Real-time dynamic 3-T MRI assessment of spine kinematics: a feasibility study utilizing three different fast pulse sequences.

BACKGROUND: Half-Fourier acquisition single-shot turbo spin-echo (HASTE), continuous radial gradient-echo (GRE), and True FISP allow real-time dynamic assessment of the spine. PURPOSE: To evaluate the feasibility of adding dynamic sequences to routine spine magnetic resonance imaging (MRI) for assessment of spondylolisthesis. MATERIAL AND METHODS: Retrospective review was performed of patients referred for dynamic MRI of the cervical or lumbar spine between January 2017 and 2018 who had flexion-extension radiographs within two months of MRI. Exclusion criteria were: incomplete imaging; spinal hardware; and inability to tolerate dynamic examination. Blinded, independent review by two board-certified musculoskeletal radiologists was performed to assess for spondylolisthesis (>3 mm translation); consensus review of dynamic radiographs served as the gold standard. Cervical spinal cord effacement was assessed. Inter-reader agreement and radiographic concordance was calculated for each sequence. RESULTS: Twenty-one patients were included (8 men, 13 women; mean age 47.9 ± 16.5 years). Five had MRI of the cervical spine and 16 had MRI of the lumbar spine. Mean acquisition time was 18.4 ± 1.7 min with dynamic sequences in the range of 58-77 s. HASTE and True FISP had the highest inter-reader reproducibility (κ = 0.88). Reproducibility was better for the lumbar spine (κ = 0.94) than the cervical spine (κ = 0.28). Sensitivity of sequences for spondylolisthesis was in the range of 68.8%-78.6%. All three sequences had high accuracy levels: ≥90.5% averaged across the cervical and lumbar spine. Cervical cord effacement was observed during dynamic MRI in two cases (100% agreement). CONCLUSION: Real-time dynamic MRI sequences added to spine MRI protocols provide reliable and accurate assessment of cervical and lumbar spine spondylolisthesis during flexion and extension.

Utility of Natural Sitting Lateral Radiograph in the Diagnosis of Segmental Instability for Patients with Degenerative Lumbar Spondylolisthesis.

BACKGROUND: Segmental instability in patients with degenerative lumbar spondylolisthesis is an indication for surgical intervention. The most common method to evaluate segmental mobility is lumbar standing flexion-extension radiographs. Meanwhile, other simple radiographs, such as standing upright radiograph, a supine sagittal magnetic resonance imaging (MRI) or supine lateral radiograph, or a slump or natural sitting lateral radiograph, have been reported to diagnose segmental instability. However, those common posture radiographs have not been well characterized in one group of patients. Therefore, we measured slip percentage in a group of patients with degenerative lumbar spondylolisthesis using radiographs of patients in standing upright, natural sitting, standing flexion, and standing extension positions as well as supine MRI. QUESTIONS/PURPOSES: We asked: (1) Does the natural sitting radiograph have a larger slip percentage than the standing upright or standing flexion radiograph? (2) Does the supine sagittal MRI reveal a lower slip percentage than the standing extension radiograph? (3) Does the combination of the natural sitting radiograph and the supine sagittal MRI have a higher translational range of motion (ROM) and positive detection rate of translational instability than traditional flexion-extension mobility using translational instability criteria of greater than or equal to 8%? METHODS: We retrospectively performed a study of 62 patients (18 men and 44 women) with symptomatic degenerative lumbar spondylolisthesis at L4 who planned to undergo a surgical intervention at our institution between September 2018 and June 2019. Each patient underwent radiography in the standing upright, standing flexion, standing extension, and natural sitting positions, as well as MRI in the supine position. The slip percentage was measured three times by single observer on these five radiographs using Meyerding's technique (intraclass correlation coefficient 0.88 [95% CI 0.86 to 0.90]). Translational ROM was calculated by absolute values of difference between two radiograph positions. Based on the results of comparison of slip percentage and translational ROM, we developed the diagnostic algorithm to evaluate segmental instability. Also, the positive rate of translational instability using our diagnostic algorithms was compared with traditional flexion-extension radiographs. RESULTS: The natural sitting radiograph revealed a larger mean slip percentage than the standing upright radiograph (21% ± 7.4% versus 17.7% ± 8.2%; p < 0.001) and the standing flexion radiograph (21% ±7.4% versus 18% ± 8.4%; p = 0.002). The supine sagittal MRI revealed a lower slip percentage than the standing extension radiograph (95% CI 0.49% to 2.8%; p = 0.006). The combination of natural sitting radiograph and the supine sagittal MRI had higher translational ROM than the standing flexion and extension radiographs (10% ± 4.8% versus 5.4% ± 3.7%; p < 0.001). More patients were diagnosed with translational instability using the combination of natural sitting radiograph and supine sagittal MRI than the standing flexion and extension radiographs (61% [38 of 62] versus 19% [12 of 62]; odds ratio 3.9; p < 0.001). CONCLUSION: Our results indicate that a sitting radiograph reveals high slip percentage, and supine sagittal MRI demonstrated a reduction in anterolisthesis. The combination of natural sitting and supine sagittal MRI was suitable to the traditional flexion-extension modality for assessing translational instability in patients with degenerative lumbar spondylolisthesis. LEVEL OF EVIDENCE: Level III, diagnostic study.

Preoperative and Postoperative, Three-dimensional Gait Analysis in Surgically Treated Patients With High-grade Spondylolisthesis.

BACKGROUND: High-grade spondylolisthesis (HGS) (Myerding grade III-V) in adolescents can lead to a marked alteration of gait pattern and maybe the presenting symptom in these patients. This characteristic gait pattern in patients with HGS has been referred to as the "pelvic waddle." Modern 3-dimensional (3D) gait analysis serves an important tool to objectively analyze the different components of this characteristic gait preoperatively and postoperatively and is an objective measure of postoperative improvement.This study demonstrates the use of 3D gait analysis preoperatively and postoperatively in a cohort of 4 consecutive patients with HGS treated surgically at a single tertiary referral center and utilize this to objectively evaluate outcome of surgical treatment in these patients. This has not been reported previously in a cohort of patients. METHODS: This is a prospective analysis of patients with HGS who underwent surgical intervention for spondylolisthesis at a single institution. Patient demographics, clinical, and radiologic assessment were recorded, and all patients underwent 3D gait analysis before and after surgical intervention. Kinetic, kinematic, and spatial parameters were recorded preoperatively and postoperatively for all patients. This allowed the outcome of change in gait deviation index, before and after surgical treatment, to be evaluated. RESULTS: We were able to review complete records of 4 adolescent patients who underwent surgical treatment for HGS. Mean age at surgery was 13.5 years with a minimum follow-up of 2.5 years postoperatively (average 40 mo). Preoperative gait analysis revealed marked posterior pelvic tilt in 2 patients, reduced hip and knee extension in all 4 patients and external foot progression in 3 of the 4 patients. Along with an observed improvement in gait, there was an objective improvement in gait parameters postoperatively in all 4 patients. Gait deviation index score improved significantly from 78.9 to 101.3 (mean). CONCLUSIONS: Preoperative gait abnormalities exist in HGS and can be objectively analyzed with gait analysis. Surgical intervention may successfully resolve these gait abnormalities and gait analysis is a useful tool to assess the outcome of surgery and quantify an otherwise intangible benefit of surgical intervention. LEVEL OF EVIDENCE: Level IV-case series.

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

BACKGROUND Trapezoidal changes of the vertebral body are more common in patients with lumbar spondylolisthesis than in others. However, we lack an understanding of factors predisposing to the development of a marked trapezoidal deformity. Also, no associations between a trapezoidal vertebrae (TV) and spine-pelvis sagittal parameters have been previously reported. MATERIAL AND METHODS A total of 73 subjects with lumbar spondylolisthesis were enrolled and we collected their clinical data. Vertebral body parameters and spine-pelvis sagittal alignment parameters were measured via lumbar spine X-ray. Using the lumbar index (LI), patients were divided into a TV group (LI >0.8, n=24) and a control group (LI >0.8, n=49). The clinical data and spine-pelvic sagittal parameters of the 2 groups were compared using the t test or chi-squared test. Pearson's correlation analysis and multiple linear regression were used to determine relationships among the parameters. RESULTS The TV and control groups differed significantly in terms of the slipped segment, extent of slippage, intervertebral disc height (IDH), and sagittal parameters (all P<0.05). Pearson's correlation analysis and multiple linear regression analysis showed that the slipped segment (r=-0.606), extent of slippage (r=-0.660), and IDH (r=0.698) were risk factors for the development of a TV body. Also, vertebral trapezoidal deformation was closely associated with sagittal parameters. CONCLUSIONS The vertebral body affected by lumbar spondylolisthesis exhibits a trapezoidal change closely associated with the slipped segment, the extent of slippage, and IDH. The TV group exhibited greater pelvic incidence values and lumbar lordosis, which may have caused wedging of the slipped vertebra.

A new lever reduction technique for the surgical treatment of elderly patients with lumbar degenerative Spondylolisthesis.

BACKGROUND: Proper reduction method for Lumbar degenerative spondylolisthesis (LDS) is still controversial. The aim of this study was to determine the safety and effectiveness of lever reduction combined with traditional elevating-pull reduction technique for the treatment of elderly patients with LDS. METHODS: From May 2015 to December 2017, 142 elderly patients (≥65 years) diagnosed with LDS were enrolled in this study with a mean follow-up of 25.42 ± 8.31 months. All patients were operated using lever reduction combined with traditional elevating-pull reduction technique. Patient age, sex, body mass index, bone mineral density, preoperative comorbidities, surgical duration, blood loss, and surgical complications were collected form patient charts. Clinical data as visual analog scale (VAS), Oswestry Disability Index (ODI), and 36-Item Short Form Health Survey (SF-36) were collected preoperatively, 1 month postoperatively, and at the final follow-up. Radiographic evaluation included slip percentage, slip angle (SA), lumbar lordosis (LL), and fusion status. RESULTS: The clinical parameters of VASback, VASleg, ODI, and SF-36 had significantly improved at both follow-ups after surgery. A significant improvement was indicated for slippage reduction at both follow-ups, showing no significant correction loss after surgery. SA significantly increased after surgery and was well maintained at the final follow-up. LL was not affected by the surgery. At the final follow-up, complete fusion was obtained in 121 patients (85.2%) and partial fusion in 21 (14.8%). Revision surgery was performed for one patient. Screw loosening was observed in 3 (2.11%) cases. No nerve root injury or adjacent segment disease was observed. CONCLUSIONS: This new lever reduction combined with traditional elevating-pull reduction technique for the surgical treatment of elderly patients with LDS is both safe and effective. Satisfactory correction and fusion rates were achieved with acceptable correction loss and reduction-related complications.

Etiology and clinical manifestations of double-level versus single-level lumbar degenerative spondylolisthesis.

BACKGROUND: The differences in etiology, clinical manifestation, and whole body standing alignment between single-level LDS (sLDS) and double-level LDS (dLDS) have not been sufficiently clarified. We hypothesized that the etiology and manifestations of dLDS differ from those of sLDS. This study aimed to test this hypothesis. METHODS: A total of 112 cases with sLDS, 25 cases with dLDS, and 50 healthy volunteers as a normal control were enrolled in the study. Following the data collection on demographic and Health-related quality of life (HRQOL) by ODI and SRS-22, radiologic measurement by EOS system and MRI examination including lumbar spinal stenosis (LSS), facet angle, and segmental instability defined by facet opening were performed. All the parameters were compared among the groups. Correlations among radiologic parameters and HRQOL were analyzed. Risk factors for sLDS and dLDS were investigated respectively using multivariate logistic analysis. RESULTS: Age is the most important etiologic factor of sLDS; whereas high PI, age, and sagittally oriented facet joints are the important factors for dLDS. HRQOL significantly correlates with sagittal alignment. HRQOL does not, however, significantly differ between patients with sLDS and dLDS. Although the mean value of %slip was higher in the dLDS group than in the sLDS group, the difference was not statistically significant. %slip positively correlated with the PI. The number of spinal stenoses (LSS) per patient is significantly higher in patients with dLDS than in patients with sLDS. The HRQOL does not, however, correlate with the number of LSS. CONCLUSIONS: Age is the most important etiologic factor of sLDS; whereas high PI, age, and sagittally oriented facet joints are the important factors for dLDS. HRQOL does not significantly differ between patients with sLDS and dLDS. Number of LSS is significantly higher in dLDS than in sLDS without statistical difference in terms of HRQOL outcome.

Restoration of normal pelvic balance from surgical reduction in high-grade spondylolisthesis.

PURPOSE: To investigate the effectiveness of surgical reduction in high-grade spondylolisthesis in maintaining or restoring a normal pelvic balance, as related to the QoL. METHODS: It is a retrospective analysis of prospectively collected data of 60 patients (17 males, 43 females) aged 15 ± 3.1 years who underwent surgery for high-grade spondylolisthesis and were followed for a minimum of 2 years after surgery. Patients with a residual high-grade slip following surgery were referred to the postoperative high-grade (PHG) group, while patients with a residual low-grade slip were referred to the postoperative low-grade (PLG) group. Pelvic balance was assessed from pelvic tilt and sacral slope, in order to identify patients with a balanced pelvis or unbalanced pelvis. The SRS-22 questionnaire was completed before surgery and at last follow-up. RESULTS: Postoperatively, there were 36 patients with a balanced pelvis and 24 patients with an unbalanced pelvis. The improvement in QoL was better in patients with a postoperative balanced pelvis. There were 14 patients in the PHG group and 46 patients in the PLG group. Four of seven patients (57%) in the PHG group and 21 of 26 patients (81%) in the PLG group with a preoperative balanced pelvis maintained a balanced pelvis postoperatively (P = 0.1). None of the patients in the PHG group and 11 of 20 patients (55%) in the PLG group improved from an unbalanced to a balanced pelvis postoperatively (P < 0.05). CONCLUSIONS: Surgical reduction in high- to low-grade slip is more effective in maintaining and restoring a normal pelvic balance postoperatively. These slides can be retrieved under Electronic Supplementary Material.

Concomitant low-grade isthmic L5-spondylolisthesis does not affect the course of adolescent idiopathic scoliosis.

BACKGROUND: Scoliosis with spondylolisthesis was described in 4.4-48%. No information on clinical impact or outcome is available. PURPOSE: To determine the prevalence of this pathology and to investigate its affect on the course of adolescent idiopathic scoliosis (AIS). METHODS: A retrospective comparative study using patients' records, radiographs, the national inpatient registry, and Patient-rated outcome measures (PROM): Oswestry disability index (ODI), modif.SRS-24 questionnaire, WHO-Quality of life index (WHOQoL), Numerical rating scale (NRS) for pain. Clinical follow-up time was 4.4 (4.3) years, and follow-up rate was 95%. PROM follow-up time 26.4 (2.8) years χ2 statistics and t-tests were applied. Significance threshold was set at P < 0.05. RESULTS: Out of 1531 consecutive Caucasian AIS patients, aged 13.9 (1.8) years, primary curve 29.2 (11.5) drs., 120 (7.8%) had low-grade isthmic L5-slip of mean 15.0 (8.3)% (Study group = S). The distribution of the curve types in the study group was comparable to the remaining 1411 patients with AIS only. In comparison with a pair-matched control group (C) at admission, back pain interfering with activities of daily living had 4.2% of the study group and 1.7% of the control group, at clinical follow-up 2.6/4.2% resp. (n.s.). Between groups S/C, there was no significant difference concerning scoliosis treatment: observation 38.3/45.8%, bracing 48.3/46.6%, surgery 10.8/10.2%. Results of treatment were equal in both groups. Long-term outcomes (ODI, SRS-24, WHOQoL, NRS-back/leg pain) were comparable. CONCLUSIONS: The prevalence of low-grade isthmic L5-spondylolisthesis in AIS patients was 7.8%. The presence of low-grade isthmic spondylolisthesis did not influence the curve type of AIS nor did it affect the course or long-term outcome. These slides can be retrieved under Electronic Supplementary Material.

Decompression alone versus decompression with instrumental fusion the NORDSTEN degenerative spondylolisthesis trial (NORDSTEN-DS); study protocol for a randomized controlled trial.

BACKGROUND: Fusion in addition to decompression has become the standard treatment for lumbar spinal stenosis with degenerative spondylolisthesis (DS). The evidence for performing fusion among these patients is conflicting and there is a need for further investigation through studies of high quality. The present protocol describes an ongoing study with the primary aim of comparing the outcome between decompression alone and decompression with instrumented fusion. The secondary aim is to investigate whether predictors can be used to choose the best treatment for an individual. The trial, named the NORDSTEN-DS trial, is one of three studies in the Norwegian Degenerative Spinal Stenosis (NORDSTEN) study. METHODS: The NORDSTEN-DS trial is a block-randomized, controlled, multicenter, non-inferiority study with two parallel groups. The surgeons at the 15 participating hospitals decide whether a patient is eligible or not according to the inclusion and exclusion criteria. Participating patients are randomized to either a midline preserving decompression or a decompression followed by an instrumental fusion. Primary endpoint is the percentage of patients with an improvement in Oswestry Disability Index version 2.0 of more than 30% from baseline to 2-year follow-up. Secondary outcome measurements are the Zürich Claudication Questionnaire, Numeric Rating Scale for back and leg pain, Euroqol 5 dimensions questionnaire, Global perceived effect scale, complications and several radiological parameters. Analysis and interpretation of results will also be conducted after 5 and 10 years. CONCLUSION: The NORDSTEN/DS trial has the potential to provide Level 1 evidence of whether decompression alone should be advocated as the preferred method or not. Further on the study will investigate whether predictors exist and if they can be used to make the appropriate choice for surgical treatment for this patient group. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02051374 . First Posted: January 31, 2014. Last Update Posted: February 14, 2018.

The correlation analysis between sagittal alignment and cross-sectional area of paraspinal muscle in patients with lumbar spinal stenosis and degenerative spondylolisthesis.

BACKGROUND: The relationship between spinal alignment and skeletal muscle mass (SMM) has attracted attention in recent years. Sagittal alignment is known to deteriorate with age, but it is not known whether this is related to paraspinal muscles. Therefore, the purpose of this study is to elucidate the role of the multifidus (MF) and psoas major (PS) muscles in maintaining global spinal alignment in patients with lumbar spinal stenosis (LSS) and/or degenerative spondylolisthesis (DS), and to analyze whether each muscles' cross-sectional area (CSA) correlates with whole-body SMM using bioimpedance analysis (BIA). METHODS: We retrospectively evaluated 140 patients who were hospitalized for surgery to treat LSS and/or DS. Spinal alignment, CSA of spinal muscles, and body composition parameters were measured from full-length standing whole-spine radiography, MRI, and BIA before surgery. The following standard measurements were obtained from radiographs: sagittal balance (C7-SVA), cervical lordosis (CL; C2-C7), lumbar lordosis (LL; L1-S1), thoracic kyphosis (TK; T5-T12), pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS). RESULTS: The average PS CSA (AveCSA) was highest at L4-L5, whereas MF AveCSA was highest at L5-S1. Paraspinal muscle CSAs were greater in males than in females. There was no statistically significant difference between the left and right CSA for either MF or PS. Correlation coefficient showed strong correlations between the PS AveCSA (L4-L5) and whole body SMM (r = 0.739). Correlation coefficient analysis also showed weak correlation between SMM and PT (r = - 0.184). Furthermore, PS AveCSA (L4-L5) correlated with the PT (r = - 0.183) and age (r = - 0.156), while PT correlated with the whole body SMM (r = - 0.184) but not with age. CONCLUSIONS: Whole body SMM showed correlation with PS AvCSA (L4-L5) and with PT among the spinal parameters, which was the same result in MF AvCSA (L4-L5). These findings suggest that the posterior inclination of the pelvis may be correlated with paraspinal muscle area rather than age.

Primary pain generator identification by CT-SPECT in patients with degenerative spinal disease.

OBJECTIVE: Axial spinal pain generators are difficult to identify using current diagnostic modalities. Merging CT with SPECT (CT-SPECT) scans allows for accurate identification of areas with increased osteoblastic activity, which may reflect pain generators. In this study, the authors aimed to evaluate the degree of pain improvement in patients who underwent surgery, addressing primary pain generators identified by CT-SPECT. METHODS: The authors retrospectively reviewed all patients with chronic axial spine pain who underwent diagnostic CT-SPECT at their institution and analyzed pain improvement in those who underwent surgical treatment in order to determine whether CT-SPECT correctly identified the primary pain generator. RESULTS: A total of 315 patients underwent diagnostic CT-SPECT between January 2014 and August 2018. Forty-eight patients underwent either cervical or lumbar fusion; there were 26 women (16 cervical, 10 lumbar) and 22 men (9 cervical, 13 lumbar). The overall axial spinal pain, as assessed through self-reporting of visual analog scale scores at 6 months postoperatively, improved from 9.04 ± 1.4 to 4.34 ± 2.3 (p = 0.026), with cervical fusion patients improving from 8.8 ± 1.8 to 3.92 ± 2.2 (p = 0.019) and lumbar fusion patients improving from 9.35 ± 0.7 to 4.87 ± 2.3 (p = 0.008). CONCLUSIONS: CT-SPECT may offer a diagnostic advantage over current imaging modalities in identifying the primary pain generator in patients with axial spinal pain.

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.

A comparative study of gait characteristics associated with and without degenerative lumbar spondylolisthesis in patients with lumbar spinal stenosis.

BACKGROUND: Reported characteristics of DS include forward slippage of the superior lumbar relative to the inferior lumbar, lumbar instability, increased lumbar lordotic angle, and high body mass index (BMI). However, to our knowledge, only static measurements were conducted in previous studies, and no dynamic observations exist. In this crosssectional study, the gait of patients with and without DS in LSS was compared, and their characteristics were examined using a three-dimensional motion analysis system. METHODS: In total, 42 patients with LSS were included. Lumbar lordosis angle, sacral tilt angle, lumbar slip rate determined from X-ray images, the Zurich Claudication Questionnaire (ZCQ), the visual analog scale (VAS), and BMI were evaluated. U-COM length was the distance between the upper center of mass (COM) and the body's COM, while L-COM length was the distance between the lower COM and the COM. Each DS and Non-DS group evaluation was compared using the Mann-Whitney U-test. Additionally, multivariate analysis was performed using factors with significant differences as explanatory variables and with or without DS as the target variable. RESULTS: Lumbar lordotic angle was significantly higher in the DS group and there was a significant difference between U-COM and L-COM lengths in the sagittal planes at heel contact (HC) and toe-off (TO). L-COM length at HC and TO was a significant variable when the lumbar lordotic angle was adjusted as a confounding factor in multivariate analysis. CONCLUSIONS: The U-COM and L-COM lengths in the DS group were both extended and the line connecting each COM was inclined backward on the sagittal plane at HC and TO during gait. Our study showed that L-COM length was associated with or without DS.

The importance of proximal femoral angle on sagittal balance and quality of life in children and adolescents with high-grade lumbosacral spondylolisthesis.

PURPOSE: Previous studies did not specifically assess the influence of proximal femoral angle (PFA) on sagittal balance in high-grade spondylolisthesis (HGS). In addition, the relationship between PFA and quality of life (QOL) remains unknown. This study determines if increased PFA is associated with decreased QOL and sagittal balance in lumbosacral HGS. METHODS: This retrospective case-control study was performed on a cohort of 56 normal subjects and 42 patients with HGS. Initially, PFA was measured twice by 3 raters in a random subset of 30 subjects (15 normal and 15 HGS) to determine the intrarater and interrater reliability of the measurement technique. PFA was then measured for all subjects. For the 42 patients with HGS, QOL was assessed from the SRS-22 questionnaire, in addition to the evaluation of the spino-pelvic balance. RESULTS: The intrarater and interrater intraclass correlation coefficients for the measurement of PFA were, respectively, 0.951 and 0.958, suggesting excellent reliability. PFA was significantly higher in HGS patients (8.3° ± 6.7°; range - 5° to 24°) when compared to normal subjects (3.0° ± 3.1°; range - 6° to 10°). The PFA in HGS was 5.6° ± 5.6° (range - 5° to 18°), 8.9° ± 6.7° (range - 2° to 24°), and 14.0° ± 6.0° (range 7°-23°) in type 4 (balanced pelvis), type 5 (unbalanced pelvis/balanced spine), and type 6 (unbalanced pelvis and spine) subjects, respectively. There were, respectively, 23.5% (4/17), 26.3% (5/19), and 83.3% (5/6) of HGS patients with abnormal PFA ≥ 10° in type 4, type 5, and type 6 subgroups. Increased PFA in HGS patients was related with deteriorating self-image, pain, function and total SRS-22 score, as well as with increasing pelvic tilt and decreasing sacral slope. CONCLUSION: A PFA ≥ 10° is proposed as a criterion to define abnormal PFA. PFA was increased in HGS and increased along with deteriorating sagittal balance and QOL. PFA is a clinically relevant parameter of sagittal balance, and can be useful in the evaluation and management of patients with HGS.

ISSLS PRIZE IN BIOENGINEERING SCIENCE 2018: dynamic imaging of degenerative spondylolisthesis reveals mid-range dynamic lumbar instability not evident on static clinical radiographs.

PURPOSE: Degenerative spondylolisthesis (DS) in the setting of symptomatic lumbar spinal stenosis is commonly treated with spinal fusion in addition to decompression with laminectomy. However, recent studies have shown similar clinical outcomes after decompression alone, suggesting that a subset of DS patients may not require spinal fusion. Identification of dynamic instability could prove useful for predicting which patients are at higher risk of post-laminectomy destabilization necessitating fusion. The goal of this study was to determine if static clinical radiographs adequately characterize dynamic instability in patients with lumbar degenerative spondylolisthesis (DS) and to compare the rotational and translational kinematics in vivo during continuous dynamic flexion activity in DS versus asymptomatic age-matched controls. METHODS: Seven patients with symptomatic single level lumbar DS (6 M, 1 F; 66 ± 5.0 years) and seven age-matched asymptomatic controls (5 M, 2 F age 63.9 ± 6.4 years) underwent biplane radiographic imaging during continuous torso flexion. A volumetric model-based tracking system was used to track each vertebra in the radiographic images using subject-specific 3D bone models from high-resolution computed tomography (CT). In vivo continuous dynamic sagittal rotation (flexion/extension) and AP translation (slip) were calculated and compared to clinical measures of intervertebral flexion/extension and AP translation obtained from standard lateral flexion/extension radiographs. RESULTS: Static clinical radiographs underestimate the degree of AP translation seen on dynamic in vivo imaging (1.0 vs 3.1 mm; p = 0.03). DS patients demonstrated three primary motion patterns compared to a single kinematic pattern in asymptomatic controls when analyzing continuous dynamic in vivo imaging. 3/7 (42%) of patients with DS demonstrated aberrant mid-range motion. CONCLUSION: Continuous in vivo dynamic imaging in DS reveals a spectrum of aberrant motion with significantly greater kinematic heterogeneity than previously realized that is not readily seen on current clinical imaging. LEVEL OF EVIDENCE: Level V data These slides can be retrieved under Electronic Supplementary Material.

[Preoperative Disability and Its Influencing Factors in Patients With Lumbar Spondylolisthesis].

BACKGROUND: Patients with lumbar spondylolisthesis typically suffer from symptom discomfort and various degrees of disability for months or years prior to receiving surgical treatments. Knowing the factors that influence the disability status of these patients will help healthcare providers develop effective preventive measures. PURPOSE: To explore preoperative disability and its important predictive factors in patients with lumbar spondylolisthesis. METHODS: A predictive correlational design was used and a convenience sample of eighty-six lumbar spondylolisthesis preoperative patients were recruited from a medical center in northern Taiwan. Data were collected using a study questionnaire, which included the Oswestry disability index, the revised geriatric depression scale-short form, and a pain numeric rating scale. RESULTS: The average disability index of the participants was 48.52 (SD = 16.14). The multiple linear regression analyses identified lower back pain, depression, age, and gender as significant predictors of preoperative disability, collectively explaining 40.9% of the variation in disability severity. Being female, being older, having a higher degree of lower back pain, and having depression were significantly associated with preoperative disability. CONCLUSIONS / IMPLICATIONS FOR PRACTICE: The results of the present study indicate that lumbar spondylolisthesis patients who are older in age, female, currently experiencing lower back pain, and suffering from depression face a higher risk of preoperative disability. Patients in these at-risk categories should be assessed actively and provided with appropriate patient education in order to enhance their quality of life.

Classification of spondylolytic clefts in patients with spondylolysis or isthmic spondylolisthesis using positional MRI.

Background Posterior instability is a pathologic movement occurring in the spondylolytic cleft. Purpose To present a new classification system for the evaluation of spondylolytic cleft by positional magnetic resonance imaging (MRI) and determine the prevalence of the different types. Material and Methods A total of 176 segments of the lumbar spine with spondylolysis or isthmic spondylolisthesis were examined using positional MRI. Scans were obtained in neutral sitting, flexion, and extension positions. No visible movement in the cleft was defined as type A, fluid displaced into the cleft as type BI, displacement of the flava ligaments at the level of the cleft as type BII, and intraspinal cysts arising from the spondylolytic cleft as type BIII. The movements were characterized by a radiologist and a neurosurgeon experienced in positional MRI. Clinical findings were correlated with the different types of instability. Results A high agreement was found between the two observers. In total, 131 segments were characterized as type A, six as type BI, 24 as type BII, and 10 as type BIII. In five segments, the type differed between the right and the left side. Two patients had a mixed type BI/II, another two patients had a mixed type BII/III, and one patient had a mixed type BI/III. Patients with type BII and BIII instabilities suffered more often from radicular symptoms compared to patients without any instability. Conclusion The presented classification might help to better understand and study changes encountered in the spondylolytic cleft in patients with spondylolysis and isthmic spondylolisthesis using positional MRI.

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.

Return of motor evoked potentials after knee flexion in the setting of high-grade spondylolisthesis.

PURPOSE: To present a case of loss of motor-evoked potentials (MEPs) to the left foot in the supine position after a partial reduction and instrumented fusion from L4 to pelvis which was managed successfully without revision or removal of implants. METHODS: We report a patient with high-grade spondylolisthesis who demonstrated loss of motor-evoked potentials after posterior spinal fusion and transfer to supine position. The patient's knees were flexed to 90° and signals were immediately restored. Systemic steroids were administered and circumferential fusion was delayed 21 days. Anterior-interbody cage was placed without complication. RESULTS: She was discharged on post-operative day 2. At 7 months, she is pain free and doing well with plans to return to gymnastics completely. CONCLUSIONS: Knee flexion can be instituted when encountering a neuromonitoring signal change following posterior spinal fusion for spondylolisthesis as a means to alleviate acute nerve stretch injury and may in some cases prevent the need to lessen the correction. LEVEL OF EVIDENCE: IV.

Correlation between facet tropism and lumbar degenerative disease: a retrospective analysis.

BACKGROUND: The aim of this study was to investigate the correlation between facet tropism and spinal degenerative diseases, such as degenerative lumbar spondylolisthesis, degenerative lumbar scoliosis, and lumbar disc herniation. METHODS: This study retrospectively analysed clinical data from the Department of Orthopaedics at The First Affiliated Hospital of Nanchang University. Ninety-two patients were diagnosed with lumbar spondylolisthesis, 64 patients with degenerative scoliosis, and 86 patients with lumbar disc herniation between 1 October 2014 and 1 October 2016. All patients were diagnosed using 3.0 T magnetic resonance imaging and underwent conservative or operative treatment. Facet tropism was defined as greater than a ten degree between the facet joint angles on both sides. RESULTS: For L3-L4 degenerative lumbar spondylolisthesis, one out of six cases had tropism compared to seven out of the 86 controls (p = 0.474). At the L4-L5 level, 17/50 cases had tropism compared to 4/42 cases in the control group (p = 0.013). At the L5-S1 level, 18/36 cases had tropism compared to 7/56 controls (p = 0.000). For degenerative lumbar scoliosis at the L1-L5 level, 83/256 cases had tropism as compared to 36/256 controls (p = 0.000). For L3-L4 lumbar disc herniation two out of eight cases had tropism compared to 14/78 controls (p = 0.625). At the L4-L5 level, 19/44 cases had tropism compared to four out of 42 controls (p = 0.001). At the L5-S1 level, 24/34 cases had tropism compared to 10/52 controls (p = 0.000). CONCLUSION: At the L4-5 and L5-S1 levels, facet tropism is associated with degenerative spondylolisthesis. In the degenerative lumbar scoliosis group, the number of case with facet tropism was significantly higher than that of the control group. Facet tropism was associated with lumbar disc herniation at the L4-5 and L5-S1 levels. Overall, in these three lumbar degenerative diseases, facet tropism is a common phenomenon.