Rotation Of Spine Research Articles

Axial tension/compression and torsional loading of diamond and gyroid lattice structures for biomedical implants: Simulation and experiment

Lattice structures are increasingly used in biomedical implants, notably intervertebral cages, requiring a better understanding of their behavior for the different types of loading they undergo during application. Strut-based diamond and sheet-based gyroid structures with porosity levels ranging from 50 to 80 % and an identical pore size of 750 μm were manufactured from Ti6Al4V alloy, tested experimentally and simulated numerically in axial tension/compression and in torsion to simulate flexion/extension, compression and rotation of the human spine. The manufactured structures were within 5 % of the targeted porosity. However, numerical simulations overestimated the experimental apparent (effective) stiffness and strength of the structures by an average of 25 %, likely due to the presence in them of manufacturing defects, especially in the higher porosity lattices. Experimental and numerical results showed that the structures have quasi-identical mechanical properties in compression and in tension. However, a comparison of the torsion and axial results indicated that conventional bulk material failure theories such as the von Mises limitation criterion do not apply to the apparent properties of lattice structures. Studied lattices exhibited adequate resistance for use in intervertebral cages, however their stiffness was greater than those of the vertebrae, while situated in the stiffness range of cortical bone.

Association between age, sex and cervical and upper cervical rotation tests. Descriptive and correlational study in healthy volunteers.

Active cervical spine rotation (ACROM Rot) shows cervical rotation and flexion rotation test (FRT); side-bending rotation test (SBRT) and upper cervical axial rotation test (C0-C2ART) are described to measure upper cervical rotation. The objectives of this study are (1) to describe the normal range of motion (ROM) of ACROM Rot, and the ROM in FRT, SBRT and C0-C2ART tests; (2) to explore the correlation among the four tests and (3) to investigate the influence of age and sex in their ROM. A cross-sectional study was carried out with healthy volunteers from 18 to 75 years of age. Tests were measured using a CROM device and a bubble inclinometer. Descriptive analysis was performed to establish normative data for the ROM tests. Correlation analysis was conducted to understand the relation between upper and global cervical rotation ROM and among the three upper cervical rotation tests. Linear regression models were developed to understand the influence of age and sex in the ROM of all tests. Normative values were obtained from 122 healthy volunteers (50% male), by sex and age strata. The degree of correlation ranged between 0.582 (p < 0.01) for FRT and ACROM Rot left and 0.217 (p < 0.05) for SBRT and C0-C2ART left. Linear regression models showed the influence of sex for ACROM Rot right (men -4.64° less than women), SBRT (men -4.1° less than women) left and C0-C2ART right and left (men -2.24° and -1.78° less than women). The age influenced rotation ROM with a decrease for every 10 years of -2.11° and -1.96° for ACROM Rot right and left, of -1.72° and -1.26° for FRT right and left and -0.58° and -0.41° for C0-C2ART right and left in the linear regression models. No association was found between age and SBRT (p = 0.63 for right SBRT and p = 0.49 for left SBRT). Weak-to-moderate correlation was found between the upper cervical spine rotation tests and with the ACROM. Women had a larger ROM in ACROM Rot right, SBRT left and C0-C2ART. Decreases in ROM related with age were observed for ACROM Rot, FRT and C0-C2ART but not for SBRT.

Kinetics of the front-arm technique in cricket fast bowling

The aim of this study was to investigate the kinetics of the front arm in cricket fast bowling. Eighteen male fast bowlers (mean age = 17.2 ± 1.6 years; mean height = 1.89 ± 0.05 m; mean mass = 85.0 ± 10.0 kg) were recruited from NSW grade club level and their bowling actions recorded by a Cortex 2.0 motion analysis system (200 Hz). The interaction between joint power and joint angular velocity data was observed simultaneously for the front shoulder and elbow joints. A joint actuation strategy (active or controlled) was assigned to shoulder flexion–extension, abduction–adduction, and elbow flexion–extension motion to understand whether the joint kinematics followed the time-history of the joint torque. The results only partially agreed with the commonly prescribed coaching maxim of “pulling down” the front arm for faster ball speeds. Active extension and adduction of the front shoulder joint were observed during the delivery phase of the action, whereas the acceleration phase was marked by periods of controlled shoulder extension and active shoulder flexion. At the elbow joint, active elbow flexion was observed at a time when it may reduce the moment of inertia about the thoracic and lumbar spine rotation axes. Overall, combinations of active and controlled joint powers were observed for the front shoulder and elbow joints, implying that this sample of bowlers did not adhere to the traditional notion of “pulling down” the front arm as fast as possible.

Developing a Spine Internal Rotation Angle Measurement System Based Machine Learning Using CT Reconstructed X-ray Anteroposterior Image

The purpose of this study was to develop a predictive model for estimating the rotation angle of the vertebral body on X-ray anteroposterior projection (AP) image by applying machine learning. This study is intended to replace internal/external rotation of the thoracic spine (T-spine), which can only be observed through computed tomography (CT), with an X-ray AP image. 3-dimension (3D) T-spine CT images were used to acquired reference spine axial angle and various internal rotation T-spine reconstructed X-ray AP image. Distance from the pedicle to the outside of the spine and change in distance between the periphery of the pedicle according to the rotation of the spine were designated as main variables using reconstructed X-ray AP image. The number of measured spines was 453 and the number of variables for each spine was 13, creating a total of 5889 data. We applied a total of 24 regression machine learning methods using MATLAB software, performed learning with the acquired data, and finally, the Gaussian regression method showed the lowest RMSE value. X-rays obtained with the phantom of the human body tilted by 16 degrees showed results with reproducibility within the RMSE range.

Towards improving the accuracy of musculoskeletal simulation of dynamic three-dimensional spine rotations with optimizing model and algorithm.

The accuracy of musculoskeletal simulations greatly relies on model structures and optimization algorithms. This study investigated the unclarified influence of accounting for several commonly-simplified different model components and optimization criteria on spinal musculoskeletal simulations. The study constructed a full-body musculoskeletal model with passive components of functional spinal units and spinal muscles subject-specifically refined. A muscle redundancy solver was built with 15 optimization criteria. Three-dimensional spine rotations and spinal muscle activities were measured using optical motion capture and electromyogram techniques when eight healthy volunteers performed standing, flexion/extension, lateral bending, and axial rotation. The effect of the model with four different conditions of the passive components and the sensitivity of the 15 optimization criteria on simulations were investigated. Accounting for the refined passive components significantly improved the simulation accuracy. Different optimization criteria behaved distinctly for different motions. Generally minimizing the sum of squared muscle activations outperformed the others, with the highest averaged correlation coefficient (0.82) between the estimated erector spinae muscle activations and measured electromyography and with the estimated joint compression forces comparable to in vivo reference data. This study highlights the importance of passive model components and proposes a suitable optimization framework for realistic spinal musculoskeletal simulations.

Finite Element Analysis and Validation of Segments C2-C7 of the Cervical Spine

As an important part of the human spine, the cervical spine has a complex structure and easily suffers from diseases. Analysis of the biomechanical mechanism of cervical spine structure using the finite element model is not only helpful for the diagnosis, treatment and prevention of cervical spine diseases but also has positive significance for the performance evaluation of cervical spine implants. In this paper, a method of establishing a cervical C2-C7 finite element model based on CT image data is studied. Through the preprocessing of cervical CT images, the C2-C7 three-dimensional finite element model of the cervical spine was established. The pure moment loads of 0.33 Nm, 0.5 Nm, 1 Nm, 1.5 Nm and 2 Nm were applied to simulate flexion/extension, and the moment of 1 Nm was used to simulate the left and right lateral bending and axial rotation of the cervical spine. The relative range of motion (ROM) between each vertebral body was calculated. At the same time, the stress on some segments under axial load was analyzed. The results were basically consistent with the experimental data of in vitro studies, which verified the validity of the model.

Nordic walking with an integrated resistance shock absorber affects the femur strength and muscles torques in postmenopausal women

Deterioration of the structure and function of the musculoskeletal system represents a significant problem during aging and intervention with a suitable load of physical activity may improve the quality of life. Nordic walking (NW) has become a popular and easily accessible form of activity, especially for older adults people around the world. Thus, the purpose of the study was to evaluate the influence of an Nordic walking training program with classic poles (NW) and with integrated resistance shock absorber (RSA) on bone mineral density and the peak torques of upper limb muscles and to compare the effects of both intervention programs. 25 women were randomly assigned to two training groups: 10 subjects using RSA (68 ± 4.19 years) and 15 subjects using NW poles (65 ± 3.40 years), which completed 8 weeks of training program. The hip, spine and forearm areal bone mineral density, torques of the flexors and extensors at the elbow and shoulder joints were measured before starting the training programs and after their completion. The most significant effect was found in differences between the two groups of women with respect to the femur strength index (p = 0.047) and the ratio of the flexors to extensors in the elbow (p = 0.049) and shoulder (p = 0.001) joints and peak torque of flexors in the shoulder joint (p = 0.001) for the left arm. A significant difference was also found in the index of torque asymmetry of flexors in the shoulder joint (p = 0.002). The study shows that Nordic walking with RSA poles for postmenopausal women led to beneficial changes in the femur strength index. However, we found no significant influence on bone mineral density values measured on the whole body, the femoral neck, forearm or lumbar spine regions. The occurrence of asymmetry in biomechanical muscle parameters, which was observed using RSA poles, may suggest the necessity of systematic controlling the gait technique to avoid the adverse consequences of asymmetrical rotation of the lumbar spine.

Síndrome Facetária Lombar

Low back pain originating from lumbar facet joints or zygapophyseal joints has been identified as a potential cause of low back pain. Facet osteoarthritis, a degenerative pathology, is the most common cause of facet pain, and its prevalence increases with age. Facet syndrome is a frequent diagnosis in rhythmic and acrobatic gymnastics athletes, surfing, bodyboarding, and yoga, due to its characteristic repetitive and / or maintained movements of hyperextension and rotation of the lumbar spine. The facet syndrome does not yet reach consensus from its diagnosis to the therapeutic strategies adopted, being still poorly understood, and probably underdiagnosed, which implies the need for further investigation.

Where should Scoliometer and EOS Imaging be Applied when Evaluating Spinal Rotation in Adolescent Idiopathic Scoliosis -A Preliminary Study with Reference to CT Images.

Retrospective study. Our purpose was to evaluate spinal rotation measurement by scoliometer or EOS Imagings with reference to that by CT images, and to clarify their applicability in clinical practice. Patients with adolescent idiopathic scoliosis (AIS) who were indicated for surgery were enrolled and the informed consents were obtained. The angle of trunk rotation (ATR) was measured by the scoliometer. Apical vertebral rotation (AVR) was measured with EOS Imaging and CT images. Paired T tests were used to compare the measurements between ATR or AVR-EOS and AVR-CT. Pearson correlation analysis was performed to explore the relationship between ATR or AVR-EOS and AVR-CT. Then subgroup analysis was performed. Forty-seven consecutive AIS patients with 62 curves were identified. In the whole group, the ATR, as well as AVR-EOS, was significantly smaller than the AVR-CT. Both ATR and AVR-EOS correlated with AVR-CT, although AVR-EOS correlated better. In thoracic group, there was no significant difference between ATR and AVR-CT (P = .236). A significant correlation was found between ATR and AVR-CT(r = .574, P < .001). In TL/L group, no significant difference was noted between AVR-EOS and AVR-CT (P = .414), and a significant correlation was found between AVR-EOS and AVR-CT(r = .824, P < .001). ATR by scoliometer is numerically similar to AVR by CT and may evaluate the spinal rotation more appropriately in thoracic spine. AVR by EOS is numerically similar to AVR by CT and may be more applicable in TL/L spine. Appropriate methods could be selected according to the location of the curve.

Kinematic and biomechanical responses of the spine to distraction surgery in children with early onset scoliosis: A 3-D finite element analysis.

Periodical and consecutive distraction is an effective treatment for severe early onset scoliosis (EOS), which enables the spinal coronal and sagittal plane deformity correction. However, the rate of rod fractures and postoperative complications was still high mainly related to the distraction process. Previous studies have primarily investigated the maximum safe distraction force without a rod broken, neglecting the spinal re-imbalance and distraction energy consumption, which is equally vital to evaluate the operative value. This study aimed to reveal the kinematic and biomechanical responses occurring after spinal distraction surgery, which were affected by traditional bilateral fixation. The spinal models (C6-S1) before four distractions were reconstructed based on CT images and the growing rods were applied with the upward displacement load of 0–25 mm at an interval of 5 mm. Relationships between the distraction distance, the distraction force and the thoracic and lumbar Cobb angle were revealed, and the spinal displacement and rotation in three-dimensional directions were measured. The spinal overall imbalance would also happen during the distraction process even under the safe force, which was characterized by unexpected cervical lordosis and lateral displacement. Additionally, the law of diminishing return has been confirmed by comparing the distraction energy consumption in different distraction distances, which suggests that more attention paid to the spinal kinematic and biomechanical changes is better than to the distraction force. Notably, the selection of fixed segments significantly impacts the distraction force at the same distraction distance. Accordingly, some results could provide a better understanding of spinal distraction surgery.

MRI and Anatomical Determinants Affecting Neuroforaminal Stenosis Evaluation: A Descriptive Observational Study.

PurposeNeuroforaminal stenosis (NFS), a narrowing of the intervertebral foramen, is a cause of disability in the aging population. Formal magnetic resonance imaging (MRI) classification of NSF has been developed recently and contradictory findings have been reported. This study aims to assess whether in-plane, anatomically conformed two-dimensional (2D) views of the neuroforamen characterize NFS more accurately than traditional axial, coronal, and sagittal views in healthy individuals with and without simulated scoliosis.Patients and methodsThis observational study was approved by the designated institutional review board at our academic tertiary care center. Four volunteers underwent lumbar spine MRI twice, once in the supine position and once with intentionally introduced hip tilt. The latter resulted in lumbar curvature mimicking positioning errors approximating degenerative lumbar scoliosis. Anatomically oriented cuts such as axial with endplate correction and coronally obliqued parasagittals, also called coronal obliques, were performed. Standard sagittal and axial views were also performed in both the supine and rotated groups.ResultsCoronal oblique and anatomically oriented axial views demonstrated the highest correlation with true neuroforaminal caliber. Deviation from anatomical congruence resulted in false measurements of neuroforaminal size. The hip-tilt studies produced MR that were less favorable to characterization of the caliber of neuroforamina. Coronal sections demonstrated reliability only when performed at the mid-pedicular lines. Standard axial views were reliable only when taken at the upper one-third of the neuroforamen. Coronal oblique views demonstrated superiority when evaluating consecutive neuroforamen on one image compared to non-obliqued parasagittal slices.ConclusionTo minimize error in neuroforaminal analysis, imaging specialists should perform anatomically oriented cuts to conform to individual patient anatomy. When this cannot be performed due to a patient’s spine rotation or position, the MRI reader should view oblique, axial, and coronal images simultaneously and dynamically for proper foraminal characterization.

Altered Cervical Spine Position Results in Decreased Shoulder Rotation Strength.

Strength testing of shoulder rotation is commonly used in clinical examinations of the shoulder. People prone to shoulder injury, such as overhead athletes and manual trade workers, place their shoulders under tremendous amounts of stress when the cervical spine is in nonneutral positions. If these nonneutral cervical spine positions result in decreased shoulder strength, it may help explain the etiology of the high prevalence of shoulder injuries in these populations. Given standard clinical strength assessments are performed with a neutral cervical spine, an investigation into the effects of cervical spine rotation is warranted. We sought to compare isokinetic shoulder rotation strength while in a neutral position with rotated cervical spine positions, specifically (1) with the cervical spine rotated contralaterally with the shoulder elevated in the frontal plane and (2) with the cervical spine rotated ipsilaterally and the shoulder elevated in the scapular plane. A convenience sample of 52 individuals (height 170 ± 10 cm; weight 73 ± 18 kg, age 21 ± 2 years; 18 males, 34 females), without shoulder or cervical spine pathology participated in this study. Participants were screened for eligibility via questionnaire. Concentric shoulder internal and external rotation torque was measured through a 90° arc on an isokinetic dynamometer with the shoulder elevated 90° in the frontal plane, and again 45° anterior to the frontal plane (scapular plane). Two repetitions were performed in a single testing session with the participant's cervical spine in neutral in both planes, maximally rotated contralaterally in the frontal plane, and maximally rotated ipsilaterally with the shoulder in the scapular plane; the second repetition was used for analysis. The testing order was randomized. Data were imported into a platform for statistical parametric mapping analysis (a technique that allows data from the entire arc of motion to be compared with data from another arc to identify differences in the wave form) to compare strength between positions throughout 90° arc of motion. Rotating the cervical spine contralaterally with the shoulder in the frontal plane resulted in a decrease in external (2.24 Nm or 12% average difference; p < 0.001) and internal (2.22 Nm or a 6% average difference; p = 0.02) rotation strength with the forearm within 15° and 20° of the vertical position. Rotating the cervical spine ipsilaterally with the shoulder in the scapular plane resulted in a decrease in external rotation strength (1.27 Nm or a 6% average difference; p < 0.001) throughout nearly all the motion, with peaks approximately 20° and 60° from the horizontal position, and internal rotation strength (1.78 Nm or 5% average difference; p < 0.001) the last 60° towards the horizontal position. Patient populations who require strenuous use of their shoulders in altered cervical spine positions may be at increased risk for injury from decreased shoulder rotator strength. Clinicians should assess shoulder strength in the position the patient requires to use their shoulder because cervical spine position may cause weakness that would be missed in standard testing positions.

In Vivo Changes in Dynamic Adjacent Segment Motion 1 Year After One and Two-Level Cervical Arthrodesis.

Biomechanical cadaver testing indicates adjacent segment motion increases after one-level anterior cervical spine arthrodesis, and two-level arthrodesis exacerbates these effects. There is little in vivo evidence to support those biomechanical studies. The purpose of this study was to assess the effects of one- and two-level cervical arthrodesis on adjacent segment motion. Fifty patients received either one-level C56 arthrodesis or two-level C456 or C567 arthrodesis and were tested preoperatively (PRE) and 1 year postoperatively (1YR-POST) along with 23 asymptomatic controls. A validated CT model-based tracking technique was used to measure 3D vertebral motion from biplane radiographs collected during dynamic flexion-extension and axial rotation of the cervical spine. Head and adjacent segment intervertebral end-range range of motion (ROM) and mid-range ROM were compared between one-level and two-level arthrodesis patients and controls. Small (2.3° or less) but non-significant increases in adjacent segment end-range ROM were observed from PRE to 1YR-POST. Mid-range flexion-extension ROM in the C67 motion segment inferior to the arthrodesis and mid-range axial rotation ROM in the C45 motion segment superior to the arthrodesis increased from PRE to 1YR-POST (all p < 0.022). This study provides in vivo evidence that contradicts long-held beliefs that adjacent segment end-range ROM increases appreciably after anterior cervical arthrodesis and that two-level arthrodesis exacerbates these effects. Mid-range ROM appears to be more useful than end-range ROM for detecting early changes in adjacent segment motion after cervical spine arthrodesis.

Analysis of cervical and upper thoracic spinal segmental rotation angles during end-range neck rotation: Comparison with and without neck pain

ABSTRACT Background Neck pain is a common manifestation of musculoskeletal disorders of the cervical and thoracic spine. Manual therapy interventions to the thoracic spine are recommended for treating patients with several types of neck pain. However, only a few studies have investigated the thoracic spine mobility associated with neck movement. Objectives Compare cervical and upper thoracic rotation angles in subjects with and without neck pain. Methods The subjects included nine individuals who experienced neck pain (pain, Group P) and 11 who did not (non-pain, Group N). The rotation angle was measured using MRI. The imaging limb position was at 90% of the maximum neck rotation. The MR images were analyzed using image analysis software to calculate the rotation angle of C1 to Th3. The rotation angle of the segment was then calculated by subtracting the rotation angle corresponding to the lower vertebra from that corresponding to the upper vertebra. The total rotation of each segment was calculated as the sum of the right and left rotation angle. Then, the segmental rotation angles were compared between groups. Results/findings The rotation angles of C3-C4, C7-Th1, and Th1-Th2 were significantly smaller in Group P than in Group N, and C5-C6 and C6-C7 were significantly larger in Group P than in Group N. There was no statistical difference in rotational angle at all other spinal levels measured. Conclusions The results of this study indicate subjects with neck pain had hypermobility of the lower cervical spine and hypomobility of the cervico-thoracic junction and upper thoracic spine compared with subjects without neck pain. These results add to current understanding of biomechanical factors that may be related to neck pain.

Manipulation for degenerative lumbar spondylolisthesis: A systematic review of randomized controlled trials

To assess the effectiveness and safety of manipulation intervention for degenerative lumbar spondylolisthesis (DLS). This is a systematic review and meta-analysis. A full-scale retrieval method was performed until February 1, 2021, including nine databases. The homogeneity of different studies was summarized using the Review Manager. The quality of studies was determined with the Cochrane risk-of-bias tool. The evidence quality was graded with the Grading of Recommendations, Assessment, Development, and Evaluations approach. A total of 6 studies involving 524 participants were included. The review demonstrated that manipulation has statistically significant improvements for treating DLS according to Japanese Orthopedic Association scores (mean difference, 3.76; 95% confidence interval, 2.63 to 4.90; P < .001) and visual analog scale scores (mean difference, −1.50; 95% confidence interval, −1.66 to −1.33; P < .001) compared to the control group. One study reported that the difference in the Oswestry Disability Index between the traction group and the combination of manipulation and traction group was statistically significant ( P < .05), while another reported that manipulation treatment can significantly improve the lumbar spine rotation angle on X-ray images compared with the baseline data ( P < .05). Moreover, the manipulation group (experimental group) had fewer adverse events than the lumbar traction group (control group). Manipulation intervention is more effective and safer for DLS. Nevertheless, large-scale randomized controlled trials are required to confirm the current conclusions.

A multi-stage intervention assessing, advising and customising sports bras for elite female British athletes

ABSTRACT Appropriate breast support is recommended in sport; however, what constitutes appropriate support is complex, individual and often sports specific, particularly in elite sport given the wear duration. This intervention educated, assessed and advised elite British female athletes on breasts and bras; those with unresolved issues engaged in bespoke bra interventions. Following educational workshops (n = 80), breast/bra surveys (n = 60), individual bra assessments (n = 37); a rower, shooter, and hockey player participated in the bespoke bra intervention. Eighty-three per cent of athletes rated their breast/bra knowledge as ≤average. Fifty-one per cent experienced breast pain, affecting performance for 29%; seven used medication and one surgery to relieve symptoms. In individual bra assessments most wore ill-fitting, unsupportive bras and wanted bra advice. Bespoke bra interventions eliminated breast pain: for the rower, improved breast position and spine rotation; for the shooter, repositioned tissue and improved performance; and for the hockey player, accommodated smart devices. Whilst bespoke bra development is challenging, most elite athlete breast/bra issues are resolved via education, advice and fitting.

Task-related trunk training on balance, trunk control, pulmonary function and quality of life in patients with Parkinson's disease. A randomised controlled trial

Background/Aims Stooped posture and ‘en-bloc’ movement of the trunk in people with Parkinson's disease are related to balance issues, pulmonary dysfunction and difficulty in daily tasks. The primary objective of this study was to examine the effects of task-related trunk training on balance in people with Parkinson's disease. The secondary objective was to observe whether trunk control, thoracic rotation range, pulmonary function and quality of life would change for patients with Parkinson's disease after trunk training. Methods A total of 32 individuals participated in this randomised controlled trial. They had a mean age of 70.8 years, with a modified Hoehn and Yahr Scale grade of 1.5–3, could take more than six steps in the 360° turn test, were scored as grade I or II on the retropulsion test and had an absence of severe cognitive deficits. Task-related trunk training emphasised the thoracic spine's extension and rotation in prone position on elbows, hands and knees and in kneeling, sitting and standing positions. Standard physiotherapy included breathing exercises, stretching of shoulder and neck muscles, balance and walking training. Both groups practised for 1 hour a day, 3 days a week over 6 weeks. The primary outcome measure was the Mini-Balance Evaluation Systems Test. The secondary outcome measures were the Trunk Control Test, thoracic rotation range of movement, Pulmonary Function Test and Parkinson's Disease Questionnaire-39. Results Repeated measure analysis of variance revealed significant group by time interaction for the Mini-Balance Evaluation Systems Test and thoracic rotation range (P&lt;0.05), but not for the pulmonary function test and quality of life measures. Conclusions Task-related trunk training appears to be more beneficial in the balance capacity of individuals with Parkinson's disease than standard physiotherapy, but does not have any significant effects for pulmonary function and health-related quality of life.

The effect of cervical spine rotation on electromyographic activity of the trapezius and serratus anterior during selected shoulder complex movements

Purpose: The purpose of the study was the assessment of the effect of cervical spine rotation on the activity of the upper (UT) and lower (LT) trapezius and serratus anterior (SA) muscles during selected shoulder movements. Methods: The investigation included 33 healthy individuals (mean age ± SD: 22 ± 1.73 years). Bioelectrical activity of the right (R) and left (L) UT, LT, SA muscles was assessed during the following movements: elevation, flexion, abduction in the scapular and right coronal planes of the dominant (right) arm accompanied by three cervical spine positions (neutral, right rotation, left rotation). Results: RLT EMG activity was higher during right shoulder abduction with right spine rotation vs. that registered during abduction without cervical spine rotation (p &lt; 0.001). RUT EMG activity during right shoulder abduction was higher when abduction was associated with left cervical spine rotation (p &lt; 0.01) and lower during right shoulder flexing with right cervical spine rotation, compared to shoulder movements with neutral spine position (p &lt; 0.001). A higher RSA EMG activity was seen during shoulder flexing (p &lt; 0.001) and abducting (p &lt; 0.05) (both in the frontal and scapular plane) when the movement was performed with right cervical spine rotation, compared to RSA activity during shoulder movements without spinal rotation. Conclusions: The present results suggest that inclusion of appropriate cervical spine rotation during shoulder movements may result in improved activity of the trapezius and serratus anterior.

A Robotic Torso Joint With Adjustable Linear Spring Mechanism for Natural Dynamic Motions in a Differential-Elastic Arrangement

To be operated in unknown or complex environments, modern robots have to fulfill various challenging criteria. Among them, one finds requirements such as a high level of robustness to withstand impacts and the capabilities to physically interact in a safe manner. One way to achieve that is to integrate variable-stiffness actuators into the systems, enabling compliant behavior through the elastic components and providing the additional adaptability of the impedance. Here, we introduce a novel adjustable linear stiffness joint mounted in a differential-elastic arrangement. The mechanism is integrated into the anthropomorphic upper body of the DLR David robot and responsible for the spinal rotation. Consequently, the actuator is crucial for the overall workspace of the robot and the realization of energy-efficient natural motions such as in dynamic running. The proposed hardware setup is experimentally validated in terms of the linearity in the spring characteristics, intrinsic damping, the excitation of resonance frequencies, and the ability to alter these resonance frequencies through stiffness adaptation during dynamic motions.

Relationship between Arm Swing Amplitude and Asymmetry and Spinal Rotation of Gait in Healthy Elderly Females

Relationship between Arm Swing Amplitude and Asymmetry and Spinal Rotation of Gait in Healthy Elderly Females