The intrinsic shape of the human lumbar spine in the supine, standing and sitting postures: characterization using an active shape model

Comprehensive assessment of global spinal sagittal alignment and related normal spinal loads in a healthy population

Abnormal postoperative global sagittal alignment (GSA) is associated with an increased risk of mechanical complications after spinal surgery. Typical assessment of sagittal alignment relies on a few selected measures, disregarding global complexity and variability of the sagittal curvature. The normative range of spinal loads associated with GSA has not yet been considered in clinical evaluation. The study objectives were to develop a new GSA assessment method that holistically describes the inherent relationships within GSA and to estimate the related spinal loads. Vertebral endplates were annotated on radiographs of 85 non-pathological subjects. A Principal Component Analysis (PCA) was performed to derive a Statistical Shape Model (SSM). Associations between identified GSA variability modes and conventional alignment measures were assessed. Simulations of respective Shape Modes (SMs) were performed using an established musculoskeletal AnyBody model to estimate normal variation in cervico-thoraco-lumbar loads. The first six principal components explained 97.96% of GSA variance. The SSM provides the normative range of GSA and a visual representation of the main variability modes. Normal variation relative to the population mean in identified alignment features was found to influence spinal loads, e.g. the lower bound of the second shape mode (SM2-2σ) corresponds to an increase in L4L5-compression by 378.64 N (67.86%). Six unique alignment features were sufficient to describe GSA almost entirely, demonstrating the value of the proposed method for an objective and comprehensive analysis of GSA. The influence of these features on spinal loads provides a normative biomechanical reference, eventually guiding surgical planning of deformity correction in the future.

Lumbar Spine Anatomy in Supine versus Weight- Bearing Magnetic Resonance Imaging: Detecting Significant Positional Changes and Testing Reliability of Quantification

STUDY DESIGN

Testing between and within group differences and assessing reliability of measurements.

PURPOSE

To study and compare lumbar spine morphology in supine and weight-bearing (WB) magnetic resonance imaging (MRI).

OVERVIEW OF LITERATURE

Upright lumbar MRI may uncover anatomical changes that may escape detection when using conventional supine imaging. This study quantified anatomical dimensions of the lumbar spine in the supine and WB MRI, compared specific morphometric differences between them, and tested the intra-rater reliability of the measurements. Repeated measures analysis was used to compare within- and between-session measurements performed on the supine and WB images. Reliability and agreement were assessed by calculating intraclass correlation (ICC) coefficient.

METHODS

Data from 12 adults without any history of back pain were used in this study. Sagittal T2-weighted images of the lumbar spine were acquired in the supine and WB positions twice (in two separate sessions scheduled within a week). Linear, angular dimensions, and cross-sectional areas (CSAs) were measured using proprietary software. Supine and WB data acquired from the two imaging sessions were tested for intra-rater reliability. Quantified data were normalized for each session to test the significance of differences. ICC was calculated to test the reliability of the measurements.

RESULTS

Linear, angular, and CSA measurements demonstrated strong within-position (supine and WB) correlations (r -values, 0.75-0.97). Between-position (supine vs. WB) differences were significant for all measured dimensions (p<0.05). Between-session measurements demonstrated a strong correlation (r -values, 0.64-0.83). Calculated ICC showed strong agreement among the measurements.

CONCLUSIONS

Anatomical dimensions of the lumbar spine may demonstrate consistent and significant differences between supine and WB MRI for specific structural parameters.

Load-Bearing Shifts in Laminar and Ligament Morphology: Comparing Spinal Canal Dimensions Using Supine versus Upright Lumbar MRI in Adults without Back Pain

Purpose  The effects of weight bearing on lumbar spinal canal dimensions are not well reported the low back pain (LBP) literature. Since axial loading induces changes in anatomical configuration of the lumbar spine, supine spine imaging may not uncover dimensional changes associated with physiological weight bearing that could be demonstrated in imaging in the upright position. Methods  This study compared anteroposterior spinal canal dimensions measured at the level of the intervertebral discs in the supine and upright lumbar spine magnetic resonance images in adults without a history or current back pain. Additionally, interlaminar distances were measured between the centers of adjacent laminae involving a spinal segment. These parameters were utilized to ascertain the deformation incurred at the ligamentum flavum due to load bearing. Results  Within and between-sessions t -tests, factorial and repeated-measures analysis of variance showed significant alterations in canal dimensions at certain levels, secondary to the upright positioning of the spine. Measurement reliability assessed between sessions and scanning positions using intraclass correlation coefficients demonstrated strong agreement. Conclusion  Imaging studies involving physiological weight bearing may be useful to understand the potential etiological effects of such changes in mechanical LBP.

Morphable models of the lumbar spine to vary geometry based on pathology, demographics, and anatomical measurements

The shape of the lumbar spine influences its function and dysfunction. Yet examining the influence of geometric differences associated with pathology or demographics on lumbar biomechanics is challenging in vivo where these effects cannot be isolated, and the use of simple anatomical measurements does not fully capture the complex three-dimensional geometry. The goal of this work was to develop and share morphable models of the lumbar spine that allow geometry to be varied according to pathology, demographics, or anatomical measurements. Partial least squares regression was used to generate statistical shape models that quantify geometric differences associated with pathology, demographics, and anatomical measurements from the lumbar spines of 87 patients. To determine if the morphable models detected meaningful geometric differences, the ability of the morphable models to classify spines was compared with models generated from random labels. The models for disc herniation (p < 0.04), spondylolisthesis (p < 0.001), and sex (p < 0.01) all performed significantly better than the random models. Age was predicted with a root mean square error of 14.1 years using the age-based model. The morphable models for anatomical measurements were able to produce instances with root mean square errors less than 0.8°, 0.3 cm², and 0.7 mm between desired and resulting measurements. This method can be used to produce morphable models that enable further analysis of the relationship among shape, pathology, demographics, and function through computational simulations. The morphable models and code are available at https://github.com/aclouthier/morphable-lumbar-model.

Using Statistical Shape and Appearance Modelling to characterise the 3D shape and material properties of human lumbar vertebrae: A proof of concept study

Patient variation affects the outcomes of a range of spinal interventions, from disc replacement to vertebral fixation and vertebroplasty. Statistical Shape and Appearance Modelling (SSAM) can be used to describe anatomical variation and pathological differences within the population. To better understand how bone density and shape variation affect load transfer with respect to surgical treatments, Finite Element (FE) models can be generated from a SSAM. The aim for this study is to understand whether geometric and density variation as well as multiple vertebral levels can be incorporated into a single SSAM and whether this can be used to investigate the relationships between, and effects of, the various modes of variation. FE models of 14 human lumbar vertebrae that had been μCT imaged and validated through experimental testing were used as input specimens for a SSAM. The validity of the SSAM was evaluated by using principal component analysis to identify the primary modes of geometric and bone density variation and comparing to those in the input set. FE models were generated from the SSAM to examine the response to loading. The mean error between the input set and generated models for volume, mean density and FE compressive stiffness were 10%, 3% and 10% respectively. Principal Component (PC) 1 captured the majority of the bone density variation. The remaining PCs described specific geometric variation. The FE models generated from the SSAM showed the variations in vertebral stiffness as a result of complex relationships between bone density and shape. The SSAM created has limited data for its input set, however, it acts as a proof of concept for the novel combination of material and shape variation into a single shape model. This approach and the tools developed can be applied to wider patient groups and treatment scenarios to improve patient stratification and to optimise treatments.

A statistical lumbar spine geometry model accounting for variations by Age, Sex, Stature, and body mass index

The objective of this study was to develop a statistical lumbar spine geometry model accounting for morphological variations among the adult population. Five lumber vertebrae and lumber spine curvature were collected from CT scans of 82 adult subjects through CT segmentation, landmark identification, and template mesh mapping. Generalized Procrustes Analysis (GPA), Principal Component Analysis (PCA), and multivariate regression analysis were conducted to develop the statistical lumbar spine model. Two statistical models were established to predict the vertebrae geometry and lumbar curvature respectively. Using the statistical models, a lumbar spine finite element (FE) model could be rapidly generated with a given set of age, sex, stature, and body mass index (BMI). The results showed that the lumbar spine vertebral size was significantly affected by stature, sex and age, and the lumbar spine curvature was significantly affected by stature and age. This statistical lumbar spine model could serve as the geometric basis for quantifying effects of human characteristics on lumbar spine injury risks in impact conditions.

Load Distribution in the Lumbar Spine During Modeled Compression Depends on Lordosis

Excessive or incorrect loading of lumbar spinal structures is commonly assumed as one of the factors to accelerate degenerative processes, which may lead to lower back pain. Accordingly, the mechanics of the spine under medical conditions, such as scoliosis or spondylolisthesis, is well-investigated. Treatments via both conventional therapy and surgical methods alike aim at restoring a "healthy" (or at least pain-free) load distribution. Yet, surprisingly little is known about the inter-subject variability of load bearings within a "healthy" lumbar spine. Hence, we utilized computer tomography data from 28 trauma-room patients, whose lumbar spines showed no visible sign of degeneration, to construct simplified multi-body simulation models. The subject-specific geometries, measured by the corresponding lumbar lordosis (LL) between the endplates of vertebra L1 and the sacrum, served as ceteris paribus condition in a standardized forward dynamic compression procedure. Further, the influence of stimulating muscles from the M. multifidus group was assessed. For the range of available LL from 28 to 66°, changes in compressive and shear forces, bending moments, as well as facet joint forces between adjacent vertebrae were calculated. While compressive forces tended to decrease with increasing LL, facet forces were tendentiously increasing. Shear forces decreased between more cranial vertebrae and increased between more caudal ones, while bending moments remained constant. Our results suggest that there exist significant, LL-dependent variations in the loading of "healthy" spinal structures, which should be considered when striving for individually appropriate therapeutic measures.

A comparison of Cartesian-only vs. Cartesian-spherical hybrid coordinates for statistical shape modeling in the lumbar spine

OBJECTIVE

The purpose of this study was to compare two methods for quantifying differences in geometric shapes of human lumbar vertebra using statistical shape modeling (SSM).

METHODS

A novel 3D implementation of a previously published 2D, nonlinear SSM was implemented and compared to a commonly used, Cartesian method of SSM. The nonlinear method, or Hybrid SSM, and Cartesian SSM were applied to lumbar vertebra shapes from a cohort of 18 full lumbar triangle meshes derived from CT scans. The comparison included traditional metrics for cumulative variance, generality, and specificity and results from application-based biomechanics using finite element simulation.

RESULTS

The Hybrid SSM has less compactness - likely due to the increased number of mathematical constraints in the SSM formulation. Similar results were found between methods for specificity and generality. Compared to the previously validated, manually-segmented FE model, both SSM methods produced similar and agreeable results.

CONCLUSION

Visual, statistical, and biomechanical findings did not convincingly support the superiority of the Hybrid SSM over the simpler Cartesian SSM.

SIGNIFICANCE

This work suggests that, of the two methods compared, the Cartesian SSM is adequate to capture the variations in shape of the posterior spinal structures for biomechanical modeling applications.

Preliminary investigation of spinal level and postural effects on thoracic muscle morphology with upright open MRI

OBJECTIVE

Spinal-muscle morphological differences between weight-bearing and supine postures have potential diagnostic, prognostic, and therapeutic applications. While the focus to date has been on cervical and lumbar regions, recent findings have associated spinal deformity with smaller paraspinal musculature in the thoracic region. We aim to quantitatively investigate the morphology of trapezius (TZ), erector spinae (ES) and transversospinalis (TS) muscles in upright postures with open upright MRI and also determine the effect of level and posture on the morphological measures.

METHODS

Six healthy volunteers (age 26 ± 6 years) were imaged (0.5 T MROpen, Paramed, Genoa, Italy) in four postures (supine, standing, standing with 30° flexion, and sitting). Two regions of the thorax, middle (T4-T5), and lower (T8-T9), were scanned separately for each posture. 2D muscle parameters such as cross-sectional area (CSA) and position (radius and angle) with respect to the vertebral body centroid were measured for the three muscles. Effect of spinal level and posture on muscle parameters was examined using 2-way repeated measures ANOVA separately for T4-T5 and T8-T9 regions.

RESULTS

The TZ CSA was smaller (40%, P = .0027) at T9 than at T8. The ES CSA was larger at T5 than at T4 (12%, P = .0048) and at T9 than at T8 (10%, P = .0018). TS CSA showed opposite trends at the two spinal regions with it being smaller (16%, P = .0047) at T5 than at T4 and larger (11%, P = .0009) at T9 than at T8. At T4-T5, the TZ CSA increased (up to 23%), and the ES and TS CSA decreased (up to 10%) in upright postures compared to supine.

CONCLUSION

Geometrical parameters that describe muscle morphology in the thorax change with level and posture. The increase in TZ CSA in upright postures could result from greater activation while upright. The decrease in ES CSA in flexed positions likely represents passive stretching compared to neutral posture.

Motor development in infancy and spine shape in early old age: Findings from a British birth cohort study

Spine shape changes dramatically in early life, influenced by attainment of developmental milestones such as independent walking. Whether these associations persist across life is unknown. Therefore, we investigated associations between developmental milestones and spine shape, as determined using statistical shape models (SSMs) of lumbar spine from dual-energy X-ray absorptiometry scans in 1327 individuals (688 female) at 60 to 64 years in the MRC National Survey of Health and Development. Lumbar lordosis angle (L4 inferior endplate to T12 superior endplate) was measured using the two-line Cobb method. In analyses adjusted for sex, height, lean and fat mass, socioeconomic position, and birthweight, later walking age was associated with greater lordosis described by SSM1 (regression coefficient, 0.023; 95% CI, 0.000-0.047; P = .05) and direct angle measurement. Modest associations between walking age and less variation in anterior-posterior vertebral size caudally (SSM6) were also observed (0.021; 95% CI, -0.002 to 0.044; P = .07). Sex interactions showed that later walking was associated with larger relative vertebral anterior-posterior dimensions in men (SSM3; -0.043; 95% CI, -0.075 to 0.01; P = .01) but not women (0.018; 95% CI, -0.0007 to 0.043; P = .17). Similar associations were observed between age at independent standing and SSMs but there was little evidence of association between sitting age and spine shape. Unadjusted associations between walking age and SSMs 1 and 6 remained similar after adjustment for potential confounders and mediators. This suggests that these associations may be explained by altered mechanical loading of the spine during childhood growth, although other factors could contribute. Early life motor development, particularly walking, may have a lasting effect on the features of spine morphology with clinical significance.

Restoring lumbar lordosis: a systematic review of controlled trials utilizing Chiropractic Bio Physics® (CBP®) non-surgical approach to increasing lumbar lordosis in the treatment of low back disorders

[Purpose] To systematically review controlled trial evidence for the use of lumbar extension traction by Chiropractic BioPhysics^® methods for the purpose of increasing lumbar lordosis in those with hypolordosis and low back disorders. [Methods] Literature searches were performed in Pubmed, PEDro, CINAHL, Cochrane, and ICL databases. Search terms included iterations related to the lumbar spine, low back pain and extension traction rehabilitation. [Results] Four articles detailing 2 randomized and 1 non-randomized trial were located. Trials demonstrated increases in radiographic measured lordosis of 7–11°, over 10–12 weeks, after 30–36 treatment sessions. Randomized trials demonstrated traction treated groups mostly maintained lordosis correction, pain relief, and disability after 6-months follow-up. The non-randomized trial showed lordosis and pain intensity were maintained with periodic maintenance care for 1.5 years. Importantly, control/comparison groups had no increase in lumbar lordosis. Randomized trials showed comparison groups receiving physiotherapy-less the traction, had temporary pain reduction during treatment that regressed towards baseline levels as early as 3-months after treatment. [Conclusion] Limited but good quality evidence substantiates that the use of extension traction methods in rehabilitation programs definitively increases lumbar hypolordosis. Preliminarily, these studies indicate these methods provide longer-term relief to patients with low back disorders versus conventional rehabilitation approaches tested.

Is intrinsic lumbar spine shape associated with lumbar disc degeneration? An exploratory study

Background

Lumbar disc degeneration (LDD) is a condition associated with recurrent low back pain (LBP). Knowledge regarding effective management is limited. As a step towards the identification of risk, prognostic or potentially modifiable factors in LDD patients, the aim of this study was to explore the hypothesis that intrinsic lumbar spine shape is associated with LDD and clinical outcomes in symptomatic adults.

Methods

3 T MRI was used to acquire T2-weighted sagittal images (L1-S1) from 70 healthy controls and LDD patients (mean age 49 years, SD 11, range 31–71 years). Statistical Shape Modelling (SSM) was used to describe lumbar spine shape. SSM identified variations in lumbar shape as ‘modes’ of variation and quantified deviation from the mean. Intrinsic shape differences were determined between LDD groups using analysis of variance with post-hoc comparisons. The relationship between intrinsic shape and self-reported function, mental health and quality of life were also examined.

Results

The first 7 modes of variation explained 91% of variance in lumbar shape. Higher LDD sum scores correlated with a larger lumbar lordosis (Mode 1 (55% variance), P = 0.02), even lumbar curve distribution (Mode 2 (12% variance), P = 0.05), larger anterior-posterior (A-P) vertebral diameter (Mode 3 (10% variance), P = 0.007) and smaller L4-S1 disc spaces (Mode 7 (2% variance), P ≤ 0.001). In the presence of recurrent LBP, LDD was associated with a larger A-P vertebral diameter (Mode 3) and a more even lumbar curvature with smaller L5/S1 disc spaces (Mode 4), which was significantly associated with patient quality of life (P = 0.002–0.04, r_p = 0.43–0.61)).

Conclusions

This exploratory study provides new evidence that intrinsic shape phenotypes are associated with LDD and quality of life in patients. Longitudinal studies are required to establish the potential role of these risk or prognostic shape phenotypes.

Introduction and evaluation of a novel multi-camera surface topography system

BACKGROUND

Surface topography can be used for the evaluation of spinal deformities without any radiation. However, so far this technique is limited to posterior trunk measurements due to the use of a single posterior camera.

RESEARCH QUESTION

Purpose of this study was to introduce a new multi camera surface topography system and to test its reliability and validity.

METHODS

The surface topograph uses a two-camera system for imaging and evaluating the subjects front and back simultaneously. Inter- and intra-rater reliability was tested on 40 human subjects by two observers. For validation human, subjects were scanned by MRI and surface-topography. For additional validation we used a phantom with an anthropomorphic body which was scanned by CT and surface topography.

RESULTS

Inter- (0.97-0.99) and intra-rater reliability (0.81-0.98) testing revealed good and excellent results in the detection of the body surface structures and measurement of areas and volumes. CT based validation revealed good correspondence between systems in the imaging and evaluation of the phantom model (0.61-10.52 %). Results on validation of human subjects revealed good to moderate results in the detection and measurements of almost all body surface structures (1.36-13.34 %). Only measurements using jugular notch as a reference showed moderate results in validity (0.62-27.5%) testing.

SIGNIFICANCE

We have introduced a novel and innovative surface topography system that allows for simultaneous anterior and posterior trunk measurements. The results of our reliability and validity tests are satisfactory. However, in particular around the jugular notch region further improvements in the surface topography reconstruction are needed.

Assessment of Lumbar Lordosis Distribution with a Novel Mathematical Approach and Its Adaptation for Lumbar Intervertebral Disc Degeneration

Introduction

Low back pain and disc degeneration could be linked to global spinal geometry. Our study aimed to develop a reliable new mathematical method to assess the local distribution of total lumbar lordosis with a single numeric parameter and compare it with lumbar intervertebral disc degeneration using routine MRI scans.

Methods

An online, open access, easy-to-use platform for measurements was developed based on a novel mathematical approach using MRIs of 60 patients. Our Spinalyze Software can be used online with uploaded MRIs. Several new parameters were introduced and assessed to describe variation in segmental lordosis distribution with a single numerical value. The Pfirrmann grading system was used for the classification of lumbar intervertebral disc degeneration. Relationships were investigated between the grade categories of L1-S1 lumbar discs and the MRI morphological parameters with correlation analysis.

Results

Results confirm that the determination of measurement points and calculated parameters are reliable (ICCs and Pearson r values > 0.90), and these parameters were independent of gender. The digression percentage (K%), one of our new parameters, did not show a statistical relationship with the Cobb-angle. According to our results, the maximum deflection breaking-point of lumbar lordosis and its location can be different with the same Cobb-angle and the distribution of global lordosis is uneven because the shape of the lumbar lordosis is shifted downward and centered around the L4 lumbar vertebra. The interobserver reliability of the Pfirrmann grades reading was in the excellent agreement category (88.33% agreement percentage, 0.84 kappa), and digression percentage (K%) showed a significant negative correlation with all L1-S1 disc grades with increasing r correlation values. This means that the smaller the value of digression percentage (K%), the more the number of worn discs in the lower lumbar sections.

Conclusions

Spinalyze Software based on a novel mathematical approach provides a free, easy-to-use, reliable, and online measurement tool using standard MRIs to approximate the curvature of lumbar lordosis. The new reliable K% (digression percentage) is one single quantitative parameter to assess the local distribution of total lumbar lordosis. The results indicate that digression percentage (K%) may possibly be associated with the development of lumbar intervertebral disc degeneration. Further evaluation is needed to assess its behavior and advantage.

Development of Pelvic Incidence and Lumbar Lordosis in Children and Adolescents

Pelvic incidence (PI) is a measure of the sagittal orientation of the sacrum relative to the acetabula and is not dependent on posture. In asymptomatic adults, PI correlates with lumbar lordosis. Lumbar lordosis is shown to increase with age following the onset of unassisted bipedal locomotion in children, but to what extent PI changes in relation to lumbar lordosis during skeletal maturation is unclear. The purpose of this study is to understand how PI, lumbar lordosis, and age are related in children and adolescents. PI, supine lumbar lordosis (SLL), and individual wedging angles of the lumbar vertebral bodies were measured on mid-sagittal reformatted images from 144 abdominal computed tomographic scans of individuals aged 2-20 years old, divided into three separate age categories representing pre-growth spurt (ages 2-9), growth spurt (10-15), and post-growth spurt (16-20). Our results showed that, while SLL significantly increased with age during development, PI did not. Despite the fact that PI hardly changed with age, the difference between PI and SLL decreased nonlinearly with age. SLL did not correlate with PI in the youngest age category, but positively correlated with PI in the middle and oldest age categories. The relationship between lumbar lordosis and PI, which is correlated in adults, was significant in our older age categories and not in our youngest age category. Our results indicate that PI in children and adolescents may have some predictive value for adult lumbar lordosis. Anat Rec, 302:2132-2139, 2019. © 2019 American Association for Anatomy.

Perinatal factors associate with vertebral size and shape but not lumbar lordosis in 10-year-old children

The intrauterine environment is known to influence foetal development and future health. Low birthweight has been linked to smaller vertebral canals in children and decreased adulthood spine bone mineral content. Perinatal factors affecting lumbar spine curvature have not yet been considered but could be important for adult spinal health, as lumbar movement during lifting, a risk factor for backpain, is associated with lordosis. To investigate this, lumbar spine magnetic resonance images at age 10 years and perinatal and maternal data (birthweight, placental weight, gestation length, crown-heel length, maternal age, height, weight and smoking status) from 161 children born in Aberdeen in 1988-1989 were acquired. Statistical shape modelling, using principal component analysis, quantified variations in lumbar spine shape and resulting modes of variation were assessed in combination with perinatal data using correlations and analyses of covariance, adjusted for potential confounders. Spine modes 1-3 (SM1-SM3) captured 75% of the variation in lumbar spine shape. The first and third modes described the total amount (SM1) and evenness of curvature distribution (SM3). SM2 accounted for variations in antero-posterior vertebral diameter relative to vertebral height, increasing positive scores representing a larger relative diameter. Adjusting for gestation length and sex, SM2 positively correlated with birthweight (r = 0.25, P < 0.01), placental weight (r = 0.20, P = 0.04), crown-heel length (r = 0.36, P < 0.001) and maternal weight (r = 0.19, P = 0.04), and negatively with maternal age (r = -0.22, P = 0.02). SM2 scores were lower in girls (P < 0.001) and in the low birthweight group (P = 0.02). There were no significant differences in SM1 and SM3 scores between birthweight groups, boys and girls or children of smokers (31%) and non-smokers (69%). In conclusion, some perinatal factors were associated with vertebral body morphology but had little effect on lumbar curvature.

Assessment of In Vivo Lumbar Inter-Vertebral Motion: Reliability of a Novel Dynamic Weight-Bearing Magnetic Resonance Imaging Technique Using a Side-Bending Task

Study Design

Between-session reliability of a magnetic resonance imaging (MRI) based experimental technique to quantify lumbar inter-vertebral motion in humans.

Purpose

We have developed a novel, dynamic, MRI-based approach for quantifying in vivo lumbar inter-vertebral motion. In this study, we present the protocol’s reliability results to quantify inter-vertebral spine motion.

Overview of Literature

Morphometric studies on intervertebral displacements using static, supine MRI and quantification of dynamic spine motion using different X-ray based radiography techniques are commonly found in the literature. However, reliability testing of techniques assessing real-time lumbar intervertebral motion using weight-bearing MRI has rarely been reported.

Methods

Ten adults without a history of back pain performed a side-bending task on two separate occasions, inside an open-MRI, in a weight-bearing, upright position. The images were acquired during the task using a dynamic magnetic resonance (MR) sequence. The MRI imaging space was externally calibrated before the study to recreate the imaging volume for subsequent use in an animation software. The dynamic MR images were processed to create side-bending movement animations in the virtual environment. Participant-specific three-dimensional models were manually superimposed over vertebral image silhouettes in a sequence of image frames, representing the motion trials. Inter-vertebral axes and translation and rotational displacements of vertebrae were quantified using the animation software.

Results

Quantification of inter-vertebral rotations and translations shows high reliability. Between-session reliability results yielded high values for the intra-class correlation coefficient (0.86–0.93), coefficient of variation (13.3%–16.04%), and Pearson’s correlation coefficients (0.89–0.98).

Conclusions

This technique may be developed further to improve its speed and accuracy for diagnostic applications, to study in vivo spine stability, and to assess outcomes of surgical and non-surgical interventions applied to manage pathological spine motion.

Increasing the cervical and lumbar lordosis is possible despite overt osteoarthritis and spinal stenosis using extension traction to relieve low back and leg pain in a 66-year-old surgical candidate: a CBP® case report

[Purpose] To present the case of the dramatic relief of low back pain, leg pain and disability in an older female with osteoarthritis, lumbar spinal stenosis and hypolordosis of the cervical and lumbar spine. [Participant and Methods] A 66-year-old female presented with chronic low back pain, right leg pain, numbness and weakness. Despite being recommended for surgery, the patient sought alternative treatment. The patient was treated with Chiropractic BioPhysics^® rehabilitation of the spine with the objective to increase the lumbar and cervical lordoses. Cervical and lumbar extension exercises and traction were performed as well as spinal manipulation. Treatment was performed approximately three times per week for 6.5 months. [Results] Re-assessment after treatment demonstrated significant reduction of low back pain, leg pain and other health improvements. X-rays showed structural improvements in the cervical and lumbar spine despite advanced osteoarthritis. [Conclusion] Lumbar and cervical hypolordosis subluxation may be increased in those with spinal deformity caused symptoms, despite the presence of osteoarthritis and degenerative stenosis of the spine. Spinal x-rays as used in the assessment and monitoring of patients being treated with contemporary spinal rehabilitation methods are not harmful and should be used for routine screening purposes.

Associations between back pain across adulthood and spine shape in early old age in a British birth cohort

We aimed to examine whether back pain across adulthood was associated with spine shape at age 60–64 years. Data were from 1405 participants in the MRC National Survey of Health and Development, a nationally representative British birth cohort. Back pain was ascertained during nurse interviews at ages 36, 43, 53 and 60–64 years. Cumulative exposure to back pain was then derived by counting the number of ages at which back pain was reported. Statistical shape modelling was used to characterise thoracolumbar spine shape using lateral dual-energy x-ray absorptiometry images which were ascertained at age 60–64 years. Linear regression models were used to test associations of spine shape modes (SM) with: (1) cumulative exposure to back pain; (2) back pain reports during different periods of adulthood. After adjusting for sex, higher cumulative exposure to back pain across adulthood was associated with wedge-shaped L4-5 disc (lower SM4 scores) and smaller disc spaces (higher SM8 scores) in both sexes. In addition, reporting of back pain at ages 53 and/or 60–64 years was associated with smaller L4-5 disc space (lower SM6 scores) in men but not women. These findings suggest that back pain across adulthood may be associated with specific variations in spine shapes in early old age.

Variation in lifting kinematics related to individual intrinsic lumbar curvature: an investigation in healthy adults

Objective

Lifting postures are frequently implicated in back pain. We previously related responses to a static load with intrinsic spine shape, and here we investigate the role of lumbar spine shape in lifting kinematics.

Methods

Thirty healthy adults (18-65 years) performed freestyle, stoop and squat lifts with a weighted box (6-15 kg, self-selected) while being recorded by Vicon motion capture. Internal spine shape was characterised using statistical shape modelling (SSM) from standing mid-sagittal MRIs. Associations were investigated between spine shapes quantified by SSM and peak flexion angles.

Results

Two SSM modes described variations in overall lumbar curvature (mode 1 (M1), 55% variance) and the evenness of curvature distribution (mode 2 (M2), 12% variance). M1 was associated with greater peak pelvis (r=0.38, p=0.04) and smaller knee flexion (r=-0.40, p=0.03) angles; individuals with greater curviness preferred to lift with a stooped lifting posture. This was confirmed by analysis of those individuals with very curvy or very straight spines (|M1|>1 SD). There were no associations between peak flexion angles and mode scores in stoop or squat trials (p>0.05). Peak flexion angles were positively correlated between freestyle and squat trials but not between freestyle and stoop or squat and stoop, indicating that individuals adjusted knee flexion while maintaining their preferred range of lumbar flexion and that 'squatters' adapted better to different techniques than 'stoopers'.

Conclusion

Spinal curvature affects preferred lifting styles, and individuals with curvier spines adapt more easily to different lifting techniques. Lifting tasks may need to be tailored to an individual's lumbar spine shape.

Body mass index and waist circumference in early adulthood are associated with thoracolumbar spine shape at age 60-64: The Medical Research Council National Survey of Health and Development

This study investigated associations between measures of adiposity from age 36 and spine shape at 60-64 years. Thoracolumbar spine shape was characterised using statistical shape modelling on lateral dual-energy x-ray absorptiometry images of the spine from 1529 participants of the MRC National Survey of Health and Development, acquired at age 60-64. Associations of spine shape modes with: 1) contemporaneous measures of total and central adiposity (body mass index (BMI), waist circumference (WC)) and body composition (android:gynoid fat mass ratio and lean and fat mass indices, calculated as whole body (excluding the head) lean or fat mass (kg) divided by height2 (m)2); 2) changes in total and central adiposity between age 36 and 60-64 and 3) age at onset of overweight, were tested using linear regression models. Four modes described 79% of the total variance in spine shape. In men, greater lean mass index was associated with a larger lordosis whereas greater fat mass index was associated with straighter spines. Greater current BMI was associated with a more uneven curvature in men and with larger anterior-posterior (a-p) vertebral diameters in both sexes. Greater WC and fat mass index were also associated with a-p diameter in both sexes. There was no clear evidence that gains in BMI and WC during earlier stages of adulthood were associated with spine shape but younger onset of overweight was associated with a more uneven spine and greater a-p diameter. In conclusion, sagittal spine shapes had different associations with total and central adiposity; earlier onset of overweight and prior measures of WC were particularly important.

Radiophobia: 7 Reasons Why Radiography Used in Spine and Posture Rehabilitation Should Not Be Feared or Avoided

Evidence-based contemporary spinal rehabilitation often requires radiography. Use of radiography (X-rays or computed tomography scans) should not be feared, avoided, or have their exposures lessened to decrease patient dose possibly jeopardizing image quality. This is because all fears of radiation exposures from medical diagnostic imaging are based on complete fabrication of health risks based on an outdated, invalid linear model that has simply been propagated for decades. We present 7 main arguments for continued use of radiography for routine use in spinal rehabilitation: (1) the linear no-threshold model for radiation risk estimates is invalid for low-dose exposures; (2) low-dose radiation enhances health via the body's adaptive response mechanisms (ie, radiation hormesis); (3) an X-ray with low-dose radiation only induces 1 one-millionth the amount of cellular damage as compared to breathing air for a day; (4) radiography is below inescapable natural annual background radiation levels; (5) radiophobia stems from unwarranted fears and false beliefs; (6) radiography use leads to better patient outcomes; (7) the risk to benefit ratio is always beneficial for routine radiography. Radiography is a safe imaging method for routine use in patient assessment, screening, diagnosis, and biomechanical analysis and for monitoring treatment progress in daily clinical practice.

Statistical shape modelling of hip and lumbar spine morphology and their relationship in the MRC National Survey of Health and Development

The anatomical shape of bones and joints is important for their proper function but quantifying this, and detecting pathological variations, is difficult to do. Numerical descriptions would also enable correlations between joint shapes to be explored. Statistical shape modelling (SSM) is a method of image analysis employing pattern recognition statistics to describe and quantify such shapes from images; it uses principal components analysis to generate modes of variation describing each image in terms of a set of numerical scores after removing global size variation. We used SSM to quantify the shapes of the hip and the lumbar spine in dual-energy x-ray absorptiometry (DXA) images from 1511 individuals in the MRC National Survey of Health and Development at ages 60-64 years. We compared shapes of both joints in men and women and hypothesised that hip and spine shape would be strongly correlated. We also investigated associations with height, weight, body mass index (BMI) and local (hip or lumber spine) bone mineral density. In the hip, all except one of the first 10 modes differed between men and women. Men had a wider femoral neck, smaller neck-shaft angle, increased presence of osteophytes and a loss of the femoral head/neck curvature compared with women. Women presented with a flattening of the femoral head and greater acetabular coverage of the femoral head. Greater weight was associated with a shorter, wider femoral neck and larger greater and lesser trochanters. Taller height was accompanied by a flattening of the curve between superior head and neck and a larger lesser trochanter. Four of the first eight modes describing lumbar spine shape differed between men and women. Women tended to have a more lordotic spine than men with relatively smaller but caudally increasing anterior-posterior (a-p) vertebral diameters. Men were more likely to have a straighter spine with larger vertebral a-p diameters relative to vertebral height than women, increasing cranially. A weak correlation was found between body weight and a-p vertebral diameter. No correlations were found between shape modes and height in men, whereas in women there was a weak positive correlation between height and evenness of spinal curvature. Linear relationships between hip and spine shapes were weak and inconsistent in both sexes, thereby offering little support for our hypothesis. In conclusion, men and women entering their seventh decade have small but statistically significant differences in the shapes of their hips and their spines. Associations with height, weight, BMI and BMD are small and correspond to subtle variations whose anatomical significance is not yet clear. Correlations between hip and spine shapes are small.

Effects of spine loading in a patient with post-decompression lumbar disc herniation: observations using an open weight-bearing MRI

PURPOSE

Our objective was to use an open weight-bearing MRI to identify the effects of different loading conditions on the inter-vertebral anatomy of the lumbar spine in a post-discectomy recurrent lumbar disc herniation patient.

METHODS

A 43-year-old male with a left-sided L5-S1 post-decompression re-herniation underwent MR imaging in three spine-loading conditions: (1) supine, (2) weight-bearing on standing (WB), and (3) WB with 10 % of body mass axial loading (WB + AL) (5 % through each shoulder). A segmentation-based proprietary software was used to calculate and compare linear dimensions, angles and cross sections across the lumbar spine.

RESULTS

The L5 vertebrae showed a 4.6 mm posterior shift at L5-S1 in the supine position that changed to an anterior translation >2.0 mm on WB. The spinal canal sagittal thickness at L5-S1 reduced from supine to WB and WB + AL (13.4, 10.6, 9.5 mm) with corresponding increases of 2.4 and 3.5 mm in the L5-S1 disc protrusion with WB and WB + AL, respectively. Change from supine to WB and WB + AL altered the L5-S1 disc heights (10.2, 8.6, 7.0 mm), left L5-S1 foramen heights (12.9, 11.8, 10.9 mm), L5-S1 segmental angles (10.3°, 2.8°, 4.3°), sacral angles (38.5°, 38.3°, 40.3°), L1-L3-L5 angles (161.4°, 157.1°, 155.1°), and the dural sac cross sectional areas (149, 130, 131 mm²). Notably, the adjacent L4-L5 segment demonstrated a retro-listhesis >2.3 mm on WB.

CONCLUSION

We observed that with weight-bearing, measurements indicative of spinal canal narrowing could be detected. These findings suggest that further research is warranted to determine the potential utility of weight-bearing MRI in clinical decision-making.

Morphological and postural sexual dimorphism of the lumbar spine facilitates greater lordosis in females

Previous work suggests females are evolutionarily adapted to have greater lumbar lordosis than males to aid in pregnancy load-bearing, but no consensus exists. To explore further sex-differences in the lumbar spine, and to understand contradictions in the literature, we conducted a cross-sectional retrospective study of sex-differences in lumbar spine morphology and sacral orientation. In addition, our sample includes data for separate standing and supine samples of males and females to examine potential sex-differences in postural loading on lumbosacral morphology. We measured sagittal lumbosacral morphology on 200 radiographs. Measurements include: lumbar angle (L1-S1), lumbar vertebral body and disc wedging angles, sacral slope and pelvic incidence. Lumbar angle, representative of lordotic curvature between L1 and S1, was 7.3° greater in females than males, when standing. There were no significant sex-differences in lumbar angle when supine. This difference in standing lumbar angle can be explained by greater lordotic wedging of the lumbar vertebrae (L1-L5) in females. Additionally, sacral slope was greater in females than males, when standing. There were no significant sex-differences in pelvic incidence. Our results support that females have greater lumbar lordosis than males when standing, but not when supine - suggesting a potentially greater range of motion in the female spine. Furthermore, sex-differences in the lumbar spine appear to be supported by postural differences in sacral-orientation and morphological differences in the vertebral body wedging. A better understanding of sex-differences in lumbosacral morphology may explain sex-differences in spinal conditions, as well as promote necessary sex-specific treatments.

Etiology of lumbar lordosis and its pathophysiology: a review of the evolution of lumbar lordosis, and the mechanics and biology of lumbar degeneration

The goal of this review is to discuss the mechanisms of postural degeneration, particularly the loss of lumbar lordosis commonly observed in the elderly in the context of evolution, mechanical, and biological studies of the human spine and to synthesize recent research findings to clinical management of postural malalignment. Lumbar lordosis is unique to the human spine and is necessary to facilitate our upright posture. However, decreased lumbar lordosis and increased thoracic kyphosis are hallmarks of an aging human spinal column. The unique upright posture and lordotic lumbar curvature of the human spine suggest that an understanding of the evolution of the human spinal column, and the unique anatomical features that support lumbar lordosis may provide insight into spine health and degeneration. Considering evolution of the skeleton in isolation from other scientific studies provides a limited picture for clinicians. The evolution and development of human lumbar lordosis highlight the interdependence of pelvic structure and lumbar lordosis. Studies of fossils of human lineage demonstrate a convergence on the degree of lumbar lordosis and the number of lumbar vertebrae in modern Homo sapiens. Evolution and spine mechanics research show that lumbar lordosis is dictated by pelvic incidence, spinal musculature, vertebral wedging, and disc health. The evolution, mechanics, and biology research all point to the importance of spinal posture and flexibility in supporting optimal health. However, surgical management of postural deformity has focused on restoring posture at the expense of flexibility. It is possible that the need for complex and costly spinal fixation can be eliminated by developing tools for early identification of patients at risk for postural deformities through patient history (genetics, mechanics, and environmental exposure) and tracking postural changes over time.

The lumbar spine has an intrinsic shape specific to each individual that remains a characteristic throughout flexion and extension

PURPOSE

We have previously shown that the lumbar spine has an intrinsic shape specific to the individual and characteristic of sitting, standing and supine postures. The purpose of this study was to test the hypothesis that this intrinsic shape is detectable throughout a range of postures from extension to full flexion in healthy adults.

METHODS

Sagittal images of the lumbar spine were taken using a positional MRI with participants (n = 30) adopting six postures: seated extension, neutral standing, standing with 30, 45 and 60° and full flexion. Active shape modelling (ASM) was used to identify and quantify 'modes' of variation in the shape of the lumbar spine.

RESULTS

ASM showed that 89.5% of the variation in the shape of the spine could be explained by the first two modes; describing the overall curvature and the distribution of curvature of the spine. Mode scores were significantly correlated between all six postures (modes 1-9, r = 0.4-0.97, P < 0.05), showing that an element of intrinsic shape was maintained when changing postures. The spine was most even in seated extension (P < 0.001) and most uneven between 35 and 45° flexion (P < 0.05).

CONCLUSIONS

This study shows that an individual's intrinsic lumbar spine shape is quantifiable and detectable throughout lumbar flexion and extension. These findings will enable the role of lumbar curvature in injury and low back pain to be assessed in the clinic and in the working and recreational environments.

The relationship between sagittal curvature and extensor muscle volume in the lumbar spine

A previous modelling study predicted that the forces applied by the extensor muscles to stabilise the lumbar spine would be greater in spines that have a larger sagittal curvature (lordosis). Because the force-generating capacity of a muscle is related to its size, it was hypothesised that the size of the extensor muscles in a subject would be related to the size of their lumbar lordosis. Magnetic resonance imaging (MRI) data were obtained, together with age, height, body mass and back pain status, from 42 female subjects. The volume of the extensor muscles (multifidus and erector spinae) caudal to the mid-lumbar level was estimated from cross-sectional area measurements in axial T1-weighted MRIs spanning the lumbar spine. Lower lumbar curvature was determined from sagittal T1-weighted images. A stepwise linear regression model was used to determine the best predictors of muscle volume. The mean lower lumbar extensor muscle volume was 281 cm(3) (SD = 49 cm(3)). The mean lower lumbar curvature was 30 ° (SD = 7 °). Five subjects reported current back pain and were excluded from the regression analysis. Nearly half the variation in muscle volume was accounted for by the variables age (standardised coefficient, B = -3.2, P = 0.03) and lower lumbar curvature (B = 0.47, P = 0.002). The results support the hypothesis that extensor muscle volume in the lower lumbar spine is related to the magnitude of the sagittal curvature; this has implications for assessing muscle size as an indicator of muscle strength.

The pathogenesis of degeneration of the intervertebral disc and emerging therapies in the management of back pain

This article reviews the current knowledge of the intervertebral disc (IVD) and its association with low back pain (LBP). The normal IVD is a largely avascular and aneural structure with a high water content, its nutrients mainly diffusing through the end plates. IVD degeneration occurs when its cells die or become dysfunctional, notably in an acidic environment. In the process of degeneration, the IVD becomes dehydrated and vascularised, and there is an ingrowth of nerves. Although not universally the case, the altered physiology of the IVD is believed to precede or be associated with many clinical symptoms or conditions including low back and/or lower limb pain, paraesthesia, spinal stenosis and disc herniation.

New treatment options have been developed in recent years. These include biological therapies and novel surgical techniques (such as total disc replacement), although many of these are still in their experimental phase. Central to developing further methods of treatment is the need for effective ways in which to assess patients and measure their outcomes. However, significant difficulties remain and it is therefore an appropriate time to be further investigating the scientific basis of and treatment of LBP.

MODELING THE EFFECT OF VARIATION IN SAGITTAL CURVATURE ON THE FORCE REQUIRED TO PRODUCE A FOLLOWER LOAD IN THE LUMBAR SPINE

The aim of this study was to investigate how the forces required to stabilize the lumbar spine in the standing posture may be affected by variation in its shape. A two-dimensional model of the lumbar spine in the sagittal plane was developed that included a simplified representation of the lumbar extensor muscles. The shape of the model was varied by changing both the magnitude and distribution of the lumbar curvature. The forces required to produce a resultant load traveling along a path as close to the vertebral body centroids as possible (a follower load) were determined. In general,the forces required to produce a follower load increased as the curvature became larger and more evenly distributed. The results suggest that the requirements of the lumbar muscles to maintain spinal stability in vivo will vary between individuals. This has implications for understanding the role of spinal curvature and muscle atrophy in back pain.