Pelvic retroversion is the key protective mechanism of L4-5 degenerative spondylolisthesis

The triadic relationship between spinal posture, loading, and degeneration

Introduction

Degenerative changes in the lumbar spine may affect many structures, among them the intervertebral discs and the facet joints. The individual load distribution within the spine linked to posture and mass distribution is a probable cause of disease. This study had a dual aim: first, to systematically summarize previously reported associations between sagittal balance parameters and the occurrence of lumbar spine degeneration. Second, to complement these insights with additional biomechanical findings meant to elucidate the link between spine load and alignment as well as selected demographic descriptors.

Methods

A systematic literature search was performed on PubMed to identify clinical studies that quantified the association between spinal alignment and the occurrence of disc herniation, disc degeneration, facet joint degeneration, and spondylolisthesis. Further, a previously published musculoskeletal model was used to link sagittal spinal alignment and subject characteristics to joint loading within the lumbar spine for a cohort of 144 subjects.

Results

The literature review yielded 49 publications evaluating the relationship between spinal alignment and the occurrence of pathologies in the lumbar spine. The results indicate that a straight spine might negatively affect the health status of the intervertebral disc, likely because of a lack of damping and associated high compressive loads. These loads further show a major dependence on body weight. On the other hand, facet degeneration and spondylolisthesis may be linked to higher anterior-posterior shear forces acting on the relevant spinal structures because of a generally more sagittally curved spine. A straight lumbar spine is more likely to stress the disc, whereas highly curved spines with a high pelvic incidence are more likely to stress the posterior structures. The biggest influencing factors on the resulting force and consequently potentially the wear of the anatomical structures are the intervertebral inclination from an anatomical point of view and the weight from a demographic point of view.

Discussion

Information concerning spinal loading resulting from spinal alignment and body descriptors could impact both conservative treatment and operative planning for patients afflicted by spine disease through targeted changes in posture.

Does Adherence to Treatment Guidelines from the Ghailane-Gille Classification for Degenerative Spondylolisthesis of the Lumbar Spine Impact Surgical Outcomes? A Match-Mismatch Study

Background/Objectives: satisfactory sagittal alignment when treating degenerative spondylolisthesis of the lumbar spine (DSLS) may produce better clinical and radiographic outcomes compared to treatment focused solely on isolated segments when indicated. Ghailane et al. proposed a treatment guideline based on their classification system. The aim of this study was to investigate the impact of adherence to Ghailane-Gille (GG) treatment guidelines on surgical outcomes in patients with DSLS. Methods: A monocentric retrospective cohort analysis was performed from 2021 to September 2024. Data were collected from patients treated for DSLS, covering the period from baseline to one-year follow-up. Patients were divided into two groups based on GG treatment guidelines: the "Match group" (patients who underwent surgery following GG guidelines) and the "Mismatch group" (patients who did not adhere to these guidelines). Preoperative and postoperative clinical outcomes, patient satisfaction, and operative parameters were collected and compared between groups. Results: A total of 80 patients were enrolled, with 52 in the Match group and 28 in the Mismatch group. At baseline, the Oswestry Disability Index (ODI) score demonstrated significant variation among classification subtypes and a positive correlation. The Match group exhibited a significant reduction in ODI scores one year postoperatively and maintained high levels of satisfaction; no significant intraoperative differences were noted. Additionally, patients in the Mismatch group were more frequently classified as American Society of Anesthesiologists (ASA) III compared to the Match group (70% vs. 30%), suggesting clinicians' hesitance to fully implement GG guidelines in aggressive treatment strategies for those patients. Conclusions: Adhering to the GG treatment guidelines for restoring sagittal alignment in DSLS patients is associated with decreased ODI scores regardless of age, ensuring patient satisfaction at one-year follow-up. This approach could potentially benefit ASA III patients as well.

Posterior lumbar interbody fusion for degenerative spondylolisthesis; slippage reduction can be a risk factor for adjacent segment disease

PURPOSE

Several risk factors for adjacent segment disease (ASD) after posterior lumbar interbody fusion (PLIF) have been reported. High pelvic incidence (PI) has been identified as risk factors for L4 anterior slip in cases of lumbar degenerative spondylolisthesis. Correcting the slip with L4-L5 fixation merely restores the lumbar alignment, but the PI itself remains unchanged. We hypothesized that the fused L4 vertebral body might continue to be subject to the slip-inducing force, even after fixation, and that slip correction might be a cause of ASD. The purpose of this study is to identify the risk factors for adjacent ASD following single-segment PLIF in patients with L4 spondylolisthesis, with a particular focus on the reduction of vertebral body slippage.

METHODS

Fifty-two patients who underwent posterior lumbar interbody fusion at the L4-L5 level for L4 degenerative spondylolisthesis were investigated. Patients were divided into two groups: the ASD group (n = 12) and the non-ASD group (n = 40). %Slip before surgery and at follow-up, Δ%Slip (Δ%Slip = %Slip before surgery-%Slip at follow-up), L4-L5 interbody height, and L4-L5 lordosis angle were evaluated.

RESULTS

Stepwise multivariate regression analysis revealed Δ%Slip to be a risk factor for ASD (odds ratio: 1.22, 95% confidence interval: 1.04-1.43, p = 0.015). In the receiver operating characteristic analysis, the cutoff value for Δ%Slip was 7.3% (sensitivity: 75.0%, specificity: 67.5%, and area under the curve = 0.725).

CONCLUSIONS

Our findings suggest that the reduction of L4 slippage may contribute to the development of ASD in patients with L4 spondylolisthesis.

Artificial intelligence automatic measurement technology of lumbosacral radiographic parameters

Background

Currently, manual measurement of lumbosacral radiological parameters is time-consuming and laborious, and inevitably produces considerable variability. This study aimed to develop and evaluate a deep learning-based model for automatically measuring lumbosacral radiographic parameters on lateral lumbar radiographs.

Methods

We retrospectively collected 1,240 lateral lumbar radiographs to train the model. The included images were randomly divided into training, validation, and test sets in a ratio of approximately 8:1:1 for model training, fine-tuning, and performance evaluation, respectively. The parameters measured in this study were lumbar lordosis (LL), sacral horizontal angle (SHA), intervertebral space angle (ISA) at L4-L5 and L5-S1 segments, and the percentage of lumbar spondylolisthesis (PLS) at L4-L5 and L5-S1 segments. The model identified key points using image segmentation results and calculated measurements. The average results of key points annotated by the three spine surgeons were used as the reference standard. The model's performance was evaluated using the percentage of correct key points (PCK), intra-class correlation coefficient (ICC), Pearson correlation coefficient (r), mean absolute error (MAE), root mean square error (RMSE), and box plots.

Results

The model's mean differences from the reference standard for LL, SHA, ISA (L4-L5), ISA (L5-S1), PLS (L4-L5), and PLS (L5-S1) were 1.69°, 1.36°, 1.55°, 1.90°, 1.60%, and 2.43%, respectively. When compared with the reference standard, the measurements of the model had better correlation and consistency (LL, SHA, and ISA: ICC = 0.91-0.97, r = 0.91-0.96, MAE = 1.89-2.47, RMSE = 2.32-3.12; PLS: ICC = 0.90-0.92, r = 0.90-0.91, MAE = 1.95-2.93, RMSE = 2.52-3.70), and the differences between them were not statistically significant (p > 0.05).

Conclusion

The model developed in this study could correctly identify key vertebral points on lateral lumbar radiographs and automatically calculate lumbosacral radiographic parameters. The measurement results of the model had good consistency and reliability compared to manual measurements. With additional training and optimization, this technology holds promise for future measurements in clinical practice and analysis of large datasets.

The Impact of Preoperative Sagittal Imbalance on Long-term Postoperative Outcomes Following Minimally Invasive Laminectomy

Background: Postoperative sagittal alignment has been shown to be associated with patient-reported outcome measures (PROMs) following open lumbar decompression procedures, although it is unknown whether preoperative sagittal imbalance affects clinical outcomes of minimally invasive surgical (MIS) decompression only surgery. Purpose: We sought to evaluate the impact of preoperative pelvic incidence-lumbar lordosis (PI-LL) imbalance on PROMs after MIS laminectomy for the treatment of neurogenic claudication symptoms. Methods: We conducted a retrospective cohort study of adult patients undergoing MIS laminectomy for degenerative lumbar spinal stenosis between April 2017 and April 2021 at a single institution. Of the 52 patients included (mean follow-up, 17 months) radiographs were taken prior to surgery and assessed for sagittal alignment parameters. Patients were grouped based on the preoperative PI-LL (balanced vs unbalanced). Changes in PROMs were compared between unbalanced PI-LL and balanced PI-LL groups. Minimal clinically important difference (MCID) for Oswestry Disability Index (ODI) was also assessed. Results: Of the 52 patients, 17 (32.7%) had unbalanced age-adjusted preoperative PI-LL. There was no significant difference found in PROMs between unbalanced and balanced PI-LL groups preoperatively or at final follow-up. Compared with those with unbalanced PI-LL, patients with balanced PI-LL were shown to have no added benefit in achieving MCID for ODI at long-term follow-up and no added benefit in the time to achieving MCID. Conclusion: These retrospective findings suggest that patients with unbalanced preoperative PI-LL may experience significant benefit in long-term clinical outcomes following MIS laminectomy, similarly to those with balanced PI-LL at baseline. The findings also suggest that the presence of sagittal imbalance preoperatively may not appreciably influence the long-term clinical outcomes following MIS laminectomy. Prospective study involving a larger population is warranted.

Lumbar degenerative spondylolisthesis: role of sagittal alignment

PURPOSE

To evaluate the sagittal alignment of the lumbar spine in patients with degenerative spondylolisthesis at the L4-5 level.

METHODS

Patients with untreated degenerative spondylolisthesis at L4-5 were retrospectively identified from the clinical practice of spine surgeons at an academic medical center. All patients had standing X-rays that were reviewed by the senior surgeon to confirm the presence of degenerative spondylolisthesis at L4-5. Radiographs were analyzed for the following: lumbar lordosis (LL), lower lumbar lordosis (L4-S1; LLL), L5-S1 lordosis, pelvic incidence (PI), and pelvic tilt (PT). From these measurements, lumbar distribution index (LLL/LL × 100; LDI), ideal lumbar lordosis (PI × 0.62 + 29; ILL), PI-LL mismatch, and relative lumbar lordosis (LL-ILL; RLL) were calculated. These parameters were used to evaluate the sagittal alignment of the lumbar spine. Normal alignment was defined based on previous studies and clinical experience.

RESULTS

117 participants met inclusion criteria, with an average age of 67.2 years. The majority of the cohort demonstrated hypolordotic sagittal alignment of the L5-S1 segment when assessed in relation to ILL, PI, and LL (73.5%, 61.5%, and 50.4% respectively). Evaluation of the lower lumbar spine (L4-S1) demonstrated normal sagittal alignment when evaluated via LDI and LLL (65%, 52.1%, respectively), suggesting the presence of compensatory hyperextension at L4-5 in response to the L5-S1 hypolordosis. Consequently, normal sagittal alignment of the regional lumbar spine was maintained when evaluated using LL, PI-LL mismatch, and RLL (51.3%, 47%, and 62.4% respectively).

CONCLUSIONS

This study demonstrates that there is a high incidence of relative hypolordosis at the L5-S1 level among patients who present with degenerative spondylolisthesis at L4-5. The L5-S1 hypolordosis is associated with L4-5 hyperlordosis, such that the lower lumbar lordosis (L4-S1; LLL) and regional lumbar lordosis (LL) are still within normal range. It is probable that L5-S1 hypolordosis was the initial pathologic event that incited compensatory L4-5 hyperlordosis, which in turn may have led to facet degeneration and laxity, and eventually to development of 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.

How does long thoracolumbar realignment surgery of adult spinal kyphotic deformity affect lower extremity compensation? Using full body radiograph

PURPOSE

By using full body radiograph, the aim of the current study was to elucidate the expected degree of lower extremity compensatory change after long thoracolumbar realignment surgery with adult spinal deformity patient who had normal or only mild osteoarthritis on lower extremities.

METHODS

Two novel parameters were used for assessment of regional compensation of the lower extremity. The Pearson correlation test was used to assess the correlation of postoperative changes of lower extremity compensation with the other spinopelvic parameters.

RESULTS

Overall, 113 spinal deformity patients (mean age was 54.5 years) were recruited and the average number of fused vertebrae was 13.3 ± 3.5. Except pelvic tilt (PT), postoperative sacrum-femur angle (SF) changes showed only moderate correlation with all angular spinopelvic parameters (r = 0.323-0.374; p < .001 to p = .001). Also C7 sagittal vertical axis showed no significant correlation with SF (p = .584-.621). However, postoperative changes of sagittal femur-tibia angle (SFT) reported strong correlation with all parameters evaluated (r = 0.455-0.586; p < .001 to p = .046).

CONCLUSION

For adult spinal deformity patients who had normal or only mild osteoarthritis on the lower extremities underwent long thoracolumbar realignment surgery, the surgeon could expect improvement of compensatory change of the knee with correction of spinopelvic parameters. However, the degree of hip compensation improvement was relatively difficult to predict than that of the knee, except PT.

Analysis of Risk Factors for Adjacent Segment Degeneration after Minimally Invasive Transforaminal Interbody Fusion at Lumbosacral Spine

Background. Adjacent segment degeneration (ASD) has been considered as a serious complication from changes in the biological stress pattern after spinal fusion. The sagittal balance significantly associated with lumbar loading is largely dependent on L5-S1 segment. However, the evidence indicating risk factors for radiological and symptomatic ASD after minimally invasive transforaminal interbody fusion (MIS-TLIF) remains insufficient. Methods. This single-central retrospective study recruited patients with lumbosacral degeneration receiving MIS-TLIF at the L5-S1 level from January 2015 to December 2018. The targeted variables included demographic information, radiological indicators, surgery-related parameters, and patient-reported outcomes (PROs) extracted from the electronic medical system by natural language processing. In these patients, a minimum of 3-year follow-up was done. After reviewing the preoperative and postoperative follow-up digital radiographs, patients were assigned to radiological ASD group (disc height narrowing ≥3 mm, progressive slipping ≥3 mm, angular motion >10°, and osteophyte formation >3 mm), symptomatic ASD group, and control group. We identified potential predictors for radiological and symptomatic ASD with the service of stepwise logistic regression analysis. Results. Among the 157 consecutive patients treated with MIS-TLIF in our department, 16 cases (10.2%) were diagnosed with radiological ASD at 3-year follow-up. The clinical evaluation did not reveal suspicious risk factors, but several significant differences were confirmed in radiological indicators. Multivariate logistic regression analysis showed postoperative PI, postoperative DA, and ∆PI-LL in radiological ASD group were significantly different from those in control group. Nevertheless, for patients diagnosed with simultaneously radiological and symptomatic ASD, postoperative DA and postoperative PT as risk factors significantly affected the clinical outcome following MIS-TLIF. Conclusion. In this study, while approximately 10% of lumbosacral degenerations develop radiographic ASD, prognosis-related symptomatic ASD was shown not to be a frequent postoperative complication. Postoperative PI, postoperative DA, and mismatched PI-LL are risk factors for radiological ASD, and postoperative DA and postoperative PT are responsible for the occurrence of symptomatic ASD following MIS-TLIF. These radiological risk factors demonstrate that restoration of normal sagittal balance is an effective measure to optimize treatment strategies for secondary ASD prevention.

Management of degenerative spondylolisthesis: development of appropriate use criteria

BACKGROUND CONTEXT

Outcomes of treatment in care of patients with spinal disorders are directly related to patient selection and treatment indications. However, for many disorders, there is absence of consensus for precise indications. With the increasing emphasis on quality and value in spine care, it is essential that treatment recommendations and decisions are optimized.

PURPOSE

The purpose of the North American Spine Society Appropriate Use Criteria was to determine the appropriate (ie reasonable) multidisciplinary treatment recommendations for patients with degenerative spondylolisthesis across a spectrum of more common clinical scenarios.

STUDY DESIGN

A Modified Delphi process was used.

METHODS

The methodology was based on the Appropriate Use Criteria development process established by the Research AND Development Corporation. The topic of degenerative spondylolisthesis was selected by the committee, key modifiers determined, and consensus reached on standard definitions. A literature search and evidence analysis were completed by one work group simultaneously as scenarios were written, reviewed, and finalized by another work group. A separate multidisciplinary rating group was assembled. Based on the literature, provider experience, and group discussion, each scenario was scored on a nine-point scale on two separate occasions, once without discussion and then a second time following discussion based on the initial responses. The median rating for each scenario was then used to determine if indications were rarely appropriate (1 - 3), uncertain (4-6), or appropriate (7-9). Consensus was not mandatory.

RESULTS

There were 131 discrete scenarios. These addressed questions on bone grafting, imaging, mechanical instability, radiculopathy with or without neurological deficits, obesity, and yellow flags consisting of psychosocial and medical comorbidities. For most of these, appropriateness was established for physical therapy, injections, and various forms of surgical intervention. The diagnosis of spondylolisthesis should be determined by an upright x-ray. Scenarios pertaining to bone grafting suggested that patients should quit smoking prior to surgery, and that use of BMP should be reserved for patients who had risk factors for non-union. Across all clinical scenarios, physical therapy (PT) had an adjusted mean of 7.66, epidural steroid injections 5.76, and surgery 4.52. Physical therapy was appropriate in most scenarios, and most appropriate in patients with back pain and no neurological deficits. Epidural steroid injections were most appropriate in patients with radiculopathy. Surgery was generally more appropriate for patients with neurological deficits, higher disability scores, and dynamic spondylolisthesis. Mechanical back pain and presence of yellow flags tended to be less appropriate, and obesity in general had relatively little influence on decision making. Decompression alone was more strongly considered in the presence of static versus dynamic spondylolisthesis. On average, posterior fusion with or without interbody fusion was similarly appropriate, and generally more appropriate than stand-alone interbody fusion which was in turn more appropriate than interspinous spacers.

CONCLUSIONS

Multidisciplinary appropriate treatment criteria were generated based on the Research AND Development methodology. While there were consistent and significant differences between surgeons and non-surgeons, these differences were generally very small. This document provides comprehensive evidence-based recommendations for evaluation and treatment of degenerative spondylolisthesis. The document in its entirety will be found on the North American Spine Society website (https://www.spine.org/Research-Clinical-Care/Quality-Improvement/Appropriate-Use-Criteria).

Dynamic global sagittal alignment in patients with lumbar spinal stenosis: Analysis of the effects of decompression surgery on gait adaptations

BACKGROUND

Lumbar spinal stenosis (LSS) leads patients to adapt their posture and walking parameters. Pelvic retroversion might be a compensation mechanism of pain. Pelvic and lower limbs compensations during gait are still not precisely understood, as well as the effect of a surgical decompression on them. These dynamic parameters can be studied through three-dimensional gait analysis.

RESEARCH QUESTION

Is the dynamic pelvic tilt modified after decompression surgery in LSS patients compared to asymptomatic subjects?

MATERIAL AND METHODS

50 asymptomatic subjects (C-group) and 37 patients operated on for lumbar decompression underwent a three-dimensional gait analysis one month before (M0) and six months after (M6) the surgery. 3D gait analysis was performed and hip and knee flexion, trunk kinematics, walking speed, stride length and pelvic tilt during gait or dynamic pelvic tilt (dPT) were recorded. Health-related quality of life (HRQL) scores (Oswestry Disability Index (ODI) and Visual Analogic Scales (VAS)) and radiological assessment were performed preoperatively and postoperatively.

RESULTS

Mean values of maximum and minimum dPT in the LSS-group preoperatively were significantly higher compared to the C-group (respectively 10.9 (6.2)° versus 7.3 (5.6)°, p = 0.003; 7.7 (6.1)° versus 4.8 (5.8)°, p = 0.011), and were significantly lowered at M6 (respectively 10.9 (6.2)° versus 8.1 (4.8)°, p = 0.0087; and 7.7 (6.1)° versus 5.1 (4.7)°, p = 0.012), and became similar to the C-group. The dPT range of motion at M0 and M6 were similar, and were both significantly higher than control values. Mean values of maximum and minimum hip flexion were significantly higher at M0 compared to the C-group, and were significantly lowered at M6. No difference was found between the pre- and postoperative radiographic pelvic tilt. The VAS for lumbar pain, the VAS for radicular pain and the ODI were significantly decreased at M6.

SIGNIFICANCE

Compared to asymptomatic people, LSS patients walked with a pelvic anteversion, a hip flessum and a knee flessum before surgery, which tended to disappear after the surgical decompression. These differences were not noticed on static radiographs.

Comparison study of clinical outcomes and sagittal alignment improvement between anterior and posterior fusion techniques for multilevel cervical spondylotic myelopathy

PURPOSE

To compare the sagittal alignment of different surgical approaches in patients with multiple levels cervical spondylotic myelopathy and explore the relationship between the cervical sagittal alignment and patient's health relative quality of life.

METHOD

A total of 97 multiple levels cervical spondylotic myelopathy patients who underwent surgery from January 2013 to January 2019 were collected in this study. Patients were divided into three groups: anterior cervical discectomy with fusion, anterior cervical corpectomy with fusion and laminectomy with fusion groups. Clinical outcomes and sagittal alignment parameters were compared preoperative and postoperative.

RESULTS

There were no significant differences in the average age and sex ratio among the groups. Sagittal parameters correlated to health relative quality of life were C7 slope, occipito-C2 angle, external auditory meatus tilt and cervical sagittal vertical axis. Both anterior cervical discectomy with fusion and anterior cervical corpectomy with fusion groups exhibited better sagittal alignment and clinical outcomes improvement postoperatively. Anterior cervical discectomy with fusion provided better clinical outcomes and the better improvement of cervical lordosis, C7 slope, occipito-C2 angle and cervical sagittal vertical axis compared with patients with Laminectomy with fusion.

CONCLUSION

C7 slope, occipito-C2 angle, external auditory meatus tilt and cervical sagittal vertical axis are the most important cervical sagittal parameters correlated to clinical outcomes in patients with multilevels cervical spondylotic myelopathy; anterior cervical discectomy with fusion and anterior cervical corpectomy with fusion provides more efficient to restoration of cervical sagittal alignment.

Pathomechanisms and Predisposing Factors for Degenerative Lumbar Spondylolisthesis: A Narrative Review

The pathomechanism of degenerative lumbar spondylolisthesis (DLS) is not fully understood and is likely to be multifactorial. The primary cause of DLS likely is age-related degeneration of all of the components of the segments and their surroundings. Subsequently, additional factors, such as anatomical, hormonal, and mechanical stress factors, may drive the spinal segments to DLS. Reported predisposing factors that have shown a consistent association with DLS include older age, female sex, sagittal facet joint orientation, and high pelvic incidence. Future prospective epidemiological studies that include large groups of subjects and use multivariate analyses of the possible predisposing factors are needed.

Automated Measurement of Lumbar Lordosis on Radiographs Using Machine Learning and Computer Vision

STUDY DESIGN

Cross sectional database study.

OBJECTIVE

To develop a fully automated artificial intelligence and computer vision pipeline for assisted evaluation of lumbar lordosis.

METHODS

Lateral lumbar radiographs were used to develop a segmentation neural network (n = 629). After synthetic augmentation, 70% of these radiographs were used for network training, while the remaining 30% were used for hyperparameter optimization. A computer vision algorithm was deployed on the segmented radiographs to calculate lumbar lordosis angles. A test set of radiographs was used to evaluate the validity of the entire pipeline (n = 151).

RESULTS

The U-Net segmentation achieved a test dataset dice score of 0.821, an area under the receiver operating curve of 0.914, and an accuracy of 0.862. The computer vision algorithm identified the L1 and S1 vertebrae on 84.1% of the test set with an average speed of 0.14 seconds/radiograph. From the 151 test set radiographs, 50 were randomly chosen for surgeon measurement. When compared with those measurements, our algorithm achieved a mean absolute error of 8.055° and a median absolute error of 6.965° (not statistically significant, P > .05).

CONCLUSION

This study is the first to use artificial intelligence and computer vision in a combined pipeline to rapidly measure a sagittal spinopelvic parameter without prior manual surgeon input. The pipeline measures angles with no statistically significant differences from manual measurements by surgeons. This pipeline offers clinical utility in an assistive capacity, and future work should focus on improving segmentation network performance.

Straighter low lumbar curvature in isthmic spondylolisthesis at L4

BACKGROUND

This study was conducted to compare differences in imaging features and clinical symptoms between patients with single-level isthmic spondylolisthesis (IS) at L4 and at L5 and to investigate the correlation between imaging and clinical parameters.

METHODS

This cross-sectional study evaluated patients with single-level IS who were enrolled between June 2011 and June 2018. A total of 139 patients, 44 in the L4 IS group and 95 in the L5 IS group, met the study criteria and were included. Imaging and clinical parameters obtained from the two groups were compared and analyzed.

RESULTS

Patients in the L4 IS group had smaller lower lumbar lordosis (LLL) (27.1 ± 8.2 vs. 30.9 ± 9.3, P = 0.021) and were of older age (58.5 ± 8.7 vs. 52.8 ± 10.1, P < 0.01) than those in the L5 IS group. As per the Roussouly classification system, most patients with L4 IS were classified as Type 2 (43.2%), whereas most patients with L5 IS fell under Type 3 (44.2%). In the L5 IS group, pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), and L5 incidence (L5I) were positively associated with slippage rate (SR), but the lumbosacral angle (LSA) was negatively associated with SR (P < 0.01). In the L4 IS group, only L5I showed a positive association with SR (P < 0.01). More significant associations were found among sagittal lumbo-pelvic parameters in the L5 IS group, but none were found between SR and Oswestry Disability Index (ODI) in either group.

CONCLUSIONS

When compared with patients with L5 IS, patients with L4 IS were of older age and had straighter low lumbar curvature when they were obviously symptomatic. PI was an important parameter for patients with L5 IS while for those with L4 IS, L5I deserved more attention for its significantly positive correlation with the degree of slippage.

The correlation between sagittal spinopelvic alignment and degree of lumbar degenerative spondylolisthesis

BACKGROUND

Recently, several authors reported that a high pelvic incidence (PI) might be a predisposing factor to the development of anterior slip in the vertebral body in degenerative spondylolisthesis (DS). The purpose of this study was to analyze patients with DS using a multiple linear regression model, in terms of the correlation between the sagittal spinopelvic parameters and the severity of slip in each lumbar spine, including both anterior and posterior directions.

METHODS

Standing lateral radiographs were taken of 104 patients (59 women and 45 men) with lower back pain. The spinopelvic parameters, including PI, sacral slope (SS) and pelvic tilt (PT), angle of thoracic kyphosis (TK), angle of lumbar lordosis (LL), and sagittal vertical axis offset (SVA) were measured. Additionally, the %Slip was measured at each level between the L1 and L5. The slip direction was presented as plus to the anterior, and minus to the posterior.

RESULTS

The PI, SS, and/or LL correlate with L3, L4, and/or L5%Slips. The TK and SVA did not correlate with %Slip. A multiple linear regression model shows that PI and LL were significant predictors for L4 %Slip. The ROC curve demonstrated a PI cutoff value of 51.3° and an LL cutoff value of 45.0° to be predictors of anterior slip at L4. Also, our regression models revealed that PI for L3 %Slip and SS for L5 %Slip constitute significant risk factors, while determination coefficients were low.

CONCLUSIONS

Our results suggest that high PI and LL are significant predictors for L4 anterior slip. At L4, the anterior slip risk-factor cutoff value was 51.3° for PI and 45.0°for LL. Additionally, our results suggest that high PI and SS could comprise risk factors for L3 anterior slip and L5 anterior slip, respectively.

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

STUDY DESIGN

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

OBJECTIVE

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

SUMMARY OF BACKGROUND DATA

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

METHODS

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

RESULTS

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

CONCLUSION

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

LEVEL OF EVIDENCE

N/A.

High-Grade Lumbar Spondylolisthesis

Most high-grade spondylolistheses are resultant from isthmic spondylolisthesis, as complete discontinuity of the pars is typically necessary to allow for this degree of anterior vertebral translation, although can occur less commonly in other scenarios. Higher-grade slips can affect the global sagittal balance of the patient and often result in altered gait patterns and compensatory posturing. Management usually entails surgical decompression and fusion with instrumentation. The addition of anterior column support carries many advantages, including greater surface area for fusion, dynamic compression load sharing at the lumbosacral junction, and a powerful adjunct for deformity correction.

Potential pathological mechanisms of L3 degenerative spondylolisthesis in lumbar spinal stenosis patients: A case-control study

BACKGROUND

Degenerative spondylolisthesis (DS) occurs mostly at L4. However, there are a small number of patients in whom it occurs only at L3. Accordingly, past reports elucidating the factors of DS have been primarily concerned with L4 DS, and few reports are available on DS at L3. The objective of this study was to compare the differences between lumbar spinal stenosis patients with or without L3 DS and to identify the possible pathological mechanisms of their L3 DS.

METHODS

Among the 369 patients with lumbar spinal stenosis who underwent lumbar surgery, we assessed 25 patients who had DS only at L3 and compared them against 50 other age- and gender-matched lumbar spinal stenosis patients without any DS. The following radiographic parameters: pelvic incidence, sacral slope, pelvic tilt, L3 slope, L4 slope, L5 slope, and lumbar lordosis were measured on radiographs. The orientation of facet joints and disc heights were measured via computed tomography.

RESULTS

Imaging findings showed that the L3, L4, and L5 slopes in the L3 DS group were significantly greater than in the non-DS group, and only L3/4 facet joints in the L3 DS group were significantly more sagittally oriented than in the control group. The number of patients with low disc heights at L4/5 in the L3 DS group was significantly greater than in the control group.

CONCLUSIONS

The results suggested that the greater lumbar slope, including L3 together with more sagittally oriented facet joints only at L3/4 and not at L4/5, may lead to DS only at L3.

Radiographic Analysis of Minimally Invasive Transforaminal Lumbar Interbody Fusion versus Conventional Open Surgery on Sagittal Lumbar-Pelvic Alignment for Degenerative Spondylolisthesis

OBJECTIVE

To compare the impact of minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) with open posterior lumbar interbody fusion (PLIF) on sagittal lumbar-pelvic radiographic parameters for degenerative spondylolisthesis (DS).

METHODS

Of 48 patients with L4 single segmental DS, 25 underwent MIS-TLIF with Quadrant system and 23 underwent conventional open PLIF. Comparisons of data from the preoperative and final follow-up standing lateral lumbar x-rays, with the bilateral femoral heads, of the 2 groups were conducted using the following parameters: slip percentage (SP), lumbar lordosis (LL), pelvic incidence, pelvic tilt (PT), sacral slope, lumbosacral angle, slip angle (SA), and the L1 axis and S1 distance (LASD).

RESULTS

The slip reduction rate (ΔSP) in the OPEN group was significantly higher than in the MIS group (67 ± 34% vs. 37 ± 51%, P = 0.018). The change of SA (ΔSA) in the OPEN group was significantly higher than in the MIS group (3 ± 7° vs. -3 ± 5°, P = 0.003). The change of LASD (ΔLASD) in the OPEN group was significantly lower than in the MIS group (-4 ± 15 mm vs. 4 ± 9 mm, P = 0.033). There were positive correlations between the preoperative SP and LASD, and ΔSA and the change of LL (ΔLL), and a negative correlation between ΔLL and the change of PT (ΔPT).

CONCLUSIONS

For low-grade DS, open PLIF has a higher rate of slip reduction compared to MIS-TLIF, and significantly reduces LASD, therefore, it is more conducive to improving lumbar sagittal balance.

Radiographic Classification for Degenerative Spondylolisthesis of the Lumbar Spine Based on Sagittal Balance: A Reliability Study

STUDY DESIGN

Inter- and intraobserver reliability study.

OBJECT

To assess the reliability of a new radiographic classification of degenerative spondylolisthesis of the lumbar spine (DSLS).

SUMMARY OF BACKGROUND DATA

DSLS is a common cause of chronic low back and leg pain in adults. To this date, there is no consensus for a comprehensive analysis of DSLS. The reliability of a new DSLS classification system based on sagittal alignment was assessed.

METHODS

Ninety-nine patients admitted to our spinal surgery department for surgical treatment of DSLS between January 2012 and December 2015 were included. Three observers measured sagittal alignment parameters with validated software: segmental lordosis (SL), lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), and sagittal vertical axis (SVA). Full body low-dose lateral view radiographs were analyzed and classified according to three main types: Type 1A: preserved LL and SL; Type 1B: preserved LL and reduced SL (≤5°); Type 2A: PI-LL ≥10° without pelvic compensation (PT <25°); Type 2B: PI-LL ≥10° with pelvic compensation (PT ≥25°); Type 3: global sagittal malalignment (SVA ≥40 mm). The three observers classified radiographs twice with a 3-week interval for intraobserver reproducibility. Interobserver reproducibility was calculated using Fleiss κ and intra-class coefficient. Intraobserver reproducibility was calculated using Cohen κ.

RESULTS

Mean age was 68.8 ± 9.8 years. Mean sagittal alignment parameters values were the following: PI: 60.1° ± 12.7°; PI-LL was 12.2° ± 13.9°, PT: 24.7° ± 8.5°; SVA: 44.9 mm ± 44.6 mm; SL: 16.6° ± 8.4°. Intraobserver repeatability showed an almost perfect agreement (ICC > 0.92 and Cohen κ > 0.89 for each observer). Fleiss κ value for interobserver reproducibility was 0.82, with percentage agreement among observers between 88% and 89%.

CONCLUSION

This new classification showed an excellent inter- and intraobserver reliability. This simple method could be an additional sagittal balance tool helping surgeons improve their preoperative DSLS analysis.

The pelvic radius technique in the assessment of spinopelvic sagittal alignment of degenerative spondylolisthesis and lumbar spinal stenosis

BACKGROUND

Degenerative spondylolisthesis (DS) and lumbar spinal stenosis (LSS) are the most common degenerative spinal diseases. The evaluating of spinopelvic sagittal alignment of the two diseases using pelvic radius (PR) technique have not been reported. The purpose of this study was to use PR measurement technique to compare the differences in spinopelvic sagittal alignment between DS and LSS.

METHODS

A total of 145 patients with DS or LSS were retrospectively reviewed. Seventy patients with DS (DS group) and 75 age-matched patients with LSS (LSS group) were enrolled. Spinopelvic parameters including pelvic angle (PA), regional lumbopelvic lordosis (PR-L1, PR-L2, PR-L3, PR-L4 and PR-L5), total lumbopelvic lordosis (PR-T12), pelvic morphology (PR-S1), sagittal vertical axis from the C7 plumb line (SVA), lumbar lordosis (LL), thoracic kyphosis (TK), L4 slope and L5 slope were assessed in the two groups. Several parameters of DS and LSS group were compared with the normal population (NP).

RESULTS

The PR-L4, PR-L5 and PR-S1 in the DS group were significantly smaller than those in the LSS group. There was no difference in PR-T12 between the DS group and NP (p > 0.05), while PR-T12 of the LSS group were significantly lower (p < 0.01). Degree of correlations among spinopelvic parameters differed between the two groups. PR-T12 of the DS group was more strongly correlated with PA (r = -0.829, p < 0.001) than with LL (r = 0.664, p < 0.001), TK (r = 0.582, p < 0.001). PR-T12 of the LSS group was more strongly correlated with LL (r = 0.854, p < 0.001), TK (r = 0.616, p < 0.001) than with PA (r = -0.582, p < 0.001).

CONCLUSIONS

PR-L4 and PR-L5 may be the predisposing factors for DS development. Spinopelvic morphology differed in patients with DS and LSS compared to NP. The compensatory mechanisms to maintain spinopelvic sagittal alignment in DS and LSS patients may be different.

Correlation between the sagittal spinopelvic alignment and degenerative lumbar spondylolisthesis: a retrospective study

Background

Pain and disability associated with degenerative lumbar spondylolisthesis (DLS) results in significant burden on both the patients’ quality of life and healthcare costs. Currently, there is controversy regarding the specificity of spinopelvic measures of sagittal plane alignment with respect to DLS. Moreover, the correlation among spinopelvic parameters of sagittal plane alignment remains to be clarified. Our aim in this study was to compare these measurements between patients with single-segment DLS at L5 and a control group with no history of DLS.

Methods

Our study group was formed of 132 patients who underwent full length lateral view radiographs of the spine in a relaxed standing posture. Among these, DLS at L5 was identified in 72 patients, forming the DLS group, with no radiographic evidence of lumbar spine disease in the remaining 60 patients, forming the control group. The patient and control groups were balanced with regard to age and sex distribution. The following spinopelvic parameters of sagittal plane alignment were measured: angle of incidence (PI) and tilt (PT) of the pelvis; sacral slope (SS); thoracic kyphosis (TK); lumbar lordosis (LL); and the spinal sagittal vertical axis (SVA). The Meyerding grade of L5 slippage was quantified for each patient in the DLS group.

Results

Measures of TK, PI, SS, and LL were significantly greater in the DLS than control group (P <  0.05), with no between-group difference in SVA and PT. In the DLS group, the grade of L5 slippage correlated with SS (r = 0.873, P <  0.0001), PI (r = 0.791, P <  0.0001) and LL (r = 0.790, P <  0.0001). Moreover, the measurement for SS correlated more strongly with the PI (r = 0.94, P <  0.01) than the LL (r = 0.69, P <  0.01).

Conclusion

Measurements of SS, PI, and LL were specifically associated with DLS, with measurements correlating positively with the grade of slippage.

Electronic supplementary material

The online version of this article (10.1186/s12891-018-2073-z) contains supplementary material, which is available to authorized users.

Inflammation Intensity-Dependent Expression of Osteoinductive Wnt Proteins Is Critical for Ectopic New Bone Formation in Ankylosing Spondylitis

OBJECTIVE

To investigate the molecular mechanism underlying inflammation-related ectopic new bone formation in ankylosing spondylitis (AS).

METHODS

Spinal tissues and sera were collected from patients with AS and healthy volunteers and examined for the expression of Wnt proteins. An in vitro cell culture system mimicking the local inflammatory microenvironment of bone-forming sites was established to study the relationship between inflammation and Wnt expression, the regulatory mechanism of inflammation-induced Wnt expression, and the role of Wnt signaling in new bone formation. Modified collagen-induced arthritis (CIA) and proteoglycan-induced spondylitis (PGIS) animal models were used to confirm the key findings in vivo.

RESULTS

The levels of osteoinductive Wnt proteins were increased in sera and spinal ligament tissues from patients with AS. Constitutive low-intensity tumor necrosis factor (TNF) stimulation, but not short-term or high-intensity TNF stimulation, induced persistent expression of osteoinductive Wnt proteins and subsequent bone formation through NF-κB (p65) and JNK/activator protein 1 (c-Jun) signaling pathways. Furthermore, inhibition of either the Wnt/β-catenin or Wnt/protein kinase Cδ (PKCδ) pathway significantly suppressed new bone formation. The increased expression of Wnt proteins was confirmed in both the modified CIA and PGIS models. A kyphotic and ankylosing phenotype of the spine was seen during long-term observation in the modified CIA model. Inhibition of either the Wnt/β-catenin or Wnt/PKCδ signaling pathway significantly reduced the incidence and severity of this phenotype.

CONCLUSION

Inflammation intensity-dependent expression of osteoinductive Wnt proteins is a key link between inflammation and ectopic new bone formation in AS. Activation of both the canonical Wnt/β-catenin and noncanonical Wnt/PKCδ pathways is required for inflammation-induced new bone formation.

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.

Focal disorders of the spine with compensatory deformities: how to define them

PURPOSE

In this paper, the authors propose classifying the epiphenomenon of spinal deformity in two different categories: structural deformity, when the main driver of the observed deformity is a fixed and stiff alteration of the spinal segments, and compensatory deformity, which includes cases where the observed deformity is due to focal abnormalities. This last category comprises, but is not limited to, spinal stenosis, spondylolisthesis, disc herniation, infection or tumor, hip disease or neurological disease (such as Parkinson's disease).

METHOD

Narrative review article.

RESULTS

We analyzed the focal diseases of the spine that may cause a compensatory deformity inducing adaptation in the unaffected part of the spine.

CONCLUSION

The compensatory mechanisms involved in adaptive deformity represent an attempt to maintain a global alignment, to escape from pain or to control body posture. These slides can be retrieved under Electronic Supplementary material.

Increased PT/SS may play an important role in the pathogenesis of lumbar spondylolisthesis with degenerative lumbar scoliosis

OBJECTIVE

To explore the clinical and spinopelvic features in patients with lumbar spondylolisthesis and degenerative lumbar scoliosis (LSDLS) and those with standalone lumbar spondylolisthesis (SALS).

PATIENTS AND METHODS

We retrospectively analyzed 130 patients with lumbar spondylolisthesis seen between 05/2013 and 12/2016 in our hospital. Propensity score matching was used to reduce an age distribution imbalance between the two groups. Clinical and spinopelvic parameters were compared by independent samples t test and chi-square test. Nonlinear binary logistic regression analysis was used to analyze the independent factors.

RESULTS

There was no significant difference between groups for body mass index, level of intercrest line, level of spondylolisthesis, grade of spondylolisthesis, sagittal translation, segmental angulation, thoracic kyphosis, or sagittal vertical axis. The LSDLS group had significantly lower lumbar lordosis (LL) than the SALS group. The LSDLS group showed significantly greater pelvic tilt (PT) and ratio of PT to SS (sacral slope) (PT/SS), and lower SS. The pelvic incidence (PI) was not significantly different. The LSDLS group showed stronger significant differences in PT/SS compared to the SALS group. With each 0.1 increase in PT/SS, the risk of LSDLS increased 1.465 times.

CONCLUSIONS

Patients with spondylolysis are less prone to development of DLS. Lower LL and SS, and higher PT are associated with the occurrence of LSDLS. Increased PT/SS may play an important role in the pathogenesis of LSDLS.

A new classification system for degenerative spondylolisthesis of the lumbar spine

PURPOSE

There is no consensus for a comprehensive analysis of degenerative spondylolisthesis of the lumbar spine (DSLS). A new classification system for DSLS based on sagittal alignment was proposed. Its clinical relevance was explored.

METHODS

Health-related quality-of-life scales (HRQOLs) and clinical parameters were collected: SF-12, ODI, and low back and leg pain visual analog scales (BP-VAS, LP-VAS). Radiographic analysis included Meyerding grading and sagittal parameters: segmental lordosis (SL), L1-S1 lumbar lordosis (LL), T1-T12 thoracic kyphosis (TK), pelvic incidence (PI), pelvic tilt (PT), and sagittal vertical axis (SVA). Patients were classified according to three main types-1A: preserved LL and SL; 1B: preserved LL and reduced SL (≤5°); 2A: PI-LL ≥10° without pelvic compensation (PT < 25°); 2B: PI-LL ≥10° with pelvic compensation (PT ≥ 25°); type 3: global sagittal malalignment (SVA ≥40 mm).

RESULTS

166 patients (119 F: 47 M) suffering from DSLS were included. Mean age was 67.1 ± 11 years. DSLS demographics were, respectively: type 1A: 73 patients, type 1B: 3, type 2A: 8, type 2B: 22, and type 3: 60. Meyerding grading was: grade 1 (n = 124); grade 2 (n = 24). Affected levels were: L4-L5 (n = 121), L3-L4 (n = 34), L2-L3 (n = 6), and L5-S1 (n = 5). Mean sagittal parameter values were: PI: 59.3° ± 11.9°; PT: 24.3° ± 7.6°; SVA: 29.1 ± 42.2 mm; SL: 18.2° ± 8.1°. DSLS types were correlated with age, ODI and SF-12 PCS (ρ = 0.34, p < 0.05; ρ = 0.33, p < 0.05; ρ = -0.20, and p = 0.01, respectively).

CONCLUSION

This classification was consistent with age and HRQOLs and could be a preoperative assessment tool. Its therapeutic impact has yet to be validated.

LEVEL OF EVIDENCE

4.

Pelvic retroversion: a compensatory mechanism for lumbar stenosis

OBJECTIVE

The flexed posture of the proximal (L1–3) or distal (L4–S1) lumbar spine increases the diameter of the spinal canal and neuroforamina and can relieve symptoms of neurogenic claudication. Distal lumbar flexion can result in pelvic retroversion; therefore, in cases of flexible sagittal imbalance, pelvic retroversion may be compensatory for lumbar stenosis and not solely compensatory for the sagittal imbalance as previously thought. The authors investigate underlying causes for pelvic retroversion in patients with flexible sagittal imbalance.

METHODS

One hundred thirty-eight patients with sagittal imbalance who underwent a total of 148 fusion procedures of the thoracolumbar spine were identified from a prospective clinical database. Radiographic parameters were obtained from images preoperatively, intraoperatively, and at 6-month and 2-year follow-up. A cohort of 24 patients with flexible sagittal imbalance was identified and individually matched with a control cohort of 23 patients with fixed deformities. Flexible deformities were defined as a 10° change in lumbar lordosis between weight-bearing and non–weight-bearing images. Pelvic retroversion was quantified as the ratio of pelvic tilt (PT) to pelvic incidence (PI).

RESULTS

The average difference between lumbar lordosis on supine MR images and standing radiographs was 15° in the flexible cohort. Sixty-eight percent of the patients in the flexible cohort were diagnosed preoperatively with lumbar stenosis compared with only 22% in the fixed sagittal imbalance cohort (p = 0.0032). There was no difference between the flexible and fixed cohorts with regard to C-2 sagittal vertical axis (SVA) (p = 0.95) or C-7 SVA (p = 0.43). When assessing for postural compensation by pelvic retroversion in the stenotic patients and nonstenotic patients, the PT/PI ratio was found to be significantly greater in the patients with stenosis (p = 0.019).

CONCLUSIONS

For flexible sagittal imbalance, preoperative attention should be given to the root cause of the sagittal misalignment, which could be compensation for lumbar stenosis. Pelvic retroversion can be compensatory for both the lumbar stenosis as well as for sagittal imbalance.

The relationships between low back pain and lumbar lordosis: a systematic review and meta-analysis

BACKGROUND CONTEXT

Clinicians regard lumbar lordotic curvature (LLC) with respect to low back pain (LBP) in a contradictory fashion. The time-honored point of view is that LLC itself, or its increment, causes LBP. On the other hand, recently, the biomechanical role of LLC has been emphasized, and loss of lordosis is considered a possible cause of LBP. The relationship between LLC and LBP has immense clinical significance, because it serves as the basis of therapeutic exercises for treating and preventing LBP.

PURPOSE

This study aimed to (1) determine the difference in LLC in those with and without LBP and (2) investigate confounding factors that might affect the association between LLC and LBP.

STUDY DESIGN

Systematic review and meta-analysis.

PATIENT SAMPLE

The inclusion criteria consisted of observational studies that included information on lumbar lordotic angle (LLA) assessed by radiological image, in both patients with LBP and healthy controls. Studies solely involving pediatric populations, or addressing spinal conditions of nondegenerative causes, were excluded.

METHODS

A systematic electronic search of Medline, Embase, Cochrane Library, CINAHL, Scopus, PEDro, and Web of Science using terms related to lumbar alignment and Boolean logic was performed: (lumbar lordo*) or (lumbar alignment) or (sagittal alignment) or (sagittal balance). Standardized mean differences (SMD) and 95% confidence intervals (CI) were estimated, and chi-square and I² statistics were used to assess within-group heterogeneity by random effects model. Additionally, the age and gender of participants, spinal disease entity, and the severity and duration of LBP were evaluated as possible confounding factors.

RESULTS

A total of 13 studies consisting of 796 patients with LBP and 927 healthy controls were identified. Overall, patients with LBP tended to have smaller LLA than healthy controls. However, the studies were heterogeneous. In the meta-regression analysis, the factors of age, severity of LBP, and spinal disease entity were revealed to contribute significantly to variance between studies. In the subgroup analysis of the five studies that compared patients with disc herniation or degeneration with healthy controls, patients with LBP had smaller LLA (SMD: -0.94, 95% CI: -1.19 to -0.69), with sufficient homogeneity based on significance level of .1 (I²=45.7%, p=.118). In the six age-matched studies, patients with LBP had smaller LLA than healthy controls (SMD: -0.33, 95% CI: -0.46 to -0.21), without statistical heterogeneity (I²=0%, p=.916).

CONCLUSIONS

This meta-analysis demonstrates a strong relationship between LBP and decreased LLC, especially when compared with age-matched healthy controls. Among specific diseases, LBP by disc herniation or degeneration was shown to be substantially associated with the loss of LLC.

Correction of Grade 2 Spondylolisthesis Following a Non-Surgical Structural Spinal Rehabilitation Protocol Using Lumbar Traction: A Case Study and Selective Review of Literature

Objective

Discuss the use of non-surgical spinal rehabilitation protocol in the case of a 69-year-old female with a grade 2 spondylolisthesis. A selective literature review and discussion are provided.

Clinical Features

A 69-year-old female presented with moderate low back pain (7/10 pain) and severe leg cramping (7/10 pain). Initial lateral lumbar x-ray revealed a grade 2 spondylolisthesis at L4-L5 measuring 13.3 mm.

Interventions and Outcomes

The patient completed 60 sessions of Mirror Image® spinal exercises, adjustments, and traction over 45 weeks. Post-treatment lateral lumbar x-ray showed a decrease in translation of L4-L5 from 13.3 mm to 2.4 mm, within normal limits.

Conclusions

This case provides the first documented evidence of a non-surgical or chiropractic treatment, specifically Chiropractic BioPhysics®, protocols of lumbar spondylolisthesis where spinal alignment was corrected. Additional research is needed to investigate the clinical implications and treatment methods.

One-Level Lumbar Degenerative Spondylolisthesis and Posterior Approach: Is Transforaminal Lateral Interbody Fusion Mandatory?: A Randomized Controlled Trial With 2-Year Follow-Up

STUDY DESIGN

A monocentric open-label randomized controlled trial (MRCT).

OBJECTIVE

Comparison of clinical and radiological outcomes between isolated instrumented posterior fusion (PLF) and associated instrumented posterior fusion and interbody fusion by transforaminal approach (PLF + TLIF) for patients suffering from one-level lumbar degenerative spondylolisthesis (DS) undergoing surgery.

SUMMARY OF BACKGROUND DATA

DS is a common cause of symptomatic lumbar stenosis. PLF has shown better clinical outcome than decompression with noninstrumented posterolateral fusion. TLIF with interbody cage showed better fusion rate than PLF. There is a need for randomized controlled trials to compare PLF with and without TLIF as to clinical and radiological outcomes.

METHODS

This is a MRCT comparing PLF and TLIF techniques in surgical treatment of DS. Sixty patients were included in a secured database from 2009 to 2011 and randomized into two groups: 30 PLF with posterior pedicle screws and intertransverse autologuous graft, and 30 TLIF in which an interbody fusion by transforaminal approach was added. Data included clinical (pain and disability), surgical (blood loss and operating time), and radiological (alignment and fusion) parameters at baseline and 2-year follow-up. Comparison was made by Student t test and Chi-square test.

RESULTS

There was a significant improvement in each group for pain and disability but no difference between the groups. Radiographic assessment showed better posterolateral fusion rate for TLIF without superiority in segmental lordosis improvement. A case of deformity cascade with spino-pelvic mismatch at baseline was noted in PLF.

CONCLUSION

Posterior decompression and instrumented fusion is an efficient technique that proved its significant clinical benefit in the surgical treatment of DS. TLIF did not show its superiority neither in clinical nor alignment parameters despite a better fusion rate. These results suggest that TLIF is not mandatory in this specific indication. Sagittal alignment analysis by standing full-body images should be considered in DS care.

LEVEL OF EVIDENCE

2.

Radiological analysis of upper lumbar disc herniation and spinopelvic sagittal alignment

PURPOSE

A retrospective cross-sectional study was designed to explore the role of spinopelvic sagittal alignment in upper lumbar disc herniation (ULD) development.

METHODS

A total of 207 consecutive patients who underwent surgery for single-level lumbar disc herniation [24 with ULD and 183 with lower lumbar disc herniation (LLD)] and 40 asymptomatic volunteers were enrolled. Full-length radiographs of the spine were taken to evaluate pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), thoracic kyphosis (TK), lumbar lordosis (LL), and sagittal vertical axis (SVA). The Roussouly classification was utilized to categorize all subjects according to their sagittal alignment. Spinopelvic parameters and Roussouly classification results were compared between groups.

RESULTS

There were significant differences in PI, SS, PT, LL, and SVA between the ULD, LLD, and control groups. PI in the ULD (40.9°) was significantly lower than in the LLD and control groups (48.8° and 47.6°, respectively). LL was significantly lower in the ULD than in the LLD (-32.4° and -40°, respectively). There were significant differences between the three groups in Roussouly types. The LLD had a significantly higher proportion (62.6 %) of type 2 lordosis (flat back), and the ULD had a higher proportion (33.3 %) of type 1 lordosis than the other groups.

CONCLUSIONS

This study demonstrated the importance of PI and lumbar curvature in the pathogenesis of ULD. The higher prevalence of short LL and long TK with low PI in the ULD group implies that an increased mechanical stress at this level may be one of the risk factors of ULD.

Radiographic Parameters in Adult Degenerative Scoliosis and Different Parameters Between Sagittal Balanced and Imbalanced ADS Patients

A retrospective study. To summarize and describe the radiographic parameters of adult degenerative scoliosis (ADS) and explore the radiological parameters which are significantly different in sagittal balanced and imbalanced ADS patients. ADS is the most common type of adult spinal deformity. However, no comprehensive description of radiographic parameters in ADS patients has been made, and few studies have been performed to explore which radiological parameters are significantly different between sagittal balanced and imbalanced ADS patients. Medical records of ADS patients in our outpatient clinic from January 2012 to January 2014 were reviewed. Demographic data including age and sex, and radiographic data including the coronal Cobb angle, location of apical vertebra/disc, convexity of the curve, degree of apical vertebra rotation, curve segments, thoracic kyphosis (TK), lumbar lordosis (LL), thoracolumbar kyphosis (TL), sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI), sagittal vertical axis (SVA), and PI minus LL (PI-LL) were reviewed to make comprehensive description of radiographic parameters of ADS. Furthermore, patients were divided into 2 groups according to whether the patients' sagittal plane was balanced: Group A (imbalanced, SVA > 5 cm) and Group B (balanced, SVA  ≤ 5 cm). Demographic and radiological parameters were compared between these 2 groups. A total of 99 patients were included in this study (Group A = 33 and Group B = 66; female = 83 and male = 16; sex ratio = 5:1). The median of age were 67 years (range: 41-92 years). The median of coronal Cobb angle and length of curve was 23 (range: 10-75°) and 5 segments (range: 3-7), respectively. The most common location of apical vertebra was at L2 to L3 (81%) and the median of degree of apical vertebra rotation was 2° (range: 1-3). Our study also showed significant correlations between coronal Cobb angle and curve segments (r = 0.23, P < 0.005) and degree of apical vertebra rotation (r = 0.53, P < 0.005). With regard to the sagittal balance, there were significant differences in age, LL, PT, coronal Cobb angle, degree of apical vertebra rotation, and PI-LL between imbalanced group and balanced group (all P < 0.05); however, no significant difference was observed in gender, TK, TL, SS, and PI. Our study provided the general radiographic parameters of ADS. Weak or moderate but significant correlations between coronal Cobb angle and curve segments and degree of apical vertebra rotation were observed. Furthermore, age, coronal Cobb angle, LL, PT, and PI-LL were significantly different between sagittal balanced and imbalanced ADS patients.