Lumbosacral transitional vertebra in spondylolisthesis: frequency, demographic findings, and clinical characteristics.

BACKGROUND: The association of LSTV with low back pain has been debated in the literature for nearly a century, but the relationship between LSTV and spondylolisthesis is still under discussion. There is currently no valid information about LSTV's prevalence in Iran. This study investigated the relationship between the presence of LSTV and lumbosacral spondylolisthesis regarding frequency, gender and age variation, grade and level of spondylolisthesis, and clinical signs and symptoms. METHODS: This cross-sectional study included spondylolisthesis patients admitted for surgery between March 2021 to December 2022. All patients underwent CT imaging. After evaluating medical records, the baseline data were collected. Patients were categorized into No LSTV, Sacralization, and Lumbarization groups. Demographic and clinical characteristics of the studied groups were compared using an independent T-test and Chi-Square. Multiple logistic regression was used to assess the age and sex variations between groups. RESULTS: 219 patients with a mean age of 57.07 ± 11.04 were included. A significant relationship was observed between the presence of sacralization and gender diversity with female predominance (P = 0.01). The level of spondylolisthesis and the presence of motor deficits (paresis) significantly differed among study groups (P < 0.05). Sacralization group exhibited a greater prevalence of higher grades of listhesis compared to the other groups. CONCLUSIONS: LSTV is frequently seen in spondylolisthesis patients. Sacralization is the common type of LSTV in spondylolisthesis patients, possibly leading to an increased risk for higher grades of vertebral slip and higher rates of motor deficit signs and symptoms. The presence of sacralization results in a significant increase in the incidence of higher levels of spondylolisthesis, especially the L4-L5*(sacralized L5) level. There is no relationship between age and the presence of LSTV in spondylolisthesis.

Association between spinopelvic alignment and the development of degenerative spondylolisthesis: a systematic review and meta-analysis.

INTRODUCTION: Spinopelvic parameter may result in the development of degenerative spondylolisthesis. However, previous studies show conflicting results; some found a significant relationship of some of these parameters with degenerative spondylolisthesis, while others did not. Previously, there was no meta-analysis regarding the association between spinopelvic alignment and degenerative spondylolisthesis. This meta-analysis aims to determine the association between spinopelvic alignment and degenerative spondylolisthesis. METHODS: Systematic reviews and meta-analyses are based on the selected item reporting method for systematic review and meta-analysis (PRISMA). A literature search was performed using PubMed, EMBASE, ScienceDirect, Cochrane, and Google Scholar. Methodological quality is based on the cross-sectional checklist of the Agency for Healthcare Research and Quality (AHRQ) quality check methodology and the Newcastle-Ottawa scale (NOS) for cohort studies. Statistical analysis was performed using Rev-Man 5.3. Subgroup analyses were performed based on ethnicity and study design to ascertain racial relations and heterogeneity. RESULTS: A total of 3236 articles were obtained. Of these, we found that pelvic incidence (mean difference [MD] = 11.94 [1.81-22.08], P = 0.02), pelvic tilt (MD = 4.47 [0.81-8.14]), P = 0.02), and age (MD = 11.94 [1.81-22.08], P = 0.02) were associated with the development of degenerative spondylolisthesis. CONCLUSION: This meta-analysis proves that pelvic incidence, pelvic tilt, and age are associated with degenerative spondylolisthesis.

Modified unilateral iliac screw fixation with partial reduction in the treatment of high-grade spondylolisthesis at L5/S1 in adult patients: introduction of key technique, report of clinical outcomes and analysis of spinopelvic parameters.

BACKGROUND: Management of high-grade spondylolisthesis (HGS) remains challenging. Spinopelvic fixation such as iliac screw (IS) was developed to deal with HGS. However concerns regarding constructs prominence and increased infection-related revision surgery have complicated it's use. We aim to introduce the modified iliac screw (IS) technique in treating high-grade L5/S1 spondylolisthesis and it's clinical and radiological outcomes. METHODS: Patients with L5/S1 HGS who underwent modified IS fixation were enrolled. Pre- and postsurgical upright full spine radiographs were obtained to analyze sagittal imbalance, spinopelvic parameters, pelvic incidence-lumbar lordosis mismatch (PI-LL), slip percentage, slip angle (SA), and lumbosacral angle (LSA). Visual analogue scale (VAS), Oswestry disability index (ODI) were evaluated pre- and postoperatively for clinical outcomes assessment. Estimated blood loss, operating time, perioperative complications and revision surgery were documented. RESULTS: From Jan 2018 to March 2020, 32 patients (15 males) with mean age of 58.66 ± 7.77 years were included. The mean follow-up period was 49 months. The mean operation duration was 171.67 ± 36.66 min. At the last follow-up: (1) the VAS and ODI score were significantly improved (p < 0.05), (2) PI increased by an average of 4.3°, the slip percent, SA and LSA were significantly improved (p < 0.05), (3) four patients (16.7%) with global sagittal imbalance recovered a good sagittal alignment, PI-LL within ± 10° was observed in all patients. One patient experienced wound infection. One patient underwent a revision surgery due to pseudoarthrosis at L5/S1. CONCLUSION: The modified IS technique is safe and effective in treating L5/S1 HGS. Sparing use of offset connector could reduce hardware prominence, leading to lower wound infection rate and less revision surgery. The long-term clinical affection of increased PI value is unknown.

Traumatic cervical posterior spondyloptosis: report of a rare case.

Traumatic spinal spondyloptosis is the extreme degree of spondylolisthesis and is not common. Traumatic cervical anterior spondyloptosis has been reported but we could not find reports of posterior traumatic cervical spondyloptosis. We present an 18-year-old female with this type of injury and cervical complete cord syndrome below C5 and explain our treatment approach.

Traumatic spondylolisthesis of axis: clinical and imaging experience at a level one trauma center.

PURPOSE: Traumatic spondylolisthesis of the axis (TSA) with bilateral pars interarticularis fracture (a pattern also known as Hangman's fractures) accounts for 4-5% of all cervical fractures. Various classification systems have been described to assist therapeutic decision-making. The goal is to reassess the utility of these classifications for treatment strategy and evaluate additional imaging associations. METHODS: This is an IRB approved, retrospective analysis of patients with imaging diagnosis of TSA from 2016 to 2019. Consensus reads were performed classifying TSA into various Levine and Edwards subtypes and typical vs. atypical fractures. Other imaging findings such as additional cervical fractures, traumatic brain injury, spinal cord injury, and vertebral artery injury were recorded. Treatment strategy and outcome were reviewed from clinical charts. Fisher exact test was used for statistical analysis. RESULTS: A total of 58 patients were included, with a mean age of 62.7 ± 25 years, and male to female ratio of 1:1.2. Motor vehicle collision was the most common cause of TSA. Type I and III injuries were the most and the least common injuries, respectively. Patients with type I injuries were found to have good healing rates with conservative management (p < 0.001) while type IIa and III injuries were managed with surgical stabilization (p = 0.04 and p = 0.01, respectively). No statistical difference was observed in the treatment strategy for type II fractures (p = 0.12) and its prediction of the associated injuries. Atypical fractures were not found to have a higher incidence of SCI (p = 0.31). A further analysis revealed significantly higher-grade vertebral artery injuries (grades III and IV according to Biffl grading) in patients with type IIa and III injuries (p = 0.001) and an 11-fold increased risk of TBI compared to type I and type II fractures (p = 0.013). CONCLUSION: TSA fracture types were not associated with any clinical outcome. Levine and Edwards type II classification itself is not enough to guide the treatment plan and does not account for associated injuries. Additional imaging markers may be needed.

Does fusion status following posterolateral lumbar fusion in the treatment for stable lumbar degenerative spondylolisthesis affect the long-term surgical outcomes? A propensity score-weighted analysis of consecutive patients.

BACKGROUND: The surgical strategy of lumbar degenerative spondylolisthesis (LDS) is controversial, especially regarding whether or not fusion should be used. Although some reports have indicated that decompression combined with fusion may be better than decompression alone in the treatment of LDS, the effect of fusion status after uninstrumented posterolateral lumbar fusion (PLF) on the outcomes of patients with stable LDS remains unknown. This study aimed to evaluate the surgical outcomes of uninstrumented PLF for stable LDS and clarify whether radiographic fusion status could affect surgical outcomes. METHODS: A total of 93 consecutive patients who had undergone single-level uninstrumented PLF for Meyerding grade I LDS without preoperative dynamic instability with a minimum follow-up period of 5 years were retrospectively studied. Patients were divided into two groups: nonunion (52 patients) and union (41 patients). The primary outcomes were the 5-year percent recovery of postoperative Japanese Orthopaedic Association (JOA) scores, Oswestry Disability Index (ODI), Visual analog scale (VAS) scores, and reoperation rate. The outcome scores were compared between the groups using the inverse probability weighting method using propensity scores. RESULTS: The union and nonunion groups had comparable weighted means of the 5-year postoperative clinical score for the percent recovery of the JOA score (70.2% vs. 71.1%, P = 0.86), ODI (14.5 vs.14.6, P = 0.98), VAS of low back pain (20.3 vs. 18.7 mm, P = 0.72), and VAS of leg pain (24.0 vs. 19.4 mm, P = 0.43). The reoperation rate was 2.4% (one case of adjacent segment pathology) in the union group and 0% in the nonunion group (P = 0.44). CONCLUSION: The fusion status following uninstrumented PLF had no significant effect on the 5-year postoperative clinical outcomes and reoperation rate in patients with Meyerding grade I LDS without dynamic instability.

Risk factors for cage subsidence and clinical outcomes after transforaminal and posterior lumbar interbody fusion.

BACKGROUND: Cage subsidence is a very common complication after lumbar interbody fusion. It may compromise vertebral interbody fusion through progressive spinal deformity and consequently cause compression of neural elements. Clinical relevance remains, however, unclear, with few studies on this subject and even less information regarding its correlation with clinical findings. The aim of this study was to identify risk factors for cage subsidence and clinical evaluation after transforaminal (TLIF) and posterior (PLIF) lumbar interbody fusion. METHODS: A retrospective study in patients submitted to TLIF and PLIF between 2008 and 2017 was conducted. RESULTS: A total of 165 patients were included (123 TLIF and 42 PLIF). Univariate analysis showed an increased risk of cage subsidence in spondylolisthesis comparing with degenerative disk disease (p = 0.007). A higher preoperative lumbar lordosis angle (p = 0.014) and cage placement in L2-L3 (p = 0.012) were associated with higher risk of subsidence. The posterior cage positioning on vertebral endplate was associated with a higher risk of subsidence (p = 0.028) and significant subsidence (p = 0.005), defined as cage migration > 50% of cage height. PLIF presented a higher risk when comparing with TLIF (p = 0.024). Hounsfield unit (HU) values < 135 (OR6; 95% CI [1.95-34]) and posterior positioning (OR7; 95% CI [1.7-27.3]) were independent risk factors for cage subsidence and significant subsidence, respectively, in multivariate analysis. There was a tendency for significant subsidence in degrees ≥ 2 of Meyerding spondylolisthesis (OR4; 95% CI [0.85-21.5]). Significant cage subsidence was not associated with worse clinical results. Other analyzed factors, such as age (p = 0.008), low bone mineral density (BMD) (p = 0.029) and type of surgery (TLIF) (p = 0.004), were associated with worse results. CONCLUSION: The present study shows that lower BMD and posterior cage positioning are relevant risk factors for lumbar cage subsidence. Low BMD is also a predictor of poor clinical results, so it must be properly evaluated and considered, through HU values measurement in CT scan, a feasible and reliable tool in perioperative planning.

Degenerative spondylolisthesis: a prospective cross-sectional cohort study on the role of weakened anterior abdominal musculature on causation.

PURPOSE: Degenerative spondylolisthesis (DS) is a degenerative condition of the spine which, unlike others, is more common in a female population. Previous studies have highlighted possible causative factors such as facet tropism and pregnancy as reasons for this. This study sets out to assess the possible link between abdominal musculature and DS. METHOD: A prospective cross-sectional cohort study in a single surgeon practice assessed all patients aged over 50 years attending for degenerative lumbar spinal complaints. Patient demographics, as well as the number of pregnancies, children, abdominal surgical procedures, were recorded. RESULTS: We found 205 patients that met our inclusion criteria (98 Males/107 Females). Women with multiple pregnancies (p = 0.036) and abdominal surgeries (p = 0.021) were more likely to develop DS. Males with ventral hernias were more likely to have developed DS (p = 0.004). CONCLUSION: This study highlights the important role that the abdominal musculature plays in stabilization of the spine and highlights its potential role as a factor in the development of DS. These slides can be retrieved under Electronic Supplementary Material.

Is radiographic lumbar spondylolisthesis associated with occupational exposures? Findings from a nested case control study within the Wakayama spine study.

BACKGROUND: To explore the relationship between radiographic spondylolisthesis and occupational factors in a case-control study nested within the Wakayama Spine Study (WSS). METHODS: The WSS is a cross-sectional observational study amongst Japanese adults. All participants completed a lifetime occupational history and underwent X-rays of the lumbar spine (L1-S1) according to a pre-defined protocol. One trained surgeon graded the presence of a spondylolisthesis based upon ≥5% anterior or posterior slip at one or more levels. Cases, with lumbar spondylolisthesis, were compared with controls without, for their principal occupation and occupational exposures. RESULTS: In total, data were available for 722 adults (245 men and 477 women), mean age 70.1 (range 53-93) years. According to the pre-defined radiographic criteria, 117 were defined with spondylolisthesis (cases), leaving 605 controls. Cases were not significantly different from controls for age, gender, BMI, smoking or alcohol intake. However, cases were more than twice as likely to report occupational driving ≥4 h/day (OR 2.39, 95% CI 1.08-5.27) after adjustment for age, gender and BMI. Additionally, after stratification by age using 75 years as a cut-point, cases were more than 3-fold more likely to report having worked in the agricultural/ fishing industries (OR 3.47, 95% CI 1.29-9.29) among those aged < 75 years. A reduced risk of being a case was associated with climbing slopes/steps and walking. CONCLUSIONS: A history of occupational driving and working in the agricultural/fishing industry were associated with radiographic spondylolisthesis in this cross-sectional population study. This finding requires further evaluation in longitudinal studies.

Increased risk of symptomatic progression of instability following decompression for lumbar canal stenosis in patients receiving chronic glucocorticoids therapy.

BACKGROUND: Lumbar decompression surgery is a commonly used treatment for degenerative lumbar spinal stenosis; however, some patients develop symptomatic spinal instability following decompression surgery. The objective of this study was to reveal risk factors for delayed instability following decompression surgery for lumbar spinal stenosis. METHODS: One hundred ten patients who underwent single-level lumbar decompression between 2008 and 2014 were retrospectively reviewed. Surgical indication for decompression surgery was symptomatic lumbar canal stenosis without spondylolisthesis or with minimum spondylolisthesis (less than 4 mm translation). Patients with gross segmental motion (>10° in disc angle, >2 mm translation) on flexion-extension lumbar radiographs were excluded. Age, sex, body mass index, smoking history, diabetes mellitus, autoimmune connective tissue diseases including rheumatoid arthritis, and the use of glucocorticoids were investigated. Radiographic measurements included disc angle, disc height, slippage, facet angle, segmental motion (flexion-extension), lumbar alignment, facet effusion, and disc degeneration. Data were analyzed using multivariate forward selection stepwise logistic regression, chi-square tests, and Student t-test. RESULTS: Six of 110 patients (5.5%) developed symptomatic spinal instability at the operative level and underwent spinal fusion surgery at an average of 2.1 years postoperatively. Autoimmune connective tissue disorders and chronic use of glucocorticoids were associated with the occurrence of symptomatic spinal instability requiring spine fusion surgery, while there was no significant difference in radiographic parameters and demographic factors excluding autoimmune connective tissue diseases between reoperation and non-reoperation groups. CONCLUSIONS: Patients with autoimmune connective tissue disorders receiving chronic glucocorticoid therapy are more likely to develop symptomatic spinal instability following decompression surgery for lumbar canal stenosis without or with minimal spondylolisthesis.

Mild (not severe) disc degeneration is implicated in the progression of bilateral L5 spondylolysis to spondylolisthesis.

BACKGROUND: Spondylolytic (or lytic) spondylolisthesis is often associated with disc degeneration at the index-level; however, it is not clear if disc degeneration is the cause or the consequence of lytic spondylolisthesis. The main objective of this computed tomography based finite element modelling study was to examine the role of different grades of disc degeneration in the progression of a bilateral L5-lytic defect to spondylolisthesis. METHODS: High-resolution computed tomography data of the lumbosacral spine from an anonymised healthy male subject (26 years old) were segmented to build a 3D-computational model of an INTACT L1-S1 spine. The INTACT model was manipulated to generate four more models representing a bilateral L5-lytic defect and the following states of the L5-S1 disc: nil degeneration (NOR LYTIC), mild degeneration (M-DEG LYTIC), mild degeneration with 50% disc height collapse (M-DEG-COL LYTIC), and severe degeneration with 50% disc height collapse(S-COL LYTIC). The models were imported into a finite element modelling software for pre-processing, running nonlinear-static solves, and post-processing of the results. RESULTS: Compared with the baseline INTACT model, M-DEG LYTIC model experienced the greatest increase in kinematics (Fx range of motion: 73% ↑, Fx intervertebral translation: 53%↑), shear stresses in the annulus (Fx anteroposterior: 163%↑, Fx posteroanterior: 31%↑), and strain in the iliolumbar ligament (Fx: 90%↑). The S-COL LYTIC model experienced a decrease in mobility (Fx range of motion: 48%↓, Fx intervertebral translation: 69%↓) and an increase in normal stresses in the annulus (Fx Tensile: 170%↑; Fx Compressive: 397%↑). No significant difference in results was noted between M-DEG-COL LYTIC and S-COL LYTIC models. CONCLUSIONS: In the presence of a bilateral L5 spondylolytic defect, a mildly degenerate index-level disc experienced greater intervertebral motions and shear stresses compared with a severely degenerate index-level disc in flexion and extension bending motions. Disc height collapse, with or without degenerative changes in the stiffness properties of the disc, is one of the plausible re-stabilisation mechanisms available to the L5-S1 motion segment to mitigate increased intervertebral motions and shear stresses due to a bilateral L5 lytic defect.

Spondylolisthesis is Common, Early, and Severe in Loeys-Dietz Syndrome.

BACKGROUND: We studied the prevalence and treatment outcomes of spondylolisthesis in patients with Loeys-Dietz syndrome (LDS). METHODS: Clinical data and lumbosacral imaging of 138 patients with LDS were reviewed. Spondylolisthesis (L4-L5 or L5-S1) and spondylolysis were characterized by multimodal imaging and correlated with clinical data. Treatments and outcomes were characterized for patients with spondylolisthesis. Associations were determined using the Fisher exact, Mann-Whitney, and Student t tests (α=0.05). RESULTS: Twenty-four patients (17%) had spondylolysis and 23 (17%) had spondylolisthesis. Median age at spondylolisthesis diagnosis was 11 (interquartile range, 9.5) years. In patients in whom measurement was possible (n=20), mean (±SD) slip was 48% (±35%). Nineteen patients had L5-S1 slip and 4 had L4-L5 slip. Of the patients with spondylolisthesis, 5 had no evidence of spondylolysis; of those with spondylolysis, all but 6 had spondylolisthesis. Eleven patients with spondylolisthesis underwent posterior spinal fusion (PSF) to treat slip progression, pain, and/or neurological deficit. Spondylolisthesis recurred in 1 patient who underwent PSF with bone graft arthrodesis alone (no instrumentation). The other 10 patients underwent PSF with instrumentation and fusion. Three patients additionally underwent Bohlman interbody fusion. Two patients developed implant failure. S2 fixation was performed at revision to achieve fusion in these patients. Mean Meyerding grade improved in patients who underwent arthrodesis, from 3.9 (±1.2) to 1.9 (±1.3) (P=0.002). Complications were 2 cerebrospinal fluid leaks, 2 transient postoperative paresthesias, and 1 case each of pseudarthrosis at S1-S2, wound dehiscence, and transient urinary incontinence. No significant associations between LDS type and lumbosacral abnormalities were found. CONCLUSIONS: High-grade spondylolisthesis is common in LDS and usually associated with spondylolysis. Patients requiring surgery for spondylolisthesis present during childhood and do well after instrumented PSF. Interbody fusion and stabilization of S1 and S2 can prevent physeal deformation. LDS should be considered in patients with high-grade spondylolisthesis. Patients with LDS should be monitored for spondylolisthesis and spondylolysis starting when they are young. LEVEL OF EVIDENCE: Level IV-retrospective study.

Acquired spondylolysis and spinopelvic sagittal alignment.

Acquired spondylolysis represents an uncommon complication of spine surgery, of an unknown incidence and etiology. We studied patients presenting this rare entity, with the purpose to investigate the incidence, imaging findings, patients' clinical characteristics, as well as to provide an interpretation of the mechanisms that may lead to this phenomenon. The presented working hypothesis, regarding etiology, suggests that there is a relation between variations in spinopelvic sagittal alignment and acquired spondylolysis. Between January 2010 and January 2015, six patients presented spondylolysis after short-segment transforaminal lumbar interbody fusion, at a mean time of 43 months after surgery. The preoperative intactness and postoperative defect of pars interarticularis were documented with computed tomography scans in all patients. Standard radiographical spinopelvic parameters were measured before and after surgery. The optimum values of lumbar lordosis (LL) and pelvic incidence minus lumbar lordosis modifier (PI-LL mismatch) were calculated as well. The incidence of acquired spondylolysis was 0.95% among patients with short-segment lumbar fusion. Patients presented high-grade PI with a vertically orientated sacral endplate, while LL was found 9° greater and PI-LL mismatch 9° lower than the respective optimum values, indicating a non-harmonized alignment. In conclusion, acquired spondylolysis, though rare, may occur in patients with high-grade PI and sacral slope, and suboptimal spinopelvic sagittal alignment after lumbar spine surgery, thereby highlighting the importance of detailed preoperative planning in spine surgery, along with the study of sagittal balance.

Circumferential fusion for degenerative lumbar spondylolisthesis complicated by distal junctional grade 4 spondylolisthesis in the sub-acute post-operative setting.

INTRODUCTION: Surgical management for lumbar stenosis is generally safe and provides significant improvements in pain, disability, and function. Successful lumbar decompression hinges on removing an appropriate amount of lamina and other compressive pathology in the lateral recess. Too little bony decompression can result in persistent pain and disability, while over resection of the pars and/or facets may jeopardize spinal stability. CASE REPORT: In this unique report, we present for the first time an acute iatrogenic grade 4 L5-S1 spondylolisthesis distal to a L3-5 laminectomy and circumferential instrumented fusion due to bilateral iatrogenic L5 pars fractures and its management and clinical outcomes after revision operation. The patient presented with worsening pain, neurologic compromise, and severe sagittal imbalance. The iatrogenic, high-grade spondylolisthesis was urgently addressed with a L5-S1 anterior lumbar interbody fusion and extension of posterior instrumentation to the pelvis, which resulted in considerable pain relief, resolution of neurologic deficits, and reconstitution of acceptable sagittal imbalance. CONCLUSION: All attempts during a lumbar decompression should be made to prevent iatrogenic pars fractures, as they may result in severe sagittal imbalance, neurologic compromise, and persistent disability. Iatrogenic, high-grade L5-S1 spondylolisthesis can be successfully treated with reduction using circumferential fusion of the lumbosacral junction.

Effects of shear force on intervertebral disc: an in vivo rabbit study.

PURPOSE: A new in vivo rabbit model was developed to investigate the effects of shear force on intervertebral disc (IVD). METHODS: Japanese white rabbits (n = 38) were used for this study. The L4/5 discs in Group A (n = 10) were subjected to a constant shear force (50 N) using a custom-made external loading device for 1 month; in Group B (n = 10) for 2 months; whereas in Group C (n = 10), loading device was attached to the spine but the discs remained unloaded. Group D (n = 8) was a non-operated intact control group. After loading, the loading devices were taken out and the animals were given X-ray and MRI examination. After X-ray and MRI examination, the animals were euthanized for histological analysis. RESULTS: After 1 and 2 months of loading, radiographic findings showed significant disc height narrowing in L4/5 discs of the animals in loading groups, and slight lumbar spondylolisthesis in some animals of Group B. MRI showed a significant decrease in nucleus pulposus (NP) area and signal intensity from T2-weighted images. Histologically, loss of normal NP cells and disorganization of the architecture of the annulus occurred, and proteoglycan stain decreased. CONCLUSIONS: The results of this study suggest that disc degeneration can be induced by hyper-physiological shear loading in the rabbit IVD. Long-term shear loading may result in structural disc failure inducing lumbar spondylolisthesis and progressive disc degeneration, which, however, has to be proven by further studies.

Iatrogenic spondylolisthesis following laminectomy for degenerative lumbar stenosis: systematic review and current concepts.

OBJECT Decompression without fusion for degenerative lumbar stenosis is an effective treatment for both the pain and disability of neurogenic claudication. Iatrogenic instability following decompression may require further intervention to stabilize the spine. The authors review the incidence of postsurgical instability following lumbar decompression, and assess the impact of surgical technique as well as study design on the incidence of instability. METHODS A comprehensive literature search was performed to identify surgical cohorts of patients with degenerative lumbar stenosis, with and without preexisting spondylolisthesis, who were treated with laminectomy or minimally invasive decompression without fusion. Data on patient characteristics, surgical indications and techniques, clinical and radiographic outcomes, and reoperation rates were collected and analyzed. RESULTS A systematic review of 24 studies involving 2496 patients was performed, assessing both open laminectomy and minimally invasive bilateral canal enlargement. Postoperative pain and functional outcomes were similar across the various studies, and postoperative radiographie instability was seen in 5.5% of patients. Instability was seen more frequently in patients with preexisting spondylolisthesis (12.6%) and in those treated with open laminectomy (12%). Reoperation for instability was required in 1.8% of all patients, and was higher for patients with preoperative spondylolisthesis (9.3%) and for those treated with open laminectomy (4.1%). CONCLUSIONS Instability following lumbar decompression is a common occurrence. This is particularly true if decompression alone is selected as a surgical approach in patients with established spondylolisthesis. This complication may occur less commonly with the use of minimally invasive techniques; however, larger prospective cohort studies are necessary to more thoroughly explore these findings.

Spondylolisthesis, Sacro-Pelvic Morphology, and Orientation in Young Gymnasts.

STUDY DESIGN: Cross-sectional evaluation of sacro-pelvic morphology and orientation as well as spondylolisthesis prevalence in a cohort of young gymnasts. OBJECTIVE: To evaluate the prevalence of spondylolisthesis in a cohort of gymnasts, as well as the associated demographic characteristics and sacro-pelvic morphology and orientation. SUMMARY OF BACKGROUND DATA: Numerous studies have shown that sagittal sacro-pelvic morphology and orientation is abnormal in spondylolisthesis. Sacro-pelvic morphology and orientation in gymnasts and their relationship with spondylolisthesis have never been analyzed. METHODS: Radiologic evaluation of 92 gymnasts was performed to identify spondylolisthesis, and to measure pelvic incidence, pelvic tilt, sacral slope, and sacral table angle. In the presence of spondylolisthesis, the slip percentage was measured. Different demographic and training characteristics were evaluated. Radiographic parameters were compared with reference values published for asymptomatic children and adolescents, and for subjects with spondylolisthesis. RESULTS: A 6.5% prevalence of spondylolisthesis was found in our cohort. The weekly training schedule was the only statistically significant different demographic characteristic between the 2 groups, at 20.6±5.4 versus 14.4±5.6 h/wk for subjects with and without spondylolisthesis, respectively. Pelvic incidence, pelvic tilt, sacral slope, and sacral table angle were 69±20, 15±13, 54±11, and 88±7 degrees in gymnasts with spondylolisthesis, and 53±11, 10±6, 43±9, and 94±6 degrees in gymnasts without spondylolisthesis, respectively. When compared with asymptomatic individuals, pelvic incidence and pelvic tilt were slightly superior in gymnasts without spondylolisthesis. Pelvic incidence, sacral slope, and sacral table angle were significantly different between gymnasts with and without spondylolisthesis. CONCLUSIONS: The prevalence of spondylolisthesis in young gymnasts was similar to that observed in the general population. Sagittal sacro-pelvic morphology and orientation was abnormal in gymnasts with spondylolisthesis. Sagittal sacro-pelvic morphology and orientation was also slightly different in gymnasts without spondylolisthesis when compared with the normal population. The present study supports an association between spondylolisthesis and abnormal sacro-pelvic orientation and morphology.

Core curriculum illustration: pediatric traumatic spondylolisthesis of the axis.

This is the 16th installment of a series that will highlight one case per publication issue from the bank of cases available online as part of the American Society of Emergency Radiology (ASER) educational resources. Our goal is to generate more interest in and use of our online materials. To view more cases online, please visit the ASER Core Curriculum and Recommendations for Study online at http://www.aseronline.org/curriculum/toc.htm.