T-shaped handle set-up: effects of handle diameter, between-handle distance, workpiece orientation, working height, and exertion direction on two-handed torque strength, usability, comfort, and discomfort.

The use of both hands is often required for force/torque exertions, particularly when using hand tools. This study investigated the effects of handle diameter (3-5 cm), between-handle distance (0.5-1.5 shoulder span (SS), workpiece orientation (horizontal/frontal), working height (shoulder/elbow/knuckle), and exertion direction (clockwise/counter-clockwise) on maximum two-handed torque strength, usability and comfort/discomfort while using T-shaped handles. Participants (n = 20) performed 36 experimental conditions. The handle diameter had no significant main effect on torque strength. The 3 cm diameter handle was associated with better usability and comfort compared to other options. Higher torque values were recorded with between-handle distance of 1.0 and 1.5 SS, in frontal plane, in shoulder and knuckle heights, and in counter-clockwise direction. The between-handle distance of 1.0 SS had better comfort and higher usability than other conditions. Interactions between the between-handle distance and working height, between-handle distance and workpiece orientation, and workpiece orientation and working height were also significant.Practitioner summary: Effects of handle diameter, between-handle distance, workpiece orientation, working height, and exertion direction on torque exertions, and subjective measures when using T-shaped handles were evaluated. Higher levels of strength were measured with between-handle distance of 1.0-1.5 shoulder span, and in frontal plane, in shoulder/knuckle heights, and in counter-clockwise direction.

Trunk Dynamic Stability Assessment for Individuals With and Without Nonspecific Low Back Pain During Repetitive Movement.

OBJECTIVE: This study aimed to employ nonlinear dynamic approaches to assess trunk dynamic stability with speed, symmetry, and load during repetitive flexion-extension (FE) movements for individuals with and without nonspecific low back pain (NSLBP). BACKGROUND: Repetitive trunk FE movement is a typical work-related LBP risk factor contingent on speed, symmetry, and load. Improper settings/adjustments of these control parameters could undermine the dynamic stability of the trunk, hence leading to low back injuries. The underlying stability mechanisms and associated control impairments during such dynamic movements remain elusive. METHOD: Thirty-eight male volunteers (19 healthy, 19 NSLBP) enrolled in the current study. All participants performed repetitive trunk FE movements at high/low speeds, in symmetric/asymmetric directions, with/without a wearable loaded vest. Trunk instantaneous rotation angle was computed for each trial to be assessed in terms of local and orbital stability, using maximum finite-time Lyapunov exponents (LyEs) and Floquet multipliers (FMs), respectively. RESULTS: Both groups demonstrated equivalent competency in terms of trunk control and stability, suggesting functional adaptation strategies may be used by the NSLBP group. Wearing the loaded vest magnified the effects of trunk control impairment for the NSLBP group. The combined presence of high-speed and symmetrical FE movements was associated with least trunk local stability. CONCLUSION: Nonlinear dynamic techniques, particularly LyE, are potentially effective for assessing trunk dynamic stability dysfunction for individuals with NSLBP during various activities. APPLICATION: This work can be applied toward the development of quantitative personalized spinal evaluation tools with a wide range of potential occupational and clinical applications.

Using a Motion Sensor to Categorize Nonspecific Low Back Pain Patients: A Machine Learning Approach.

Nonspecific low back pain (NSLBP) constitutes a critical health challenge that impacts millions of people worldwide with devastating health and socioeconomic consequences. In today's clinical settings, practitioners continue to follow conventional guidelines to categorize NSLBP patients based on subjective approaches, such as the STarT Back Screening Tool (SBST). This study aimed to develop a sensor-based machine learning model to classify NSLBP patients into different subgroups according to quantitative kinematic data, i.e., trunk motion and balance-related measures, in conjunction with STarT output. Specifically, inertial measurement units (IMU) were attached to the trunks of ninety-four patients while they performed repetitive trunk flexion/extension movements on a balance board at self-selected pace. Machine learning algorithms (support vector machine (SVM) and multi-layer perceptron (MLP)) were implemented for model development, and SBST results were used as ground truth. The results demonstrated that kinematic data could successfully be used to categorize patients into two main groups: high vs. low-medium risk. Accuracy levels of ~75% and 60% were achieved for SVM and MLP, respectively. Additionally, among a range of variables detailed herein, time-scaled IMU signals yielded the highest accuracy levels (i.e., ~75%). Our findings support the improvement and use of wearable systems in developing diagnostic and prognostic tools for various healthcare applications. This can facilitate development of an improved, cost-effective quantitative NSLBP assessment tool in clinical and home settings towards effective personalized rehabilitation.

A Practical Sensor-Based Methodology for the Quantitative Assessment and Classification of Chronic Non Specific Low Back Patients (NSLBP) in Clinical Settings.

The successful clinical application of patient-specific personalized medicine for the management of low back patients remains elusive. This study aimed to classify chronic nonspecific low back pain (NSLBP) patients using our previously developed and validated wearable inertial sensor (SHARIF-HMIS) for the assessment of trunk kinematic parameters. One hundred NSLBP patients consented to perform repetitive flexural movements in five different planes of motion (PLM): 0° in the sagittal plane, as well as 15° and 30° lateral rotation to the right and left, respectively. They were divided into three subgroups based on the STarT Back Screening Tool. The sensor was placed on the trunk of each patient. An ANOVA mixed model was conducted on the maximum and average angular velocity, linear acceleration and maximum jerk, respectively. The effect of the three-way interaction of Subgroup by direction by PLM on the mean trunk acceleration was significant. Subgrouping by STarT had no main effect on the kinematic indices in the sagittal plane, although significant effects were observed in the asymmetric directions. A significant difference was also identified during pre-rotation in the transverse plane, where the velocity and acceleration decreased while the jerk increased with increasing asymmetry. The acceleration during trunk flexion was significantly higher than that during extension, in contrast to the velocity, which was higher in extension. A Linear Discriminant Analysis, utilized for classification purposes, demonstrated that 51% of the total performance classifying the three STarT subgroups (65% for high risk) occurred at a position of 15° of rotation to the right during extension. Greater discrimination (67%) was obtained in the classification of the high risk vs. low-medium risk. This study provided a smart "sensor-based" practical methodology for quantitatively assessing and classifying NSLBP patients in clinical settings. The outcomes may also be utilized by leveraging cost-effective inertial sensors, already available in today's smartphones, as objective tools for various health applications towards personalized precision medicine.

Improvement of Upper Limb Motor Control and Function After Competitive and Noncompetitive Volleyball Exercises in Chronic Stroke Survivors: A Randomized Clinical Trial.

OBJECTIVES: To investigate the effects of competitive and noncompetitive volleyball exercises on the functional performance and motor control of the upper limbs in chronic stroke survivors. DESIGN: Randomized clinical trial. SETTING: Outpatient rehabilitation center. PARTICIPANTS: Chronic stroke survivors (N=48). INTERVENTIONS: Participants were randomly assigned to competitive (n=16) or noncompetitive (n=16) volleyball exercise groups (60min/d volleyball exercise+30min/d traditional rehabilitation, 3d/wk for 7wk) and control group (n=16). MAIN OUTCOME MEASURES: Reach and grasp motor control measures were evaluated through kinematic analysis. Functional outcomes were assessed via Motor Activity Log, Wolf Motor Function Test (WMFT), Box and Block Test, and Wrist Position Sense Test. RESULTS: Significant improvement of functional performance was observed in both competitive (P<.0001) and noncompetitive volleyball exercise groups (P<.01), but not in the control group (P>.05), with the exception of WMFT score. Volleyball training, in general, resulted in more efficient spatiotemporal control of reach and grasp functions, as well as less dependence on feedback control as compared to the control group. Moreover, the competitive volleyball exercise group exhibited greater improvement in both functional performance and motor control levels. CONCLUSIONS: Volleyball team exercises, especially in a competitive format, resulted in enhancing the efficacy of the preprogramming and execution of reach and grasp movements, as well as a shift from feedback to feedforward control of the affected upper limb in chronic stroke survivors. This may well be a potential underlying mechanism for improving functional performance.

Can Postural Instability in Individuals with Distal Radius Fractures Be Alleviated by Concurrent Cognitive Tasks?

BACKGROUND: Although impaired postural control may be a risk factor for distal radius fractures (wrist fractures), which often are caused by falls, little attention has been given thus far to the various performance and neurophysiologic aspects involved. Although studies suggest that external focus and cognitive tasks can improve postural control, it remains unclear whether these benefits are observed in individuals with a history of distal radius fracture and to what extent. QUESTIONS/PURPOSES: (1) To compare patients with a history of distal radius fracture to age- and sex-matched controls in terms of postural stability while standing on stable and unstable support surfaces, using both postural sway and neurophysiological measures as endpoints; and (2) to determine whether internal- and external-focus strategies and cognitive tasks can improve postural stability in these patients. METHODS: Forty patients with distal radius fracture (33 females and seven males with a mean ± SD age of 56 ± 4 years) and 40 sex- and age-matched control participants participated in the study. We recruited patients with a history of fall-induced distal radius fractures occurring between 6 and 24 months before the start of our study. We excluded patients who had any of the following: fear of falling, taking any medication that may affect balance, neurologic disorders, dizziness, vestibular problems, Type II diabetes, musculoskeletal disorders or recent history of lower extremity fracture, any recent surgical interventions in the spine or lower limbs, and/or cognitive impairment. Of 120 patients who were being treated for distal radius fracture over the 18-month period, 91 (76%) agreed to participate and 40 eligible patients were finally enrolled. The control group included sex- and age-matched (within 2-year intervals) individuals who had never had a wrist fracture. This group was selected from attendants/relatives of the patients attending the neurology and physical medicine and rehabilitation outpatient departments, as well as other volunteers with no history of balance problems or wrist fractures. To address our primary research question, we compared the postural control of individuals with a history of distal radius fracture with the control group while quietly standing on different support surfaces (rigid and foam surfaces) using both postural sway measures obtained by a force plate as well as neurophysiological measures (electromyography [EMG] activity of tibialis anterior and medial gastrocnemius). To address our secondary research question, we compared the postural sway measures and EMG activity of the ankle muscles between different experimental conditions (baseline, internal focus (mentally focusing on their feet without looking), external focus (mentally focusing on rectangular papers, placed on the force plate or foam, one under each foot), difficult cognitive task (recalling maximum backward digits plus one) and easy cognitive task (recalling half of the maximum backward digits). RESULTS: Patients with distal radius fractures presented with greater postural sway (postural instability) and enhanced ankle muscle activity compared with their control counterparts, but only while standing on a foam surface (mean velocity: 5.4 ± 0.8 versus 4.80 ± 0.5 [mean difference = 0.59, 95% CI of difference, 0.44-0.73; p < 0.001]; EMG root mean square of the tibialis anterior: 52.2 ± 9.4 versus 39.30 ± 6 [mean difference = 12.9, 95% CI of difference, 11.4-14.5; p < 0.001]). Furthermore, a decrease in postural sway was observed while standing on both rigid and foam surfaces during the external focus, easy cognitive, and difficult cognitive conditions compared with the baseline (for example, mean velocity in the baseline condition compared with external focus, easy cognitive task and difficult cognitive task was: 4.9 ± 1.1 vs 4.7 ± 1 [mean difference = 0.14, 95% CI of difference, 0.11-0.17; p < 0.001], 4.6 ± 1 [mean difference = 0.25, 95% CI of difference, 0.21-0.29; p < 0.001], and 4.5 ± 1 [mean difference = 0.34, 95% CI of difference, 0.29-0.40; p < 0.001] in the wrist fracture group). The same result was obtained for muscle activity while standing on foam (EMG root mean square of tibialis anterior in the baseline condition compared with external focus, easy cognitive task and difficult cognitive task: 58.8 ± 7.2 versus 52.3 ± 6.6 [mean difference = 6.5, 95% CI of difference, 5.5-7.6; p < 0.001], 48.8 ± 7.1 [mean difference = 10.1, 95% CI of difference, 9-11.1; p < 0.001], 42.2 ± 5.3 [mean difference = 16.7 95% CI of difference, 15.1-18.2; p < 0.001] in the wrist fracture group). CONCLUSIONS: The current results suggest that patients with a history of distal radius fractures have postural instability while standing on unstable support surfaces. This instability, which is associated with enhanced ankle muscle activity, conceivably signifying an inefficient cautious mode of postural control, is alleviated by external attention demands and concurrent cognitive tasks. CLINICAL RELEVANCE: The findings of this study may serve as a basis for designing informed patient-specific balance rehabilitation programs and strategies to improve stability and minimize falls in patients with distal radius fractures. The integrative methodology presented in this work can be extended to postural control and balance assessment for various orthopaedic/neurological conditions.

Lower extremity kinematic analysis in male athletes with unilateral anterior cruciate reconstruction in a jump-landing task and its association with return to sport criteria.

BACKGROUND: Return to sport (RTS) criteria are widely being used to identify anterior cruciate ligament reconstructed (ACLR) athletes ready to return to sportive activity and reduce risk of ACL re-injury. However, studies show a high rate of ACL re-injury in athletes who passed RTS criteria. This indicates that the current RTS criteria might not be sufficient to determine return to sport time in ACLR athletes. Previous studies have reported a close association between altered lower limb kinematics and ACL re-injury. However, it is not clear how lower extremity kinematics differs between ACLR athletes who passed the RTS-criteria and who failed. This study compared lower extremity kinematics in a jump-landing task between ACLR athletes who passed the RTS criteria (Limb symmetry in hop tests, quadriceps strength and questionnaires) to those who failed and to the healthy individuals. METHODS: Participants were 27 male football players with unilateral ACLR including 14 who passed -RTS criteria and 13 failed, and 15 healthy football players. A 3D motion capture system recorded participants' lower extremity motion while performing 10 trials of a bilateral jump-landing task. Hip, knee and ankle angular motion were examined at initial contact. Two-way mixed analysis of variances (2 limbs × 3 groups) and Bonferroni post-hoc tests were performed to compare the joint angles between the limbs and groups. RESULTS: lower hip abduction angle was found in the failed (involved limb 4.1 ° ± 4.2) and passed RTS (involved limb 6.8° ± 3.3) groups compared to the healthy group (non-dominant limb 10.7° ± 3.7). Ankle inversion in the failed RTS (0.4° ± 4.9) group was significantly lower than both passed RTS (4.8° ± 4.8, p = 0.05) and healthy (8.2° ± 8.1, p < 0.001) groups. There were no significant differences between the groups in knee kinematics. CONCLUSIONS: Our findings indicate reduced hip abduction during initial contact phase of landing in athletes returned to sport. Reduced hip abduction during the complex multiplanar movement of jump-landing is a risk factor for ACL re-injury. Current RTS criteria may not be sufficient to identify ACLR athletes at high risk of re-injury. The kinematic analysis in conjunction with current RTS criteria can provide additional insight into the return to sport decision making.

Effects of cognitive load on the amount and temporal structure of postural sway variability in stroke survivors.

This study aimed to investigate the variability in postural sway patterns during quiet standing in stroke survivors. The postural sway was measured in 19 stroke survivors, as well as 19 healthy demographically matched participants, at 3 levels of postural difficulty (rigid surface with closed and open eyes, and foam surface with closed eyes), and 3 levels of cognitive difficulty (without a cognitive task, easy and difficult cognitive tasks). Both linear analyses (the amount of postural sway variability, including the standard deviation of the COP velocity in both the anteroposterior (AP) and mediolateral (ML) directions), as well as non-linear analyses [the temporal structure of the COP variability, including % Recurrence, % Determinism, Shannon Entropy, Trend and the maximum diagonal line (D max)] were employed. The results revealed that the amount of variability of the postural sway of stroke survivors was significantly greater than that of healthy participants, along both the ML and AP directions, with the highest obtained during standing on foam with closed eyes. All measures of the temporal structure of the COP variability were significantly greater in stroke survivors, as compared to the control group, along the ML direction, but not along the AP direction. The cognitive error was significantly higher during difficult cognitive tasks, although it was neither affected by postural difficulty nor by group. The different results obtained for the amount and temporal structure of the COP variability in the AP and ML directions shed light on the intricate mechanisms employed by the CNS in post-stroke balance control, and suggest that effective rehabilitative and therapeutic strategies should be patient-specific, taking both the environment/surface as well as the specific protocols into consideration.

Trunk Motion System (TMS) Using Printed Body Worn Sensor (BWS) via Data Fusion Approach.

Human movement analysis is an important part of biomechanics and rehabilitation, for which many measurement systems are introduced. Among these, wearable devices have substantial biomedical applications, primarily since they can be implemented both in indoor and outdoor applications. In this study, a Trunk Motion System (TMS) using printed Body-Worn Sensors (BWS) is designed and developed. TMS can measure three-dimensional (3D) trunk motions, is lightweight, and is a portable and non-invasive system. After the recognition of sensor locations, twelve BWSs were printed on stretchable clothing with the purpose of measuring the 3D trunk movements. To integrate BWSs data, a neural network data fusion algorithm was used. The outcome of this algorithm along with the actual 3D anatomical movements (obtained by Qualisys system) were used to calibrate the TMS. Three healthy participants with different physical characteristics participated in the calibration tests. Seven different tasks (each repeated three times) were performed, involving five planar, and two multiplanar movements. Results showed that the accuracy of TMS system was less than 1.0°, 0.8°, 0.6°, 0.8°, 0.9°, and 1.3° for flexion/extension, left/right lateral bending, left/right axial rotation, and multi-planar motions, respectively. In addition, the accuracy of TMS for the identified movement was less than 2.7°. TMS, developed to monitor and measure the trunk orientations, can have diverse applications in clinical, biomechanical, and ergonomic studies to prevent musculoskeletal injuries, and to determine the impact of interventions.

A RCT comparing lumbosacral orthosis to routine physical therapy on postural stability in patients with chronic low back pain.

Background: Poor balance performance and impaired postural control have been frequently reported in patients with low back pain. However, postural control is rarely monitored during the course of treatment even though poor postural control may contribute to chronicity and recurrence of symptoms. Therefore, the present study aimed at investigating the effect of a nonextensible lumbosacral orthosis (LSO) versus routine physical therapy on postural stability of patients with nonspecific chronic low back pain. Methods: This was a randomized controlled trial conducted between November 2015 and May 2016 at the outpatient physical therapy clinic of the School of Rehabilitation Sciences. Patients with nonspecific chronic low back pain aged 20 to 55 years were randomly allocated to the intervention and control groups. Both groups received 8 sessions of physical therapy twice weekly for 4 weeks. The intervention group received nonextensible LSO in addition to routine physical therapy. Pain intensity, functional disability, fear of movement/ (re)injury, and postural stability in 3 levels of postural difficulty were measured before and after 4 weeks of intervention. A 2×2×3 mixed model of analysis of variance (ANOVA) was used to determine the main and interactive effects of the 3 factors including group, time, and postural difficulty conditions for each variable of postural stability. Results: The LSO and control groups displayed significant improvement in postural stability at the most difficult postural task conditions (P-value for 95% area ellipse was 0.003; and for phase plane, the mean total velocity and standard deviation of velocity was <0.001). Both groups exhibited a decrease in pain intensity, Oswestry Disability Index, and Tampa Scale of Kinesiophobia after 4 weeks of intervention. A significant difference between groups was found only for functional disability, with greater improvement in the orthosis group (t = 3.60, P<0.001). Conclusion: Both routine physical therapy and LSO significantly improved clinical and postural stability outcomes immediately after 4 weeks of intervention. The orthosis group did not display superior outcomes, except for functional disability.

Epidemiological and biomechanical evaluation of airline baggage handling.

OBJECTIVES: Musculoskeletal disorders (MSDs) are prevalent among airline baggage handlers due to manual materials handling. In this study, the Nordic musculoskeletal questionnaire (NMQ), the revised National Institute for Occupational Safety and Health (NIOSH) lifting equation, and the University of Michigan 3D Static Strength Prediction Program™ (3DSSPP) were used to analyze MSDs among baggage handlers. METHODS: The NMQ was filled out by 209 baggage handlers and 46 arbitrarily selected baggage handlers were evaluated using the NIOSH method and 3DSSPP. RESULTS: The obtained results showed that the most common MSDs occurred in the lower back region. The next risky regions included knees, neck, and upper back, respectively. The NIOSH results confirmed that the subjects lifted loads heavier than the permitted limit and their lifting postures were inappropriate. The results of the 3DSSPP also indicated that compression forces exceeded the NIOSH limit in these awkward postures. CONCLUSIONS: Relying on this study, holding compulsory ergonomic lifting training courses could be proposed for workers and regulations adjusting an upper limit for maximum baggage weight must be also enacted in order to improve occupational health and prevent the prevalence of increasing MSDs.

Simulation of movement in three-dimensional musculoskeletal human lumbar spine using directional encoding-based neurocontrollers.

Despite development of accurate musculoskeletal models for human lumbar spine, the methods for prediction of muscle activity patterns in movements lack proper association with corresponding sensorimotor integrations. This paper uses the directional information of the Jacobian of the musculoskeletal system to orchestrate adaptive critic-based fuzzy neural controller modules for controlling a complex nonlinear redundant musculoskeletal system. The proposed controller is used to control a 3D 3-degree of freedom (DOF) musculoskeletal model of trunk, actuated by 18 muscles. The controller is capable of learning to control from sensory information, without relying on pre-assumed model parameters. Simulation results show satisfactory tracking of movements and the simulated muscle activation patterns conform to previous EMG experiments and optimization studies. The proposed controller can be used as a computationally inexpensive muscle activity generator to distinguish between neural and mechanical contributions to movement and for study of sensory versus motor origins of motor function and dysfunction in human spine.

The effects of experience and the presence of a scaffold handrail on postural and spinal stability in construction workers.

The goal of this study was to quantify the effect of experience and handrail presence on trunk muscle activities, rotational spinal stiffness and postural stability of construction workers. We evaluated spinal stability, and objective and subjective postural stability in 4 expert and 4 novice construction workers who were performing a manual task in a standing position on a scaffold, with and without a safety handrail. Center of pressure was computed using measurements taken with insole pressure transducers. Muscle activity was monitored using surface electrodes placed on 8 trunk muscles that predicted active trunk rotational stiffness. Standard deviations of the center of pressure, back muscle activity and spinal stiffness were greater in novices and in the absence of a handrail. We infer that the risk of a fall due to postural and spinal instability may be greater with a lower level of experience and in the absence of a safety handrail.

Enzymatic denaturation versus excessive fatigue loading degeneration: Effects on the time-dependent response of the intervertebral disc.

Degenerative disc disease (DDD), regardless of its phenotype and clinical grade, is widely associated with low back pain (LBP), which remains the single leading cause of disability worldwide. This work provides a quantitative methodology for comparatively investigating artificial IVD degeneration via two popular approaches: enzymatic denaturation and fatigue loading. An in-vitro animal study was used to study the time-dependent responses of forty fresh juvenile porcine thoracic IVDs in conjunction with inverse and forward finite element (FE) simulations. The IVDs were dissected from 6-month-old-juvenile pigs and equally assigned to 5 groups (intact, denatured, low-level, medium-level, high-level fatigue loading). Upon preloading, a sinusoid cyclic load (Peak-to-peak/0.1-to-0.8 MPa) was applied (0.01-10 Hz), and dynamic-mechanical-analyses (DMA) was performed. The DMA outcomes were integrated with a robust meta-model analysis to quantify the poroelastic IVD characteristics, while specimen-specific FE models were developed to study the detailed responses. The results demonstrated that enzymatic denaturation had a more significantly pronounced effect on the resistive strength and shock attenuation capabilities of the intervertebral discs. This can be attributed to the simultaneous disruption of the collagen fibers and water-proteoglycan bonds induced by trypsin digestion. Fatigue loading, on the other hand, primarily influenced the disc's resistance to deformation in a frequency-dependent pattern, where alterations were most noticeable at low loading frequencies. This study confirms the intricate interplay between the biochemical changes induced by enzymatic processes and the mechanical behavior stemming from fatigue loading, suggesting the need for a comprehensive approach to closely mimic the interrelated multifaceted processes of human disc degeneration.

Evaluating the effect of equipping an unloading knee orthosis with local muscle vibrators on clinical parameters, muscular activation level, and medial contact force in patients with medial knee osteoarthritis: A randomized trial.

BACKGROUND: Unloading knee orthosis is prescribed for people with unicompartmental knee osteoarthritis (OA) to unload the damaged compartment. However, despite its benefits, wearing unloading knee orthoses in the long term may decrease knee muscle activity and have a side effect on knee OA progression rate. OBJECTIVES: Therefore, this study aimed to determine whether equipping an unloading knee orthosis with local muscle vibrators improves its effectiveness in improving clinical parameters, medial contact force (MCF), and muscular activation levels. METHODS: The authors performed a clinical evaluation on 14 participants (7 participants wearing vibratory unloading knee orthoses and 7 participants wearing conventional unloading knee orthoses) with medial knee OA. RESULTS: Wearing both orthoses (vibratory and conventional) for 6 weeks significantly improved ( p < 0.05) the MCF, pain, symptoms, function, and quality of life compared with the baseline assessment. Compared with the baseline assessment, the vastus lateralis muscle activation level significantly increased ( p = 0.043) in the vibratory unloading knee orthoses group. The vibratory unloading knee orthoses significantly improved the second peak MCF, vastus medialis activation level, pain, and function compared with conventional unloading knee orthoses ( p < 0.05). CONCLUSIONS: Given the potential role of medial compartment loading in the medial knee OA progression rate, both types of unloading knee orthoses (vibratory and conventional) have a potential role in the conservative management of medial knee OA. However, equipping the unloading knee orthoses with local muscle vibrators can improve its effectiveness for clinical and biomechanical parameters and prevent the side effects of its long-term use.

The Correlation between Intersegmental Coordination Variability and Frontal Plane Hip Kinematics during Running in Persons with Patellofemoral Pain.

Background: Despite the existing evidence indicating altered hip kinematics as well as the studies showing altered movement coordination variability in persons with patellofemoral pain (PFP), there is no study investigating the correlation between hip joint kinematic and movement coordination variability in persons with patellofemoral pain (PFP). Objective: This study aims to evaluate the correlation between peak hip adduction and variability of thigh frontal-shank transverse coordination during running in persons with PFP. Material and Methods: In this cross-sectional correlational study, kinematic data were collected from 34 females (17 with and 17 without PFP) aged 18-35 years during treadmill running at preferred and fixed speeds, each for 30 s. The continuous relative phase method was used to calculate the coordination of thigh frontal-shank transverse. To calculate the deviation phase as the variability of intersegmental coordination, the standard deviation of the ensemble continuous relative phase curve points was averaged. The parameters of interest were peak hip adduction and coordination variability of thigh frontal-shank transverse. The Pearson Correlation Coefficient (r) was used to calculate the correlation between the variables. Results: The Pearson correlation coefficient showed a significant negative correlation between the peak hip adduction angle and variability of thigh frontal- shank transverse during running at both fixed (r=-0.553, P<0.05) and preferred (r=-0.660, P<0.01) speeds in persons with PFP while the control group showed a small nonsignificant correlation (r<0.29, P>0.05). Conclusion: The results indicated that greater adduction of the hip joint in persons with PFP during running is contributed to lesser variability of thigh frontal-shank transverse.

Trajectory of human movement during sit to stand: a new modeling approach based on movement decomposition and multi-phase cost function.

The purpose of this work is to develop a computational model to describe the task of sit to stand (STS). STS is an important movement skill which is frequently performed in human daily activities, but has rarely been studied from the perspective of optimization principles. In this study, we compared the recorded trajectories of STS with the trajectories generated by several conventional optimization-based models (i.e., minimum torque, minimum torque change and kinetic energy cost models) and also with the trajectories produced by a novel multi-phase cost model (MPCM). In the MPCM, we suggested that any complex task, such as STS, is decomposable into successive motion phases, so that each phase requires a distinct strategy to be performed. In this way, we proposed a multi-phase cost function to describe the STS task. The results revealed that the conventional optimization-based models failed to correctly predict the invariable features of STS, such as hip flexion and ankle dorsiflexion movements. However, the MPCM not only predicted the general features of STS with a sufficient accuracy, but also showed a potential flexibility to distinguish between the movement strategies from one subject to the other. According to the results, it seems plausible to hypothesize that the central nervous system might apply different strategies when planning different phases of a complex task. The application areas of the proposed model could be generating optimized trajectories of STS for clinical applications (such as functional electrical stimulation) or providing clinical and engineering insights to develop more efficient rehabilitation devices and protocols.

Brain Wave Patterns in Patients With Chronic Low Back Pain: A Case-control Study.

Introduction: Research evidence indicates that maladaptive reorganization of the brain plays a critical role in amplifying pain experiences and pain chronification; however, no clear evidence of change exists in brain wave activity among patients with chronic low back pain (CLBP). The objective of this study was to assess brain wave activity in patients with CLBP, compared to healthy controls. Methods: Twenty-five patients with CLBP and twenty-four healthy controls participated in the study. A quantitative electroencephalography device was used to assess brain wave activity in eyes-open and eyes-closed (EO and EC) conditions. The regional absolute and relative power of brain waves were compared between the groups. Results: Our results showed a significant increase in the absolute power of theta (F=5.905, P=0.019), alpha (F=5.404, P=0.024) waves in patients with CLBP compared to healthy subjects in both EC and EO conditions. Patients with CLBP showed a reduced delta absolute power in the frontal region (F=5.852, P=0.019) and augmented delta absolute power in the central region (F=5.597, P=0.022) in the EO condition. An increased delta absolute power was observed in the frontal (F=7.563 P=0.008), central (F=10.430, P=0.002), and parietal (F=4.596, P=0.037) regions in patients with CLBP compared to the healthy subjects in the EC condition. In the EC condition, significant increases in theta relative power (F=4.680, P=0.036) in the parietal region were also found in patients with CLBP. Conclusion: The increased absolute power of brain waves in people with CLBP may indicate cortical overactivity and changes in the pain processing mechanisms in these patients. Highlights: Chronic low back pain (CLBP) increases the alpha, theta, and delta power in the brain.CLBP is associated with increased brain wave activity in the frontal, central, and parietal regions.Our findings suggest altered central pain processing in CLBP. Plain Language Summary: Traditional diagnosis and treatment of CLBP are mainly focused on peripheral pathology. But, the modern neuroscience approach to pain highlights the role of cortical plasticity in chronic musculoskeletal pain. In this regard, several studies found structural and functional changes in the brain in patients with chronic pain. Detailed knowledge about cortical changes in CLBP can improve our understanding of mechanisms involved in CLBP, opening a new window to better treatment of LBP (Low back pain). This study investigated brain wave activity in patients with CLBP compared to healthy individuals. Our findings suggest increased brain activity in various parts of the brain in patients with chronic LBP. This finding indicates that CLBP treatment should focus on both peripheral and cortical factors rather than local tissue damage.

Normative database of response surface method for human trunk extension in isometric mode.

Recent studies show that asymmetric movements are important Low Back Disorders risk factors. Measuring the trunk strength and identifying the coupling effects in different postures can provide an objective tool to assess one's task capacity. This paper estimates the maximum performance capacity for isometric trunk extension and accompanying torques. Thirty males performed maximum voluntary isometric extension in 33 trunk postures on Sharif Lumbar Isometric Strength Tester device. Corresponding moments and angular positions were collected. Second-order full response surface models (RSM) were exploited to formulate the relationship between strengths and three trunk angles. The results of correlation coefficient, percent of standard estimation error and lack of fit reflected the adequacy of models. In conclusion, the main torque was the extension, but at the same time lateral bending and rotation torques were observed. For predicting these three torques in a specific posture and injury prevention, the second order RSM is a useful tool. The presented models can be used in the fields of ergonomics, occupational biomechanics and sport.

Effect of equipping an unloader knee orthosis with vibrators on pain, function, stiffness, and knee adduction moment in people with knee osteoarthritis: A pilot randomized trial.

BACKGROUND: Wearing unloader knee orthoses for the long term may have a side effect on knee adduction moment (KAM). RESEARCH QUESTION: This study sought to determine whether equipping an unloader knee orthosis with vibrators improves its effectiveness in pain, stiffness, function, and reducing the KAM. METHODS: The authors performed a clinical evaluation with the Western Ontario and McMaster Universities (WOMAC) questionnaire and instrumented gait analyses on 14 participants with medial compartment knee osteoarthritis in two testing sessions: before wearing the orthosis and after 6 weeks of use. RESULTS AND SIGNIFICANCE: Wearing both orthoses for 6 weeks significantly improved (p < 0.05) pain, stiffness, and function compared to the baseline assessment. There was a significantly greater reduction in the first peak KAM (p = 0.016) and KAM impulse (p = 0.008) in the vibratory unloader knee orthosis than in the conventional knee orthosis in the second session. Equipping the unloader knee orthosis with vibrators can improve its effectiveness in reducing the KAM and can prevent the side effects of its use. Furthermore, equipping the unloader knee orthosis with the vibrators did not interfere with its effectiveness on pain, stiffness, and function.