The effect of thoracic kyphosis and sagittal plane alignment on vertebral compressive loading

DXA-derived lumbar bone strain index corrected for kyphosis is associated with vertebral fractures and trabecular bone score in acromegaly

PURPOSE

The bone strain index (BSI) is a marker of bone deformation based on a finite element analysis inferred from dual X-ray absorptiometry (DXA) scans, that has been proposed as a predictor of fractures in osteoporosis (i.e., higher BSI indicates a lower bone's resistance to loads with consequent higher risk of fractures). We aimed to investigate the association between lumbar BSI and vertebral fractures (VFs) in acromegaly.

METHODS

Twenty-three patients with acromegaly (13 males, mean age 58 years; three with active disease) were evaluated for morphometric VFs, trabecular bone score (TBS), bone mineral density (BMD) and BSI at lumbar spine, the latter being corrected for the kyphosis as measured by low-dose X-ray imaging system (EOS®-2D/3D).

RESULTS

Lumbar BSI was significantly higher in patients with VFs as compared to those without fractures (2.90 ± 1.46 vs. 1.78 ± 0.33, p = 0.041). BSI was inversely associated with TBS (rho -0.44; p = 0.034), without significant associations with BMD (p = 0.151), age (p = 0.500), BMI (p = 0.957), serum IGF-I (p = 0.889), duration of active disease (p = 0.434) and sex (p = 0.563).

CONCLUSIONS

Lumbar BSI corrected for kyphosis could be proposed as integrated parameter of spine arthropathy and osteopathy in acromegaly helping the clinicians in identifying patients with skeletal fragility possibly predisposed to VFs.

Musculoskeletal spine modeling in large patient cohorts: how morphological individualization affects lumbar load estimation

Introduction: Achieving an adequate level of detail is a crucial part of any modeling process. Thus, oversimplification of complex systems can lead to overestimation, underestimation, and general bias of effects, while elaborate models run the risk of losing validity due to the uncontrolled interaction of multiple influencing factors and error propagation. Methods: We used a validated pipeline for the automated generation of multi-body models of the trunk to create 279 models based on CT data from 93 patients to investigate how different degrees of individualization affect the observed effects of different morphological characteristics on lumbar loads. Specifically, individual parameters related to spinal morphology (thoracic kyphosis (TK), lumbar lordosis (LL), and torso height (TH)), as well as torso weight (TW) and distribution, were fully or partly considered in the respective models according to their degree of individualization, and the effect strengths of these parameters on spinal loading were compared between semi- and highly individualized models. T-distributed stochastic neighbor embedding (T-SNE) analysis was performed for overarching pattern recognition and multiple regression analyses to evaluate changes in occurring effects and significance. Results: We were able to identify significant effects (p < 0.05) of various morphological parameters on lumbar loads in models with different degrees of individualization. Torso weight and lumbar lordosis showed the strongest effects on compression (β ≈ 0.9) and anterior-posterior shear forces (β ≈ 0.7), respectively. We could further show that the effect strength of individual parameters tended to decrease if more individual characteristics were included in the models. Discussion: The induced variability due to model individualization could only partly be explained by simple morphological parameters. Our study shows that model simplification can lead to an emphasis on individual effects, which needs to be critically assessed with regard to in vivo complexity. At the same time, we demonstrated that individualized models representing a population-based cohort are still able to identify relevant influences on spinal loading while considering a variety of influencing factors and their interactions.

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.

Analyzing lumbar vertebral shape and alignment in female patients with degenerative spondylolisthesis: Comparisons with spinal stenosis and risk factor exploration

PURPOSE

This study aimed to examine the vertebral body shape characteristics and spondylopelvic alignment in L4 degenerative spondylolisthesis (DS) as well as the risk factors for the development of DS.

METHODS

This cross-sectional study compared vertebral morphology and sagittal spinopelvic alignment in female patients with lumbar DS and lumbar spinal stenosis (LSS). The degree of lumbar lordosis (LL), pelvic incidence (PI), cross-sectional area (CSA), and vertebral body height ratio (ha/hp) of the lumbar spine were compared using full-length spine radiographs and computed tomography in 60 females with DS and in 60 women with LSS.

RESULTS

No significant differences in age or body mass index were observed between the two groups; however, the DS and LSS groups significantly differed in PI (mean, 58.9±10.8 vs. 47.2±11.6, P < 0.001), L4 CSA (mean, 1,166.2 m2 vs. 1,242.0 m2, P = 0.002) and ha/hp (mean, 1.134 vs. 1.007, P < 0.001). The L4 ha/hp was significantly higher in the DS group than in the LSS group. Additionally, LL values were negatively correlated with vertebral L5 CSA in the DS group (r = -0.28, P < 0.05). The LSS and DS groups demonstrated positive correlations between LL and L2, L3, and L4 ha/hp (r = 0.331, 0.267, and 0.317; P < 0.01, < 0.05, and < 0.05, respectively) and between LL and L4 and L5 ha/hp (r = 0.333, 0.331; P < 0.01, respectively). Multivariate regression analyses revealed that PI and ha/hp ratio may be independent predictors of DS development.

CONCLUSION

The DS group had significantly larger LL, PI, and L4 ha/hp and smaller L4 CSA than the LSS group. The lumbar vertebral body shape and sagittal spinopelvic alignment in females might be independent predictors of DS development.

Using inertial measurement units to estimate spine joint kinematics and kinetics during walking and running

Optical motion capture (OMC) is considered the best available method for measuring spine kinematics, yet inertial measurement units (IMU) have the potential to collect data outside the laboratory. When combined with musculoskeletal modeling, IMU technology may be used to estimate spinal loads in real-world settings. To date, IMUs have not been validated for estimates of spinal movement and loading during both walking and running. Using OpenSim Thoracolumbar Spine and Ribcage models, we compare IMU and OMC estimates of lumbosacral (L5/S1) and thoracolumbar (T12/L1) joint angles, moments, and reaction forces during gait across six speeds for five participants. For comparisons, time series are ensemble averaged over strides. Comparisons between IMU and OMC ensemble averages have low normalized root mean squared errors (< 0.3 for 81% of comparisons) and high, positive cross-correlations (> 0.5 for 91% of comparisons), suggesting signals are similar in magnitude and trend. As expected, joint moments and reaction forces are higher during running than walking for IMU and OMC. Relative to OMC, IMU overestimates joint moments and underestimates joint reaction forces by 20.9% and 15.7%, respectively. The results suggest using a combination of IMU technology and musculoskeletal modeling is a valid means for estimating spinal movement and loading.

Validity of evaluating spinal kinetics without participant-specific kinematics

Musculoskeletal models are commonly used to estimate in vivo spinal loads under various loading conditions. Typically, participant-specific measured kinematics (PSMK) are coupled with participant-specific models, but obtaining PSMK data can be costly and infeasible in large studies or clinical practice. Thus, we evaluated two alternative methods to estimate spinal loads without PSMK: 1) ensemble average kinematics (EAK) based on kinematics from all participants; and 2) using separately measured individual kinematics (SMIK) from multiple other participants as inputs, then averaging the resulting loads. This study compares the dynamic spine loading patterns and peak loads in older adults performing five lifting tasks using PSMK, EAK and SMIK. Median root mean square errors of EAK and SMIK methods versus PSMK ranged from 18 to 72% body weight for compressive loads and from 2 to 25% body weight for shear loads, with median cross-correlations ranging from 0.931 to 0.991. The root mean square errors and cross-correlations between repeated PSMK trials fell within similar ranges. Compressive peak loads evaluated by EAK and SMIK were not different than PSMK in 12 of 15 cases, while by comparison repeated PSMK trials were not different in 13 of 15 cases. Overall, the resulting spine loading magnitudes and profiles using EAK or SMIK were not notably different than using a PSMK approach, and differences were not greater than between two PSMK trials. Thus, these findings indicate that these approaches may be used to make reasonable estimates of dynamic spinal loading without direct measurement of participant kinematics.

Scheuermann Kyphosis: Current Concepts and Management

PURPOSE OF REVIEW

Scheuermann's kyphosis (SK) is a developmental deformity of the spine that affects up to 8% of children in the US. Although, the natural progression of SK is noted to be gradual over years, severe deformity can be associated with significant morbidity. Thorough clinical examination and interpretation of relevant imaging help differentiate and confirm this diagnosis. Treatment includes both operative and nonoperative approaches. The purpose of this article is to provide an updated overview of the current theories of its pathogenesis, as well as the principles of diagnosis and treatment of SK.

RECENT FINDINGS

Although a definitive, unified theory continues to be elusive, numerous reports in the past decade provide insight into the pathophysiology of SK. These include alterations in mechanical stress and/or hormonal disturbances. Candidate genes have also been identified to be linked to the inheritance of SK. Updates to nonoperative treatment include the effectiveness of dedicated exercise programs, as well as the types and duration of orthotic treatment. Advances in surgical technique can be observed with a trend toward a posterior-only approach, with supporting evidence for careful evaluation of both the sagittal and coronal planes to determine fusion levels in order to avoid postoperative junctional pathologies. SK is an important cause of structural or rigid kyphosis. It can lead to significant morbidity in severe cases. Treatment is based on curve magnitude and symptoms. Nonoperative treatment consists of physical therapy in symptomatic patients, and bracing can be added for skeletally mature patients. Operative management can be considered in patients with large, progressive, and symptomatic deformity. Future studies can benefit from a focused investigation into patient-reported outcomes after undergoing appropriate treatment.

Which trunk muscle parameter is the best predictor for physical function in older adults?

Background

Despite preliminary evidence demonstrating the relevance of trunk muscle strength for physical function in older adults, it is not clear which muscle-related trunk parameter is the best predictor for physical functions. Therefore, this study aimed to compare trunk muscle morphology or strength parameters regarding their predictive ability for physical functions.

Methods

Seventy-four older adults (38 men, 36 women, mean age 76.85 years) were tested for maximum absolute and relative isokinetic trunk flexion and extension strength, trunk lean mass, and trunk muscle quality. Functional assessment included normal and fast walking speed, repeated sit-to-stand transfer, timed up and go, and postural sway during a closed-feet and a semi-tandem stance adjusted for body height. Pearson's correlations were used to compare relationship between trunk strength adjusted and unadjusted for body weight to physical functions. Linear regression analysis including sex and age as co-variables was performed between trunk muscle and functional test parameters.

Results

Relative back extension strength was the most consistent significant predictor for all physical function tests (p = 0.004-0.04) except for postural sway. Relative trunk flexion strength was related to normal walking speed (p = 0.024). Trunk lean mass was related to timed up and go performance (p = 0.024).

Conclusion

Relative back extension strength is associated with better performance in nearly all standard tests for physical function in older adults, while trunk flexion strength and lean mass seem to play a minor role. Our findings emphasize the importance of trunk muscle strength, especially the back extensor muscles, for physical function in older adults.

The Acute Effects of Schoolbag Loading on Posture and Gait Mechanics in 10- to 13-Year-Old Children: A Cohort from the North West Province

Most schoolchildren carry schoolbags, of which a substantial proportion carry loads that exceed 15% of their body mass. Although the effects of loading have been investigated to varying degrees, the status of schoolbag loading and the acute affects thereof on gait and posture have not been thoroughly investigated within the South African context. A total of 60 participants in the 10-13-year age range volunteered for the present study. Significant differences were evident for relative load carriage (χ2(3) = 14.54, p < 0.001), forefoot and heel forces (Mdiff = 17.05-34.86 N, p < 0.001), force ratios (Mdiff = 0.02, p = 0.029), and gait speed (Mdiff = -0.18 km/hr, p = 0.016), but not for any postural angles (Mdiff = -3.37-6.08 deg, all p > 0.052). Those who exceeded 15% BM were ~9 times more likely to report pain than those below 15% BM. The children in the current study carried significantly heavier relative loads (p < 0.001) compared to similarly aged children from other countries. Loading leads to acute changes in posture and gait that are likely not meaningful. However, excessive loading (>15% BM) leads to significantly higher perceptions and reporting of pain in 10-13-year-old children.

Reference Values for Sagittal Clinical Posture Assessment in People Aged 10 to 69 Years

Poor posture is a well-known problem in all age groups and can lead to back pain, which in turn can result in high socio-economic costs. Regular assessment of posture can therefore help to identify postural deficits at an early stage in order to take preventive measures and can therefore be an important tool for promoting public health. We measured the posture of 1127 symptom-free subjects aged 10 to 69 years using stereophotogrammetry and determined the sagittal posture parameters flèche cervicale (FC), flèche lombaire (FL), and kyphosis index (KI) as well as the values standardized to the trunk height (FC%, FL%, KI%). FC, FC%, KI, and KI% showed an increase with age in men but not in women, and a difference between the sexes. FL remained largely constant with age, although FL% had significantly greater values in women than men. Postural parameters correlated only moderately or weakly with body mass index. Reference values were determined for different age groups and for both sexes. Since the parameters analyzed can also be determined by simple and non-instrumental methods in medical office, they are suitable for performing preventive checks in daily medical or therapeutic practice.

Association between sagittal alignment and loads at the adjacent segment in the fused spine: a combined clinical and musculoskeletal modeling study of 205 patients with adult spinal deformity

PURPOSE

Sagittal malalignment is a risk factor for mechanical complications after surgery for adult spinal deformity (ASD). Spinal loads, modulated by sagittal alignment, may explain this relationship. The aims of this study were to investigate the relationships between: (1) postoperative changes in loads at the proximal segment and realignment, and (2) absolute postoperative loads and postoperative alignment measures.

METHODS

A previously validated musculoskeletal model of the whole spine was applied to study a clinical sample of 205 patients with ASD. Based on clinical and radiographic data, pre-and postoperative patient-specific alignments were simulated to predict loads at the proximal segment adjacent to the spinal fusion.

RESULTS

Weak-to-moderate associations were found between pre-to-postop changes in lumbar lordosis, LL (r =  - 0.23, r =  - 0.43; p < 0.001), global tilt, GT (r = 0.26, r = 0.38; p < 0.001) and the Global Alignment and Proportion score, GAP (r = 0.26, r = 0.37; p < 0.001), and changes in compressive and shear forces at the proximal segment. GAP score parameters, thoracic kyphosis measurements and the slope of upper instrumented vertebra were associated with changes in shear. In patients with T10-pelvis fusion, moderate-to-strong associations were found between postoperative sagittal alignment measures and compressive and shear loads, with GT showing the strongest correlations (r = 0.75, r = 0.73, p < 0.001).

CONCLUSIONS

Spinal loads were estimated for patient-specific full spinal alignment profiles in a large cohort of patients with ASD pre-and postoperatively. Loads on the proximal segments were greater in association with sagittal malalignment and malorientation of proximal vertebra. Future work should explore whether they provide a causative mechanism explaining the associated risk of proximal junction complications.

Sagittal spinal alignment and mobility and their relation to physical function in women with and without mild-to-moderate knee osteoarthritis

Recent studies suggest that patients with lower extremity osteoarthritis may have altered spinal posture. We aimed to investigate age and body mass index-adjusted sagittal spinal alignment and mobility and their relation to physical function in women over 40 years of age with and without mild-to-moderate knee osteoarthritis (KOA). Thirty-two women with unilateral mild-to-moderate KOA and thirty-two asymptomatic women were included. A skin-surface device was used to assess sagittal alignment and mobility of the thoracic, lumbar, and sacral regions and trunk inclination angle. Physical function was assessed using the Timed Up and Go test. Analysis of covariance was used to compare groups and correlation coefficients were calculated separately for two groups. Women with KOA had higher thoracic kyphosis and lumbar lordosis compared to asymptomatic women (p < 0.05). The mean differences were 6.60 (%95 Confidence Interval 1.38;11.82) and -5.63 (-10.06;-1.20) for thoracic kyphosis and lumbar lordosis, respectively. Physical function score was moderately correlated with trunk inclination angle and lumbar, sacral, and trunk inclination mobility in asymptomatic women (r = 0.400, -0.504, -0.602, and -0.681, p < 0.05), but a significant correlation was not found in women with KOA (p > 0.05). In conclusion, women with KOA had altered spinal alignment. Spinal alignment and mobility were related to physical function in asymptomatic women over 40 years of age. Addressing sagittal spinal alignment in the clinical management of KOA may provide valuable data, especially for preventing possible spinal disorders.

Relationship between Intervertebral Disc Compression Force and Sagittal Spinopelvic Lower Limb Alignment in Elderly Women in Standing Position with Patient-Specific Whole Body Musculoskeletal Model

The intervertebral disc loading based on compensated standing posture in patients with adult spinal deformity remains unclear. We analyzed the relationship between sagittal alignment and disc compression force (Fm). In 14 elderly women, the alignment of the sagittal spinopelvic and lower extremities was measured. Fm was calculated using the Anybody Modeling System. Patients were divided into low sagittal vertical axis (SVA) and high SVA groups. Comparisons between the two groups were performed and the relationship between the Fm and each parameter was examined using Spearman's correlation coefficient (r). The mean lumbar Fm in the high SVA group was 67.6%; significantly higher than that in the low SVA group (p = 0.046). There was a negative correlation between cervical Fm with T1 slope (r = -0.589, p = 0.034) and lumbar Fm with lumbar lordosis (r = -0.566, p = 0.035). Lumbar Fm was positively correlated with center of gravity-SVA (r = 0.615, p = 0.029), T1 slope (r = 0.613, p = 0.026), and SVA (r = 0.612, p = 0.020). The results suggested sagittal malalignment increased the load on the thoracolumbar and lower lumbar discs and was associated with cervical disc loading.

Polg mtDNA mutator mice reveal limited involvement of vertebral bone loss in premature aging-related thoracolumbar hyperkyphosis

Background

Age-related hyperkyphosis is multifactorial and involves alterations of vertebral bone, intervertebral discs (IVD) and paraspinal muscles. The relative contribution of these tissues remains unclear. Here, we compared differences in vertebral bone microarchitecture and IVD thickness between prematurely aging mice with spinal hyperkyphosis and wild type littermates.

Methods

Thoracolumbar vertebral columns were dissected from homozygous Polg ^D257A and age-matched wild type littermates. Micro-computed tomography was performed to quantify cortical and trabecular bone parameters at anterior and posterior portions of T8-L4 vertebrae. In addition, vertebral shape, transaxial facet joint orientation and IVD thickness were quantified. Differences in anterior/posterior ratios between genotypes were compared by Student's t-test and association between vertebral bone and IVD parameters was investigated using Pearson correlation analysis.

Results

Hyperkyphotic homozygous mice displayed generalized osteopenia that was more pronounced at the posterior compared with anterior portion of thoracolumbar vertebrae. An increase in the anterior/posterior ratio of trabecular bone parameters was revealed at the thoracolumbar junction (T13-L1). Polg ^D257A displayed diffuse loss of cortical bone thickness, yet anterior/posterior ratios were unchanged. Despite generalized and regional bone loss, vertebral shape was unaffected. PolG ^D257A mice showed a 10-20 % reduction of IVD thickness at both thoracic and lumbar levels, with only minimal histopathological changes. IVD thickness was negatively correlated with anterior/posterior ratios of trabecular bone parameters, as well as with more coronally oriented facet joints, but negatively correlated with the anterior/posterior ratio of cortical bone thickness.

Conclusions

Aging-induced regional changes of vertebral trabecular and cortical bone did not lead to altered vertebral shape in Polg ^D257A mice but may indirectly cause hyperkyphosis through reduction of IVD thickness. These findings suggest a limited role for aging-induced bone loss in spinal hyperkyphosis and warrants further research on the involvement of paraspinal muscle degeneration.

Evaluation of Load-To-Strength Ratios in Metastatic Vertebrae and Comparison With Age- and Sex-Matched Healthy Individuals

Vertebrae containing osteolytic and osteosclerotic bone metastases undergo pathologic vertebral fracture (PVF) when the lesioned vertebrae fail to carry daily loads. We hypothesize that task-specific spinal loading patterns amplify the risk of PVF, with a higher degree of risk in osteolytic than in osteosclerotic vertebrae. To test this hypothesis, we obtained clinical CT images of 11 cadaveric spines with bone metastases, estimated the individual vertebral strength from the CT data, and created spine-specific musculoskeletal models from the CT data. We established a musculoskeletal model for each spine to compute vertebral loading for natural standing, natural standing + weights, forward flexion + weights, and lateral bending + weights and derived the individual vertebral load-to-strength ratio (LSR). For each activity, we compared the metastatic spines' predicted LSRs with the normative LSRs generated from a population-based sample of 250 men and women of comparable ages. Bone metastases classification significantly affected the CT-estimated vertebral strength (Kruskal-Wallis, p < 0.0001). Post-test analysis showed that the estimated vertebral strength of osteosclerotic and mixed metastases vertebrae was significantly higher than that of osteolytic vertebrae (p = 0.0016 and p = 0.0003) or vertebrae without radiographic evidence of bone metastasis (p = 0.0010 and p = 0.0003). Compared with the median (50%) LSRs of the normative dataset, osteolytic vertebrae had higher median (50%) LSRs under natural standing (p = 0.0375), natural standing + weights (p = 0.0118), and lateral bending + weights (p = 0.0111). Surprisingly, vertebrae showing minimal radiographic evidence of bone metastasis presented significantly higher median (50%) LSRs under natural standing (p < 0.0001) and lateral bending + weights (p = 0.0009) than the normative dataset. Osteosclerotic vertebrae had lower median (50%) LSRs under natural standing (p < 0.0001), natural standing + weights (p = 0.0005), forward flexion + weights (p < 0.0001), and lateral bending + weights (p = 0.0002), a trend shared by vertebrae with mixed lesions. This study is the first to apply musculoskeletal modeling to estimate individual vertebral loading in pathologic spines and highlights the role of task-specific loading in augmenting PVF risk associated with specific bone metastatic types. Our finding of high LSRs in vertebrae without radiologically observed bone metastasis highlights that patients with metastatic spine disease could be at an increased risk of vertebral fractures even at levels where lesions have not been identified radiologically.

Exploring the Association between Pain and Fracture Characteristics in Women with Osteoporotic Vertebral Fractures

Purpose: The purpose of this study was to estimate the association between pain and the number, severity, and location of fractures in women with osteoporotic vertebral fractures. Method:We used an 11-point numeric pain rating scale to assess pain during movement in the preceding week and lateral spinal radiographs to confirm number, location, and severity of vertebral fractures. In model 1, we assessed the association between pain during movement and the number, severity, and location of fractures. We adjusted model 2 for pain medication use and age. Results: The mean age of participants was 76.4 (SD 6.9) years. We found no statistically significant associations between pain and fracture number (estimated β = 0.23, 95% CI: ‒0.27, 0.68), fracture severity (estimated β = ‒0.46, 95% CI: ‒1.38, 0.49), or fracture location at T4–T8 (estimated β = 0.06, 95% CI: ‒1.26, 1.34), T9–L1 (estimated β = 0.35, 95% CI: ‒1.17, 1.74), or L2–L4 (estimated β = 0.40, 95% CI: ‒1.01, 1.75). Age and pain medication use were not significantly associated with pain. Model 1 accounted for 4.7% and model 2 for 7.2% of the variance in self-reported pain. Conclusion: The number, location, and severity of fractures do not appear to be the primary explanation for pain in women with vertebral fractures. Clinicians must consider other factors contributing to pain.

Effect of postural alignment alteration with age on vertebral strength

EOS biplane radiographs of 117 subjects between 20 and 83 years were analyzed to compute the upper body lever arm over the L1 vertebra and its impact on vertebral strength. Postural sagittal alignment alteration was observed with age and resulted in a greater lever arm causing vertebral strength to decrease.

PURPOSE

The purpose of this study was to analyze the impact of postural alignment changes with age on vertebral strength using finite element analysis and barycentremetry.

METHODS

A total of 117 subjects from 20 to 83 years were divided in three age groups: young (20 to 40 years, 62 subjects), intermediate (40 to 60 years, 26 subjects), and elderly (60 years and over, 29 subjects). EOS biplane radiographs were acquired, allowing 3D reconstruction of the spine and body envelope as well as spinal, pelvic, and sagittal alignment parameter measurements. A barycentremetry method allowed the estimation of the mass and center of mass (CoM) position of the upper body above L1, relatively to the center of the L1 vertebra (lever arm). To investigate the effect of this lever arm, vertebral strength of a generic finite element model (with constant geometry and mechanical properties for all subjects) was successively computed applying the personalized lever arm of each subject.

RESULTS

A combination of an increase in thoracic kyphosis, cervical lordosis, and pelvic tilt with a loss of lumbar lordosis was observed between the young and the older groups. Sagittal alignment parameters indicated a more forward position as age increased. The lever arm of the CoM above L1 varied from an average of 1 mm backward for the young group, to averages of 10 and 24 mm forward, respectively, for the intermediate and elderly group. As a result, vertebral strength decreased from 2527 N for the young group to 1820 N for the elderly group.

CONCLUSION

The global sagittal alignment modifications observed with age were consistent with the literature. Posture alteration with age reduced vertebral strength significantly in this simplified loading model. Postural alignment seems essential to be considered in the evaluation of osteoporotic patients.

Kyphosis After Thoracolumbar Spine Fractures: WFNS Spine Committee Recommendations

Thoracolumbar fractures change the biomechanics of the spine. Load distribution causes kyphosis by the time. Treatment of posttraumatic kyphosis is still controversial. We reviewed the literature between 2010 and 2020 using a search with keywords “thoracolumbar fracture and kyphosis.” We removed osteoporotic fractures, ankylosing spondylitis fractures, non-English language papers, case reports, and low-quality case series. Up-to-date information on posttraumatic kyphosis management was reviewed to reach an agreement in a consensus meeting of the World Federation of Neurosurgical Societies (WFNS) Spine Committee. The first meeting was conducted in Peshawar in December 2019 with WFNS Spine Committee members’ presence and participation. The second meeting was a virtual meeting via the internet on June 12, 2020. We utilized the Delphi method to administer the questionnaire to preserve a high degree of validity. We summarized 42 papers on posttraumatic kyphosis. Surgical treatment of thoracolumbar kyphosis due to unstable burst fractures can be done via a posterior only approach. Less blood loss and reduced surgery time are the main advantages of posterior surgery. Kyphosis angle for surgical decision and fusion levels are controversial. However, global sagittal balance should be taken into consideration for the segment that has to be included. Adding an intermediate screw at the fractured level strengthens the construct.

Dynamic and static postural control among fighter pilots with spinal sagittal plane deformities

Background

Fighter pilots are at high risk for sagittal deformities because they are exposed to in-flight gravitational forces. These patients have reduced proprioception and are susceptible to imbalance. The present study was conducted to assess the dynamic and static postural control among fighter pilots with kyphosis and lordosis.

Methods

This is a causal-comparative study, which was conducted on 40 employed active fighter pilots during 2019. Our aim was to identify their sagittal plane deformity for complementary medical examinations, determine their flight status and reduce the possible related air accident. First, lordosis and kyphosis angles were measured in the standing position. Then, the static balance was measured using the one-leg standing test with the eyes open and closed. Dynamic balance was measured using the star excursion balance test in eight directions with a total of 16 unilateral squats.

Results

Dynamic balance in the hypo-kyphosis was significantly different in all directions, except for postero-lateral and lateral. No significant difference was obtained between the hyper- and hypo-lordosis in dynamic balance in all directions. The mean static balance scores in the hyper-kyphosis group were significantly more than that in the hypo-kyphosis group. There was no significant difference between the hyper- and hypo-lordosis participants with respect to static balance.

Conclusions

The hypo-kyphosis had a significantly higher dynamic balance in all directions, except for posterolateral and lateral, compared to the hyper-kyphosis group. No significant static and dynamic balance differences were observed between the patients with hyper- and hypo-lordosis. The static balance was higher in the hypo-kyphosis rather than hyper-kyphosis under the eyes open and closed. The patients with hyper-lordosis had a higher static balance, rather than hyper-kyphosis.

A comparison of the effectiveness of three types of trunk orthoses on the balance performance of older people with osteoporotic hyperkyphosis: A cross-over study

BACKGROUND

Orthotic immobilization is an early treatment for osteoporotic vertebral fracture at the hyperkyphotic thoracic spine.

OBJECTIVE

This exploratory study compared the immediate impact of three types of trunk orthoses on the balance parameters of older people with osteoporosis hyperkyphosis.

METHODS

Twenty older people (aged 60-65 years) with osteoporosis kyphosis and a history of falls participated in a pilot cross-over study. Four randomized comparisons were carried out, including either soft, semi-rigid, and rigid trunk orthoses worn on the participants compared to "no orthosis" as the control condition. Kyphosis angle, Forward Reach Test, Timed Up and Go test, and postural stability during standing on a force plate were recorded and compared between study conditions using one-way repeated measures analysis of variance test.

RESULTS

All orthoses significantly reduced the kyphosis angle (p < 0.01). None of the orthoses has a significant change in the Timed Up and Go test (p > 0.01). Rigid orthosis significantly reduced the forward reach compared to "no orthosis" (p = 0.003, 95% CI: 1.08-6.3 cm). None of the orthosis induced a significant change in postural sway velocity in anteroposterior and mediolateral directions compared to the control condition (p > 0.01).

CONCLUSION

These findings suggest that using rigid orthosis in older people with osteoporosis hyperkyphosis reduces the balance performance.

Fulcrum to Generate Maximum Extension of the Spine and Hip-Proposing A New Strategy using EOS Imaging for Patient-specific Assessment of Degenerated Lumbar Spines

STUDY DESIGN

A retrospective, radiographic comparative study conducted in a single academic institution.

OBJECTIVE

This study aims to compare fulcrum extension with conventional extension imaging to determine maximum "hip lordosis" (HL), an important novel patient-specific parameter in spinal realignment surgery, as well as understand the extension capabilities of the lower lumbar spine, which together, are key contributors to whole-body balancing.

SUMMARY OF BACKGROUND DATA

Recent literature recognizes the hip as an important contributor to whole-body lordosis beyond a compensator for spinal imbalance.

METHODS

Patients >45 years' old with mechanical low back pain due to degenerative spinal conditions were included and grouped based on the imaging performed-fulcrum or conventional extension. All imaging was performed using EOS under standardized instructions and visual aids. Radiographic parameters include global lumbar angle (GLA), inflexion-S1 (Inf-S1) angle, segmental lumbar angles, pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), femoral alignment angle (FAA), HL and spinocoxa angle (SCA). Unpaired t test was used to compare between radiographic parameters.

RESULTS

One hundred patients (40 males and 60 females, mean age 63.0 years) underwent either fulcrum or conventional extension EOS® imaging. Both groups had comparable baseline radiographic parameters. Fulcrum extension gave a larger mean GLA (-60.7° vs. -48.5°, P = 0.001), Inf-S1 angle (-58.8° vs. -48.8°, P = 0.003), SCA (-36.5° vs. -24.8°, P < 0.001), L4/5 and L5/S1 lordosis (-20.7° vs. -17.7°, P = 0.041, and -22.3° vs. -17.1°, P = 0.018, respectively), compared to conventional extension. PI, SS, PT, FAA, and HL were similar between both extension postures.

CONCLUSION

Fulcrum extension, compared to conventional extension, is better at generating lordosis in the lower lumbar spine, thus improving preoperative assessment of stiffness or instability of the lumbar spine. Both extension methods were equally effective at determining the patient-specific maximum HL to assess the flexibility and compensation occurring at the hip, potentially guiding surgical management of patients with degenerative spines.Level of Evidence: 3.

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.

Thoracic and Lumbar Sagittal Spinal Curvature Adaptations between Elite Iranian Road and Speed Cyclists

Background:

Despite existing some research on the effects of professional cycling on cyclist’s spinal curvature angles, no research is available concentrating on possible differences in various types of professional cycling. Road (outdoor) and speed (indoor) cyclists have different anthropometric and predominant postures during cycling. The current study aims to investigate if cyclists with different types of cycling may have dissimilar spinal curvature adaptations.

Objective:

Forty-eight male subjects, including 16 elite road cyclists, 16 elite sprint cyclists and 16 non-athletes as the control group were recruited in this non-experimental study.

Material and Methods:

In this cross-sectional study, a spinal mouse was used to measure the thoracic and lumbar curvature angles in standing position.

Results:

The mean values of thoracic kyphosis and lumbar lordosis angles were found as follows 48.3±7.2º & -20.3±7.2º for elite road cyclists; 46.6±8.1º & -22.5±7.7º for elite sprint cyclists; and 37.5±4.1º & -19±6.3º for the control group. The results confirmed that both the road and sprint cyclists showed significantly more hyper-kyphosis posture in their thoracic region when compared to the control group (p<0.05).

Conclusion:

All road cyclists showed no significantly higher degrees of thoracic angle relative to the sprint cyclists (p>0.05). However, all the cyclists and the control groups showed a normal range of lumbar lordosis angle. As a conclusion, the results of this study confirmed that an elite cyclist may predispose these subjects to the risk of hyper-kyphotic posture. The road cycling may result in more hyper-kyphosis due to the longer time, spent in flexed position.

Estimation and assessment of sagittal spinal curvature and thoracic muscle morphometry in different postures

Spine models are typically developed from supine clinical imaging data, and hence clearly do not fully reflect postures that replicate subjects' clinical symptoms. Our objectives were to develop a method to: (i) estimate the subject-specific sagittal curvature of the whole spine in different postures from limited imaging data, (ii) obtain muscle lines-of-action in different postures and analyze the effect of posture on muscle fascicle length, and (iii) correct for cosine between the magnetic resonance imaging (MRI) scan plane and dominant fiber line-of-action for muscle parameters (cross-sectional area (CSA) and position). The thoracic spines of six healthy volunteers were scanned in four postures (supine, standing, flexion, and sitting) in an upright MRI. Geometry of the sagittal spine was approximated with a circular spline. A pipeline was developed to estimate spine geometry in different postures and was validated. The lines-of-action for two muscles, erector spinae (ES) and transversospinalis (TS) were obtained for every posture and hence muscle fascicle lengths were computed. A correction factor based on published literature was then computed and applied to the muscle parameters. The maximum registration error between the estimated spine geometry and MRI data was small (average RMSE∼1.2%). The muscle fascicle length increased (up to 20%) in flexion when compared to erect postures. The correction factor reduced muscle parameters (∼5% for ES and ∼25% for TS) when compared to raw MRI data. The proposed pipeline is a preliminary step in subject-specific modeling. Direction cosines of muscles could be used while improving the inputs of spine models.

Prevalence of spine degeneration diagnosis by type, age, gender, and obesity using Medicare data

Identifying the prevalence of degenerative spinal pathologies and relevant demographic risk factors is important for understanding spine injury risk, prevention, treatment, and outcome, and for distinguishing acute injuries from degenerative pathologies. Prevalence data in the literature are often based on small-scale studies focused on a single type of pathology. This study evaluates the prevalence of diagnosis of selected degenerative spinal pathology diagnoses using Medicare insurance claim data in the context of published smaller-scale studies. In addition, the data are used to evaluate whether the prevalence is affected by age, sex, diagnosed obesity, and the use of medical imaging. The Medicare Claims 5% Limited Data Set was queried to identify diagnoses of degenerative spinal pathologies. Unique patient diagnoses per year were further evaluated as a function of age, gender, and obesity diagnosis. Participants were also stratified by coding for radiological imaging accompanying each diagnosis. The overall prevalence of diagnosed spinal degenerative disease was 27.3% and increased with age. The prevalence of diagnosed disc disease was 2.7 times greater in those with radiology. The results demonstrate that degenerative findings in the spine are common, and, since asymptomatic individuals may not receive a diagnosis of degenerative conditions, this analysis likely underestimates the general prevalence of these conditions.

Effect of heel lifts in elderly individuals with spinal kyphosis

BACKGROUND

The present study aimed to elucidate the effects of heel lifts on spinal alignment, walking, and foot pressure pattern in elderly individuals with spinal kyphosis.

METHODS

The spinal alignment, walking speed, step length and foot pressure of 33 community-dwelling elderly individuals with spinal kyphosis (3 men, 30 women; mean age 77.3 years) were examined before and after the application of 10-mm moderately elastic heel lifts.

FINDINGS

Spinal alignment of total inclination (mean value 6.9°vs 4.5°) and thoracic angle (43.6°vs 36.2°) were significantly lower after the application of heel lifts than before the application. The lumbar angle (7.3°vs 10.0°) was significantly higher after the application than before the application. Walking speed (0.78 vs 0.88 m/s) and step length (0.42 m vs 0.45 m) were significantly higher after the application. The partial foot pressure as a percentage of body weight of the hallux (6.7% vs 9.0%) and lateral toes (6.5% vs 9.0%) was significantly higher after the application of heel lifts than before the application. The partial foot pressure as a percentage of body weight of the heel (68.9% vs 57.5%) was significantly lower after the application than before the application.

INTERPRETATION

In conclusion, heel lifts influenced the sagittal spinal alignment of elderly individuals. Walking speed and step length increased after the application of these devices. Increase in foot pressure in the hallux and lateral toe areas was probably related to these improvements in walking parameters.

Kickboxers and crossfitters vertebral column curvatures in sagittal plane: Crossfit practice influence in kickboxers body posture

BACKGROUND

In combat sports, long-term training load can lead to sport-specific functional and body posture adaptations. The most often observed changes are in the shape of the anterior-posterior spinal curvatures. The abnormal inclination of the thoracic and lumbar regions of the spine may lead to an additional overload of the musculoskeletal system and spinal pain or decrease sports performance. Therefore it is crucial to prevent disadvantageous body posture features.

AIM

The aim was to examine differences in vertebral column's sagittal curves parameters between kickboxing fighters, kickboxing fighters who also trained CrossFit and CrossFit athletes and evaluate these parameters' predictive ability to predict sport disciplines. Received results show if CrossFit training influences vertebral column curvatures in the sagittal plane among Kickboxers is an effective method in proper body posture shaping.

METHODS

The study involved 45 men aged 25.2 years divided into three groups depending on the sport they practiced: group kickboxing (KB), kickboxing and CrossFit (KBCF), and CrossFit (CF). The body posture was observed using the photogrammetric method. The parameters of the sagittal plane were analyzed.

RESULTS

Among the kickboxers, it was observed that the angle of the thoracolumbar region, the angle of inclination of the thoracolumbar and lumbosacral regions significantly increased compared to other groups of athletes (p < 0.05).

CONCLUSION

Practicing kickboxing can be a factor in increasing the risk of postural defects. It was found that CrossFit training has a beneficial effect on the shape of physiological curvatures of the spine in combat sports athletes.

The effect of a postural exercise program on muscle power in Italian high school students

[Purpose] The present study aimed to investigate the effect of an innovative postural program (the Canali Postural Method, CPM) on muscle power in Italian high school students. It is note that deficits in posture control may, in long term, generate posture weakness as early as childhood and adolescence. Postural programs based on stretching and strengthening exercises can remove these deficits and can be framed in general physical or sport activities. [Participants and Methods] Thirty-four students completed a 8-week postural program. The intervention, consisting of stretching and muscle activation exercises, was integrated in physical education lessons. For the evaluation of the effect of CPM program, we have used the countermovement jump (CMJ), a simple and versatile test that measures muscle power. [Results] The CPM program resulted in significantly increased vertical jump height of the students. The average difference between Initial and Final CMJ was 2.1 cm. [Conclusion] This finding indicates the benefic effect of this new postural program on physical performance in the youth. Further randomized control trials should be conducted to evaluate CPM long-term implications in the prevention of posture weaknesses and its inclusion in the regular school curriculum.

Validity of flexicurve and motion capture for measurements of thoracic kyphosis vs standing radiographic measurements

Thoracic kyphosis varies among healthy adults and typically increases with age. Excessive kyphosis (hyperkyphosis) is associated with negative health. Spinal alignment also affects spine loading, with implications for conditions such as vertebral fractures and back pain. Valid measurements of kyphosis are necessary for clinical and research assessment of age-related posture changes, and to support improved biomechanical understating of spine conditions. Independent validation of non-radiographic techniques, however, remains limited. The goal of this study was to compare standing radiographic kyphosis measurements with non-radiographic measurements and predictions of thoracic kyphosis using flexicurve and motion analysis markers, in order to determine their validity. Thirteen non-radiographic measures of thoracic kyphosis were obtained in each of 40 adult subjects who also underwent standing radiographs of the thoracic spine. Measures included estimates derived by fitting of polynomials or circles to the non-radiographic data, as well as predictions calculated using previously published methods. Intra-class correlations (ICC) and root-mean square errors (RMSEs) were calculated between radiographic and non-radiographic measures to determine validity. Most non-radiographic estimates of kyphosis show similar, weak to moderate levels of validity when compared to radiographic measurements, and RMSEs ranging from 8.0° to 20.8°. Unbiased estimates of radiographic measurements with moderate to good ICCs were identified, however, based on marker measurements, and new prediction equations were created with similar validity that also account for age and body habitus. Clinical significance: These non-radiographic measurements of thoracic kyphosis can be applied to clinical practice or to clinical studies with recognition of specific limitations.

Is Breast Size Related to Prevalent Thoracic Vertebral Fracture? A Cross-Sectional Study

Large breasts may increase the likelihood of thoracic vertebral fractures by increasing the mechanical loading of the spine. We examined breast size as a factor associated with prevalent thoracic vertebral fractures, also considering its relationship with thoracic kyphosis and upper back extensor muscle endurance. Using a cross-sectional study, the design measurements collected were thoracic vertebral fractures (≥20% loss in vertebral body height on lateral radiograph), breast size (bra size converted to an ordinal breast size score), BMD (g/cm² averaged femoral neck, DXA), upper back extensor muscle endurance (isometric chest raise test), body composition (DXA), thoracic kyphosis (radiograph), and upper back pain (numerical rating scale). Correlations and multivariable logistic regression examined relationships between characteristics and their association with vertebral fracture. Participants were 117 healthy postmenopausal women. The 17 (15%) women with ≥1 thoracic vertebral fracture had larger breast size (mean difference [MD]: 2.2 sizes; 95% CI, 0.6 to 3.8 sizes), less upper back extensor muscle endurance (MD: -38.6 s; 95% CI, -62.9 to -14.3 s), and greater thoracic kyphosis (MD: 7.3°; 95% CI, 1.7° to 12.8°) than those without vertebral fracture. There were no between group differences in age, height, weight, and BMD. Breast size (r = -0.233, p = 0.012) and thoracic kyphosis (r = -0.241, p = 0.009) correlated negatively with upper back extensor muscle endurance. Breast size was unrelated to thoracic kyphosis (r = 0.057, p = 0.542). A (final) multivariable model containing breast size (OR 1.85; 95% CI, 1.10 to 3.10) and thoracic kyphosis (OR 2.04; 95%CI, 1.12 to 3.70) explained 18% of the variance in vertebral fracture. Breast size had a significant, but weak relationship with vertebral fracture (R ² = 0.10), which was independent of BMD and unrelated to thoracic kyphosis. Further work is needed to confirm larger breast size as a risk factor for vertebral fracture. © 2020 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

A novel method for prediction of postoperative global sagittal alignment based on full-body musculoskeletal modeling and posture optimization

Associations between spinal sagittal balance and pain and disability are well documented. Reciprocal changes after spinal surgery might be critical for the outcomes, but assessing their extent remains a challenge. This paper proposes a method for predicting full-body sagittal alignment including reciprocal changes in response to spinal fusion, based on musculoskeletal modeling and inverse-inverse dynamics approach. An established body model (AnyBody) was used, with fused segments modeled as rigid. Posture was optimized based on muscle expenditure minimization, following the concept of the cone of economy. The data of adult spinal fusion patients were obtained retrospectively from an ongoing clinical study. Patient spino-pelvic alignment, body weight and height, age- and pathology-related muscle deterioration, and underwent treatment details were represented in the model. Predicted postural changes were compared to follow-up radiographs to evaluate method validity. Twenty-one cases were analyzed in this preliminary study (age range = 48-74; number of fused segments 1-14). The model predictions correlated well with the radiographic measures at follow-up: TPA, r = 0.83; ΔPILL, r = 0.90; LL, r = 0.90; TK, r = 0.77. The model demonstrated high accuracy in predicting sagittal imbalance (positive predictive value = 1.00, negative predictive value = 0.75). The presented method for patient- and treatment-specific postoperative posture prediction can be used to guide preoperative planning of spinal fusion, but more extensive validation is needed.

Association of vertebral endplate microstructure with bone strength in men and women

Epidemiological and biomechanical evidence indicates that the risk of vertebral fracture differs between men and women, and that vertebral fracture frequently involves failure of the endplate region. The goal of this study was to compare the bone microstructure of the endplate region-defined as the (bony) vertebral endplate and underlying subchondral trabecular bone-between sexes and to determine whether any such sex differences are associated with vertebral strength. The bone density (volume fraction, apparent density and tissue mineral density) of the superior-most 2 mm of the vertebra, and the bone density and trabecular architecture of the next 5 mm were quantified using micro-computed tomography in human T8 (12 female, 16 male) and L1 (13 female, 12 male) vertebrae. Average density of the vertebra (integral bone mineral density (BMD)) was determined by quantitative computed tomography and compressive strength by mechanical testing. Few differences were found between male and female vertebrae in the density of the endplate region; none were found in trabecular architecture. However, whereas endplate volume fraction was positively correlated with integral BMD in male vertebrae (r = 0.654, p < .001), no correlation was found in the female vertebrae (r = 0.157, p = .455). Accounting for the density of the endplate region improved predictions of vertebral strength (p < .034) and eliminated sex-specificity in the strength prediction that was based on integral BMD alone. These results suggest that the density of the endplate region influences vertebral fracture and that non-invasive assessment of this region's density can contribute to predictions of vertebral strength in men and women.

Body composition indices in a sample of female adolescents with postural deformity: a case control study

Objectives

Normal posture is considered to be an indicative of good musculoskeletal health in school aged adolescents. Little is known about the body composition indices in relation with postural deformities in adolescents. The aim of this study was to assess relation of body composition analysis indices with postural deformities in a sample of female high school adolescents.

Results

In this case–control study, 37 eligible female adolescents with any postural deformities and 33 normal posture subjects enrolled in the study by random cluster sampling. Body composition analysis performed by bioelectrical impedance analysis (BIA) method to quantity body fat mass (BFM), soft lean mass (SLM) and lean body mass (LBM). The binary logistic regressions were performed to evaluate the associations of body composition indices which were significantly different between two groups at significance level of 0.05 with postural disorders in the two groups. There was no significant difference between subjects with postural disorders with their normal controls concerning demographic variables. We observed an inverse association between postural deformity risk and LBM (OR = 0.803; 95% CI 0.690–0.934) and SLM (OR = 0.774; 95% CI 0.649–0.922) after adjusting the analysis by height of participants.

The Impact of Whole-Body Electromyostimulation on Body Posture and Trunk Muscle Strength in Untrained Persons

Muscular imbalances of the trunk muscles are held responsible for changes in body posture. At the same time, whole-body electromyostimulation (WB-EMS) has been established as a new training method that enables simultaneous stimulation of many muscle groups. This study was aiming to analyze if a 10 weeks WB-EMS training changes posture-relevant parameters and/or improves isometric strength of the trunk extensors and flexors, and if there are differences based on stimulation at 20 Hz and 85 Hz. Fifty eight untrained adult test persons were divided into three groups (control, CON; training with 20 Hz stimulation, TR20; training with 85 Hz, TR85). Anthropometric parameters, trunk extension and flexion forces and torques, and posture parameters were determined before (n = 58) and after (n = 53: CON: n = 15, TR20: n = 19, TR85: n = 19) a 10 weeks WB-EMS training program (15 applications, 9 exercises). Differences between the groups were calculated for pre- and post-tests using univariate ANOVA and between the test times using repeated (2 × 3) ANOVA. Comparisons of pairs were calculated post hoc based on Fisher (LSD). No differences between the groups were found for the posture parameters. The post hoc analysis of both trunk flexion and trunk extension forces and torques showed a significant difference between the groups TR85 and CON but no difference between the other group pairs. A 10 weeks whole-body electrostimulation training with a stimulation frequency of 85 Hz in contrast to training with a stimulation frequency of 20 Hz improves the trunk muscle strength of an untrained group but does not significantly change posture parameters.

Exercise for improving outcomes after osteoporotic vertebral fracture

BACKGROUND

Vertebral fractures are associated with increased morbidity (e.g. pain, reduced quality of life) and mortality. Therapeutic exercise is a non-pharmacological conservative treatment that is often recommended for patients with vertebral fractures to reduce pain and restore functional movement. This is an update of a Cochrane Review first published in 2013.

OBJECTIVES

To assess the effects (benefits and harms) of exercise intervention of four weeks or greater (alone or as part of a physical therapy intervention) versus non-exercise/non-active physical therapy intervention, no intervention or placebo among adults with a history of vertebral fractures on incident fragility fractures of the hip, vertebra or other sites. Our secondary objectives were to evaluate the effects of exercise on the following outcomes: falls, pain, physical performance, health-related quality of life (disease-specific and generic), and adverse events.

SEARCH METHODS

We searched the following databases until November 2017: the Cochrane Library (Issue 11 of 12), MEDLINE (from 2005), Embase (from 1988), CINAHL (Cumulative Index to Nursing and Allied Health Literature, from 1982), AMED (from 1985), and PEDro (Physiotherapy Evidence Database, from 1929). Ongoing/recently completed trials were identified by searching the World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov. Conference proceedings were searched via ISI and SCOPUS, and targeted searches of proceedings of the American Congress of Rehabilitation Medicine and American Society for Bone and Mineral Research. Search terms or MeSH headings included terms such as vertebral fracture AND exercise OR physical therapy. For this update, the search results were limited from 2011 onward.

SELECTION CRITERIA

We included all randomized controlled trials and quasi-randomized trials comparing exercise or active physical therapy interventions with placebo/non-exercise/non-active physical therapy interventions or no intervention implemented in individuals with a history of vertebral fracture.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials and extracted data using a pre-tested data extraction form. Disagreements were resolved by consensus, or third-party adjudication. We used Cochrane's tool for assessing risk of bias to evaluate each study. Studies were grouped according to duration of follow-up (i.e. a) 4-12 weeks; b) 16-24 weeks; c) 52 weeks); a study could be represented in more than one group depending on the number of follow-up assessments. For dichotomous data, we reported risk ratios (RR) and corresponding 95% confidence intervals (95% CI). For continuous data, we reported mean differences (MD) of the change from baseline and 95% CI. Data were pooled for Timed Up and Go test, self-reported physical function measured by the QUALEFFO-41 physical function subscale score (scale of zero to 100; lower scores indicate better self-reported physical function), and disease-specific quality of life measured by the QUALEFFO-41 total score (scale of zero to 100; lower scores indicate better quality of life) at 12 weeks using a fixed-effect model.

MAIN RESULTS

Nine trials (n = 749, 68 male participants; two new trials in this review update) were included. Substantial variability across the trials prevented any meaningful pooling of data for most outcomes. Risk of bias across all studies was variable; low risk across most domains in four studies, and unclear/high risk in most domains for five studies. Performance bias and blinding of subjective outcome assessment were almost all high risk of bias.One trial reported no between-group difference in favor of the effect of exercise on incident fragility fractures after 52 weeks (RR 0.54, 95% CI 0.17 to 1.71; very low-quality evidence with control: 184 per 1000 and exercise: 100 per 1000, 95% CI 31 to 315; absolute difference: 8%, 95% CI 2 to 30). One trial reported no between-group difference in favor of the effect of exercise on incident falls after 52 weeks (RR 1.06, 95% CI 0.53 to 2.10; very low-quality evidence with control: 262 per 1000 and exercise: 277 per 1000; 95% CI 139 to 550; absolute difference: 2%, 95% CI -12 to 29). These findings should be interpreted with caution because of the very serious risk of bias in these studies and the small sample sizes resulting in imprecise estimates.We are uncertain that exercise could improve pain, self-reported physical function, and disease-specific quality of life, because certain studies showed no evidence of clinically important differences for these outcomes. Pooled analyses revealed a small between-group difference in favor of exercise for Timed Up and Go (MD -1.13 seconds, 95% CI -1.85 to -0.42; studies = 2), which did not change following a sensitivity analysis (MD -1.09 seconds, 95% CI -1.78 to -0.40; studies = 3; moderate-quality evidence). Exercise improved QUALEFFO-41 physical function score (MD -2.84 points, 95% CI -5.57 to -0.11; studies = 2; very low-quality evidence) and QUALEFFO-41 total score (MD -3.24 points, 95% CI -6.05 to -0.43; studies = 2; very low-quality evidence), yet it is unlikely that we observed any clinically important differences. Three trials reported four adverse events related to the exercise intervention (costal cartilage fracture, rib fracture, knee pain, irritation to tape, very low-quality evidence).

AUTHORS' CONCLUSIONS

In conclusion, we do not have sufficient evidence to determine the effects of exercise on incident fractures, falls or adverse events. Our updated review found moderate-quality evidence that exercise probably improves physical performance, specifically Timed Up and Go test, in individuals with vertebral fracture (downgraded due to study limitations). However, a one-second improvement in Timed Up and Go is not a clinically important improvement. Although individual trials did report benefits for some pain and disease-specific quality of life outcomes, the findings do not represent clinically meaningful improvements and should be interpreted with caution given the very low-quality evidence due to inconsistent findings, study limitations and imprecise estimates. The small number of trials and variability across trials limited our ability to pool outcomes or make conclusions. Evidence regarding the effects of exercise after vertebral fracture in men is scarce. A high-quality randomized trial is needed to inform safety and effectiveness of exercise to lower incidence of fracture and falls and to improve patient-centered outcomes (pain, function) for individuals with vertebral fractures (minimal sample size required is approximately 2500 untreated participants or 4400 participants if taking anti-osteoporosis therapy).

Thoracic Kyphosis on Chest CT Scans Is Associated With Incident Vertebral Fractures in Smokers

Greater kyphosis angles lead to increased loading on vertebral bodies in computational models. However, results about the relationship between severity of kyphosis and incident vertebral fracture (VF) risk have been conflicting. Therefore, the aim of this study was to evaluate associations between 1) prevalent VFs and severity of kyphosis, and 2) severity of kyphosis and incident VF risk in smokers with or without chronic obstructive pulmonary disease (COPD). Former and current smokers with or without COPD were included. CT scans were made at baseline, 1-year, and 3-year follow-up. VFs were evaluated on superposed sagittal CT reconstructions. Kyphosis was measured as the angle between the lines above T₄ and below T₉ or T₁₂ . We included 1239 subjects (mean age 61.3 ± 8.0 years, 61.1% male, 80.6% with COPD), of whom 253 (20.4%) had a prevalent VF and 294 (23.7%) an incident VF within 3 years. Presence, number, and severity of prevalent VFs were associated with a greater kyphosis angle. The mean increase in kyphosis angle within 3 years was small but significantly greater in subjects with incident VFs compared with those without (2.2 ± 4.1 versus 1.2 ± 3.9 degrees, respectively, for T₄ to T₁₂ angle, p < 0.001). After adjustment for bone attenuation (BA) and prevalent VFs, baseline kyphosis angle was associated with incident VFs within 1 and 3 years (angle T₄ to T₁₂ per +1 SD, hazard ratio [HR] = 1.34 [1.12-1.61] and HR 1.29 [1.15-1.45], respectively). Our data showed that a greater kyphosis angle at baseline was independently associated with increased risk of incident VFs within 1 and 3 years, supporting the theory that greater kyphosis angle contributes to higher biomechanical loads in the spine. © 2019 American Society for Bone and Mineral Research.

Effect of a semirigid thoracolumbar orthosis on gait and sagittal alignment in patients with an osteoporotic vertebral compression fracture

Background

An important goal in the treatment of osteoporotic vertebral compression fractures (OVCFs) is the prevention of new vertebral fractures and the subsequent progression to global sagittal malalignment. Current conservative treatment is multimodal and comprises analgesics, medication for osteoporosis, and physical therapy. However, little is known about the value of orthoses in the treatment of OVCFs.

Aims

The primary purpose of this study was to examine the direct effect of a semirigid thoracolumbar orthosis on gait in patients suffering from an OVCF. The secondary purpose was to evaluate changes in gait, radiographic sagittal alignment, pain, and quality of life over time.

Methods

Fifteen postmenopausal patients with an OVCF were treated with a semirigid thoracolumbar orthosis. At baseline, after 6 weeks, and after 6 months, gait analysis was performed with a dual belt-instrumented treadmill with a 180° projection screen providing a virtual environment (computer-assisted rehabilitation environment) combined with clinical and radiographic assessments.

Results

At baseline, bracing caused a significantly more upright posture during walking and patients walked faster, with larger strides, longer stride times, and lower cadence compared to walking without orthosis. After 6 weeks, radiographic and dynamic sagittal alignment had improved compared to baseline. The observed effect was gone after 6 months, when the orthosis was not worn anymore.

Conclusion

A semirigid thoracolumbar orthosis seems to have a positive effect on gait and stability in patients suffering from an OVCF, as was shown by a more upright posture, which may result in decreased compressive loading of the vertebrae. For studying the true effectiveness of dynamic bracing in the treatment of OVCFs, a prospective, randomized controlled trial will be needed.

Targeted Athletic Training Improves the Neuromuscular Performance in Terms of Body Posture From Adolescence to Adulthood - Long-Term Study Over 6 Years

Poor posture in childhood and adolescence is held responsible for the occurrence of associated disorders in adult age. This study aimed to verify whether body posture in adolescence can be enhanced through the improvement of neuromuscular performance, attained by means of targeted strength, stretch, and body perception training, and whether any such improvement might also transition into adulthood. From a total of 84 volunteers, the posture development of 67 adolescents was checked annually between the age of 14 and 20 based on index values in three posture situations. 28 adolescents exercised twice a week for about 2 h up to the age of 18, 24 adolescents exercised continually up to the age of 20. Both groups practiced other additional sports for about 1.8 h/week. Fifteen persons served as a non-exercising control group, practicing optional sports of about 1.8 h/week until the age of 18, after that for 0.9 h/week. Group allocation was not random, but depended on the participants’ choice. A linear mixed model was used to analyze the development of posture indexes among the groups and over time and the possible influence of anthropometric parameters (weight, size), of optional athletic activity and of sedentary behavior. The post hoc pairwise comparison was performed applying the Scheffé test. The significance level was set at 0.05. The group that exercised continually (TR20) exhibited a significant posture parameter improvement in all posture situations from the 2nd year of exercising on. The group that terminated their training when reaching adulthood (TR18) retained some improvements, such as conscious straightening of the body posture. In other posture situations (habitual, closed eyes), their posture results declined again from age 18. The effect sizes determined were between η² = 0.12 and η² = 0.19 and represent moderate to strong effects. The control group did not exhibit any differences. Anthropometric parameters, additional athletic activities and sedentary behavior did not influence the posture parameters significantly. An additional athletic training of 2 h per week including elements for improved body perception seems to have the potential to improve body posture in symptom free male adolescents and young adults.

Reliability of sagittal vertical axis measurement and association with measures of age-related hyperkyphosis

[Purpose] Persons with age-related hyperkyphosis often have concomitant sagittal plane imbalance of the spine. This study investigated the reliability of sagittal vertical axis (SVA) measurement of sagittal balance, association between thoracic Cobb angle of kyphosis and SVA measure of sagittal balance, and compared the degree of SVA in males and females with age-related hyperkyphosis. [Participants and Methods] Measurements of SVA and Cobb angle of kyphosis were obtained from baseline radiographs of 112 community-dwelling males and females, mean age 70.0 (SD=5.7) years with kyphosis ≥40 degrees, recruited for a randomized controlled trial. Spearman correlation coefficients were used to determine associations between SVA and kyphosis, and Wilcoxon nonparametric tests to compare SVA between genders. [Results] SVA was acquired with excellent intra-rater [0.95 (95% CI: 0.88, 0.98)] and inter-rater reliability [0.93 (95% CI: 0.83,0.97)]. There was no significant correlation between Cobb angle of thoracic kyphosis and SVA, (r=−0.05). More males than females had sagittal imbalance (SVA≥5 cm). [Conclusion] In older adults with hyperkyphosis, SVA was a reliable measure of sagittal balance, and more extreme in males. SVA was not associated with Cobb angle of thoracic kyphosis, and could be considered an independent phenotype of age-related hyperkyphosis to be targeted in future intervention trials.

Mechanical loading, an important factor in the evaluation of ion release from bone augmentation materials

The controlled release of therapeutic inorganic ions from biomaterials is an emerging area of international research. One of the foci for this research is the development of materials, which spatially and temporally modulate therapeutic release, via controlled degradation in the intended physiological environment. Crucially however, our understanding of the release kinetics for such systems remains limited, particularly with respect to the influence of physiological loading. Consequently, this study was designed to investigate the effect of dynamic mechanical loading on a composite material intended to stabilize, reinforce and strengthen vertebral bodies. The composite material contains a borate glass engineered to release strontium as a therapeutic inorganic ion at clinically relevant levels over extended time periods. It was observed that both cyclic (6 MPa 2 Hz) and static (4.3 MPa) compressive loading significantly increased the release of strontium ions in comparison to the static unloaded case. The observed alterations in ion release kinetics suggest that the mechanical loading of the implantation environment should be considered when evaluating the ion release kinetics.

Analysis of the Risk Factors for Unfavorable Radiologic Outcomes after Fusion Surgery in Thoracolumbar Burst Fracture : What Amount of Postoperative Thoracolumbar Kyphosis Correction is Reasonable?

Objective

The aims in the management of thoracolumbar spinal fractures are not only to restore vertebral column stability, but also to obtain acceptable alignment of the thoracolumbar junction (T-L junction) to prevent complications. However, insufficient surgical correction of the thoracolumbar spine would be likely to cause late progression of abnormal kyphosis. Therefore, we identified the surgical factors that affected unfavorable radiologic outcomes of the thoracolumbar spine after surgery.

Methods

This study was conducted in a single institution from January 2007 to December 2013. A total of 98 patients with unstable thoracolumbar spine fracture were included. In these patients, fixation was done through transpedicular screws with rods by three surgical patterns. We reviewed digital radiographs and analyzed the images preoperatively and postoperatively during follow-up visits to compare the change of the thoracolumbar Cobb angle with radiologic parameters and clinical outcomes. The unfavorable radiologic group was defined as the patients who were measured as having greater than 20 degrees of thoracolumbar Cobb angle on the last follow-up, or who underwent kyphotic progression of thoracolumbar Cobb angle greater than 10 degrees from the immediate postoperative state to final follow-up, or who had overt instrument failure with/without additional surgery. We assessed the risk factors that affected the unfavorable radiologic outcomes.

Results

We had 43 patients with unfavorable radiologic outcomes, including 35 abnormal thoracolumbar alignments and 14 instrumental failures with/without additional surgery. The multivariate logistic regression test showed that immediate postoperative T-L junction Cobb angle less than 10.5 degrees was a statistically significant risk factor, as well as the presence of osteoporosis (p=0.017 and 0.049, respectively).

Conclusion

Insufficient correction of thoracolumbar kyphosis was considered to be a major factor of an unfavorable radiological outcome. The spinal surgeon should consider that having a T-L junction Cobb angle larger than 10.5 degrees immediately after surgery could result in an unfavorable radiological outcome, which is related to a poor clinical outcome.

The influence of spinal-pelvic parameters on the prevalence of endplate Modic changes in degenerative thoracolumbar/lumbar kyphosis patients

Background

The typical degeneration of the vertebral endplate shown in MRI imaging is Modic change. The aim of this study was to observe the distribution of the Modic changes of vertebral endplate in degenerative thoracolumbar/lumbar kyphosis (DTK/LK) patients and analyse the correlation between spinal-pelvic parameters and Modic changes.

Methods

The imaging data of 58 patients diagnosed with DTK/LK (coronal Cobb angle<10°with sagittal imbalance) in our hospital from March 2016 to May 2017 were reviewed retrospectively. Observe the prevalence, type and distribution characteristics of Modic changes occurred at the vertebral endplate from T10 to S1;analyse the correlation between Modic changes and disc degeneration, the sagittal vertical axis (SVA), thoracic kyphosis (TK), thoracolumbar kyphosis (TLK), lumbar lordosis (LL), sacral slope (SS), pelvic tilt (PT) and pelvic incidence (PI).

Results

Of the 928 intervertebral endplates from 58 patients, Modic changes occurred at 90 endplates (9.7%) of 30 patients (51.7%). 5 endplates (0.5%) of 3 patients (5.2%) were classified as type I, 68 endplates (7.3%) of 25 patients (43.1%) as type II, 17 endplates (1.8%) of 9 patients (15.5%) as type III. The location of the degenerative endplates: 2 (2.2%) superior and inferior endplates of L1, 3 (3.3%) inferior endplates of T11and T12, 4 (4.4%) superior endplates of L2, 6 (6.7%) inferior endplates of L2 and L4, 8 (8.9%) superior endplates of S1, 9 (10%) superior endplates of L3, 11 (12.2%) inferior endplates of L3 and L5 and superior endplates of L4, 12 (13.3%) superior endplates of L5. Modic changes were significantly correlated with intervertebral disc degeneration (r = 0.414, p<0.01); the amount of Modic changes were significantly correlated with LL (r = -0.562, p = 0.012), SS (r = -0.46, p = 0.048), PT (r = 0.516, p = 0.024).

Conclusions

Most of the Modic changes of vertebral endplates in DTK/LK patients are type II which are prevalently located at L3/4, L4/5 and L5/S1. The Modic changes of vertebral endplates were found to be significantly correlated with disc degeneration, LL, SS, and PT.

Sexual Dimorphism and the Origins of Human Spinal Health

Recent observations indicate that the cross-sectional area (CSA) of vertebral bodies is on average 10% smaller in healthy newborn girls than in newborn boys, a striking difference that increases during infancy and puberty and is greatest by the time of sexual and skeletal maturity. The smaller CSA of female vertebrae is associated with greater spinal flexibility and could represent the human adaptation to fetal load in bipedal posture. Unfortunately, it also imparts a mechanical disadvantage that increases stress within the vertebrae for all physical activities. This review summarizes the potential endocrine, genetic, and environmental determinants of vertebral cross-sectional growth and current knowledge of the association between the small female vertebrae and greater risk for a broad array of spinal conditions across the lifespan.

Estimating apparent maximum muscle stress of trunk extensor muscles in older adults using subject-specific musculoskeletal models

Maximum muscle stress (MMS) is a critical parameter in musculoskeletal modeling, defining the maximum force that a muscle of given size can produce. However, a wide range of MMS values have been reported in literature, and few studies have estimated MMS in trunk muscles. Due to widespread use of musculoskeletal models in studies of the spine and trunk, there is a need to determine reasonable magnitude and range of trunk MMS. We measured trunk extension strength in 49 participants over 65 years of age, surveyed participants about low back pain, and acquired quantitative computed tomography (QCT) scans of their lumbar spines. Trunk muscle morphology was assessed from QCT scans and used to create a subject-specific musculoskeletal model for each participant. Model-predicted extension strength was computed using a trunk muscle MMS of 100 N/cm² . The MMS of each subject-specific model was then adjusted until the measured strength matched the model-predicted strength (±20 N). We found that measured trunk extension strength was significantly higher in men. With the initial constant MMS value, the musculoskeletal model generally over-predicted trunk extension strength. By adjusting MMS on a subject-specific basis, we found apparent MMS values ranging from 40 to 130 N/cm² , with an average of 75.5 N/cm² for both men and women. Subjects with low back pain had lower apparent MMS than subjects with no back pain. This work incorporates a unique approach to estimate subject-specific trunk MMS values via musculoskeletal modeling and provides a useful insight into MMS variation. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:498-505, 2018.

Vertebral cross-sectional growth: A predictor of vertebral wedging in the immature skeleton

The degree of vertebral wedging, a key structural characteristic of spinal curvatures, has recently been found to be negatively related to vertebral cross-sectional area (CSA). The purpose of this longitudinal study was to examine the relation between vertebral cross-sectional growth and vertebral wedging progression within the immature lumbar spine. Using magnetic resonance imaging (MRI), we analyzed the potential association between increases in lumbar vertebral CSA and changes in L5 vertebral wedging in 27 healthy adolescent girls (ages 9–13 years) twice within a two-year period. Vertebral CSA growth was negatively associated with changes in posteroanterior vertebral wedging (r = -0.61; p = 0.001). Multiple regression analysis showed that this relation was independent of gains in age, height, and weight. When compared to the 14 girls whose vertebral wedging progressed, the 13 subjects whose vertebral wedging decreased had significantly greater vertebral cross-sectional growth (0.39 ± 0.25 vs. 0.75 ± 0.23 cm²; p = 0.001); in contrast, there were no significant differences in increases in age, height, or weight between the two groups. Changes in posteroanterior vertebral wedging and the degree of lumbar lordosis (LL) positively correlated (r = 0.56, p = 0.002)—an association that persisted even after adjusting for gains in age, height, and weight. We concluded that in the immature skeleton, vertebral cross-sectional growth is an important determinant of the plasticity of the vertebral body; regression of L5 vertebral wedging is associated with greater lumbar vertebral cross-sectional growth, while progression is the consequence of lesser cross-sectional growth.

Thoracolumbar spine loading associated with kinematics of the young and the elderly during activities of daily living

Excessive mechanical loading of the spine is a critical factor in vertebral fracture initiation. Most vertebral fractures develop spontaneously or due to mild trauma, as physiological loads during activities of daily living might exceed the failure load of osteoporotic vertebra. Spinal loading patterns are affected by vertebral kinematics, which differ between elderly and young individuals. In this study, the effects of age-related changes in spine kinematics on thoracolumbar spinal segmental loading during dynamic activities of daily living were investigated using combined experimental and modeling approach. Forty-four healthy volunteers were recruited into two age groups: young (N = 23, age = 27.1 ± 3.8) and elderly (N = 21, age = 70.1 ± 3.9). The spinal curvature was assessed with a skin-surface device and the kinematics of the spine and lower extremities were recorded during daily living tasks (flexion-extension and stand-sit-stand) with a motion capture system. The obtained data were used as input for a musculoskeletal model with a detailed thoracolumbar spine representation. To isolate the effect of kinematics on predicted loads, other model properties were kept constant. Inverse dynamics simulations were performed in the AnyBody Modeling System to estimate corresponding spinal loads. The maximum compressive loads predicted for the elderly motion patterns were lower than those of the young for L2/L3 and L3/L4 lumbar levels during flexion and for upper thoracic levels during stand-to-sit (T1/T2-T8/T9) and sit-to-stand (T3/T4-T6/T7). However, the maximum loads predicted for the lower thoracic levels (T9/T10-L1/L2), a common site of vertebral fractures, were similar compared to the young. Nevertheless, these loads acting on the vertebrae of reduced bone quality might contribute to a higher fracture risk for the elderly.

Association Between Vertebral Cross-sectional Area and Vertebral Wedging in Children and Adolescents: A Cross-sectional Analysis

A small vertebral cross-sectional area (CSA) imparts a mechanical disadvantage that escalates the risk for vertebral fractures in elderly populations. We examined whether a small vertebral CSA is also associated with a greater degree of vertebral wedging in children. Measurements of vertebral CSA, lumbar lordosis (LL) or thoracic scoliosis angle, and vertebral wedging were obtained in 100 healthy adolescents (50 boys and 50 girls) and 25 girls with adolescent idiopathic scoliosis (AIS) using magnetic resonance imaging. Vertebral CSA of the lumbar vertebrae negatively correlated to the degree of posteroanterior vertebral wedging at L₅ (r = -0.49; p < 0.0001); this was true whether all subjects were analyzed together or boys and girls independently. In contrast, we found a positive correlation between the degree of LL and vertebral wedging (r = 0.57; p < 0.0001). Multiple regression analysis showed that the association between vertebral CSA and wedging was independent of age and body mass index. In girls with AIS, vertebral CSA negatively correlated to the degree of lateral thoracic vertebral wedging (r = -0.66; p = 0.0004), an association that persisted even after accounting for age and body mass index. Additionally, Cobb angle positively correlated to lateral thoracic vertebral wedging (r = 0.46; p = 0.021). Our cross-sectional results support the hypothesis that smaller vertebral CSA is associated with greater vertebral deformity during growth, as in adulthood. © 2017 American Society for Bone and Mineral Research.