Quantifying spinal gait kinematics using an enhanced optical motion capture approach in adolescent idiopathic scoliosis

Optical Marker-Based Motion Capture of the Human Spine: A Scoping Review of Study Design and Outcomes

Biomechanical analysis of the human spine is crucial to understanding injury patterns. Motion capture technology has gained attention due to its non-invasive nature. Nevertheless, traditional motion capture studies consider the spine a single rigid segment, although its alignment changes during movement. Moreover, guidelines that indicate where markers should be placed for a specific exercise do not exist. This study aims to review the methods used to assess spine biomechanics using motion capture systems to determine the marker sets used, the protocols used, the resulting parameters, the analysed activities, and the characteristics of the studied populations. PRISMA guidelines were used to perform a Scoping Review using SCOPUS and Web of Science databases. Fifty-six journal and conference articles from 1997 to 2023 were considered for the analysis. This review showed that Plug-in-Gait is the most used marker set. The lumbar spine is the segment that generates the most interest because of its high mobility and function as a weight supporter. Furthermore, angular position and velocity are the most common outcomes when studying the spine. Walking, standing, and range of movement were the most studied activities compared to sports and work-related activities. Male and female participants were recruited similarly across all included articles. This review presents the motion capture techniques and measurement outcomes of biomechanical studies of the human spine, to help standardize the field. This work also discusses trends in marker sets, study outcomes, studied segments and segmentation approaches.

Can external work during walking in scoliosis patients be estimated from spatiotemporal parameters?

BACKGROUND

Patients with scoliosis present gait impairments compared to healthy subjects. Clinically, spine deformity is evaluated with Cobb angle, a standard measurement to determine and track the progression of scoliosis. Scoliosis is a biomechanical trouble, dependant of external forces and muscular activity. External work is currently analyzed in patients with scoliosis because this work sums up consequences and evolutions of spine deformity. Habitually, biomechanics approach is used to compute this work. For asymptomatic subjects, a regression model let to compute external work. So, considering the area of research to facilitate the follow-up at lower cost, this regression function could be applied to patients with scoliosis but need to be validated.

RESEARCH QUESTION

can external work during walking in scoliosis patients be estimated from spatiotemporal parameters with a regression model?

METHOD

This retrospective study included twenty untreated patients with idiopathic scoliosis and sixteen asymptomatic participants. We used a regression model defined in case of asymptomatic subjects in literature and proposed a new specific model in case of patients with scoliosis.

FINDINGS

The external work in patients with scoliosis calculated with the Wirta's regression eq. (0.23 ± 0.04 J.kg-1.m-1) was underestimated compared to the external work calculated using a biomechanical method (0.33 ± 0.06 J.kg-1.m-1). A new regression model including Cobb angle and spatio-temporal parameter presents a high coefficient of determination.

INTERPRETATION

In opposition to biomechanical method, our new model let to compute external work without expensive gait laboratory. This specific model is more reliable than the model developed from asymptomatic subjects.

Concurrent Validity of the Ergotex Device for Measuring Low Back Posture

Highlighting the crucial role of monitoring and quantifying lumbopelvic rhythm for spinal curvature, the Ergotex IMU, a portable, lightweight, cost-effective, and energy-efficient technology, has been specifically designed for the pelvic and lumbar area. This study investigates the concurrent validity of the Ergotex device in measuring sagittal pelvic tilt angle. We utilized an observational, repeated measures design with healthy adult males (mean age: 39.3 ± 7.6 y, body mass: 82.2 ± 13.0 kg, body height: 179 ± 8 cm), comparing Ergotex with a 3D optical tracking system. Participants performed pelvic tilt movements in anterior, neutral, and posterior conditions. Statistical analysis included paired samples t-tests, Bland-Altman plots, and regression analysis. The findings show minimal systematic error (0.08° overall) and high agreement between the Ergotex and optical tracking, with most data points falling within limits of agreement of Bland-Altman plots (around ±2°). Significant differences were observed only in the anterior condition (0.35°, p < 0.05), with trivial effect sizes (ES = 0.08), indicating that these differences may not be clinically meaningful. The high Pearson's correlation coefficients across conditions underscore a robust linear relationship between devices (r > 0.9 for all conditions). Regression analysis showed a standard error of estimate (SEE) of 1.1° with small effect (standardized SEE < 0.26 for all conditions), meaning that the expected average deviation from the true value is around 1°. These findings validate the Ergotex as an effective, portable, and cost-efficient tool for assessing sagittal pelvic tilt, with practical implications in clinical and sports settings where traditional methods might be impractical or costly.

Non-Invasive Assessment of Back Surface Topography: Technologies, Techniques and Clinical Utility

(1) Background: Frequent exposure to ionising radiation is often used to determine the diagnosis of adolescent idiopathic scoliosis (AIS), a lateral curvature of the spine in those aged between 10 and 18 years, and a treatment plan according to Cobb angle. This narrative review outlines the clinical utility of surface topography (ST), a radiation-free imaging modality. (2) Methods: Publicly available databases were searched to yield literature related to ST. Identified articles were classified based on the equipment used and in order of how it was developed, i.e., historical, recent developments, and state-of-the-art developments. (3) Conclusions: ST is a reliable cost-effective non-invasive technique that provides an alternative to radiation-based imaging to aid with the diagnosis and potential screening of AIS. Several scanning methods are available, which allows ST to be used in several clinical environments. Limitations of inter-reliability and differences of apparatus resulting in variations of data have been noted through this narrative review.

EMG Validation of a Subject-Specific Thoracolumbar Spine Musculoskeletal Model During Dynamic Activities in Older Adults

Musculoskeletal models can uniquely estimate in vivo demands and injury risk. In this study, we aimed to compare muscle activations from subject-specific thoracolumbar spine OpenSim models with recorded muscle activity from electromyography (EMG) during five dynamic tasks. Specifically, 11 older adults (mean = 65 years, SD = 9) lifted a crate weighted to 10% of their body mass in axial rotation, 2-handed sagittal lift, 1-handed sagittal lift, and lateral bending, and simulated a window opening task. EMG measurements of back and abdominal muscles were directly compared to equivalent model-predicted activity for temporal similarity via maximum absolute normalized cross-correlation (MANCC) coefficients and for magnitude differences via root-mean-square errors (RMSE), across all combinations of participants, dynamic tasks, and muscle groups. We found that across most of the tasks the model reasonably predicted temporal behavior of back extensor muscles (median MANCC = 0.92 ± 0.07) but moderate temporal similarity was observed for abdominal muscles (median MANCC = 0.60 ± 0.20). Activation magnitude was comparable to previous modeling studies, and median RMSE was 0.18 ± 0.08 for back extensor muscles. Overall, these results indicate that our thoracolumbar spine model can be used to estimate subject-specific in vivo muscular activations for these dynamic lifting tasks.

Hip loading asymmetry in Lenke type 1 idiopathic scoliosis: Effect of spinal fusion and sex

BACKGROUND

Thoracic curvatures are most common in patients with idiopathic scoliosis. The literature highlights an imbalance of hip joint moments in the frontal plane quantified with a symmetry index. Spinal arthrodesis can reduce this symmetry index which then tends towards 0. Furthermore, asymptomatic women present lower hip moment in the frontal plane than asymptomatic men. This difference could influence the symmetry index in the case of patients with idiopathic scoliosis. Therefore, the main objective of this study was to show a significant positive effect of spinal arthrodesis on the symmetry index. The secondary objective was to compare the symmetry index between sexes before spinal fusion.

METHOD

The retrospective study included 20 patients with Type-1 Lenke curve idiopathic scoliosis, who performed a gait analysis before and one year after spinal fusion. The gait analysis consisted of walking back and forth at spontaneous speed.

FINDINGS

While significantly lower curvatures were depicted, the symmetry index showed a significantly lower value after spinal fusion (p < 0.03). The symmetry index showed no significant difference between sexes (p > 0.05).

INTERPRETATION

The study shows the effect of surgical fusion on the symmetry index, although the latter remains significant compared to the norm. Literature reveals that spinal fusion tends to the symmetrisation of the body's center of mass and increases ranges of motion on the trunk and pelvis. This could favour symmetry of hip moment in the frontal plane. Future research should investigate other Type Lenke curves before and after surgery, and the effect of braces on this symmetry index.

Multi-Modal Data Correspondence for the 4D Analysis of the Spine with Adolescent Idiopathic Scoliosis

Adolescent idiopathic scoliosis is a three-dimensional spinal deformity that evolves during adolescence. Combined with static 3D X-ray acquisitions, novel approaches using motion capture allow for the analysis of the patient dynamics. However, as of today, they cannot provide an internal analysis of the spine in motion. In this study, we investigated the use of personalized kinematic avatars, created with observations of the outer (skin) and internal shape (3D spine) to infer the actual anatomic dynamics of the spine when driven by motion capture markers. Towards that end, we propose an approach to create a subject-specific digital twin from multi-modal data, namely, a surface scan of the back of the patient and a reconstruction of the 3D spine (EOS). We use radio-opaque markers to register the inner and outer observations. With respect to the previous work, our method does not rely on a precise palpation for the placement of the markers. We present the preliminary results on two cases, for which we acquired a second biplanar X-ray in a bending position. Our model can infer the spine motion from mocap markers with an accuracy below 1 cm on each anatomical axis and near 5 degrees in orientations.

Impacts of gait biomechanics of patients with thoracolumbar kyphosis secondary to Scheuermann's disease

Introduction: Thoracolumbar kyphosis (TLK) is a common feature in patients with spinal deformities. However, due to limited studies, the impacts of TLK on gait have not been reported. The objective of the study was to quantify and evaluate the impacts of gait biomechanics of patients with TLK secondary to Scheuermann's disease. Methods: Twenty cases of Scheuermann's disease patients with TLK and twenty cases of asymptomatic participants were recruited into this study. And the gait motion analysis was conducted. Results: The stride length was shorter in the TLK group compared to control group (1.24 ± 0.11 m vs. 1.36 ± 0.21 m, p = 0.04). Compared to control group, the stride time and step time were more prolonged in the TLK group (1.18 ± 0.11s vs. 1.11 ± 0.08 s, p = 0.03; 0.59 ± 0.06 s vs. 0.56 ± 0.04 s, p = 0.04). The gait speed of the TLK group was significantly slower than it of control group (1.05 ± 0.12 m/s vs. 1.17 ± 0.14 m/s, p = 0.01); In the sagittal plane, the range of motion (ROM) of the hip in the TLK group was significantly smaller than that of the control group (37.71 ± 4.35° vs. 40.05 ± 3.71°, p = 0.00). In the transverse plane, the adduction/abduction ROMs of the knee and ankle, as well as the internal and external rotation of the knee, were smaller in TLK group than ROMs in the control group (4.66 ± 2.21° vs. 5.61 ± 1.82°, p = 0.00; 11.48 ± 3.97° vs. 13.16 ± 5.6°, p = 0.02; 9.00 ± 5.14° vs. 12.95 ± 5.78°, p = 0.00). Discussion: The main finding of this study was that measurements of gait patterns and joint movement of the TLK group were significantly lower than those of the control group. And these impacts have the potential to exacerbate degenerative progress of joints in the lower extremities. These abnormal features of gait can also serve as a guideline for physicians to focus on TLK in these patients.

Stereophotogrammetric approaches to multi-segmental kinematics of the thoracolumbar spine: a systematic review

BACKGROUND

Spine disorders are becoming more prevalent in today's ageing society. Motion abnormalities have been linked to the prevalence and recurrence of these disorders. Various protocols exist to measure thoracolumbar spine motion, but a standard multi-segmental approach is still missing. This study aims to systematically evaluate the literature on stereophotogrammetric motion analysis approaches to quantify thoracolumbar spine kinematics in terms of measurement reliability, suitability of protocols for clinical application and clinical significance of the resulting functional assessment.

METHODS

Electronic databases (PubMed, Scopus and ScienceDirect) were searched until February 2022. Studies published in English, investigating the intersegmental kinematics of the thoracolumbar spine using stereophotogrammetric motion analysis were identified. All information relating to measurement reliability; measurement suitability and clinical significance was extracted from the studies identified.

RESULTS

Seventy-four studies met the inclusion criteria. 33% of the studies reported on the repeatability of their measurement. In terms of suitability, only 35% of protocols were deemed suitable for clinical application. The spinous processes of C7, T3, T6, T12, L1, L3 and L5 were the most widely used landmarks. The spine segment definitions were, however, found to be inconsistent among studies. Activities of daily living were the main tasks performed. Comparable results between protocols are however still missing.

CONCLUSION

The literature to date offers various stereophotogrammetric protocols to quantify the multi-segmental motion of the thoracolumbar spine, without a standard guideline being followed. From a clinical point of view, the approaches are still limited. Further research is needed to define a precise motion analysis protocol in terms of segment definition and clinical relevance.

Reliability of a three-dimensional spinal proprioception assessment for patients with adolescent idiopathic scoliosis

PURPOSE

Although it is evident that some patients with adolescent idiopathic scoliosis (AIS) have proprioceptive deficit in peripheral joints, knowledge on the proprioceptive function of the deformed spine is limited. Nonetheless, spinal proprioception in AIS may be affected three-dimensionally, prior studies only focussed on evaluating peripheral proprioception in single plane. Therefore, this study aimed to develop a novel spinal proprioception assessment using three-dimensional motion analysis in patients with AIS.

METHODS

Participants were included if they had a primary diagnosis of AIS who did not receive or failed conservative treatments. Three trunk repositioning tests involving flexion-extension, lateral-flexion, and axial-rotation were conducted. A three-dimensional kinematics of the trunk was used as the outcome measures. The proprioceptive acuity was quantified by the repositioning error. The intra-examiner and test-retest reliability were analysed by the intraclass correlation coefficient (ICC).

RESULTS

Fifty-nine patients with AIS were recruited. Regarding the trunk flexion-extension test, the single measure ICC showed moderate reliability (0.46) and the average measures ICC demonstrated good reliability (0.72). As for the trunk lateral-flexion test, the reliability of single measure and average measures ICC was moderate (0.44) and good (0.70) reliability, respectively. For the trunk axial-rotation test, the single measure ICC indicated fair reliability (0.32), while the average measures ICC showed moderate reliability (0.59).

CONCLUSION

This is the first study to evaluate the reliability of novel three-dimensional spinal proprioception assessments in patients with AIS. The trunk flexion-extension repositioning test may be preferable clinical test given its highest reliability.

Limited trunk motion and posterior pelvic tilting in ambulatory children treated with bilateral rib to pelvis implants for spinal deformity control

In young children, growth-friendly spinal implants with bilateral rib to pelvis fixation are used to control progressive spinal deformity. Whereas curve progression, complications and side-effects have been extensively studied in this patient population, no data are available on gait pattern changes and postural body adjustments. Our study evaluates whether gait pattern changed for ambulatory children treated with bilateral rib to pelvis implants compared to age-matched healthy children. In this small cohort study, gait analysis was performed using spatiotemporal and kinematic parameters of four ambulatory children with severe scoliosis and growth-friendly spinal implants using the bilateral rib to pelvis fixation. Data were statistically analyzed and compared to seven healthy age-matched children. Between both groups, no differences were seen in walking speed, cadence and stride length. The treated patients showed a lower range of motion of the pelvic obliquity and of the trunk obliquity and rotation, but a higher knee flexion. Growth-friendly spinal implants with bilateral rib to pelvis fixation are commonly used in wheelchair children and rarely indicated in ambulatory patients. The presented data show reduced trunk and pelvis motion using this implant construct. These findings help to understand body postural adjustments and add valuable information for families and care providers when considering this surgery. Level of evidence: Therapeutic level IV.

Walking Biomechanics and Spine Loading in Patients With Symptomatic Lumbar Spinal Stenosis

Symptomatic lumbar spinal stenosis is a leading cause of pain and mobility limitation in older adults. It is clinically believed that patients with lumbar spinal stenosis adopt a flexed trunk posture or bend forward and alter their gait pattern to improve tolerance for walking. However, a biomechanical assessment of spine posture and motion during walking is broadly lacking in these patients. The purpose of this study was to evaluate lumbar spine and pelvic sagittal angles and lumbar spine compressive loads in standing and walking and to determine the effect of pain and neurogenic claudication symptoms in patients with symptomatic lumbar spinal stenosis. Seven participants with symptomatic lumbar spinal stenosis, aged 44–82, underwent a 3D opto-electronic motion analysis during standing and walking trials in asymptomatic and symptomatic states. Passive reflective marker clusters (four markers each) were attached to participants at T1, L1, and S2 levels of the spine, with additional reflective markers at other spinal levels, as well as the head, pelvis, and extremities. Whole-body motion data was collected during standing and walking trials in asymptomatic and symptomatic states. The results showed that the spine was slightly flexed during walking, but this was not affected by symptoms. Pelvic tilt was not different when symptoms were present, but suggests a possible effect of more forward tilt in both standing (p = 0.052) and walking (p = 0.075). Lumbar spine loading during symptomatic walking was increased by an average of 7% over asymptomatic walking (p = 0.001). Our results did not show increased spine flexion (adopting a trunk-flexed posture) and only indicate a trend for a small forward shift of the pelvis during both symptomatic walking and standing. This suggests that provocation of symptoms in these patients does not markedly affect their normal gait kinematics. The finding of increased spine loading with provocation of symptoms supports our hypothesis that spine loading plays a role in limiting walking function in patients with lumbar spinal stenosis, but additional work is needed to understand the biomechanical cause of this increase.

Subject-Specific Spino-Pelvic Models Reliably Measure Spinal Kinematics During Seated Forward Bending in Adult Spinal Deformity

Image-based subject-specific models and simulations are recently being introduced to complement current state-of-the-art mostly static insights of the adult spinal deformity (ASD) pathology and improve the often poor surgical outcomes. Although the accuracy of a recently developed subject-specific modeling and simulation framework has already been quantified, its reliability to perform marker-driven kinematic analyses has not yet been investigated. The aim of this work was to evaluate the reliability of this subject-specific framework to measure spine kinematics in ASD patients, in terms of 1) the overall test-retest repeatability; 2) the inter-operator agreement of spine kinematic estimates; and, 3) the uncertainty of those spine kinematics to operator-dependent parameters of the framework. To evaluate the overall repeatability 1], four ASD subjects and one control subject participated in a test-retest study with a 2-week interval. At both time instances, subject-specific spino-pelvic models were created by one operator to simulate a recorded forward trunk flexion motion. Next, to evaluate inter-operator agreement 2], three trained operators each created a model for three ASD subjects to simulate the same forward trunk flexion motion. Intraclass correlation coefficients (ICC's) of the range of motion (ROM) of conventional spino-pelvic parameters [lumbar lordosis (LL), sagittal vertical axis (SVA), thoracic kyphosis (TK), pelvic tilt (PT), T1-and T9-spino-pelvic inclination (T1/T9-SPI)] were used to evaluate kinematic reliability 1] and inter-operator agreement 2]. Lastly, a Monte-Carlo probabilistic simulation was used to evaluate the uncertainty of the intervertebral joint kinematics to operator variability in the framework, for three ASD subjects 3]. LL, SVA, and T1/T9-SPI had an excellent test-retest reliability for the ROM, while TK and PT did not. Inter-operator agreement was excellent, with ICC values higher than test-retest reliability. These results indicate that operator-induced uncertainty has a limited impact on kinematic simulations of spine flexion, while test-retest reliability has a much higher variability. The definition of the intervertebral joints in the framework was identified as the most sensitive operator-dependent parameter. Nevertheless, intervertebral joint estimations had small mean 90% confidence intervals (1.04°-1.75°). This work will contribute to understanding the limitations of kinematic simulations in ASD patients, thus leading to a better evaluation of future hypotheses.

The Influence of Kinematic Constraints on Model Performance During Inverse Kinematics Analysis of the Thoracolumbar Spine

Motion analysis is increasingly applied to spine musculoskeletal models using kinematic constraints to estimate individual intervertebral joint movements, which cannot be directly measured from the skin surface markers. Traditionally, kinematic constraints have allowed a single spinal degree of freedom (DOF) in each direction, and there has been little examination of how different kinematic constraints affect evaluations of spine motion. Thus, the objective of this study was to evaluate the performance of different kinematic constraints for inverse kinematics analysis. We collected motion analysis marker data in seven healthy participants (4F, 3M, aged 27–67) during flexion–extension, lateral bending, and axial rotation tasks. Inverse kinematics analyses were performed on subject-specific models with 17 thoracolumbar joints allowing 51 rotational DOF (51DOF) and corresponding models including seven sets of kinematic constraints that limited spine motion from 3 to 9DOF. Outcomes included: (1) root mean square (RMS) error of spine markers (measured vs. model); (2) lag-one autocorrelation coefficients to assess smoothness of angular motions; (3) maximum range of motion (ROM) of intervertebral joints in three directions of motion (FE, LB, AR) to assess whether they are physiologically reasonable; and (4) segmental spine angles in static ROM trials. We found that RMS error of spine markers was higher with constraints than without (p < 0.0001) but did not notably improve kinematic constraints above 6DOF. Compared to segmental angles calculated directly from spine markers, models with kinematic constraints had moderate to good intraclass correlation coefficients (ICCs) for flexion–extension and lateral bending, though weak to moderate ICCs for axial rotation. Adding more DOF to kinematic constraints did not improve performance in matching segmental angles. Kinematic constraints with 4–6DOF produced similar levels of smoothness across all tasks and generally improved smoothness compared to 9DOF or unconstrained (51DOF) models. Our results also revealed that the maximum joint ROMs predicted using 4–6DOF constraints were largely within physiologically acceptable ranges throughout the spine and in all directions of motions. We conclude that a kinematic constraint with 5DOF can produce smooth spine motions with physiologically reasonable joint ROMs and relatively low marker error.

Spinal Palpation Error and Its Impact on Skin Marker-Based Spinal Alignment Measurement in Adult Spinal Deformity

Spinal alignment measurement in spinal deformity research has recently shifted from using mainly two-dimensional static radiography toward skin marker-based motion capture approaches, allowing three-dimensional (3D) assessments during dynamic conditions. The validity and accuracy of such skin marker-based methods is highly depending on correct marker placement. In this study we quantified, for the first time, the 3D spinal palpation error in adult spinal deformity (ASD) and compared it to the error in healthy spines. Secondly, the impact of incorrect marker placement on the accuracy of marker-based spinal alignment measurement was investigated. 3D, mediolateral and inferosuperior palpation errors for thoracolumbar and lumbar vertebral levels were measured on biplanar images by extracting 3D positions of skin-mounted markers and their corresponding anatomical landmarks in 20 ASD and 10 healthy control subjects. Relationships were investigated between palpation error and radiographic spinal alignment (lordosis and scoliosis), as well as body morphology [BMI and soft tissue (ST) thickness]. Marker-based spinal alignment was measured using a previously validated method, in which a polynomial is fit through the marker positions of a motion trial and which allows for radiograph-based marker position correction. To assess the impact of palpation error on spinal alignment measurement, the agreement was investigated between lordosis and scoliosis measured by a polynomial fit through, respectively, (1) the uncorrected marker positions, (2) the palpation error-corrected (optimal) marker positions, and (3) the anatomically corrected marker positions (toward the vertebral body), and their radiographic equivalents expressed as Cobb angles (ground truth), using Spearman correlations and root mean square errors (RMSE). The results of this study showed that, although overall accuracy of spinal level identification was similar across groups, mediolateral palpation was less accurate in the ASD group (ASD_mean: 6.8 mm; Control_mean: 2.5 mm; p = 0.002). Significant correlations with palpation error indicated that determining factors for marker misplacement were spinal malalignment, in particular scoliotic deformity (r = 0.77; p < 0.001), in the ASD group and body morphology [i.e., increased BMI (r _s = 0.78; p = 0.008) and ST thickness (r _s = 0.66; p = 0.038)] in healthy spines. Improved spinal alignment measurements after palpation error correction, shows the need for radiograph-based marker correction methods, and therefore, should be considered when interpreting spinal kinematics.

A Self-Contained 3D Biomechanical Analysis Lab for Complete Automatic Spine and Full Skeleton Assessment of Posture, Gait and Run

Quantitative functional assessment of Posture and Motion Analysis of the entire skeleton and spine is highly desirable. Nonetheless, in most studies focused on posture and movement biomechanics, the spine is only grossly depicted because of its required level of complexity. Approaches integrating pressure measurement devices with stereophotogrammetric systems have been presented in the literature, but spine biomechanics studies have rarely been linked to baropodometry. A new multi-sensor system called GOALS-E.G.G. (Global Opto-electronic Approach for Locomotion and Spine-Expert Gait Guru), integrating a fully genlock-synched baropodometric treadmill with a stereophotogrammetric device, is introduced to overcome the above-described limitations. The GOALS-EGG extends the features of a complete 3D parametric biomechanical skeleton model, developed in an original way for static 3D posture analysis, to kinematic and kinetic analysis of movement, gait and run. By integrating baropodometric data, the model allows the estimation of lower limb net-joint forces, torques and muscle power. Net forces and torques are also assessed at intervertebral levels. All the elaborations are completely automatised up to the mean behaviour extraction for both posture and cyclic-repetitive tasks, allowing the clinician/researcher to perform, per each patient, multiple postural/movement tests and compare them in a unified statistically reliable framework.

Untreated adolescent idiopathic scoliotic girls display altered balance modalities during self-paced voluntary body sways compared to able-bodied girls

INTRODUCTION

This study investigated self-paced voluntary oscillations of scoliotic and non-scoliotic girls. Temporal variables and frequency coherence were calculated for the overall, low and high frequency bandwidths of the center of pressure excursions and free-moment to identify which variables best describe sway balance modalities in both groups.

METHODS

Twenty-three girls with adolescent idiopathic moderate scoliosis (spinal curves to the right) formed the scoliotic group and 19 matched able-bodied girls formed the non-scoliotic group. Each girl performed self-paced voluntary medio-lateral and antero-posterior sways while standing on a force platform. Center of pressure displacements, out of plane deviation and free-moment were measured and their frequency content calculated. The magnitude of the coherence was calculated for each signal pairs for three frequency ranges.

RESULTS

In both sway conditions, the center of pressure excursion parameters were on average 28% higher for the scoliotic group. Factor analysis revealed that balance modalities were essentially based on frequency coherence pair interactions whereas temporal parameters play a secondary role. However, these balance modalities were altered in the scoliotic group. They relied essentially on 2 additional principal components and 3 additional variables reflecting a fine tuning of the control mechanism to maintain dynamic balance.

INTERPRETATION

Scoliotic girls appear to be performing a wide ellipsoidal trajectory when performing whole body oscillations. Superfluous variables could be related to the difficulty in preserving balance during body sway tasks and could parasitize the scoliotic dynamic control balance modalities. Self-paced voluntary sways could be an appropriate complementary balance test for untreated scoliotic girls.

Gait oxygen consumption in adolescent idiopathic scoliosis and the effect of brace use

BACKGROUND

Despite studies showing that gait is affected in adolescent idiopathic scoliosis (AIS), it remains unclear whether gait oxygen consumption is altered.

RESEARCH QUESTION

The aims of the present study were to compare energy consumption during gait between subjects with AIS and healthy controls, and to examine the effect of brace use on gait energy expenditure.

METHODS

This prospectively designed study included 15 AIS and 15 healthy girls, whose ages ranged from 10 to 16 years old and Cobb angles from 20 and 45°. At the end of the first month of brace use for the first time in individuals with AIS, oxygen consumption was measured with and without brace use on a treadmill at a gait speed of 4 km.h^-1 using a metabolic analyzer.

RESULTS

There was no statistically significant difference in gross and net gait oxygen consumption measurements between AIS and healthy individuals or between individuals with AIS with or without brace use (p >  0.05).

SIGNIFICANCE

After one month of brace treatment, AIS is not associated with an additional metabolic load with or without the brace during gait when compared to healthy subjects.

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.

Walking and running with non-specific chronic low back pain: What about the lumbar lordosis angle?

Non-specific chronic low back pain (NSCLBP) is a major health problem, affecting about one fifth of the population worldwide. To avoid further pain or injury, patients with NSCLBP seem to adopt a stiffer movement pattern during everyday living activities. However, it remains unknown how NSCLBP affects the lumbar lordosis angle (LLA) during repetitive activities such as walking or running. This pilot study therefore aimed at exploring possible NSCLBP-related alterations in LLAs during walking and running by focusing on discrete parameters as well as continuous data. Thirteen patients with NSCLBP and 20 healthy pain-free controls were enrolled and underwent a full-body movement analysis involving various everyday living activities such as standing, walking and running. LLAs were derived from markers placed on the spinous processes of the vertebrae L1-L5 and S1. Possible group differences in discrete (average and range of motion (ROM)) and continuous LLAs were analyzed descriptively using mean differences with confidence intervals ranging from 95% to 75%. Patients with NSCLBP indicated reduced average LLAs during standing, walking and running and a tendency for lower LLA-ROM during walking. Analyses of continuous data indicated the largest group differences occurring around 25% and 70% of the walking and 25% and 75% of the running cycle. Furthermore, patients indicated a reversed movement pattern during running, with increasing instead of a decreasing LLAs after foot strike. This study provides preliminary evidence that NSCLBP might affect LLAs during walking and running. These results can be used as a basis for future large-scale investigations involving hypothesis testing.

Identification of the most relevant intervertebral effort indicators during gait of adolescents with idiopathic scoliosis

The intervertebral efforts, i.e., forces and torques, during gait have been recognized as influencing the progression of scoliosis, due to the mechanical modulations according to the Hueter-Volkmann Law. Therefore, these efforts are key variables for posture correction and to control the progression of scoliosis. Using the intervertebral efforts during gait for the clinical follow-ups has never been performed. For this, it would be necessary to identify amongst all these efforts the most relevant ones, which is the objective of this study. A previously developed dynamical model of the human body was used to compute the 3 D intervertebral efforts during the gait of 15 participants with adolescent idiopathic scoliosis (AIS) and 12 typically developed adolescents (TDA). Kolmogorov-Smirnov and Two-sample t-test were applied on the calculated intervertebral efforts and the graphs of intervertebral efforts were studied. Antero-posterior (AP) forces and torques and medio-lateral (ML) forces are the most relevant intervertebral efforts amongst the other efforts in adolescents with AIS during gait. Discussion: Gait analysis in adolescents with AIS based on the relevant intervertebral efforts could be an effective means to follow-up and evaluate the progression of scoliosis during their treatment period. This study highlights the most relevant intervertebral efforts of individuals with AIS during gait. As future work, the identified intervertebral efforts could be implemented in a quantified and visual feedback tool for therapeutic and performance evaluation or interactive sessions in physiotherapy, e.g., via video games for dynamic posture self-correction.

Effect of preferred walking speed on the upper body range of motion and mechanical work during gait before and after spinal fusion for patients with idiopathic scoliosis

BACKGROUND

Scoliosis may have an effect on gait parameters, the kinematics of the lower limbs and the spine, and mechanical work with specific gait speed. Imposed gait speed may influence these effects. Following spinal fusion in the case of idiopathic scoliosis, patients fear subsequent and considerable back stiffness and kinetic consequences. The aim of this retrospective study was to evaluate the upper body range of motion and mechanical work before and after spinal fusion in of free gait speed conditions.

METHODS

Twenty-two patients with idiopathic scoliosis and twenty-two asymptomatic controls were included. Patients were analyzed before and one year after spinal fusion. Based on full body modeling and motion capture, we measured gait speed, cadence, stride length, the mobility of the upper and lower spinal segments (in each plane), and mechanical work (with and without dimensionless scaling strategy).

FINDINGS

Patients walked significantly slower than controls. The same speed was noticed before and after fusion. Only the lower back kinematics in the frontal plane was reduced before fusion. Spinal fusion further reduced the mobility of the pelvis segment in the sagittal plane in comparison to controls. Scaling external work was associated with higher values for patients.

INTERPRETATION

Spinal fusion improves pelvic and thorax-pelvis mobility (during the stance phase) in the frontal plane. The impact of scoliosis on the upper body range of motion was limited on the thorax-pelvis, corresponding to a stiffening effect. With such restrictions, an increase in normalized external work was observed for similar normalized internal work.

Musculoskeletal full-body models including a detailed thoracolumbar spine for children and adolescents aged 6-18 years

Currently available musculoskeletal inverse-dynamics thoracolumbar spine models are entirely based on data from adults and might therefore not be applicable for simulations in children and adolescents. In addition, these models lack lower extremities, which are required for comprehensive evaluations of functional activities or therapeutic exercises. We therefore created OpenSim-based musculoskeletal full-body models including a detailed thoracolumbar spine for children and adolescents aged 6-18 years and validated by comparing model predictions to in vivo data. After combining our recently developed adult thoracolumbar spine model with a lower extremity model, children and adolescent models were created for each year of age by adjusting segmental length and mass distribution, center of mass positions and moments of inertia of the major body segments as well as sagittal pelvis and spine alignment based on literature data. Similarly, muscle strength properties were adjusted based on CT-derived cross-sectional area measurements. Simulations were conducted from in vivo studies reported in the literature involving children and adolescents evaluating maximum trunk muscle strength (MTMS), lumbar disc compressibility (LDC), intradiscal pressure (IDP) and trunk muscle activity (MA). Model predictions correlated highly with in vivo data (MTMS: r ≥ 0.82, p ≤ 0.03; LDC: r = 0.77, p < 0.001; IDP: r ≥ 0.78, p < 0.001; MA: r ≥ 0.90, p < 0.001), indicating suitability for the reasonably accurate prediction of maximal trunk muscle strength, segmental loading and trunk muscle activity in children and adolescents. When aiming at investigating children or adolescents with pathologies such as idiopathic scoliosis, our models can serve as a basis for the creation of deformed spine models and for comparative purposes.

Lumbatex: A Wearable Monitoring System Based on Inertial Sensors to Measure and Control the Lumbar Spine Motion

Measuring the curvature of the lumbar spine is an important challenge in disciplines related to physical therapy, rehabilitation, and sports medicine seeking to solve the incidence of the low back pain and other spinal disorders in the population. In clinical practice, most of the methods used are manual or depend on the trained eye of the specialist who is measuring. We have developed Lumbatex: an integrated system based on inertial sensors integrated into a wearable textile device. This device is connected via Bluetooth to software, which interprets data from the sensors and provides real-time biofeedback to users in a graphical way and also a quantitative measure of the curvature and spinal motion. The system is tested in two ways: first, checking the accuracy detecting changes in curvatures; second, evaluating the usability and comfort from the user standpoint. The accuracy is checked through a static method getting curvature values from the device placed on curved platforms and a dynamic validation with volunteers performing different exercises. The results obtained showed a high accuracy measuring changes in curvature with an error lower than 1° in the static test and good usability and comfort according to the opinion of the volunteers.

What are the biomechanical consequences of a structural leg length discrepancy on the adolescent spine during walking?

BACKGROUND

Structural leg length discrepancy (LLD) is a common phenomenon. However, its effect on spinal gait kinematics remains unclear.

RESEARCH QUESTION

How does LLD affect spinal gait kinematics in patients with structural LLD and what is the immediate effect of a shoe lift?.

METHODS

10 adolescents with structural LLD (20-60 mm) and 14 healthy controls were included. All of whom were fitted with a trunk marker set and requested to walk barefoot as well as with an orthotic shoe lift (only patients). Data were collected using a 12-camera motion capture system. Group comparisons were conducted using one-dimensional Statistical Parametric Mapping (SPM).

RESULTS

Patients with LLD showed statistically significant increased frontal plane lumbar bending angles to the longer side (p = 0.007), increased pelvic drop on the shorter side (p < 0.001) and increased hip adduction angles on the longer leg (p < 0.001) compared to the healthy controls. In the sagittal plane, patients demonstrated changed knee (shorter leg) and ankle joint (longer leg) motion. All gait deviations observed in patients with LLD could immediately be altered by correcting the LLD using a shoe lift.

SIGNIFICANCE

Due to the LLD, patients showed a lateral pelvic drop on the shorter side, which appeared to be compensated for by a contralateral bending in the lumbar spine and a lateral shift of the pelvis towards the longer side. In addition, the use of an orthotic correction seems to be a suitable option to instantly normalize gait kinematics in patients with mild to moderate LLD.

Postural adjustments in adolescent idiopathic thoracic scoliosis during walking

INTRODUCTION

Adolescent idiopathic scoliosis (AIS) is the most common type of three-dimensional spinal deformity. Identifying the postural adjustments or changes for different phases and events is needed for developing programs to improve the AIS gait, but such information has been limited. The current study aimed to fill the gap via three-dimensional motion analysis of quiet standing and level walking in patients with severe thoracic AIS.

MATERIALS AND METHODS

Sixteen female adolescents with AIS (Lenke 1 or 2, age: 14.9 ± 1.7 years, height: 154.7 ± 5.0 cm, mass: 41.7 ± 7.2 kg) and sixteen sex-, age- and BMI-matched healthy controls (age: 14.8 ± 2.7 years, height: 154.9 ± 5.6 cm, mass: 44.7 ± 6.3 kg) participated in the current study with informed written consent. The kinematic and kinetic changes between the trunk, pelvis, and lower limb segments, and at the lumbosacral level at different gait events were measured during quiet standing and level walking.

RESULTS

The homogeneity of the current patient group helped reduce the effects of the level and severity of spinal deformity on inter-subject variability that has been associated with controversies over reported gait variables in AIS. The current results support the hypothesis that postural adjustments involving the trunk, pelvis and lower limb segments were needed in severe thoracic AIS during both quiet standing and level walking, and differed between concave and convex sides at different key gait events during level walking.

CONCLUSIONS

Although scoliotic spinal deformity occurred mainly in the frontal plane, postural adjustments in all three planes were present at key events during level walking with associated joint loading changes in patients with severe thoracic AIS. Monitoring of such adjustments and the associated joint kinetic changes will be helpful for assessing the disease and treatment outcomes.

Changes in thoracic and lumbar spinal motions during running in a female with scoliosis

[Purpose] The aim of this study was to analyze changes in thoracic and lumbar spinal motions during running in a female athlete with scoliosis. [Participant and Methods] A female with scoliosis who was a member of a college track team was recruited for this study. On 1.5-T magnetic resonance imaging, angles between bodies of adjacent vertebrae in the frontal plane were calculated. We measured real-time spine movement while running using a three-dimensional motion analysis system, wherein the running speed was altered (6, 9, and 12 km/h). [Results] We observed a Cobb angle of 29.0° and the right convex curvature of the thoracolumbar spine on magnetic resonance imaging. As the running speed increased, during the right stance phase, the participant increased the lateral bending angle of the thoracic spine to the left and the lumbar spine to the right. However, during the left stance phase, the runner bent the thoracic spine to the right and the lumbar spine to the left, indicating a decreased convex curvature of the spine. [Conclusion] As the running speed increased, the convex curvature of the spine was corrected during the left stance phase but was uncorrected during the right stance phase.

Sling-based infant carrying affects lumbar and thoracic spine neuromechanics during standing and walking

BACKGROUND

Regular infant carrying might be a contributing factor for the development and progression of low back and pelvic girdle pain in mothers after childbirth. However, the neuromechanical adaptations of the spine due to different sling-based carrying techniques are not sufficiently well understood in order to provide evidence-based carrying recommendations.

RESEARCH QUESTION

What are the immediate effects of different sling-based infant carrying techniques on trunk neuromechanics?

METHODS

Using a Vicon motion capture and a wireless surface electromyography system, three-dimensional pelvis and spinal kinematics as well as activation patterns of eight trunk muscles were derived from fifteen healthy young women during upright standing and level walking without carrying a load and while carrying a 6 kg-dummy with a sling in front and on either side. Data were analyzed using Statistical Parametric Mapping, allowing group comparisons of discrete parameters (standing) as well as continuous data (walking). To distinguish between clinically relevant and clinically not relevant kinematic findings, statistically significant differences were only considered in case of ≥5°.

RESULTS

Compared to unloaded walking, carrying the dummy in front was mainly associated with increased lumbar lordosis (standing: (Δ8.8°, p = 0.006; walking: (Δ ≥ 8.2°, 1-100% of gait cycle [%GC], p < 0.001). When carrying the dummy on the preferred side, increased thoracic kyphosis (standing: ≥6.4°, p ≤ 0.003; walking: Δ ≥ 5.6°, 1-100%GC, p < 0.001) and axial rotation towards the ipsilateral side (standing: Δ5.3°, p = 0.003; walking: Δ ≥ 5.0°, 46-58%GC, p = 0.002) were observed. All three conditions entailed increased paraspinal muscle activity during walking, although only unilaterally in side carrying (lumbar, preferred condition: Δ ≥ 13.2%maxMVIC, 49-57%GC, p < 0.001; thoracic, non-preferred condition: Δ ≥ 5.3%maxMVIC, 47-58%GC, p < 0.001).

SIGNIFICANCE

Carrying an infant alternating on both sides using a sling could be advantageous for preventing musculoskeletal pain resulting from excessive lumbar hyperextension and paraspinal muscle hyperactivation in women after childbirth.

Between-session reliability of opto-electronic motion capture in measuring sagittal posture and 3-D ranges of motion of the thoracolumbar spine

This study evaluated between-session reliability of opto-electronic motion capture to measure trunk posture and three-dimensional ranges of motion (ROM). Nineteen healthy participants aged 24-74 years underwent spine curvature, pelvic tilt and trunk ROM measurements on two separate occasions. Rigid four-marker clusters were attached to the skin overlying seven spinous processes, plus single markers on pelvis landmarks. Rigid body rotations of spine marker clusters were calculated to determine neutral posture and ROM in flexion, extension, total lateral bending (left-right) and total axial rotation (left-right). Segmental spine ROM values were in line with previous reports using opto-electronic motion capture. Intraclass correlation coefficients (ICC) and standard error of measurement (SEM) were calculated as measures of between-session reliability and measurement error, respectively. Retroreflective markers showed fair to excellent between-session reliability to measure thoracic kyphosis, lumbar lordosis, and pelvic tilt (ICC = 0.82, 0.63, and 0.54, respectively). Thoracic and lumbar segments showed highest reliabilities in total axial rotation (ICC = 0.78) and flexion-extension (ICC = 0.77-0.79) ROM, respectively. Pelvic segment showed highest ICC values in flexion (ICC = 0.78) and total axial rotation (ICC = 0.81) trials. Furthermore, it was estimated that four or fewer repeated trials would provide good reliability for key ROM outcomes, including lumbar flexion, thoracic and lumbar lateral bending, and thoracic axial rotation. This demonstration of reliability is a necessary precursor to quantifying spine kinematics in clinical studies, including assessing changes due to clinical treatment or disease progression.

How to squat? Effects of various stance widths, foot placement angles and level of experience on knee, hip and trunk motion and loading

Background

Squatting is a core exercise for many purposes. The tissue loading during squatting is crucial for positive adaptation and to avoid injury. This study aimed to evaluate the effect of narrow, hip and wide stance widths, foot position angles (0°, 21°, and 42°), strength exercise experience, and barbell load (0 and 50% body weight, experts only) during squatting.

Methods

Novice (N = 21) and experienced (N = 21) squatters performed 9 different variations of squats (3 stance widths, 3 foot placement angles). A 3D motion capture system (100 Hz) and two force plates (2000 Hz) were used to record mediolateral knee displacement (ΔD*), range of motion (RoM) at the hip and knee joints, and joint moments at the hip, knee, and lower back.

Results

Both stance width and foot placement angles affected the moments at the hip and knee joints in the frontal and sagittal planes. ΔD* varied with stance width, foot placement angles and between the subjects’ level of experience with the squat exercise as follows: increasing foot angle led to an increased foot angle led to an increased ΔD*, while an increased stance width resulted in a decreased ΔD*; novice squatters showed a higher ΔD*, while additional weight triggered a decreased ΔD*.

Conclusions

Suitable stance width and foot placement angles should be chosen according to the targeted joint moments. In order to avoid injury, special care should be taken in extreme positions (narrow stand-42° and wide stance-0°) where large knee and hips joint moments were observed.

Electronic supplementary material

The online version of this article (10.1186/s13102-018-0103-7) contains supplementary material, which is available to authorized users.

An index to quantify deviations from normal trunk mobility: Clinical correlation and initial test of validity

BACKGROUND

In case of people suffering from chronic low back pain, specific movements of the hip, pelvis, and trunk are associated with pain. Comparing range of motion measurements for multiple planes and from different segments and lines in reference to those of healthy individuals seems interesting but present interpretations challenge in relation to important number of variables and correlation with clinical data.

METHODS

The proposed index is based on using principal component analysis to quantify differences in trunk mobility between patients with chronic low back pain and a control group. Kinematic data were recorded for the cervical and thoracic vertebrae, the lumbar spine, and the pelvic and scapular belts during repeated trials (hip flexion and extension, hip bending, and trunk twists). Angular motion values were calculated. Principal component analysis was used to convert 10 discrete variables (kinematical data) extracted from control data into 10 independent variables.

FINDINGS

The proposed index comprises the sum of the variables. Initial demonstration of its clinical utility and statistical tests of this index validity were revealed. It establishes correlations between the psychosocial impact of chronic low back pain, trunk mobility (as summarized by the index) and the positive effects of functional restoration program.

INTERPRETATION

This index let to assess the absolute potential benefits of rehabilitation in term of kinematic motion. Functional restoration program promotes the physical functioning of patients by increasing their range of motion. This index uses kinematic motion to assess the potential benefits of such rehabilitation program.

Spinal kinematics during gait in healthy individuals across different age groups

Most studies investigating trunk kinematics have not provided adequate quantification of spinal motion, resulting in a limited understanding of the healthy spine's biomechanical behavior during gait. This study aimed at assessing spinal motion during gait in adolescents, adults and older individuals. Fourteen adolescents (10-18years), 13 adults (19-35years) and 15 older individuals (≥65years) were included. Using a previously validated enhanced optical motion capture approach, sagittal and frontal plane spinal curvature angles and general trunk kinematics were measured during shod walking at a self-selected normal speed. Postural differences indicated that lumbar lordosis and thoracic kyphosis increase throughout adolescence and reach their peak in adulthood. The absence of excessive thoracic kyphosis in older individuals could be explained by a previously reported subdivision in those who develop excessive kyphosis and those who maintain their curve. Furthermore, adults displayed increased lumbar spine range of motion as compared to the adolescents, whereas the increased values in older individuals were found to be related to higher gait speeds. This dataset on the age-related kinematics of the healthy spine can serve as a basis for understanding pathological deviations and monitoring rehabilitation progression.

Upper extremity motion during gait in adolescents with structural leg length discrepancy-An exploratory study

BACKGROUND AND PURPOSE

Depending on the extent of a structural leg length discrepancy (LLD), several compensatory mechanisms take place in order to maintain function and to optimize energy consumption during gait. However, studies describing the influence of a structural LLD on upper limb motion are lacking. The current study therefore aimed at the evaluation of upper limb motion during gait in LLD patients compared to healthy controls.

METHODS

Motion capture data from 14 patients with structural LLD and 15 healthy controls that were collected during barefoot walking at a self-selected speed were retrospectively analyzed. Specifically, kinematic parameters of the shoulder and elbow joints as well as the trunk segment were investigated and considered in relation to a minimal clinically important difference of 5°.

RESULTS

The shoulders in LLD patients were kept constantly in a more extended and at initial contact in a more adducted position as compared to healthy controls. In addition, the patients' elbow joints showed increased flexion motion and the trunk segment indicated a constant trunk lateral-flexion and axial rotation tendency towards the affected side.

CONCLUSIONS

Patients with structural LLD indicated clinically relevant secondary deviations in shoulder and elbow motion. While some of these deviations were most likely passive physical effects, others might have occurred as active strategies to maintain balance or to regulate total body angular momentum. These findings contribute to the understanding of secondary gait deviations induced by a structural LLD and might serve as a basis for further investigations using complex musculoskeletal models.

Measurement and Geometric Modelling of Human Spine Posture for Medical Rehabilitation Purposes Using a Wearable Monitoring System Based on Inertial Sensors

This paper presents a mathematical model that can be used to virtually reconstruct the posture of the human spine. By using orientation angles from a wearable monitoring system based on inertial sensors, the model calculates and represents the curvature of the spine. Several hypotheses are taken into consideration to increase the model precision. An estimation of the postures that can be calculated is also presented. A non-invasive solution to identify the human back shape can help reducing the time needed for medical rehabilitation sessions. Moreover, it prevents future problems caused by poor posture.

Gait and energy consumption in adolescent idiopathic scoliosis: A literature review

BACKGROUND

Adolescent idiopathic scoliosis (AIS) is a progressive growth disease that affects spinal anatomy, mobility, and left-right trunk symmetry. The disease can modify human gait.

OBJECTIVE

We aimed to review articles describing the measurement of gait parameters and energy consumption in AIS during walking without any intervention.

STUDY DESIGN

Literature review.

METHODS

The search strategy was based on the Population Intervention Comparison Outcome method and included all relevant articles published from 1996 to 2015. Articles were searched in MEDLINE via PubMed, Science Direct, Google Scholar, and ISI Web of Knowledge databases.

RESULTS

We selected 33 studies investigating the effect of scoliosis deformity on gait parameters and energy expenditure during walking. Most of the studies concluded no significant differences in walking speed, cadence and step width in scoliosis patients and normal participants. However, patients showed decreased hip and pelvic motion, excessive energy cost of walking, stepping pattern asymmetry and ground reaction force asymmetry.

CONCLUSION

We lack consistent evidence of the effect of scoliosis on temporal spatial and kinematic parameters in AIS patients as compared with normal people. However, further research is needed to assess the effect of scoliosis on gait and energy consumption.

Orthotic correction of lower limb function during gait does not immediately influence spinal kinematics in spastic hemiplegic cerebral palsy

BACKGROUND AND PURPOSE

Foot equinus and leg length discrepancy (LLD) are common problems in hemiplegic cerebral palsy (hCP), both causing secondary deviations of pelvic motion during gait. It can therefore be assumed that the spinal deviations observed in hCP patients are secondary as a compensation for the position of the pelvis arising from the disturbed leg function. This study investigated the effects of correcting lower extremity function by orthotics on spinal gait kinematics in hCP patients.

METHODS

Ten adolescent hCP patients and 15 healthy controls were included. Using a validated and previously used enhanced marker set, sagittal and frontal plane spinal curvature angles as well as general trunk and lower extremity kinematics were measured while walking barefoot as well as with an orthotic correction (only hCP patients) using a 12-camera motion capture system.

RESULTS

The hCP patients in both the barefoot and orthotic conditions indicated clinically relevant greater lumbar lordosis angles (d≥0.96, p≤0.071), smaller thoracic kyphosis angles (d≥0.84, p≤0.142) and differences in frontal plane lumbar curvature angles (d≥1.00, p≤0.105) compared to controls. However, these angles were not influenced by the successful restoration of a normal heel-to-toe gait pattern and the correction of any LLD using lower extremity orthotics.

CONCLUSIONS

Spinal gait deviations in adolescents with mild hCP seemed not to result secondarily from foot equinus or LLD, but probably from structural deformities such as hip flexor contractures. Future research should address long-term effects of an AFO treatment as well as the relationship between spinal kinematics and severity of disease.