Changes of spinopelvic parameters in different positions

Comparing Spinopelvic Angles and Magnification on Supine MRI With Standing Radiographs in Lumbar Spinal Stenosis

STUDY DESIGN

Radiologic cross-sectional study based on a prospective cohort study (level III).

OBJECTIVE

Investigate whether lumbar lordosis (LL) and sacral slope (SS) differ significantly on supine magnetic resonance imaging (MRI) versus standing radiographs in nondeformity lumbar spinal stenosis (LSS). Secondly, to quantify the amount of magnification on standing lumbar radiographs.

SUMMARY OF BACKGROUND DATA

Supine MRI is routinely performed when diagnosing LSS. Standing radiographs are often supplemented to measure spinopelvic angles. Little research has been done on whether LL and SS translate from standing radiographs to supine MRI. Previous studies have trended to significant changes in LL and SS; however, none have been performed exclusively in nondeformity LSS.

MATERIALS AND METHODS

Review of preoperative standing lateral lumbar radiographs and midsagittal T2-weighted supine lumbar MRI in 211 patients with LSS without concomitant degenerative spondylolisthesis, measuring LL (L1-S1), segmental lumbar lordosis (sLL) (L4-S1) and SS, in addition to the anteroposterior diameter and height of the L3 vertebral body. We conducted a reliability study and performed a Pearson's correlation analysis. Data was presented in Bland-Altman plots.

RESULTS

Interobserver reliability was good to excellent, with ICC ranging from 0.77 to 0.94 for all parameters. Statistically significant differences were observed in LL and SS between image modalities. The mean radiographic measurements were as follows: LL 48.9 (SD: 12.8), sLL 32.3 (SD: 8.1), and SS 37.3 (SD: 8.7) degrees. The mean MRI measurements were as follows: LL 46.0 (SD: 10.5), sLL 32.3 (SD: 7.1), and SS 38.1 (SD: 7.1) degrees. Mean vertebral body magnification was between 21% and 23% for L3 anteroposterior diameter and height.

CONCLUSIONS

Our results suggest that supine lumbar MRI might be a viable alternative to standing lateral lumbar radiographs for measuring LL and SS in routine follow-up for patients with LSS without concomitant spinal deformity. Standing radiographs are recommended as part of the initial investigation for LSS. Standing lumbar radiographs may yield high grades of magnification.

Changes in sagittal spinopelvic alignment are associated with increased pain and impaired function in multiple myeloma patients

PURPOSE

Multiple myeloma (MM), a type of B-cell non-Hodgkin lymphoma, frequently causes osteolytic spinal lesions, increasing the risk of fracture and poor sagittal spinopelvic alignment. In relapsed patients, these changes may contribute to increased pain and functional impairment.

METHODS

The clinical data of 86 MM patients (48 males, 38 females) who underwent ≥ 3 whole-body CT scans between 2009 and 2024, with a mean interscan interval of 19.2 months and a total follow-up duration of 37.5 months, were analyzed in this retrospective study. Spinopelvic parameters were measured, and clinical data (pain intensity, analgesic use, ECOG classification, and ASIA classification) were assessed.

RESULTS

Over the disease course, thoracic kyphosis (TK) increased significantly (from 38.5° to 46.7°, p < 0.0001), whereas the Dens axis-S1 distance decreased (from 53.2 cm to 49.3 cm, p < 0.0001). These changes correlated with increased pain levels (median VAS score increasing from 2.0 to 6.0, p < 0.0001) and increased analgesic use (median WHO analgesic level increasing from 1.0 to 3.0, p < 0.001). Other spinopelvic parameters remained stable, and no significant changes were observed in the ECOG or ASIA classifications. Notably, an increase in TK exceeding nine degrees was strongly associated with increased pain levels (mean VAS score of 7.3 vs. 4.9, p < 0.001), whereas new vertebral fractures did not significantly impact pain intensity or analgesic consumption.

CONCLUSION

In MM patients, progressive TK and a reduced Dens axis-S1 distance are key contributors to worsening pain and increased analgesic requirements. Surgical strategies should prioritize kyphosis correction, particularly in cases where increases in TK exceeding nine degrees, to optimize pain management. Future studies should further explore these findings.

Assessing the Diagnostic Validity of Torsobarography in Scoliosis

Adolescent idiopathic scoliosis (AIS) is treated with various forms of conservative care or surgery, depending on the degree of severity. When AIS is detected early, it can be monitored and initially treated with reduced invasiveness to prevent further progression. AIS manifests itself through deformations of the trunk, which are mostly identified as asymmetries in manual clinical examination. Torsobarography is a new pressure-based surface topographic system for posture analysis and evaluates such associated morphologic asymmetries. The aim of this study is to investigate the diagnostic validity of torsobarography by examining correlation of extracted torsobarographic indices with the Cobb angle and its ability to differentiate between different severities of scoliosis: no scoliosis, mild scoliosis, and moderate scoliosis. A total of 87 subjects (51 females and 36 males) were examined with torsobarography. Six torsobarographic indices were calculated for all subjects: torsobarography angle (TBA), sagittal imbalance index (SII), torso asymmetry index (TAI), shoulder asymmetry angle (SAA), waist asymmetry angle (WAA), and pelvis asymmetry Angle (PAA). These indices were correlated with the Cobb angle, and the differences between severities were statistically analyzed. Three out of six indices (TBA, TAI, and WAA) were able to significantly distinguish between mild and moderate scoliosis. Additionally, those indices showed moderate correlation (ρ = 0.37-0.50) with the Cobb angle measurements. The WAA was the only statistically significant index capable of differentiating between no scoliosis and moderate scoliosis. This study is the first to demonstrate that torsobarography can distinguish between different severities of scoliosis and thus identify a scoliotic deformity that requires bracing over monitoring.

Reliability of the Risser+ grade for assessment of bone maturity in pediatric scoliosis cases: Investigation using standing and supine whole-spine radiograph

BACKGROUND

Although several radiography-based systems for assessing skeletal maturity are available to clinicians, the classical Risser grading system remains a clinical gold standard. For scoliosis follow-up, a standing whole-spine radiograph is usually used. However, in our clinical practice, we have occasionally encountered cases in which ossification of the iliac crest is seen differently in the standing and supine whole-spine radiography. Here, we aimed to clarify the reliability of the Risser+ grading system for supine versus standing position radiographs.

METHODS

This study recruited patients with all types of scoliosis who had been radiographed in both the standing and supine positions. We retrospectively evaluated the Risser+ grade of standing and supine whole-spine radiographs taken consecutively. Kappa statistics were computed to investigate the agreement between standing and supine Risser+ grades for this study.

RESULTS

We evaluated 111 patients (age: 12.6 ± 2.0; male-to-female = 23:88). The Kappa value for the standing and supine Risser+ grade systems was 0.74. The degree of agreement between the two positions for each Risser+ grade revealed high agreement for grades 0 and 5 in all cases, whereas grades 2 and 3 had low agreement.

CONCLUSIONS

Overall, there was substantial agreement between the Risser+ grades assigned to standing and supine position radiographs. However, disagreement was observed between standing and supine position radiographs assigned Risser+ grades of 2 or 3. Therefore, we have found a wide range in the visibility of iliac apophysis ossification of the iliac depending on the posture, and there are limitations in assessing bone maturity using the Risser+ grade alone. Clinicians should use other evaluation systems, in addition to the Risser+ system, to achieve a more accurate bone maturity assessment, especially for cases with standing position radiographs assigned Risser grades of 2 or 3.

Spine surgeon versus AI algorithm full-length radiographic measurements: a validation study of complex adult spinal deformity patients

INTRODUCTION

Spinal measurements play an integral role in surgical planning for a variety of spine procedures. Full-length imaging eliminates distortions that can occur with stitched images. However, these images take radiologists significantly longer to read than conventional radiographs. Artificial intelligence (AI) image analysis software that can make such measurements quickly and reliably would be advantageous to surgeons, radiologists, and the entire health system.

MATERIALS AND METHODS

Institutional Review Board approval was obtained for this study. Preoperative full-length standing anterior-posterior and lateral radiographs of patients that were previously measured by fellowship-trained spine surgeons at our institution were obtained. The measurements included lumbar lordosis (LL), greatest coronal Cobb angle (GCC), pelvic incidence (PI), coronal balance (CB), and T1-pelvic angle (T1PA). Inter-rater intra-class correlation (ICC) values were calculated based on an overlapping sample of 10 patients measured by surgeons. Full-length standing radiographs of an additional 100 patients were provided for AI software training. The AI algorithm then measured the radiographs and ICC values were calculated.

RESULTS

ICC values for inter-rater reliability between surgeons were excellent and calculated to 0.97 for LL (95% CI 0.88-0.99), 0.78 (0.33-0.94) for GCC, 0.86 (0.55-0.96) for PI, 0.99 for CB (0.93-0.99), and 0.95 for T1PA (0.82-0.99). The algorithm computed the five selected parameters with ICC values between 0.70 and 0.94, indicating excellent reliability. Exemplary for the comparison of AI and surgeons, the ICC for LL was 0.88 (95% CI 0.83-0.92) and 0.93 for CB (0.90-0.95). GCC, PI, and T1PA could be determined with ICC values of 0.81 (0.69-0.87), 0.70 (0.60-0.78), and 0.94 (0.91-0.96) respectively.

CONCLUSIONS

The AI algorithm presented here demonstrates excellent reliability for most of the parameters and good reliability for PI, with ICC values corresponding to measurements conducted by experienced surgeons. In future, it may facilitate the analysis of large data sets and aid physicians in diagnostics, pre-operative planning, and post-operative quality control.

How Sagittal Spinal Parameters Predict Anterolateral Spinal Ossification Severity: A Study Based on CT Classification

STUDY DESIGN

Retrospective observational study.

OBJECTIVE

The purpose of this study was to establish a CT classification system of anterolateral spinal ossification and analyze the effects of sagittal spinal parameters on ossification.

SUMMARY OF BACKGROUND DATA

Patients with diffuse idiopathic skeletal hyperostosis often present with anterolateral ossification of the spine. Few reports consider anterolateral spinal ossification at each spinal level or explore the influence of sagittal alignment.

MATERIALS AND METHOD

One hundred and twenty patients (79 males and 41 females) over 60 years old who underwent whole spinal CT scans from October 2018 to November 2021 were analyzed. Volume rendering technique images were used to assess the degree of anterolateral spinal ossification in each intervertebral space, and a classification system was established. Sagittal parameters, such as thoracic kyphosis, lumbar lordosis (LL), cervical lordosis, sacral slope, and thoracolumbar junction angle of the patients were measured. Multifactor stepwise linear regression analysis and ordered logistic regression analysis were used to study the effects of the sagittal parameters on ossification grades.

RESULTS

The median age of the study population was 67 years (63-72 IQR). The new classification system classifies the severity of anterolateral spinal ossification in each intervertebral space into grades 0 to 3 with an intra-observer intraclass correlation coefficient value of 0.909 and inter-observer intraclass correlation coefficient value of 0.900. Multivariate stepwise linear regression analysis showed that age (OR=1.30, P <0.001), weight (OR=1.23, P =0.013), and cervical lordosis (OR=1.19, P <0.001) were significantly correlated with total ossification grade. Multifactor ordered logistic regression analysis showed that there was a statistically significant correlation between cervical lordosis and the ossification grades of each intervertebral space of T1~T4 ( P ≤0.005), between thoracic kyphosis and each intervertebral space in T4~T12 ( P ≤0.019), and between thoracolumbar junction angle and each intervertebral space in T10~L3 ( P ≤0.025). LL was significantly and positively correlated with the ossification grades of each intervertebral space in T7~T11 ( P ≤0.041). LL and sacral slope were significantly negatively correlated with the ossification grades of each intervertebral space in L3~S1 ( P ≤0.047).

CONCLUSION

Our new classification scheme demonstrated good accuracy and reliability for the evaluation of the severity of anterolateral spinal ossification. The effect of sagittal parameters on anterolateral spinal ossification was position-specific. The greater the kyphosis or the smaller the lordosis of a spinal region, the more severe the degree of ossification in the corresponding region.

LEVEL OF EVIDENCE

3.

Posterior Pubic Incidence: A Novel Morphologic Spinopelvic Parameter Nearly Equal to Pelvic Incidence

BACKGROUND

Pelvic incidence (PI) and Jackson's angle are 2 major spinopelvic parameters that define the position of the sacrum within the pelvis. These parameters are measured on standing lateral radiography, and the identification of the hip axis is essential for measurements. Moreover, identifying the hip axis in patients with hip diseases or femoral head deformity is challenging. In this study, we described a novel parameter named posterior pubic incidence (PPI) that could be measured using the posterior pubic edge instead of the hip axis.

METHODS

Group A comprised 50 volunteers who underwent standing lateral lumbosacral radiography. Group B comprised 54 patients with abdominal or urologic problems who underwent supine computed tomography. The PI, pelvic tilt (PT), sacral slope, PPI, and posterior pubic tilt were measured. The differences between PI and PPI were evaluated. Linear regression analysis was used to predict the PI value from PPI.

RESULTS

The mean PI and PPI values were 47.41° ± 12.32° and 49.32° ± 11.94° in group A and 49.19° ± 9.99° and 49.99° ± 9.25° in group B, respectively. The mean absolute differences in groups A and B were 2.41° ± 1.63° and 1.9° ± 1.62°, respectively. High correlations were obtained between PI/PPI and pelvic tilt/posterior pubic tilt. PI could be calculated as PI° = PPI° - 2° on plain radiography and as PI° = PPI° - 1° on computed tomography.

CONCLUSIONS

PPI was strongly correlated with PI, which was nearly equal to PI, and may replace PI in formulas containing PI.

Impact of Spino-Pelvic Parameters on the Prediction of Lumbar and Thoraco-Lumbar Segment Angles in the Supine Position

Background: The correction of malposition according to vertebral fractures is difficult because the alignment at the time before the fracture is unclear. Therefore, we investigate whether the spinal alignment can be determined by the spino-pelvic parameters. Methods: Pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), adjacent endplate angles (EPA), age, sex, body weight, body size, BMI, and age were used to predict mono- and bisegmental EPA (mEPA, bEPA) in the supine position using linear regression models. This study was approved by the Ethics Committee of the Medical Association of Saxony-Anhalt Germany on 20 August 2020, under number 46/20. Results: Using data from 287 patients, the prediction showed R2 from 0.092 up to 0.972. The adjacent cranial and caudal EPA showed by far the most frequently significance in the prediction of all parameters used. Anthropometric and spino-pelvic parameters showed sparse impact, which was frequently in the lower lumbar regions. On average, a very good prediction was found. For two mEPA (L3/4 R2 = 0.914, L4/5 R2 = 0.953) and two bEPA (L3 R2 = 0.899, L4 R2 = 0.972), the R2 was >0.8. However, the predicted EPA differed for individual patients, even in these very effective prediction models—roughly around ±10° as compared to the measured EPA. Conclusions: In general, the prediction showed good to perfect results. In the supine position, the spinopelvic and anthropometric parameters show sparse impact on the prediction of mEPA or bEPA.

Pelvic incidence measurement with supine magnetic resonance imaging: A validity and reliability study

OBJECTIVE

Classically, pelvic incidence (PI) and other spinopelvic sagittal parameters are measured using plain x-ray obtained with the patient standing. However, it is difficult to obtain a perfect mid-sagittal appearance of the sacral endplate and superimposition of both femoral heads from a plain x-ray. Overlapping of the iliac wings also could obscure the appearance of the sacral endplate. Recent studies showed that MRI was more reliable than x-ray for evaluating some spinal sagittal parameters. To our knowledge, measurements of spinopelvic sagittal parameters using supine MRI have not been reported previously. We assessed the validity and reliability of measurements of spinopelvic sagittal parameters from standing lateral x-rays and supine magnetic resonance imaging (MRI).

METHODS

We recruited 26 asymptomatic volunteers for this study. Standing lateral lumbosacral radiographs, including femoral heads and spinopelvic MRI images with coronal images of the femoral heads were performed. The anatomic reference point required to measure PI was found on coronal MRI images and transferred to the midline sagittal MRI using the bladder wall as a second reference point. PI, sacral slope (SS), and pelvic tilt (PT) were measured on x-ray and MRI images. Validity and reliability of results also were tested.

RESULTS

Of 14 males and 12 females (average age, 31.30), PI was obtained from x-ray and MRI in 52. ± 6.89 and 51.42 ± 6.43, respectively. From standing x-ray to supine MRI, PT decreased by 3.16°, while SS increased 2.5°. A paired t-test showed a significant difference between PT values from x-ray and MRI. The correlation was highest between the x-ray and MRI measurements of PI, PT, and SS, respectively. Intraobserver and interobserver reliabilities were between 0.88 and 0.96 on x-ray and MRI. All reliabilities were excellent, although MRI values were higher.

CONCLUSION

MRI was more reliable in the measurement of spinopelvic parameters than classic standing x-ray examination. Higher reliability and being radiation-free could make MRI a good alternative to standing x-ray.

Changes in lumbar lordosis and predicted minimum 5-year surgical outcomes after short-segment transforaminal lumbar interbody fusion

Although most patients who undergo transforaminal lumbar interbody fusion (TLIF) show favorable surgical results, some still have unfavorable results for various reasons. This study aimed to investigate the influence of differences in lumbar lordosis (LL) between the standing and supine positions (DiLL: supine LL–standing LL) on minimum 5-year surgical outcomes after short-segment TLIF. Ninety-one patients with lumbar degenerative disease who underwent short-segment TLIF (1–2 levels) were categorized based on preoperative differences in LL as DiLL (+) and DiLL (−). Comparison and correlation analyses were performed. The incidence of adjacent segment disease (ASD) by radiology (R-ASD) and symptomatic ASD (S-ASD), bony fusion rates, and pre- and postoperative clinical scores (visual analog scale [VAS]; Japanese Orthopaedic Association [JOA] score; Oswestry disability index (ODI); and Nakai’s score) were evaluated. Postoperatively, VAS for low back pain (LBP) in the sitting position, JOA scores for LBP, lower leg pain, intermittent claudication, ODI, and Nakai’s score were significantly worse in the DiLL (+) group than in the DiLL (−) group. DiLL values were significantly correlated with VAS for LBP, ODI, and Nakai’s score, postoperatively. Positive DiLL values were associated with poorer postoperative outcomes. DiLL is a simple and useful method for predicting mid-term outcomes after TLIF.

The effect of lumbar spinal fusion on native acetabular anteinclination in standing position

PURPOSE

The complex and dynamic spinopelvic interplay is not well understood. The aims of the present study were to investigate the following: (1) whether native acetabular anteinclination (AI) in standing position changes following lumbar spinal fusion (LSF); (2) potential correlations between AI change (ΔAI) and several spinopelvic parameters such as the change in lumbar lordosis (ΔLL), pelvic tilt (ΔPT), and anterior pelvic plane angle (ΔaPP).

METHODS

A total of 485 patients (Males: 262, Females: 223) with an average age of 64 ± 13 years who underwent a primary LSF were identified from our institutional database. The difference (Δ) between pre-and postoperative acetabular anteinclination (AI), lumbar lordosis (LL), anterior pelvic plane angle (aPP), sacral slope (SS), and pelvic tilt (PT) were measured on a standing lateral radiograph (EOS®) and compared to find the effect of LSF on the lumbopelvic geometry.

RESULTS

Following LSF, the average absolute ΔAI was 5.4 ± 4 (0 to 26)°, ΔLL: 5.5 ± 4 (0 to 27)°, ΔaPP: 5.4 ± 4 (0 to 38)°, ΔPT: 7 ± 5 (0 to 33)° and ΔSS: 5.3 ± 4 (0 to 33)°. No significant differences were observed between LSF levels. A ΔAI ≥ 10° was observed in 66 (13.6%) and ΔAI ≥ 20° in 5 (1%) patients. The Pearson correlation demonstrated a strong negative correlation of ΔAI with ΔLL (r = 0.72, p < .001).

CONCLUSION

Clinical decision-making should consider the relationship between native anteinclination and lumbar lordosis to reduce the risk of functional acetabular component malalignment in patients with concomitant hip and spine pathology.

LEVEL OF EVIDENCE

Retrospective case-control study, Level III.

Postoperative loss of correction after combined posterior and anterior spinal fusion surgeries in a lumbar burst fracture patient with Class II obesity

Background:

When treating thoracolumbar fractures with severe cranial endplate injury but no or slight caudal endplate injury, it is debatable whether anterior fusion should be performed only for the injured cranial level, or for both cranial and caudal levels. We report an unexpected postoperative correction loss after combined multilevel posterior and single-level anterior fusion surgery in a patient with obesity.

Case Description:

A 28-year-old male with Class II obesity was brought to the emergency room with an L1 burst fracture with spinal canal involvement. Cranial endplate injury was severe, whereas caudal endplate injury was mild. The first surgery with 1-above 1-below posterior fixation failed to achieve sufficient stability; thus, additional surgeries (3-above 3-below posterior fixation and single-level T12-L1 anterior fusion) were performed. Postoperatively, the local kyphosis angle (LKA) between T12 and L2 was 22° in the lateral lying position and 29° in the standing position. Twenty-one-month post surgery, bony fusion between T12 and L1 was observed, and the LKA was 28° in both the lateral lying and standing positions. After posterior implants were removed 24 months after the surgery, significant correction loss both at the T12-L1 segment (6°) and L1-L2 segment (6°) occurred, and LKA was 40° at the final follow-up.

Conclusion:

In this patient, an intense axial load due to excessive body weight was at least one of the causes of postoperative correction loss. Postural differences in LKA may be useful to evaluate the stability of thoracolumbar fractures after fusion surgery and to predict postoperative correction loss.

Correlation and Differences in Lumbopelvic Sagittal Alignment Parameters Between Lumbar Radiographs and Magnetic Resonance Images

STUDY DESIGN

Imaging parameter study.

OBJECTIVE

Though lumbar alignment is better evaluated using standing radiograph than supine magnetic resonance imaging (MRI), few studies have researched this. Our study aimed to observe the correlation and difference in alignment between standing radiograph and supine MRI, and assess whether the change of position affects the lumbopelvic parameters.

METHODS

We analyzed 105 patients, measuring lumbar lordosis (LL), sacral slope (SS), pelvic tilt (PT), and pelvic incidence (PI). Inter- and intraparameter analyses were performed to identify any difference between standing radiograph and supine MRI. Statistical differences between the lumbopelvic parameters were compared.

RESULTS

There was excellent interobserver agreement for each parameter (interclass correlation coefficient > 0.75), and significant differences were observed in each parameter between radiograph and MRI (P < .05). Strong correlations were noted between the equivalent parameters in radiograph and MRI, both SS and PI were strongly correlated with LL in radiograph and MRI image, both PT and SS were strongly correlated with PI in radiograph and MRI image (r = -1.0 to -0.5 or 0.5 to 1.0).

CONCLUSION

Supine MRI obviously underestimated the measurements of lumbopelvic sagittal alignment parameters in standing radiograph. Therefore, standing lumbar radiographs should be obtained preoperatively in all surgical patients, not only supine MRI. In addition, we observed that PI was not a constant morphological parameter.

Predictors of Spontaneous Restoration of Lumbar Lordosis after Single-Level Transforaminal Lumbar Interbody Fusion for Degenerative Lumbar Diseases

Introduction

Preoperative factors that predict postoperative restoration of lumbar lordosis (LL) are not well understood. To investigate whether preoperative postural correction of LL, sagittal malalignment, or lumbar flexibility are associated with the postoperative restoration of LL in patients treated with a single-level transforaminal lumbar interbody fusion (TLIF), a retrospective cohort study was conducted.

Methods

We enrolled 104 patients (mean age: 67.5±10.7 years old; 47 men and 57 women) with lumbar degenerative diseases treated with a single-level TLIF. The pre- and postoperative LL were examined using lateral radiographs in the standing position and computed tomography (CT) images in the supine position. The correlation between postoperative LL restoration and preoperative postural correction of LL (difference in LL between the standing and supine positions: D-LL), sagittal imbalance (pelvic incidence minus LL: PI-LL), and lumbar flexibility (difference in LL between the flexion and extension postures) were analyzed. Patients were divided into two groups according to the D-LL (D-LL≥0° and D-LL<0°). The rates of postoperative LL restoration (postoperative LL-preoperative LL in standing) were compared between the two groups.

Results

Multiple regression analysis performed after adjustment for age, gender, body mass index, and cage angle revealed that postoperative LL restoration was significantly correlated with D-LL (p<0.001), but not with PI-LL, and lumbar flexibility. Patients with a preoperative D-LL≥0° showed a significantly greater increase of LL after TLIF (7.1°±11.2°) than those with D-LL<0° (1.4°±6.6°) (p=0.003).

Conclusions

A preoperative evaluation of a lateral radiograph or CT taken in the supine position is useful in predicting postoperative improvement of sagittal alignment. Postoperative improvement of sagittal spinopelvic alignment would be expected when LL is corrected in the supine position preoperatively. Surgeons should pay attention to the postural correction of LL when performing short-segment fusion surgery for lumbar degenerative disease with sagittal malalignment.

Spinopelvic alignment and lumbar vertebral shape in children: associations with structural spinal abnormalities and body composition in the generation R study

PURPOSE

To investigate the spinopelvic alignment and vertebral shape in children, and associations with body composition and structural spinal abnormalities on magnetic resonance imaging (MRI).

METHODS

We performed a cross-sectional study embedded in the Generation R Study, a prospective population-based birth cohort. Pelvic incidence and vertebral concavity ratios for each lumbar level were determined on sagittal MRI images in 9-year-old children, and structural spinal abnormalities were scored semi-quantitatively. The BMI-SD score was calculated, and body composition was assessed using DXA scans. Associations of pelvic incidence and vertebral concavity ratios with structural abnormalities and body composition measures were assessed using (multilevel) regression analyses.

RESULTS

This study included 522 participants (47.7% boys), aged 9.9 years (IQR 9.7-10.0). The mean pelvic incidence was 36.6° (SD 8.0). Vertebral concavity ratios ranged from 0.87 to 0.90, with significantly lower ratios for boys compared to girls. Associations were found for a larger pelvic incidence with decreased disc height [OR 1.03 (95% CI 1.02-1.05)], and a pelvic incidence in the lowest tertile with less disc bulging [OR 0.73 (95% CI 0.56-0.95)]. Increased vertebral concavity ratio was associated with decreased disc height [OR 14.16 (95% CI 1.28-157.13)]. Finally, increased fat-free mass index was associated with a smaller pelvic incidence [adjusted OR 0.85 (95% CI 0.07-1.63)].

CONCLUSION

The mean pelvic incidence of 9-year-old children is 36.6° on supine MRI images, and a slightly concave shape of the lumbar vertebrae is seen. Spinopelvic alignment is associated with structural spinal abnormalities, and might itself be influenced by the children's body composition.

The Quantity and Quality of Lumbar Muscles and Lumbopelvic Parameters in Patients With Degenerative Spondylolisthesis

Introduction

Lumbar degenerative spondylolisthesis (DS) is one of the most common causes of low back pain. The lumbar muscles, such as the psoas major (PM), erector spinae (ES), and multifidus (MF) muscles, play an important role in the stability and functional movement of the lumbar spine. The quantities and qualities of these muscles may be related to the occurrence of DS and lumbopelvic parameters, such as lumbar lordosis (LL) and sacral slope (SS). However,the influence of lumbar muscles on DS and lumbopelvic alignment is not well understood.

Methods

Patients with L4 DS (DS group, n=25) and without DS (non-DS group, n=25) were included. Using sagittal reconstructed CT images of patients who visited our hospital for reasons other than low back disorders, LL, upper lumbar lordosis ([ULL] L1-L4), lower lumbar lordosis ([LLL] L4-S1), and SS were examined. To evaluate the quantity and quality of lumbar muscles, the gross cross-sectional area (GCSA), functional cross-sectional area (FCSA), and fat infiltration (FI) of the PM, ES, and MF muscles were measured by CT images. The lumbopelvic parameters, FCSA, GCSA, and FI of lumbar muscles were compared between the two groups. Then, each lumbar muscle parameter was analyzed for correlation with DS and lumbopelvic parameters.

Results

DS patients displayed significantly greater ULL and lower FI of the PM and ES muscles than non-DS patients (p=0.0078, 0.031, and 0.010, respectively). The FI of the ES muscle was significantly correlated with the presence of DS (p=0.010). The FCSA of the ES and MF muscles and the GCSA of the MF muscle showed a significant correlation with LL and SS in the non-DS group (p<0.05), but not in the DS group..

Conclusion

ULL was greater in L4 DS patients, possibly related to the better quality of the ES muscle. All DS patients showed mild (grade I) spondylolisthesis, suggesting the possibility that lumbar muscle quality is better in patients with mild DS than in those without DS. The ES and MF muscles may play an important role in maintaining the lumbar lordotic angle in non-DS patients but not in DS patients.

Effects of the difference between lumbar lordosis in the supine and standing positions on the clinical outcomes of decompression surgery for lumbar spinal stenosis

OBJECTIVE

The authors sought to evaluate the relationship between the difference in lumbar lordosis (DiLL) in the preoperative supine and standing positions and spinal sagittal alignment in patients with lumbar spinal stenosis (LSS) and to determine whether this difference affects the clinical outcome of laminectomy.

METHODS

Sixty patients who underwent single-level unilateral laminectomy for bilateral decompression of LSS were evaluated. Spinopelvic parameters in the supine and standing positions were measured preoperatively and at 3 months and 2 years postoperatively. DiLL between the supine and standing positions was determined as follows: DiLL = supine LL - standing LL. On the basis of this determination patients were then categorized into DiLL(+) and DiLL(-) groups. The relationship between DiLL and preoperative spinopelvic parameters was evaluated using Pearson's correlation coefficient. In addition, clinical outcomes such as visual analog scale (VAS) and Oswestry Disability Index (ODI) scores between the two groups were measured, and their relationship to DiLL was evaluated using two-group comparison and multivariate analysis.

RESULTS

There were 31 patients in the DiLL(+) group and 29 in the DiLL(-) group. DiLL was not associated with supine LL but was strongly correlated with standing LL and pelvic incidence (PI) - LL (PI - LL). In the preoperative spinopelvic alignment, LL and SS in the standing position were significantly smaller in the DiLL(+) group than in the DiLL(-) group, and PI - LL was significantly higher in the DiLL(+) group than in the DiLL(-) group. There was no difference in the clinical outcomes 3 months postoperatively, but low-back pain, especially in the sitting position, was significantly higher in the DiLL(+) group 2 years postoperatively. DiLL was associated with low-back pain in the sitting position, which was likely to persist in the DiLL(+) group postoperatively.

CONCLUSIONS

We evaluated the relationship between DiLL and spinal sagittal alignment and the influence of DiLL on postoperative outcomes in patients with LSS. DiLL was strongly correlated with PI - LL, and in the DiLL(+) group, postoperative low-back pain relapsed. DiLL can be useful as a new spinal alignment evaluation method that supports the conventional spinal sagittal alignment evaluation.

Computed Tomographic Assessment of Age- and Gender-Specific Sagittal Lumbopelvic Alignment in a Japanese Population

Introduction

Previous studies have reported differences in lumbopelvic alignment between standing and supine positions. Computed tomography (CT) images taken in the supine position are often used for clinical studies in addition to standing radiographs, although not frequently. Our study aims to clarify normative values of CT-evaluated lumbopelvic parameters and the characteristics of age- and gender-related lumbopelvic alignment in the supine position.

Methods

Patients undergoing CT scans of abdominal or lumbar regions for reasons other than low back disorders were included (n=581). Sagittal multiplanar reconstruction CT images were obtained, and lumbar lordosis (LL), L5-S1 angle, and sacral slope (SS) were measured. Mean values of the parameters in patients aged 59 years and under, 60-69, 70-79, and 80 and over, and in males and females, were calculated. Age- and gender-related differences in these parameters were statistically analyzed.

Results

Among the four age groups, patients 80 years and over showed significantly lower LL and SS than patients aged 70-79. Females 80 years and over showed significantly lower LL and SS than all other age groups, but those in males did not. The comparison between males and females showed no significant differences in LL and SS; however, the L5-S1 angle was significantly higher in males than in females. In patients 80 years and over, females showed significantly lower LL and SS than in males.

Conclusions

This study provides normative CT-evaluated lumbopelvic parameters, such as LL, L5-S1 angle, and SS, which will be utilized for comparisons in future studies. The present study first revealed that pelvic retroversion and lumbar kyphosis occur in elderly females in the supine position, which raised a possibility that age-related decrease of LL and SS in females occurs at an older age in the supine position than in the standing position.

Influence of Preoperative Difference in Lumbar Lordosis Between the Standing and Supine Positions on Clinical Outcomes After Single-level Transforaminal Lumbar Interbody Fusion: Minimum 2-year Follow-up

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

The aim of this study was to investigate whether a preoperative difference in lumbar lordosis (D-LL) between the standing and supine positions is associated with clinical outcomes after transforaminal lumbar interbody fusion (TLIF).

SUMMARY OF BACKGROUND DATA

Several factors have been reported to be associated with surgical outcomes after TLIF. However, the association between preoperative D-LL and clinical outcomes after TLIF is unknown.

METHODS

We enrolled 45 lumbar degenerative disease patients (mean age: 65.7 ± 11.3 years old; 24 males) treated with single-level TLIF. Surgical outcomes were assessed using Oswestry disability index, visual analog scale (VAS; low back pain [LBP], lower-extremity pain, numbness, LBP in motion, in standing, and in sitting), Japanese Orthopaedic Association Back Pain Evaluation Questionnaire, Japanese Orthopaedic Association score for intermittent claudication (JOA score), and Nakai's scoring system. The preoperative D-LL between the standing radiograph and computed tomography (CT) in the supine position was defined as LL in supine CT-standing radiograph. Patients were divided into two groups according to D-LL value (D-LL >-4°, and D-LL ≤-4°). Clinical outcomes were compared between the groups, and correlations between preoperative D-LL and clinical outcomes were analyzed.

RESULTS

There were no significant differences in preoperative clinical parameters between the two groups. Postoperative VASs for lower extremity pain, numbness, LBP in standing, and JOA score in D-LL >-4° group were significantly worse than in the D-LL ≤-4° group (P < 0.05). Preoperative D-LL showed a weak correlation with postoperative lower extremity pain and numbness (P < 0.05).

CONCLUSION

This study revealed that lumbar degenerative disease patients, who have greater preoperative kyphotic lumbar alignment in the standing versus supine position, tend to have postoperative residual symptoms after TLIF. A preoperative comparison of lateral radiographs between the standing and supine positions is useful to predict patients' postoperative residual symptoms.Level of Evidence: 3.

Age-Specific Characteristics of Lumbopelvic Alignment in Patients with Spondylolysis: How Bilateral L5 Spondylolysis Influences Lumbopelvic Alignment During the Aging Process

BACKGROUND

To elucidate the influence of spondylolysis on age-related lumbar degenerative changes, age-specific lumbopelvic alignment in patients with or without spondylolysis was examined.

METHODS

Sagittal reconstructed computed tomography images of the lumbar spine in consecutive patients (n = 581) undergoing computed tomography scans of abdominal or lumbar regions for reasons other than low back disorders were obtained. Lumbar lordosis (LL), L5-S1 angle, and sacral slope (SS) were measured. Lumbopelvic parameters in patients with or without spondylolysis were evaluated in 3 age groups (<50, 50-69, and ≥70). The influence of bilateral L5 spondylolysis (L5-lysis) and L5 vertebral slip on each lumbopelvic parameter, as well as correlation between cross-sectional area (CSA) of paraspinal muscles and the degree of vertebral slip, were examined by multiple regression analysis.

RESULTS

Patients with bilateral spondylolysis showed greater LL and SS than patients without spondylolysis. When analyzing the influence of L5-lysis, only elderly patients (≥70) with L5-lysis showed significantly greater LL and SS than nonspondylolysis (nonlysis) patients. L5-lysis patients more frequently showed L5 vertebral slip than nonlysis patients, and a smaller L5-S1 angle was observed when L5 vertebral slip accompanied L5-lysis. The degree of vertebral slip was significantly correlated with CSA of psoas muscles, but not with CSA of paraspinal extensor muscles.

CONCLUSIONS

When patients have L5-lysis, lumbar lordosis and pelvic anteversion occurred age dependently. In elderly patients with L5-lysis, L5 vertebral slip with decrease of the L5-S1 angle occurs frequently. The progression of vertebral slip was correlated with atrophy of psoas muscles, but not that of paraspinal extensor muscles.

Movement of the sacroiliac joint: Anatomy, systematic review, and biomechanical considerations

Several researchers investigated the anatomy and biomechanics of the sacroiliac joint (SIJ) to understand the relationship between lower back pain and the SIJ. Many studies concluded that the SIJ has little movement; however, some studies using spinopelvic parameters mentioned high change in pelvic incidence (PI). In this study, SIJ movement and PI change reported in previous studies were reviewed according to position and posture changes. Literature on SIJ movement was reviewed by searching through the publication databases. In biomechanical studies, the result of the rotational angle in the sagittal plane was mainly investigated to compare with the results of PI change. From the results of SIJ movement studies, the minimum movement of nutation and count-nutation was 0.01°, and maximum movement was 2.27°. From the results of PI change studies with different positions and movements, the highest change was 9°, and the lowest change was 0°. Movement of the SIJ was limited by its anatomical structure; maximum movement of the SIJ was 9° in a previous study. Therefore, SIJ movement should be studied more intensely as biomechanical perspective to understand its movement.

Technical variation of trans-articular sacroiliac joint (SIJ) fusion using three screws considering the effects of sacral dysplasia in patients with non-traumatic SIJ pain

Background

This study evaluated the technical adequacy of trans-articular sacroiliac joint (SIJ) fusion using three screws for non-traumatic SIJ pain, considering different grades of sacral dysplasia.

Methods

Cadaveric CT data of unilateral sacropelvic complexes for 72 individuals (53.4 ± 8.4 years) were selected. A 3D model was reformatted into the plain lateral radiograph to mark the articular surface of the SIJ. Subjects were classified into dysplastic (DYS) and non-dysplastic sacrum (NDS) groups. Proximal (PS), middle (MS), and distal screws (DS) with 10-mm diameter were virtually introduced to the iliac bone and the SIJ on the lateral image with a 5-mm safety margin. On a corresponding axial image, each screw was advanced vertically to the sagittal plane with the same safety margin. The entry points for each screw to the endplate of S1 (S2) and to the corresponding anterior sacral margin on the lateral image were measured, along with the maximal screw lengths on the axial image. Whether each screw passed through the SIJ was determined. Different types of sacral dysplasia and screws were compared statistically.

Results

Thirty-eight (26.4%) cases were DYS, and 106 (73.6%) were NDS. The entry points of all screws were significantly more distal in DYS than in NDS groups. The PS and MS screw lengths differed significantly between the 2 groups. Incidences of short sacral fixation (< 10 mm) were significantly higher for the DS in both NDS (38.7%) and DYS (39.5%) groups. Incidences of screw pass were lowest for the MS in both NDS (43.4%) and DYS (47.4%) groups.

Conclusions

Sacral dysplasia locates the SIJ more distally and therefore affects the entry point locations and screw lengths for all screws in trans-articular SIJ fusion, compared with a non-dysplastic sacrum. Moreover, three-screw fixation risks the development of unstable DS fixation and a high extra-articular fixation rate in MS.

Visualizing Tissue Strain Under the Sacrum and Coccyx in Different Supine Postures: A Case Series

OBJECTIVE

To visually assess and report the influence of supine positioning and sacrum and coccyx anatomy on tissue deformation.

METHODS

A convenience sample of three participants was scanned using MRI. All participants were scanned in a supine position with a rig oriented in a flat or horizontal position and with the torso portion of the rig elevated to 30° to simulate head-of-bed elevation. Representative images were identified to visualize and depict (1) the differences in tissue thickness and deformation in response to changes in supine positioning (0° and 30°), (2) the relative displacement of the skeleton relative to the skin during 30° incline, and (3) differences in sacrococcygeal morphology.

RESULTS

The tissue thickness under the sacrum stayed the same or increased when torsos were elevated. Skeletons were displaced relative to the skin when the rig was elevated regardless of the pelvis location. Further, in the elevated position, coccyges flexed when pelvises were placed on the elevated segment but did not flex when pelvises were placed on the horizontal segment.

CONCLUSIONS

This case series is useful in defining new areas of research that can (1) identify the deformation induced by normal and frictional forces resulting from different positions of the bed chassis, (2) assess the impact of positioning the pelvis on elevated versus horizontal segments of the bed chassis, and (3) define the association between sacral and coccyx morphology and pressure ulcer occurrence in hospitalized patients.

Characteristics of sagittal spinopelvic alignment in asymptomatic Han Chinese adults

The aim of the present study was to investigate patterns of spine sagittal alignment in asymptotic patients using radiological analysis. A number of studies focused on investigating normal patterns of spinal and pelvic alignment in Chinese populations, while few have evaluated Caucasian and other Asian populations. A total of 10 relevant pelvic and spinal parameters, including pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), cervical lordosis (CL), thoracic kyphosis (TK), sagittal vertical axis (SVA), lumbopelvic lordosis angle (PR-T12), spino-sacral angle (SSA) and sacral pelvic angle (SPA), were evaluated in asymptomatic Chinese adults from Beijing, aged 21–65 years. Correlations among these parameters, as well as between these parameters and age, and associations with gender and body mass index (BMI) were assessed using Pearson's correlation analysis. A total of 39 males and 46 females, aged 50.9±13.2 and 41.8±13.6 years, respectively, were enrolled in the present study. The results of PI, PT, SS, LL, TK, CL, SVA, PR-T12, SSA and SPA values suggested that age was positively correlated with TK, CL and SVA, while it was negatively correlated with LL, PR-T12 and SSA. SSA and SVA were revealed to differ significantly between sexes. It was also demonstrated that LL and TK may be associated with BMI. In conclusion, the results of the present study indicate that spinopelvic parameters in the asymptomatic Chinese Han population (in Beijing) are correlated with age and may be associated with individuals' ethnicity, sex and BMI. The results of the current study may provide a basis for the restoration of LL or similar diseases.