Sagittal balance measures are more reproducible when measured in 3D vs in 2D using full-body EOS® images

A novel portable and radiation-free method for assessing scoliosis: an accurate and reproducible study

BACKGROUND

This study aimed to evaluate the accuracy and reproducibility of a newly developed portable and radiation-free three-dimensional spine sensing system (3D-SSS) for scoliosis assessment.

METHODS

A total of 145 patients underwent full-spine imaging using the EOS imaging system, and 3D-SSS data were collected between February 2023 and April 2023. A radiologist used sterEOS software to reconstruct the spine in 3D and obtain the Cobb angle. One radiologist and one orthopedist independently measured the patients using 3D-SSS, with the orthopedist performing two measurements per patient. The 3D-SSS post-processing system automatically generated the Cobb angle.

RESULTS

The mean Cobb angles obtained from EOS and 3D-SSS were 13.7 ± 9.9° (0.5∽45.7°) and 12.5 ± 8.6° (0.4∽40°), respectively. The intraclass correlation coefficient (ICC) for reliability between EOS and 3D-SSS was 0.921, indicating excellent agreement. Bland-Altman analysis revealed a bias of -1.171° between EOS and 3D-SSS, with only 10 patients outside the limits of agreement (-8.3∽6.0°). The root mean square error between EOS and 3D-SSS was 3.2°. A strong correlation was observed between the Cobb angles measured by EOS and 3D-SSS (r = 0.931, P < 0.001). The receiver operating characteristics curve showed that the diagnostic performance of 3D-SSS for scoliosis was 0.953 (P < 0.001). The sensitivity, specificity, positive predictive value, and negative predictive value of 3D-SSS for diagnosing scoliosis were 87.8%, 92.1%, 93.5%, and 85.3%, respectively. The intraobserver and interobserver ICCs for Cobb angles derived from 3D-SSS were 0.969 and 0.934, respectively, demonstrating excellent reproducibility.

CONCLUSIONS

The portable and radiation-free 3D-SSS accurately measured scoliosis and provided highly reproducible data. This system offers a novel method for clinicians to screen and monitor scoliosis in young patients.

The Importance of Pelvic Obliquity in Assessing Spinal Coronal Alignment: Normative Values, Demographic, and Radiographic Correlations

STUDY DESIGN

Prospective, cross-sectional study.

OBJECTIVE

In a geographically diverse population of asymptomatic volunteers, we sought to report the incidence of pelvic obliquity (PO), establish normative values of PO across patient factors, and assess the correlation of PO with radiographic parameters.

SUMMARY OF BACKGROUND DATA

PO is defined as the misalignment of the pelvis and can be assessed through several anatomic landmarks. Significant PO, whether caused by leg-length discrepancy or not, can lead to coronal malalignment which causes severe pain and disability. Significant emphasis has been placed on achieving appropriate sagittal alignment in recent decades; however, a greater understanding of coronal alignment is needed, and PO is a crucial aspect of evaluating the coronal plane in adult spinal deformity patients.

METHODS

Asymptomatic adult volunteers, ages 18-80 years, enrolled patients from 5 countries (France, Japan, Singapore, Tunisia, and the United States) in the "multiethnic alignment normative study" cohort (IRB 201812144). The included volunteers had no known spinal disorder(s), no significant neck or back pain (Visual Analog Scale: ≤2; Oswestry Disability Index: ≤20), and no abnormal alignment (Cobb ≤20°). PO was measured in the frontal plane as the distance between the highest points of each acetabulum, calculated along the vertical axis in millimeters (mm). The incidence of PO was defined as PO ≥10 mm. Kruskal-Wallis, Wilcoxon rank-sum, Pearson correlation, and linear regression were used.

RESULTS

A total of 467 patients were included, and PO values by age, sex, body mass index, and country were provided. The overall incidence of PO ≥10 mm was 4.3%, and a nonsignificant trend toward increased PO with age was seen ( P = 0.077). No significant differences were seen in PO between sex, ethnicity, or body mass index groups. No significant correlation existed between PO and other commonly used coronal radiographic measurements.

CONCLUSION

PO ≥10 mm occurred in 4.3% of asymptomatic volunteers. Despite the importance of recognizing PO in preventing coronal malalignment, PO did not seem to be associated with other radiographic and demographic information, which underscores the importance of intentionally assessing for any PO before surgery. These results in an asymptomatic population provide a foundation for studying PO in patients with spinal pathology.

Inter-rater and Intra-rater Reliability of a Mobile App Method to Measure Lumbar Lordosis

Background Measuring the exact quantitative values of lordotic curves is a vital factor in clinical settings to prevent musculoskeletal deformities in the future. Existing lordotic assessment methods are very diverse, expensive, inaccurate, and not handy, and their availability cannot be maintained in every clinic setup. Aim The purpose of this research was to study the reliability of a mobile app as a feasible method to measure lumbar lordosis angle using a lateral view radiograph. Methodology A lateral view low back region radiograph of 58 participants was taken based on the criteria, and the experienced physiotherapists uploaded the X-ray to the mobile app and measured the lordotic angles with the support of machine learning algorithms. Descriptive statistics were used to calculate the average and dispersion of the data of the lumbar lordosis angle measured using the mobile app method (Statistical Package for the Social Sciences (IBM SPSS Statistics for Windows, IBM Corp., Version 23, Armonk, NY)). Results Associations between and within raters were assessed using the Karl Pearson coefficient of correlation (1.000). Inter-rater and intra-rater reliability were determined by using Cronbach's alpha (.966) and the split-half method. The internal consistency of the mobile app was found to be good. Conclusions Based on our findings, we conclude that the mobile app method is reliable and useful in measuring lumbar lordosis objectively with less effort. Since the app is handy on smartphones, physiotherapists can conduct an objective lumbar lordosis assessment in clinical settings.

Scoliosis Research Society-22r score is affected by standing whole body sagittal alignment, age, and sex, but not by standing balance or skeletal muscle mass in healthy volunteers

PURPOSE

Aging and spinal disease impair standing whole body sagittal alignment (WBS alignment), which leads to stooping. When WBS alignment deteriorates, compensatory mechanisms are activated to maintain standing posture. Increase of the compensation impairs health-related quality of life (HRQOL). The purpose of this research was to determine whether postural factors, age, and sex affect HRQOL.

METHODS

This cross-sectional study evaluated the influence of WBS alignment, standing body sway (balance), skeletal muscle mass (SMM), aging, and sex on HRQOL in healthy volunteers (n = 150; mean age 40.9 years [20-76], 96 women). Age, sex, weight, height, and body mass index (BMI) were obtained. HRQOL was assessed with Scoliosis Research Society-22 (SRS-22r). WBS alignment and balance were measured by EOS imaging with simultaneous force plate measurement. SMM was measured using a medical body composition analyzer. Based on the bivariate analysis between the SRS-22r subtotal and all parameters, selected ten parameters were used for multivariate logistic regression analysis to identify affecting factors to SRS-22r.

RESULTS

Men had significantly higher weight, height, BMI, and SRS-22r score in all domains. The L4-S1 lumbar lordosis angle was greater in men, and pelvic tilt and knee hyperextension were greater in women. Women had a more stable standing posture, whereas men had significantly higher SMM values. Multivariate logistic regression analysis revealed that age, sex, and TPA were identified as significant factors affecting SRS-22r.

CONCLUSIONS

In healthy volunteers, SRS-22r is affected by aging, sex (woman had a lower score), and sagittal malalignment. Neither Standing balance nor SMM, however, affect SRS-22r.4.

Influence of lumbosacral transitional vertebrae on spinopelvic parameters using biplanar slot scanning full body stereoradiography-analysis of 291 healthy volunteers

BACKGROUND

Proper identification of lumbosacral transitional vertebrae (LSTV) is important to characterize the relationship between the transitional segment and adjacent levels. Classical classification schemes are inaccurate with respect to the whole spine. We propose a precise vertebral numbering method and investigated the relationship between LSTV and whole-body sagittal alignment.

METHODS

A total of 291 healthy adult volunteers with no history of spinal disease were evaluated with biplanar slot scanning full body stereoradiography to determine the prevalence of LSTV. Vertebrae were counted from the first cervical vertebra using both coronal and sagittal plane images. We then investigated the influence of LSTV on whole-body sagittal alignment in 279 participants. Whole-body key parameters descriptive statistics were compared among groups according to the number of vertebrae (L4, L5, and L6). Statistical analysis was performed between normal and LSTV cases using the Steel-Dwass analysis.

RESULTS

Of the 291 subjects, 14 (4.8%) had 23 vertebrae and 16 (5.5%) had 25 vertebrae. Eleven (3.8%) had Th11, 3 (1.0%) had L4, and 1 (0.3%) had Th11 + L6, 16 (5.5%) had L6. Compared with the normal group, the sacral base in relation to the pelvis was higher in the L4 group and lower in the L6 group. The C2-C7 angle and lumbar lordosis (LL) were increased in both the L4 and L6 groups. All remaining parameters were decreased in the L4 group and increased in the L6 group. The relationship between LL and PI was similar in the normal and LSTV groups, despite the difference in the sacral base location.

CONCLUSIONS

We propose a precise method for numbering the vertebrae using coronal and sagittal full body images. The spinopelvic parameters of the LSTV population significantly differed from those in the normal spine population due to differences in the sacral base location.

Pelvic thickness, sex, ethnicity, and age affect pelvic incidence in healthy volunteers of Multi-Ethnic Alignment Normative Study (MEANS) database

BACKGROUND

The purpose of this study was to investigate the affecting factors on pelvic incidence (PI) and to test the hypothesis that PI changes even after skeletal maturity probably due to hypermobility of the sacroiliac joint using a large international multi-center database.

METHODS

A prospective and cross-sectional healthy adult volunteers, ages 18-80 years, across 5 countries were used. Radiographic measurements included standard whole body alignment parameters. Bivariate regression analyses between PI versus demographics and spino-pelvic anatomical parameters were performed. An effect of sex on pelvic anatomical parameters was also investigated. Multivariate logistic regression with a forward stepwise procedure was performed to identify the contributing factors to PI, and an appropriate model was obtained.

RESULTS

PI showed a significant positive correlation with age in pooled data. Divided by sex, however, there was no correlation in men, but women showed a significant higher correlation coefficient. Pelvic thickness (PTh) had a significant negative correlation with age in pooled data. Divided by sex, no correlation was found in men, but there was a significant correlation in women with higher correlation coefficient. The stepwise multivariate analysis for the factors on PI identified four significant factors: age, sex, ethnicity, and PTh.

CONCLUSIONS

PTh, sex, ethnicity, and age affected PI. There was a positive correlation between PI and age. The tendency was more significant in woman than in man. The results support the hypothesis that PI increases with aging, but the change seems to be small and needs to be verified in a longitudinal evaluation.

Cone of Economy with the Chain of Balance-Historical Perspective and Proof of Concept

A bipedal erect posture with a horizontal gaze is a distinctly human characteristic. The standing mechanism was described by Jean Felix Dubousset in the early 1970s as the "cone of economy," in which the axial skeleton is aligned in balance with the feet, lower limbs, and pelvis (pelvic vertebra) to the spinal segments, ending with the cranium (cephalic vertebra). All the components act in concert, allowing for adaptive motion in all directions on the horizontal plane. In a normal subject, the body maintains balance within a small "cone" using minimal muscle activity, and in a subject with pathologic lesions of the locomotor system, maintaining a standing posture requires a larger "cone" and greater muscle activity. Evidence from recent studies using the EOS imaging system, force plate measurements, surface electromyography, and full-body reflective markers with surface electromyography have gradually consolidated the "cone of economy" concept, a fundamental hypothetical theory of human locomotion.

Biplanar Low-Dose Radiograph Is Suitable for Cephalometric Analysis in Patients Requiring 3D Evaluation of the Whole Skeleton

BACKGROUND

The biplanar 2D/3D X-ray technology (BPXR) is a 2D/3D imaging system allowing simultaneous stereo-corresponding posteroanterior (PA) and lateral 2D views of the whole body. The aim of our study was to assess the feasibility of cephalometric analysis based on the BPXR lateral skull view to accurately characterize facial morphology.

METHOD

A total of 17 landmarks and 11 angles were placed and/or calculated on lateral BPXR and lateral cephalograms of 13 patients by three investigators. Five methods of angle identification were performed: the direct construction of straight lines on lateral cephalograms (LC-A) and on BPXR (BPXR-A), as well as the calculation of angles based on landmark identification on lateral cephalograms (LA-L) and on BPXR with the PA image (BPXR-LPA) or without (BPXR-L). Intra- and interoperator reliability of landmark identification and angle measurement of each method were calculated. To determine the most reliable method among the BPXR-based methods, their concordance with the reference method, LC-A, was evaluated.

RESULTS

Both imaging techniques had excellent intra- and interoperator reliability for landmark identification. On lateral BPXR, BPXR-A presented the best concordance with the reference method and a good intra- and interoperator reliability.

CONCLUSION

BPXR provides a lateral view of the skull suitable for cephalometric analysis with good reliability.

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.

The odontoid-CSVL distance in a global population of asymptomatic volunteers: normative values and implications for spinal coronal alignment

PURPOSE

In a population of asymptomatic volunteers across 5 countries, we sought to: (a) establish normative values of the Odontoid-Central Sacral Vertical Line (OD-CSVL) across patient factors, and (b) assess correlations of OD-CSVL with other radiographic parameters.

METHODS

A prospective, cross-sectional study of asymptomatic adult volunteers, ages 18-80 years, were enrolled across 5 countries (France, Japan, Singapore, Tunisia, United States) forming the Multi-Ethnic Alignment Normative Study (MEANS) cohort. Included volunteers had no known spinal disorder(s), no significant neck/back pain (VAS ≤ 2; ODI ≤ 20), and no significant scoliosis (Cobb ≤ 20°). Radiographic measurements included commonly used coronal alignment parameters (mm) and angles (°). OD-CSVL was defined as the difference between the odontoid plumb line (line from the tip of the odontoid vertically down) and the CSVL (vertical line from the center of the sacrum). Chi-square, student's t tests, Kruskal-Wallis, Wilcoxon rank-sum, linear regression, and Pearson's correlation were used with significance at p < 0.05.

RESULTS

467 volunteers were included with normative OD-CSVL values by age decade, gender, BMI, and country. Mean ± SD OD-CSVL was 8.3 mm ± 6.5 mm and 31 (6.6%) volunteers were almost perfectly aligned (OD-CSVL < 1 mm). A linear relationship was seen between OD-CSVL with both age (p < 0.001) and BMI (p = 0.015). Significant variation was seen between OD-CSVL and 5 different ethnicities (p = 0.004). OD-CSVL correlated best with other coronal radiographic parameters, C7-CSVL (r = 0.743, p < 0.001), OD-knee (r = 0.230, p < 0.001), CAM-knee (r = 0.612, p < 0.001), and regional TL cobb angle (r = 0.4214, p = 0.005).

CONCLUSION

Among asymptomatic volunteers, increased OD-CSVL was significantly associated with increased age, increased BMI, and ethnicity, but not gender. OD-CSVL correlated strongest with C7-CSVL, TL cobb angle, OD-knee, and CAM-knee. OD-CSVL. These results support further study of OD-CSVL in symptomatic adult spine deformity patients.

DESCRIPTION OF A NEW METHOD OF MEASURING THE PELVIC INCIDENCE ANGLE THROUGH COMPUTED TOMOGRAPHY

ABSTRACT Objective To describe a more accurate method for measuring the pelvic incidence angle using computed tomography, without the influence of the positioning of the pelvis in relation to the X-ray tube. Methods Thirteen CT scans of the lumbosacral region, abdomen or pelvis were randomly assessed, as all these exams include the sacrum and femoral heads. All the exams were performed in multichannel devices with six channels. The technique of overlapping images, already common in other musculoskeletal exams, such as TT-TG, was used. The centered sagittal cut of the left femoral head, the center of S1, and the right femoral head were used. From these, a fourth image was created, analogous to an X-ray of the pelvis, from which measurements were taken using the dedicated software. Results Of the thirteen exams, three were of the lumbar spine and 10 were of the total abdomen, six of them being of males.. The mean age was 56 years. The mean PI was 45°, ranging from 31 to 81 degrees. Among the women, the mean was 52° (31 to 81°) and among the men, 38° (32 to 46°). Conclusion CT can be used to calculate the PI, using the technique of overlapping images common to other musculoskeletal exams, such as TT-TG. Level of Evidence IIIB. Diagnostic study; Retrospective study.