile vertebrae and the presence or absence of lumbosacral transitional vertebrae (LSTV). The prevalence of spondylolysis and SBO and the association of spinal anomalies with these disorders were evaluated. RESULTS: Normal morphology (17 mobile vertebra with no LSTV) was found in 607 men (86.5%) and 419 women (85.9%) and about 14% of patients had anomalies. Spondylolysis was found in 74 patients (6.2%), comprising 54 men (7.7%) and 20 women (4.1%). SBO involving the lumbar spine was found in 9 men (1.3%) and 2 women (0.4%). Spondylolysis was significantly more common in men with 18 vertebrae without LSTV (21.1%) than in those with 17 vertebrae without LSTV (7.2%) (p = 0.002). The prevalence of spinal anomalies was 55.6% in men and 50.0% in women with SBO that included a lumbar level was significantly higher than in both men (13.5%, p < 0.001) and women (4.8%, p = 0.003) without SBO. CONCLUSION: These findings indicate that there is a relationship between spinal anomalies and both spondylolysis and SBO, which may lead to elucidation of the mechanism of onset of spondylolysis and improve its treatment and prognosis. Awareness that patients with SBO involving the lumbar spine have an increased likelihood of a spinal anomaly may help to prevent level errors during spinal surgery.

The influence of spinal position on imaging findings: an observational study of thoracolumbar spine upright MRI in elite gymnasts.

PURPOSE: To investigate whether upright magnetic resonance imaging (MRI) has a role in defining thoracolumbar spine pathology in elite gymnastics. METHODS: A prospective cross-sectional observational study of National Senior and Junior Artistic gymnasts in three MRI positions (standard supine, upright flexed and extended positions). Two specialist musculoskeletal radiologists independently analysed images with neutral as a baseline with the effects of flexion and extension reported in line with Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement. RESULTS: Forty (18 males) gymnasts aged 13-24 years with a mean (SD) of 32 (5.3) training hours per week consented with 75% showing MRI abnormalities. Degenerative disc disease (DDD) was evident in 55% participants with vertebral end plate (VEP) changes in 42.5%. Spondylolysis was present in 40% with an additional 17% showing chronic bilateral complete L5 pars defects. 23% participants demonstrated different MRI findings in upright flexion compared to neutral. CONCLUSION: Findings suggest a high levels of MRI abnormalities in elite gymnastics including altered disc morphology and posterior element abnormalities. High prevalence of T11/12 DDD and VEP changes reflects the thoracolumbar junction being a transition zone. Upright MRI and varying spine position offer promise for enhanced visualisation of posterior element abnormalities.

Clinical evaluation of the efficacy of a new bone cement-injectable cannulated pedicle screw in the treatment of spondylolysis-type lumbar spondylolisthesis with osteoporosis: a retrospective study.

PURPOSE: To investigate the clinical efficacy and safety of a bone cement-injectable cannulated pedicle screw (CICPS) in the treatment of spondylolysis-type lumbar spondylolisthesis with osteoporosis. METHODS: A retrospective study was conducted on 37 patients (Dual-energy X-ray bone density detection showed different degrees of osteoporosis) with spondylolysis-type lumbar spondylolisthesis who underwent lumbar spondylolisthesis reduction and fusion using a new type of injectable bone cement screw from May 2011 to March 2015. Postoperative clinical efficacy was evaluated by the Visual Analogue Scale (VAS) scores and the Oswestry Disability Index (ODI). Imaging indexes were used to evaluate the stability of internal fixation of the devices 1, 3, 6, and 12 months after surgery and annually thereafter. The safety of the CICPS was assessed by the prevalence of intraoperative and postoperative complications. RESULTS: A total of 124 CICPS were implanted intraoperatively. Bone cement leakage occurred in 3 screws (2.42%), and no clinical discomfort was found in any patients. All 37 patients were followed up with an average follow-up time of 26.6 ± 13.4 months (12-58 months). In the evaluation of the clinical effects of the operation, the average postoperative VAS score of the patients decreased from 4.30 ± 1.58 before surgery to 0.30 ± 0.70 after surgery (P < 0.001), and the ODI decreased from 47.27% ± 16.97% before surgery to 3.36% ± 5.70% after surgery (P < 0.001). No screw was loose, broken or pulled out. CONCLUSION: CICPS is safe and effective in the treatment of spondylolysis-type lumbar spondylolisthesis complicated by osteoporosis.

Conservative treatment of spondylolysis involving exercise initiated early and sports activities resumed with a lumbar-sacral brace.

BACKGROUND: Conservative treatment including the use of a brace and cessation of sports activities is known to be effective in spondylolysis. However, there is some controversy regarding [1] the type of brace, and [2] the endpoint for bracing, and [3] the timing of resumption of sports activities. The aim of the current study was to investigate the appropriateness of early exercise and resumption of sports activities with a lumbar-sacral brace in very early- and early-stage lumbar spondylolysis. METHODS: This prospective cohort study enrolled 45 patients with very early- and early-stage lumbar spondylolysis. A lumbar-sacral brace, structured to be a hard brace in the back and a mesh brace in the front, was used. Isometric exercises/stretching was started immediately after the initial visit. The number of patients for whom bone fusion was fully achieved on CT and the disappearance of signal intensity change on MRI were investigated. RESULTS: In 12 cases of very early-stage spondylolysis, the average elapsed time until signal intensity disappearance as confirmed on MRI was 4.3 ± 1.6 months. Bony union on CT was confirmed in all cases. In 33 cases of early spondylolysis, signal intensity change disappeared on MRI within 5.2 ± 2.4 months. The rate of bony union was 94.3%, and the average period required to achieve bony union observable on CT was 3.7 ± 1.0 months. CONCLUSIONS: Sufficient bony union can be achieved by conservative treatment with early exercise and a lumbar-sacral brace in cases of very early and early spondylolysis.

Union evaluation of lumbar spondylolysis using MRI and CT in adolescents treated conservatively.

BACKGROUND: This study evaluated the union rate of acute lumbar spondylolysis in patients treated conservatively, according to the protocol. METHODS: The subjects included high school students and younger patients who were diagnosed with lumbar spondylolysis presenting bone marrow edema. We investigated the union rate, the period until union, unilateral or bilateral, vertebral level, laterality (right or left), and pathological stage at the first visit. Some unilateral cases included bilateral spondylolysis with contralateral pseudarthrotic lesion; therefore, the union rate of the "true" unilateral case in which the contralateral side was normal was calculated. We excluded multi-level lesions. RESULTS: With conservative treatment for lumbar spondylolysis of 189 lesions in 142 cases, 144 healed and 45 were considered as nonunion. The average treatment period until union was 106 days. The union of "true" unilateral cases in which the contralateral side was normal was noted in 68/71 lesions, but that of bilateral cases was noted in 71/94 lesions. The union in L3, L4, and L5 vertebrae was noted in 15/17, 40/49, and 89/123 lesions, respectively. The union was observed in 63/87 on the right and 86/102 on the left. The union was noted in the pre-lysis, early, and progressive stages in 36/39, 81/97, and 27/53 lesions, respectively. Furthermore, the union was noted in stages 0, 1a, 1b, 1c, and 2 in 13/15, 47/52, 30/36, 34/42, and 20/44 lesions, respectively. CONCLUSION: Accurate union evaluation using CT and MRI showed a union rate of 76% with conservative treatment for spondylolysis. The union rate of the "true" unilateral cases in which the contralateral side was normal was 96%, which was significantly higher than that of the bilateral cases. Moreover, the union rate of lesions in the axial progressive stage and sagittal stage 2 was significantly lower than that of lesions in other stages. STUDY DESIGN: clinical retrospective study.

Comparison of L5 pedicle morphology in patients with and without L5 spondylolysis.

Only a small number of studies have reported on L5 pedicle morphology in the presence of spondylolisthesis let alone isolated spondylolysis and findings are therefore variable. The aim of this radiographic study was to analyze L5 pedicle morphology in the presence and absence of L5 spondylolysis. The was a retrospective cross-sectional analysis of computed tomographic (CT) imaging. Assessment of the L5 pedicle morphology (height, width, length, transverse angle and screw length) were measured in patients with and without L5 spondylolysis. Pelvic measures including pelvic incidence, sacral anatomic orientation and sacral table angle were recorded. Patients were matched for age and gender. Twenty-three patients with spondylolysis were matched to 46 patients without. The presence of spondylolysis alone did not have a significant influence on either pelvic or pedicle morphologic parameters. Only with the presence of associated spondylolisthesis was there a difference noted with an increase in pedicle length observed. Correlation analysis suggested further morphologic changes may result with increased remodeling. Isolated spondylolysis at L5 appears to have little influence on pedicle morphology in this CT-based analysis. Morphologic changes appear likely to become significant only with associated spondylolisthesis and associated remodeling.

Role of low-intensity pulsed ultrasound on lumbar spondylolysis: A systematic review.

OBJECTIVE: To systematically review the role of low-intensity pulsed ultrasound on lumbar spondylolysis. METHODS: Literature search was conducted on PubMed, Embase, CINAHL, Web of Science, PEDro and Scopus databases to identify relevant studies published between 2010 and 2020 by using medical subject headings and applying Booleans, such as low-intensity pulsed ultrasound OR interventional ultrasound AND lumbar spine OR lumbar region AND spondylolysis OR stress fracture. Unpublished studies were hand-searched in the journals, abstracts of conferences were reviewed, and citation index was used for searching experts in the field and then contacting them for information. Studies included were the ones that had at least one of the following outcomes: bone union rate, treatment period to bone union and time to return to previous activities. RESULTS: Of the 243 studies identified, 228(94%) were full text articles and only 2(0.8%) studies were critically appraised for qualitative synthesis based on bone union rate, treatment period to bone union, and time to return to previous activities. CONCLUSIONS: Low-intensity pulsed ultrasound was found to be effective for bone union and a useful therapy for quick return to playing sports in patients with lumbar spondylolysis.

Clinical Practice Patterns of Isthmic Spondylolysis in Young Athletes: A Survey of Pediatric Research in Sports Medicine Members.

ABSTRACT: Isthmic spondylolysis is a common cause of back pain in young athletes. The condition presents to numerous medical providers who employ a variety of different practices in diagnosis and management. The purpose of this study was twofold: to review the literature of diagnosis and management of the young athlete with isthmic spondylolysis and to survey Pediatric Research in Sports Medicine (PRiSM) members during the 2021 PRiSM Annual Meeting on practice patterns of diagnosis and management of the young athlete with isthmic spondylolysis. The response rate was 27%. Per respondents: 24% obtain oblique radiographs; 90% use magnetic resonance imaging as the advanced imaging modality; 60% treat with bracing; 57% recommend rest prior to physical therapy (PT); 53% prescribe return to sport activity restrictions. Although there are similarities in the diagnosis of isthmic spondylolysis in young athletes, this survey confirmed variability in management, especially bracing, timing of PT and return to sport activity restrictions.

A delayed diagnosis of high-grade spondylolisthesis.

ABSTRACT: Spondylolysis, or pars defect, occurs in nearly half of children with back pain. Despite the marked prevalence, diagnosis of spondylolysis with spondylolisthesis often is delayed or missed secondary to referred pain and uncharacteristic presentation. This article describes an 8-year-old patient with 15 months of right heel pain who was initially treated by her primary care provider for presumed Sever disease before being referred to orthopedics. After orthopedic consultation, she was diagnosed with a high-grade spondylolisthesis with L5 nerve root compression. Although spondylolysis is an infrequent diagnosis, particularly in a patient this young, missing the diagnosis can significantly reduce a patient's quality of life.

Phenotypic characterization of Slc26a2 mutant mice reveals a multifactorial etiology of spondylolysis.

Confusion persists over pathogenesis of spondylolysis. To confirm pathogenicity of the previously identified causative mutation of spondylolysis and investigate the genetic etiology, we generate a new mouse line harboring D673V mutation in the Slc26a2 gene. D673V mutation induces delayed endochondral ossification characterized by transiently reduced chondrocyte proliferation in mice at the early postnatal stage. Adult D673V homozygotes exhibit dysplastic isthmus and reduced bone volume of the dorsal vertebra resembling the detached vertebral bony structure when spondylolysis occurs, including the postzygopophysis, vertebral arch, and spinous process, which causes biomechanical alterations around the isthmic region of L4-5 vertebrae indicated by finite element analysis. Consistently, partial ablation of Slc26a2 in vertebral skeletal cells using Col1a1-Cre; Slc26a2 fl/fl mouse line recapitulates a similar but worsened vertebral phenotype featured by lamellar isthmus. In addition, when reaching late adulthood, D673V homozygotes develop an evident bone-loss phenotype and show impaired osteogenesis. These findings support a multifactorial etiology, involving congenitally predisposed isthmic conditions, altered biomechanics, and age-dependent bone loss, which leads to SLC26A2-related spondylolysis.

What is the difference in pedicle morphology of the fifth lumbar vertebra between isthmic and degenerative L5-S1 spondylolisthesis? An anatomic study of 328 patients via multi-slice spiral computed tomography.

PURPOSE: The purpose of this study was to investigate and determine whether there are differences in L5 pedicles morphology between isthmic and degenerative L5-S1 spondylolisthesis. METHODS: One hundred and nineteen patients with isthmic spondylolisthesis and 45 patients with degenerative spondylolisthesis at L5-S1 were enrolled in the IS group and DS group, respectively, and 164 lumbar disc herniation patients without spondylolysis or spondylolisthesis were classified into the normal (NL) group. A series of pedicle parameters of the fifth lumbar vertebra, including pedicle length (PL), pedicle width (PW), pedicle screw trajectory length (PSTL), pedicle height (PH), and the pedicle camber angle (PCA), were measured using multi-slice spiral computed tomography (MSCT). The slip distance of the L5 vertebra was measured on radiography, and the percentage of slip was also recorded. RESULTS: The pedicles of the fifth lumbar vertebra were shorter and wider, and the PCA was larger in the IS group compared to the DS group and NL group. On the contrary, the pedicles in the DS group were elongated and thinner, and the PCA was smaller. The pedicle parameters of PL were significantly positively correlated with the percentage of slip in the DS group, but PW and PCA were negatively correlated with the percentage of slip. There was no correlation between the percentage of slip and L5 pedicle parameters in the IS group. CONCLUSIONS: The L5 pedicles morphology in L5-S1 isthmic spondylolisthesis shows abduction, shortness, and width, while that in the degenerative spondylolisthesis shows adduction, lengthening, and thinning compared with the normal populations. The morphology changes may be the result of pedicle stress remodelling in the development of spondylolisthesis, which should be taken into consideration when placing at the insertion of pedicle screws.