Use of optical motion capture for the analysis of normative upper body kinematics during functional upper limb tasks: A systematic review

Age-related differences in behavioral outcomes of bimanual functional motor tasks in children and adolescents with cerebral palsy: a scoping review

AIM

The objective of this review is to determine age-related differences in behavioral outcomes of bimanual motor tasks in children and adolescents with cerebral palsy (CP).

METHOD

This review followed the 6-stage Joanna Briggs Institute methodology. The Embase, EBSCO CINAHL, and PubMed databases were searched on May 2024. We included studies that employed instrumented measures to assess bimanual tasks in individuals with CP aged between 3 and 19 years.

RESULTS

Twenty-eight studies were included after full-text screening. This review reported on 544 individuals with CP. Bimanual tasks were grouped in seven categories and their varying complexities were listed and analyzed. There are numerous methods for assessing bimanual performance. The listed methods have shown that the gap between children with CP and healthy peers widens as task complexity increases. The data suggest that age-related outcomes result from a complex interaction between atypical development, the severity of deficits, and the context-dependent nature of the protocols.

CONCLUSION

The lack of standardized reporting on age-related results limits our understanding of bimanual developmental functions in CP. Standardizing these measures will enhance our understanding of bimanual function and better define the principles guiding therapeutic interventions, ultimately improving outcomes for individuals with CP.

A Prestrained Strategy Enabled Highly Sensitive Strain Sensors for Muscle Strength Assessment

Achieving high sensitivity of stretchable electronics with a wide working range is essential and challenging. While fundamental strategies using topographic design or introducing microstructures (e.g., wrinkles or cracks) can effectively improve the sensitivity, the strain-response range is still rather limited. Here, we propose a tunable and ultrasensitive piezoresistive strain sensor by leveraging a controllable kirigami design and a prestrained strategy. On the one hand, the kirigami structure enhances the sensitivity and structural stability. On the other hand, the prestrained strategy widens the surface crack to generate highly sensitive and continuous linear responses. This strategy allows general stretchable materials to versatilely realize strain sensors with ultrahigh sensitivity (GF > 1000) and good linearity in the low strain range. As a result, the increased sensitivity and conformability to soft surfaces enable the prestrained strain sensor to identify different body motions and hand grips of varying loads. The high amplitude and recognizable signal waveforms provide essential information in muscle strength assessment. With its general applicability to diverse soft materials, this prestrained strategy overcomes the material and manufactural-level limitations for imparting high sensitivity to various strain sensors, presenting a great potential in the fields of medical monitoring and rehabilitation.

Dynamic Soft Tissue Artifacts during Impulsive Loads: Measurement Errors Vary With Wearable Inertial Measurement Unit Sensor Design

OBJECTIVE

Characterize and model Inertial Measurement Unit (IMU) errors due to transient dynamic soft tissue artifacts excited by impulsive loads, such as foot strikes during running and jumping.

METHODS

We instrumented 10 participants (5 female, 5 male) with IMUs on the dominant leg. An ankle IMU measured reference vertical accelerations during impulsive loads and was cross-validated against vertical force measures. Two IMUs on the posterior shank and anterior shank were used to characterize errors caused by dynamic soft tissue artifacts with respect to the reference. Shank sensors' masses were varied to explore their effect on dynamic soft tissue artifacts.

RESULTS

Both the posterior IMU and anterior IMU overestimated peak vertical accelerations during the impulsive load (gain of 2.18 ± 0.63 and 1.55 ± 0.35 respectively). The post- impulsive load oscillation duration and natural frequency varied with sensor mass according to an underdamped second-order system, with posterior IMU and anterior IMU durations of 326 ± 75 ms and 151 ± 50 ms respectively and natural frequencies of 9.79 ± 2.68 Hz and 18.22 ± 12.10 Hz respectively. Low-pass filtering reduced overestimation of peak vertical accelerations, but also attenuated the reference measure.

CONCLUSION

Our study suggests dynamic soft tissue artifacts result in transient, but substantial measurement errors that may not be appropriately mitigated through low-pass filtering. However, these dynamic soft tissue artifacts can be modeled using an underdamped second-order system and used to estimate material properties of underlying soft tissue.

SIGNIFICANCE

We demonstrate that dynamic soft tissue artifacts can be modeled and potentially mitigated to improve accuracy in applications necessitating measurement of impulsive loads such as foot strikes.

Validity of inertial measurement units for tracking human motion: a systematic review

Human motion is often tracked using three-dimensional video motion tracking systems, which have demonstrated high levels of validity. More recently, inertial measurement units (IMUs) have been used to measure human movement due to their ease of access and application. The purpose of this study was to systematically review the literature regarding the validity of inertial sensor systems when being used to track human motion. Four electronic databases were used for the search, and eleven studies were included in the final review. IMUs have a high level of agreement with motion capture systems in the frontal and sagittal planes, measured with root mean square error (RMSE), intraclass correlation coefficient, and Pearson's correlation. However, the transverse or rotational planes began to show large discrepancies in joint angles between systems. Furthermore, as the intensity of the task being measured increased, the RMSE values began to get much larger. Currently, the use of accelerometers and inertial sensor systems has limited application in the assessment of human motion, but if the precision and processing of IMU devices improves further, it could provide researchers an opportunity to collect data in less synthetic environments, as well as improve ease of access to biomechanically analyse human movement.

Concurrent validity of inertial measurement units in range of motion measurements of upper extremity: A systematic review and meta-analysis

Inertial measurement units (IMUs) have proven to be valuable tools in measuring the range of motion (RoM) of human upper limb joints. Although several studies have reported on the validity of IMUs compared to the gold standard (optical motion capture system, OMC), a quantitative summary of the accuracy of IMUs in measuring RoM of upper limb joints is still lacking. Thus, the primary objective of this systematic review and meta-analysis was to determine the concurrent validity of IMUs for measuring RoM of the upper extremity in adults. Fifty-one articles were included in the systematic review, and data from 16 were pooled for meta-analysis. Concurrent validity is excellent for shoulder flexion-extension (Pearson's r = 0.969 [0.935, 0.986], ICC = 0.935 [0.749, 0.984], mean difference = -3.19 (p = 0.55)), elbow flexion-extension (Pearson's r = 0.954 [0.929, 0.970], ICC = 0.929 [0.814, 0.974], mean difference = 10.61 (p = 0.36)), wrist flexion-extension (Pearson's r = 0.974 [0.945, 0.988], mean difference = -4.20 (p = 0.58)), good to excellent for shoulder abduction-adduction (Pearson's r = 0.919 [0.848, 0.957], ICC = 0.840 [0.430, 0.963], mean difference = -7.10 (p = 0.50)), and elbow pronation-supination (Pearson's r = 0.966 [0.939, 0.981], ICC = 0.821 [0.696, 0.900]). There are some inconsistent results for shoulder internal-external rotation (Pearson's r = 0.939 [0.894, 0.965], mean difference = -9.13 (p < 0.0001)). In conclusion, the results support IMU as a viable instrument for measuring RoM of upper extremity, but for some specific joint movements, such as shoulder rotation and wrist ulnar-radial deviation, IMU measurements need to be used with caution.

Kinematic Assessment Utilizing Xsens Gait Motion Analysis in Upper Cross Syndrome: A Case Report

Upper crossed syndrome (UCS) characterizes a prevalent postural dysfunction involving dysfunctional tone in the musculature of the shoulder girdle and cervicothoracic region. The discordant balance among the sternocleidomastoid, pectoralis major, levator scapulae, and upper trapezius musculature potentially precipitated cervical discomfort, thereby hindering routine activities and fostering the progression of UCS. Clinical scales are routinely utilized to assess and monitor the progress of rehabilitation; nonetheless, they often present inherent limitations. In contrast, advancements in three-dimensional (3D) motion capture technology furnish detailed kinematic data, thereby augmenting the capacity to objectively quantify and elucidate movement deficits with heightened precision. This case highlights the critical significance of employing kinematic analysis with Xsens as an outcome measure to elucidate the intricacies of UCS, thereby offering invaluable insights for therapeutic interventions in similar clinical scenarios and providing objective insights into movement biomechanics, muscular function, and functional limitations. Leveraging this information, clinicians can skillfully tailor treatment modalities to address underlying musculoskeletal imbalances, ultimately optimizing patient outcomes. In this case study, we examine the kinematic analysis of a 48-year-old office worker experiencing persistent headaches, restricted range of motion, and neck and shoulder pain over a four-month period. Despite prior interventions, symptomatology deteriorated, prompting consultation with a neurophysiotherapist. The evaluation revealed localized pain in the right shoulder, upper back, and neck, characterized by gradual onset and dull ache, exacerbated by activity and alleviated by rest and medication, without diurnal fluctuations. Physical examination delineated UCS features. Following the implementation of a four-week physiotherapy rehabilitation protocol, initial assessments utilizing Xsens gait motion analysis were undertaken. Subsequent to the rehabilitation program, significant improvements were noted across various parameters. These encompassed augmented range of motion, heightened muscular strength, and enhanced flexibility. Additionally, discernible enhancements were observed in posture and gait, characterized by the restoration of normal cervical spine curvature and an expanded range of motion.

Scapular Motor Control and Upper Limb Movement Quality in Subjects with and without Chronic Shoulder Pain: A Cross-Sectional Study

Despite the existence of several studies about the scapula’s position and motion, in shoulder pain conditions, there are still conflicting findings regarding scapular adaptations and reduced research about the scapula’s role during functional tasks. The present study aimed to compare scapular-related kinematic and electromyographic outcomes during different shoulder movements (with and without load) and the drinking task, between symptomatic and asymptomatic subjects. Forty subjects (divided into two groups) participated in this cross-sectional observational study. Scapulothoracic motion, scapulohumeral rhythm, and movement quality (considering trunk compensation, time-to-peak acceleration, and smoothness), as well as the relative surface electromyographic activity and muscle ratio considering the trapezius, serratus anterior, and levator scapulae (LS), were assessed. The symptomatic group presented the following: (1) changes in scapular upward rotation (p = 0.008) and winging (p = 0.026 and p = 0.005) during backward transport and drink phases; (2) increased muscle activity level of the middle trapezius (MT) in all tasks (p < 0.0001 to p = 0.039), of LS during shoulder elevation with load (p = 0.007), and of LS and LT during most of the drinking task phases (p = 0.007 to p = 0.043 and p < 0.0001 to p = 0.014, respectively); (3) a decreased serratus anterior lower portion activity level (SAlow) during shoulder lowering with load (p = 0.030) and drink phase (p = 0.047); and (4) an increased muscular ratio between scapular abductors/adductors (p = 0.005 to p = 0.036) and elevators/depressors (p = 0.008 to p = 0.028). Compared to asymptomatic subjects, subjects with chronic shoulder pain presented scapular upward rotation and winging adaptations; increased activity levels of MT, LT, and LS; decreased activity levels of SAlow; and increased scapular muscle ratios.

Three-Dimensional Upper Limb Movement Analysis in Children and Adolescents With Brachial Plexus Birth Injury: A Systematic Review

BACKGROUND

To synthesize the current evidence on clinical use of three-dimensional upper limb movement analysis (3D-ULMA) in children and adolescents with brachial plexus birth injury (BPBI).

METHODS

MEDLINE, Embase, and Web of Science were searched for relevant studies up to April 2022. An automatic e-mail alert was installed to ensure no eligible article was missed. Articles evaluating 3D-ULMA in children and adolescents with BPBI were included. Covidence web-based platform was used for blind screening of eligible articles. Twenty-one observational studies with a final sample size of 609, encompassing 493 BPBI cases, met the inclusion criteria. Data were extracted using a custom form to support standardized extraction conforming to the Cochrane Checklist of items. Risk of bias was assessed using the Newcastle-Ottawa Scale, the Strengthening the Reporting of Observational Studies in Epidemiology checklist, and a specifically established quality assessment form for kinematic analysis studies.

RESULTS

Study setups differed, including six different types of kinematic devices. Twelve studies used the (modified) Mallet positions for their 3D-ULMA. Throughout the studies, 3D-ULMA was used for various purposes. The Newcastle-Ottawa Scale scored 16 articles with five stars or more, indicating fair to moderate quality.

CONCLUSIONS

This systematic review summarizes the different 3D-ULMA kinematic devices, test protocols, and their clinical use for BPBI. The use of 3D-ULMA provides valuable, objective, and quantified data to clinicians with regard to movement strategies; it complements existing clinical scales and can be implemented to evaluate effectiveness of therapy interventions. Implications for future research and clinical practice are discussed.

Intra-limb joint coordination measures of upper limb and hand movements: A systematic review

BACKGROUND

People with central nervous system disorders typically have difficulties in coordination of the upper limb and hand movements, which significantly impairs their activities of daily living. Laboratory-based measures can provide quantitative and objective information about intra-limb coordination to aid the rehabilitation process of this population. However, there is currently no comprehensive review of laboratory-based measures.

RESEARCH QUESTIONS

The aim of this review was to identify and summarize laboratory-based intra-limb coordination measures for different upper limb and hand movements.

METHODS

Searches were performed in the CINAHL, Embase, IEEE Xplore, MEDLINE, PubMed and Web of Science databases to identify studies published between 2013 and 2022. Two authors independently performed paper selection, data extraction and quality assessment.

RESULTS

21 papers were identified, and six types of coordination measures were classified. These included principal component analysis, continuous relative phase analysis, correlation analysis, regression analysis, uncontrolled manifold analysis, and uncorrelated surrogate data analysis, in descending order of occurrence. Regarding psychometric properties, all measures demonstrated good discriminative validity. However, only the principal component analysis approach and the continuous relative phase analysis approach were found to have good convergent validity and responsiveness, respectively. In terms of their practicality, these measures were primarily utilized for quantifying coordination in individuals with neurological disorders, with a greater emphasis on the coordination of upper limb movements rather than hand movements.

SIGNIFICANCE

This review summarized and critiqued the characteristics of six types of joint coordination measures. Researchers and clinicians should therefore select appropriate measures based on individual needs. Future research should continue on analysing coordination in individuals with pathological conditions and exploring the application of these measures in quantifying hand movement coordination, to advance current knowledge and inform rehabilitation practices.

X-Sens Inertial Sensor Technology-Based Rehabilitation on a Patient With Posterior Cruciate Ligament Avulsion Fracture and Shaft of Femur Fracture: A Case Report

The posterior cruciate ligament (PCL), one of the key ligaments in the knee, serves to prevent backward movement of the tibia relative to the femur. A simultaneous occurrence of a PCL avulsion fracture and a femur shaft fracture in a pediatric patient suggests a complex orthopedic injury resulting from significant trauma to the knee and thigh area. This study describes the rehabilitation process of a 12-year-old female involved in a road traffic accident, who suffered both a midshaft femur fracture and a PCL avulsion fracture. Following surgical procedures, the patient underwent a comprehensive physiotherapy regimen utilizing X-Sens inertial sensor technology. The rehabilitation plan comprised multiple stages targeting pain alleviation, muscle strengthening, flexibility exercises, gait retraining, and balance improvement. Various interventions including contrast baths, cryotherapy, patellar mobilization, isotonic and resistance exercises, and progressive gait training were integrated across different phases of the rehabilitation program. Over subsequent follow-up periods, the patient demonstrated significant enhancements in pain management, range of motion, muscle strength, functional capabilities, and gait metrics. This case report underscores the efficacy of a systematic physiotherapy strategy incorporating advanced technology in the successful recovery from intricate lower limb fractures, underscoring the importance of prompt intervention and multidisciplinary collaboration for optimal patient outcomes.

Upper extremity kinematics: development of a quantitative measure of impairment severity and dissimilarity after stroke

Background

Strokes are a leading cause of disability worldwide, with many survivors experiencing difficulty in recovering upper extremity movement, particularly hand function and grasping ability. There is currently no objective measure of movement quality, and without it, rehabilitative interventions remain at best informed estimations of the underlying neural structures' response to produce movement. In this article, we utilize a novel modification to Procrustean distance to quantify curve dissimilarity and propose the Reach Severity and Dissimilarity Index (RSDI) as an objective measure of motor deficits.

Methods

All experiments took place at the Medstar National Rehabilitation Hospital; persons with stroke were recruited from the hospital patient population. Using Fugl-Meyer (FM) scores and reach capacities, stroke survivors were placed in either mild or severe impairment groups. Individuals completed sets of reach-to-target tasks to extrapolate kinematic metrics describing motor performance. The Procrustes method of statistical shape analysis was modified to identify reaching sub-movements that were congruous to able-bodied sub-movements.

Findings

Movement initiation proceeds comparably to the reference curve in both two- and three-dimensional representations of mild impairment movement. There were significant effects of the location of congruent segments between subject and reference curves, mean velocities, peak roll angle, and target error. These metrics were used to calculate a preliminary RSDI score with severity and dissimilarity sub-scores, and subjects were reclassified in terms of rehabilitation goals as Speed Emphasis, Strength Emphasis, and Combined Emphasis.

Interpretation

The modified Procrustes method shows promise in identifying disruptions in movement and monitoring recovery without adding to patient or clinician burden. The proposed RSDI score can be adapted and expanded to other functional movements and used as an objective clinical tool. By reducing the impact of stroke on disability, there is a significant potential to improve quality of life through individualized rehabilitation.

Assessment of an IMU-Based Experimental Set-Up for Upper Limb Motion in Obese Subjects

In recent years, wearable systems based on inertial sensors opened new perspectives for functional motor assessment with respect to the gold standard motion capture systems. The aim of this study was to validate an experimental set-up based on 17 body-worn inertial sensors (Awinda, Xsens, The Netherlands), addressing specific body segments with respect to the state-of-the art system (VICON, Oxford Metrics Ltd., Oxford, UK) to assess upper limb kinematics in obese, with respect to healthy subjects. Twenty-three obese and thirty healthy weight individuals were simultaneously acquainted with the two systems across a set of three tasks for upper limbs (i.e., frontal arm rise, lateral arm rise, and reaching). Root Mean Square error (RMSE) was computed to quantify the differences between the measurements provided by the systems in terms of range of motion (ROM), whilst their agreement was assessed via Pearson's correlation coefficient (PCC) and Bland-Altman (BA) plots. In addition, the signal waveforms were compared via one-dimensional statistical parametrical mapping (SPM) based on a paired t-test and a two-way ANOVA was applied on ROMs. The overall results partially confirmed the correlation and the agreement between the two systems, reporting only a moderate correlation for shoulder principal rotation angle in each task (r~0.40) and for elbow/flexion extension in obese subjects (r = 0.66), whilst no correlation was found for most non-principal rotation angles (r < 0.40). Across the performed tasks, an average RMSE of 34° and 26° was reported in obese and healthy controls, respectively. At the current state, the presence of bias limits the applicability of the inertial-based system in clinics; further research is intended in this context.

Reliability, accuracy, and minimal detectable difference of a mixed concept marker set for finger kinematic evaluation

The study of finger biomechanics requires special tools for accurately recording finger joint data. A marker set to evaluate finger postures during activities of daily living is needed to understand finger biomechanics in order to improve prosthesis design and clinical interventions. The purpose of this study was to evaluate the reliability of a proposed hand marker set (the Warwick marker set) to capture finger kinematics using motion capture. The marker set consisted of the application of two and three marker clusters to the fingers of twelve participants who participated in the tests across two sessions. Calibration markers were applied using a custom palpation technique. Each participant performed a series of range of motion movements and held a set of objects. Intra and inter-session reliability was calculated as well as Standard Error of Measurement (SEM) and Minimal Detectable Difference (MDD). The findings showed varying levels of intra- and inter-session reliability, ranging from poor to excellent. The SEM and MDD values were lower for the intra-session range of motion and grasp evaluation. The reduced reliability can potentially be attributed to skin artifacts, differences in marker placement, and the inherent kinematic variability of finger motion. The proposed marker set shows potential to assess finger postures and analyse activities of daily living, primarily within the context of single session tests.

Defining humeral axial rotation with optical motion capture and inertial measurement units during functional task assessment

Humeral motion can be challenging to measure and analyze. Typically, Euler/Cardan sequences are used for humeral angle decomposition, but choice of rotation sequence has substantial effects on outcomes. A new method called True axial rotation calculation may be more precise. The objective of this study is to compare humeral axial rotation measured from two systems (optical motion capture and inertial measurement units (IMUs)) and calculated with two methods (Euler angles and True axial). Motion of torso and dominant humerus of thirty participants free from any upper limb impairments was tracked using both systems. Each participant performed a functional tasks protocol. Humeral axial rotation was calculated with Euler decomposition and the True axial method. Waveforms were compared with two-way ANOVA statistical parametric mapping. A consistent pattern emerged: axial rotation was not different between motion capture systems when using the True axial method (p > .05), but motion capture systems showed relatively large magnitude differences (~ 20-30°) when using Euler angle calculation. Between-calculation method differences were large for both motion capture systems. Findings suggest that the True axial rotation method may result in more consistent findings that will allow for precise measurements and comparison between motion capture systems. Two methods for calculating humeral axial rotation measured from optical motion capture and inertial measurement units were compared.

Age-related changes in mobility assessments correlate with repetitive goal-directed arm-movement performance

BACKGROUND

There is ample evidence that mobility abilities between healthy young and elderly people differ. However, we do not know whether these differences are based on different lower leg motor capacity or instead reveal a general motor condition that could be detected by monitoring upper-limb motor behavior. We therefore captured body movements during a standard mobility task, namely the Timed Up and Go test (TUG) with subjects following different instructions while performing a rapid, repetitive goal-directed arm-movement test (arm-movement test). We hypothesized that we would be able to predict gait-related parameters from arm motor behavior, even regardless of age.

METHODS

Sixty healthy individuals were assigned to three groups (young: mean 26 ± 3 years, middle-aged 48 ± 9, old 68 ± 7). They performed the arm-movement and TUG test under three conditions: preferred (at preferred movement speed), dual-task (while counting backwards), and fast (at fast movement speed). We recorded the number of contacts within 20 s and the TUG duration. We also extracted TUG walking sequences to analyze spatiotemporal gait parameters and evaluated the correlation between arm-movement and TUG results.

RESULTS

The TUG condition at preferred speed revealed differences in gait speed and step length only between young and old, while dual-task and fast execution increased performance differences significantly among all 3 groups. Our old group's gait speed decreased the most doing the dual-task, while the young group's gait speed increased the most during the fast condition. As in our TUG results, arm-movements were significant faster in young than in middle-aged and old. We observed significant correlations between arm movements and the fast TUG condition, and that the number of contacts closely predicts TUG timefast and gait speedfast. This prediction is more accurate when including age.

CONCLUSION

We found that the age-related decline in mobility performance that TUG reveals strongly depends on the test instruction: the dual-task and fast condition clearly strengthened group contrasts. Interestingly, a fast TUG performance was predictable by the performance in a fast repetitive goal-directed arm-movements test, even beyond the age effect. We assume that arm movements and the fast TUG condition reflect similarly reduced motor function.

TRIAL REGISTRATION

German Clinical Trials Register (DRKS) number: DRKS00016999, prospectively registered on March, 26, 2019.

Monitoring Scapular Kinematics through Wearable Magneto-Inertial Measurement Units: State of the Art and New Frontiers

Monitoring shoulder kinematics, including the scapular segment, is of great relevance in the orthopaedic field. Among wearable systems, magneto-inertial measurement units (M-IMUs) represent a valid alternative for applications in unstructured environments. The aim of this systematic literature review is to report and describe the existing methods to estimate 3D scapular movements through wearable systems integrating M-IMUs. A comprehensive search of PubMed, IEEE Xplore, and Web of Science was performed, and results were included up to May 2023. A total of 14 articles was included. The results showed high heterogeneity among studies regarding calibration procedures, tasks executed, and the population. Two different techniques were described, i.e., with the x-axis aligned with the cranial edge of the scapular spine or positioned on the flat surface of the acromion with the x-axis perpendicular to the scapular spine. Sensor placement affected the scapular motion and, also, the kinematic output. Further studies should be conducted to establish a universal protocol that reduces the variability among studies. Establishing a protocol that can be carried out without difficulty or pain by patients with shoulder musculoskeletal disorders could be of great clinical relevance for patients and clinicians to monitor 3D scapular kinematics in unstructured settings or during common clinical practice.

Conversion of Upper-Limb Inertial Measurement Unit Data to Joint Angles: A Systematic Review

Inertial measurement units (IMUs) have become the mainstay in human motion evaluation outside of the laboratory; however, quantification of 3-dimensional upper limb motion using IMUs remains challenging. The objective of this systematic review is twofold. Firstly, to evaluate computational methods used to convert IMU data to joint angles in the upper limb, including for the scapulothoracic, humerothoracic, glenohumeral, and elbow joints; and secondly, to quantify the accuracy of these approaches when compared to optoelectronic motion analysis. Fifty-two studies were included. Maximum joint motion measurement accuracy from IMUs was achieved using Euler angle decomposition and Kalman-based filters. This resulted in differences between IMU and optoelectronic motion analysis of 4° across all degrees of freedom of humerothoracic movement. Higher accuracy has been achieved at the elbow joint with functional joint axis calibration tasks and the use of kinematic constraints on gyroscope data, resulting in RMS errors between IMU and optoelectronic motion for flexion-extension as low as 2°. For the glenohumeral joint, 3D joint motion has been described with RMS errors of 6° and higher. In contrast, scapulothoracic joint motion tracking yielded RMS errors in excess of 10° in the protraction-retraction and anterior-posterior tilt direction. The findings of this study demonstrate high-quality 3D humerothoracic and elbow joint motion measurement capability using IMUs and underscore the challenges of skin motion artifacts in scapulothoracic and glenohumeral joint motion analysis. Future studies ought to implement functional joint axis calibrations, and IMU-based scapula locators to address skin motion artifacts at the scapula, and explore the use of artificial neural networks and data-driven approaches to directly convert IMU data to joint angles.

Kinematic evaluation and reliability assessment of the Nine Hole Peg Test for manual dexterity

BACKGROUND

The Nine Hole Peg Test (NHPT) is one of the most frequently used tools to assess manual dexterity. However, no kinematic parameters are provided to describe the quality of the motor performance, since time is the only score.

PURPOSE

To investigate test-retest and intra-rater reliability, correlation with clinical test score, and discriminant validity of kinematic indexes during NHPT.

STUDY DESIGN

A clinical measurement study.

METHODS

Twenty-five healthy right-handed volunteers performed the NHPT. An experienced physiotherapist administered two sessions at a 6-hour interval with two trials for dominant and non-dominant upper limbs. An optoelectronic system was used to detect NHPT performance, which was divided into nine consecutive peg-grasp, peg-transfer, peg-in-hole, hand-return phases, and one final removing phase. Outcome measures were total and single phases times, normalized jerk, mean, peak and time-to-peak of velocity, curvature index during peg-grasp and hand-return phases, and trunk 3D displacement. The statistical analysis included Intraclass Correlation Coefficients (ICCs) for test-retest and intra-rater reliability, Pearson's coefficients for correlation with the NHPT score, and paired t-tests for discriminant validity.

RESULTS

Test-retest reliability was excellent for trunk rotation (ICC: 0.91) and good to moderate for the other indexes (ICCs: 0.89-0.61). Intra-rater reliability was excellent for total and removing times (ICCs: 0.91 and 0.94) and good to moderate for the other indexes (ICCs: 0.84-0.66), except for trunk inclination (ICC: 0.37). NHPT phases, normalized jerk, mean velocity, peak of velocity, time-to-peak and curvature index correlated with total time (r-score: 0.8-0.3). NHPT phases and most kinematic indexes discriminated the dominant from non-dominant upper limb, with the greatest effect size for normalized jerk during hand-return (d = 1.16).

CONCLUSIONS

Kinematic indexes during NHPT can be considered for manual dexterity assessment. These indexes may allow for the detection of kinematic changes responsible for NHPT score variations in healthy subjects or patients with upper limb impairments.

Quantitative Assessment of Upper Limb Movement in Post-Stroke Adults for Identification of Sensitive Measures in Reaching and Lifting Activities

BACKGROUND

The assumption of this work is the achievement of objective results of the movement structure, which forms the basis for in-depth analysis and, consequently, for determining the upper limb movements that are most affected by stroke compared to healthy people.

METHODS

An analysis of relevant and systematically identified features of upper limb movement in post-stroke adults is presented based on scalable hypothesis tests. The basic features were calculated using movements defined by the x, y, and z coordinates (i.e., 3D trajectory time series) and compared to the results of post-stroke patients with healthy controls of similar age.

RESULTS

After automatic feature selection, out of the 1004 common features of upper limb movement, the most differentiated were the upper arm movements in reaching kinematics. In terms of movement type, movements in the frontal plane (shoulder abduction and adduction) were the most sensitive to changes. The largest number of discriminating features was determined on the basis of acceleration time series.

CONCLUSIONS

In the 3D assessment of functional activities of the upper limb, the upper arm turned out to be the most differentiated body segment, especially during abduction and adduction movements. The results indicate a special need to pay attention to abduction and adduction movements to improve the activities of daily living of the upper limbs after a stroke.

Defining repeatability for scapulothoracic and thoracohumeral motion during the novel work-related activities and functional task (WRAFT) protocol

Upper limb motion can be challenging to measure and analyze during work or daily life tasks. Further, humeral angle calculation method substantially influences angle outcomes. Therefore, the purpose of this study was to assess the repeatability of scapular and humeral kinematics and compare thoracohumeral angle calculation during a work-related and functional task (WRAFT) protocol. Thirty healthy young adults completed the WRAFT protocol (Comb Hair, Wash Axilla, Tie Apron, Overhead Reach, Side Reach, Forward Transfer, Floor Lift, and Overhead Lift) on two separate occasions. Peak humeral angles and select scapular angles were extracted for each task. Intra-class correlation coefficients (ICCs), standard error of measurement, and minimal detectable change (MDC) were examined. Humeral angles were compared using the XZY and ZXY rotation sequences and "true" axial rotation for incidence of gimbal lock and amplitude coherence. Results showed that for scapular kinematics, elevation-based WRAFTs produced overall better ICC scores (0.23-0.90) compared to those tasks primarily driven by lateral humeral motion (0.02-0.84). MDCs ranged from 7°-78°, suggesting some tasks demonstrated good repeatability (Comb Hair, Overhead Reach, Floor Lift), while others had very high variability (Side Reach, Tie Apron). Amplitude coherence for thoracohumeral angles was best for ZXY for all tasks except the Comb Hair and Tie Apron, for which XZY is recommended. "True" axial rotation demonstrated good coherence for all but Tie Apron. The WRAFT protocol may be used for functionally relevant scapular and humeral kinematic assessment for select task and posture combinations.

mCrutch: A Novel m-Health Approach Supporting Continuity of Care

This paper reports the architecture of a low-cost smart crutches system for mobile health applications. The prototype is based on a set of sensorized crutches connected to a custom Android application. Crutches were instrumented with a 6-axis inertial measurement unit, a uniaxial load cell, WiFi connectivity, and a microcontroller for data collection and processing. Crutch orientation and applied force were calibrated with a motion capture system and a force platform. Data are processed and visualized in real-time on the Android smartphone and are stored on the local memory for further offline analysis. The prototype's architecture is reported along with the post-calibration accuracy for estimating crutch orientation (5° RMSE in dynamic conditions) and applied force (10 N RMSE). The system is a mobile-health platform enabling the design and development of real-time biofeedback applications and continuity of care scenarios, such as telemonitoring and telerehabilitation.

Computer-assisted approaches for measuring, segmenting, and analyzing functional upper extremity movement: a narrative review of the current state, limitations, and future directions

The analysis of functional upper extremity (UE) movement kinematics has implications across domains such as rehabilitation and evaluating job-related skills. Using movement kinematics to quantify movement quality and skill is a promising area of research but is currently not being used widely due to issues associated with cost and the need for further methodological validation. Recent developments by computationally-oriented research communities have resulted in potentially useful methods for evaluating UE function that may make kinematic analyses easier to perform, generally more accessible, and provide more objective information about movement quality, the importance of which has been highlighted during the COVID-19 pandemic. This narrative review provides an interdisciplinary perspective on the current state of computer-assisted methods for analyzing UE kinematics with a specific focus on how to make kinematic analyses more accessible to domain experts. We find that a variety of methods exist to more easily measure and segment functional UE movement, with a subset of those methods being validated for specific applications. Future directions include developing more robust methods for measurement and segmentation, validating these methods in conjunction with proposed kinematic outcome measures, and studying how to integrate kinematic analyses into domain expert workflows in a way that improves outcomes.

Comparison of scapular kinematics from optical motion capture and inertial measurement units during a work-related and functional task protocol

Understanding scapular motion during everyday tasks is essential for adequate return-to-work and intervention programming, yet most scapular assessments involve restricted motion analysis within a laboratory setting. Inertial measurement units (IMUs) have been used to track scapular motion, but their validity compared to "gold standard" optical motion capture is not well defined. Further, it is unclear how different IMU sensor placements could affect scapular kinematic outcomes during a functional task protocol. To assess the reliability of scapular motion measurements with the use of the "gold standard" optical motion capture and IMUs, and to compare scapular IMU placement to assess which location (acromion or spine) was best for reliability of scapular motion, participants completed two testing sessions. During each lab visit, participant torso, humeri, and scapulae motion was tracked during 3 trials of 8 dynamic tasks and two elevation movements. Scapular angles were extracted during each task. To assess intra-session reliability, intra-class correlation coefficients (ICCs), and root mean square errors (RMSEs) were calculated. Results showed ICCs and RMSEs were acceptable. Although there appeared offsets between the two motion capture system scapular kinematics outcomes based on the plotted waveforms, the movement patterns appeared consistent between both motion capture methods. Data also showed that acromion IMU placement produced slightly more reliable outcomes than placement on the spine. Two placements of scapular tracking IMUs were tested with identical procedures.

Comparison of compensatory shoulder movements, functionality and satisfaction in transradial amputees fitted with two prosthetic myoelectric hooks

The functionalities of myoelectric hooks, such as whether they allow wrist movements, as well as the volume and design of the devices, may impact how fitted transradial amputees use their upper limbs. The aim of the current study was to compare two prosthetic myoelectric hooks in terms of compensatory shoulder movements, functionality and user satisfaction. This monocentric, randomized, controlled, cross-over trial evaluated eight transradial amputees fitted with two prosthetic myoelectric hooks, the Greifer and the Axon-Hook, during two consecutive periods. At the end of each period, shoulder abduction (mean and percentage of time with shoulder abduction > 60°) and manual dexterity were assessed using the Box and Blocks Test (BBT) on both sides, and satisfaction was assessed with the Evaluation of Satisfaction with Assistive Technology questionnaire. For each patient, data obtained with the BBT on the amputated side were compared with those obtained on the non-amputated side. Shoulder abduction was significantly higher with the Greifer (60.9°± 20.3°, p = 0.03) than with the Axon-Hook (39.8°± 16.9°) and also than with the NA side (37.6 ± 19.4°, p = 0.02). Shoulder abduction on the NA side (37.6 ± 19.4°) was close to that of the Axon-Hook (39.8°± 16.9°). The percentage of time spent with shoulder abduction > 60° during the BBT was higher with the Greifer than with the Axon-Hook or with the NA side (53.3 ± 34.4%, 17.6 ± 27.0% and 18.4 ± 34.9%, respectively), but the differences were not significant (p = 0.15). A significant strong negative correlation was found between shoulder abduction and wrist position with the Axon-Hook (r = -0.86; p < 0.01), but not with the Greifer. Manual dexterity and satisfaction did not differ significantly between the two devices. These results revealed compensatory movements, such as shoulder abduction in transradial amputees equipped with hooks, themselves influenced by the prosthetic device settings.

Analysis of the movements of the upper extremities during gait: Their role for the dynamic balance

BACKGROUND

The movement of the upper extremities is important for balance control in human walking. However, it is still unknown which mode of arm swing ensures the most stable gait due to the lack of appropriate measures which can quantify the movement of the upper extremities. In this study, we formulate a new parameter to numerically describe the arm swing. We investigated the effect of walking speed, sports activities and the subject's BMI on the movement of the upper limbs.

METHODS

Data of healthy 50 subjects from an external database was used. We used a human gait database for this analysis. All experimental trials were performed in Centre National de Rééducation Fonctionnelle et de Réadaptation - Rehazenter in Laboratoire d'Analyse du Mouvement et de la Posture in Luxembourg. Participants were asked to walk on a straight level walkway at 5 different speeds: 0-0.4 m/s, 0.4-0.8 m/s, 0.8-1.2 m/s, self-selected spontaneous and fast speeds. The human motion was recorded by using a 10-camera optoelectronic system.

FINDINGS

The amplitude of arm swing was greater in gait with self-selected fast speed then in slow walking. Higher walking speeds entailed also the more structured and repetitive movement of the upper extremities. For self-selected fast speed, the mean value of Pearson's correlation coefficient between arm swing amplitude of the left and right side was 0.935 ± 0.102, 0.943 ± 0.073 and 0.973 ± 0.020 for the young, middle aged and elderly group respectively, while in slow walking it was in the range 0.393-0.633 (for the representatives of the three groups). Our results could suggest other factors which influence arm swing, such as obesity and doing asymmetric sports.

INTERPRETATIONS

Our results suggest that choosing the lowest possible walking speed is not the best strategy as the most symmetric arm swing occurs during gait with self-selected speed.

Current Concepts in Upper-Extremity Motion Analysis: Room To Grow?

Kinematic motion analysis (KMA) is well established in the assessment of gait and lower-extremity kinematics; however, its application to upper-extremity (UE) pathology has been limited. This review provides a concise overview of information related to the KMA technology that is pertinent to the clinician. Advantages of KMA for UE assessment are discussed, along with barriers to implementation. An example of KMA used for perioperative assessment of a patient undergoing a distal humerus osteotomy for the correction of arthrogrypotic internal rotation deformity is provided to illustrate its clinical feasibility. Kinematic motion analysis has exciting potential to advance the evaluation and management of UE disorders; however, broad application will require validation and standardization of UE-specific KMA protocols in addition to decreased logistical and cost burdens.

Optical Motion Capture Systems for 3D Kinematic Analysis in Patients with Shoulder Disorders

Shoulder dysfunctions represent the third musculoskeletal disorder by frequency. However, monitoring the movement of the shoulder is particularly challenging due to the complexity of the joint kinematics. The 3D kinematic analysis with optical motion capture systems (OMCs) makes it possible to overcome clinical tests' shortcomings and obtain objective data on the characteristics and quality of movement. This systematic review aims to retrieve the current knowledge about using OMCs for 3D shoulder kinematic analysis in patients with musculoskeletal shoulder disorders and their corresponding clinical relevance. The Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines were used to improve the reporting of the review. Studies employing OMCs for 3D kinematic analysis in patients with musculoskeletal shoulder disorders were retrieved. Eleven articles were considered eligible for this study. OMCs can be considered a powerful tool in orthopedic clinical research. The high costs and organizing complexities of experimental setups are likely outweighed by the impact of these systems in guiding clinical practice and patient follow-up. However, additional high-quality studies on using OMCs in clinical practice are required, with standardized protocols and methodologies to make comparing clinical trials easier.

A Comprehensive Analysis of the Validity and Reliability of the Perception Neuron Studio for Upper-Body Motion Capture

The Perception Neuron Studio (PNS) is a cost-effective and widely used inertial motion capture system. However, a comprehensive analysis of its upper-body motion capture accuracy is still lacking, before it is being applied to biomechanical research. Therefore, this study first evaluated the validity and reliability of this system in upper-body capturing and then quantified the system's accuracy for different task complexities and movement speeds. Seven participants performed simple (eight single-DOF upper-body movements) and complex tasks (lifting a 2.5 kg box over the shoulder) at fast and slow speeds with the PNS and OptiTrack (gold-standard optical system) collecting kinematics data simultaneously. Statistical metrics such as CMC, RMSE, Pearson's r, R², and Bland-Altman analysis were utilized to assess the similarity between the two systems. Test-retest reliability included intra- and intersession relations, which were assessed by the intraclass correlation coefficient (ICC) as well as CMC. All upper-body kinematics were highly consistent between the two systems, with CMC values 0.73-0.99, RMSE 1.9-12.5°, Pearson's r 0.84-0.99, R² 0.75-0.99, and Bland-Altman analysis demonstrating a bias of 0.2-27.8° as well as all the points within 95% limits of agreement (LOA). The relative reliability of intra- and intersessions was good to excellent (i.e., ICC and CMC were 0.77-0.99 and 0.75-0.98, respectively). The paired t-test revealed that faster speeds resulted in greater bias, while more complex tasks led to lower consistencies. Our results showed that the PNS could provide accurate enough upper-body kinematics for further biomechanical performance analysis.

Topographic design in wearable MXene sensors with in-sensor machine learning for full-body avatar reconstruction

Wearable strain sensors that detect joint/muscle strain changes become prevalent at human–machine interfaces for full-body motion monitoring. However, most wearable devices cannot offer customizable opportunities to match the sensor characteristics with specific deformation ranges of joints/muscles, resulting in suboptimal performance. Adequate wearable strain sensor design is highly required to achieve user-designated working windows without sacrificing high sensitivity, accompanied with real-time data processing. Herein, wearable Ti₃C₂T_x MXene sensor modules are fabricated with in-sensor machine learning (ML) models, either functioning via wireless streaming or edge computing, for full-body motion classifications and avatar reconstruction. Through topographic design on piezoresistive nanolayers, the wearable strain sensor modules exhibited ultrahigh sensitivities within the working windows that meet all joint deformation ranges. By integrating the wearable sensors with a ML chip, an edge sensor module is fabricated, enabling in-sensor reconstruction of high-precision avatar animations that mimic continuous full-body motions with an average avatar determination error of 3.5 cm, without additional computing devices.

Wearable sensors with edge computing are desired for human motion monitoring. Here, the authors demonstrate a topographic design for wearable MXene sensor modules with wireless streaming or in-sensor computing models for avatar reconstruction.

Assessing the validity of inertial measurement units for shoulder kinematics using a commercial sensor-software system: A validation study

Background and  Aims

Wearable inertial sensors may offer additional kinematic parameters of the shoulder compared to traditional instruments such as goniometers when elaborate and time-consuming data processing procedures are undertaken. However, in clinical practice simple-real time motion analysis is required to improve clinical reasoning. Therefore, the aim was to assess the criterion validity between a portable "off-the-shelf" sensor-software system (IMU) and optical motion (Mocap) for measuring kinematic parameters during active shoulder movements.

Methods

24 healthy participants (9 female, 15 male, age 29 ± 4 years, height 177 ± 11 cm, weight 73 ± 14 kg) were included. Range of motion (ROM), total range of motion (TROM), peak and mean angular velocity of both systems were assessed during simple (abduction/adduction, horizontal flexion/horizontal extension, vertical flexion/extension, and external/internal rotation) and complex shoulder movements. Criterion validity was determined using intraclass-correlation coefficients (ICC), root mean square error (RMSE) and Bland and Altmann analysis (bias; upper and lower limits of agreement).

Results

ROM and TROM analysis revealed inconsistent validity during simple (ICC: 0.040-0.733, RMSE: 9.7°-20.3°, bias: 1.2°-50.7°) and insufficient agreement during complex shoulder movements (ICC: 0.104-0.453, RMSE: 10.1°-23.3°, bias: 1.0°-55.9°). Peak angular velocity (ICC: 0.202-0.865, RMSE: 14.6°/s-26.7°/s, bias: 10.2°/s-29.9°/s) and mean angular velocity (ICC: 0.019-0.786, RMSE:6.1°/s-34.2°/s, bias: 1.6°/s-27.8°/s) were inconsistent.

Conclusions

The "off-the-shelf" sensor-software system showed overall insufficient agreement with the gold standard. Further development of commercial IMU-software-solutions may increase measurement accuracy and permit their integration into everyday clinical practice.

Shoulder structure and function: The impact of osteoarthritis and rehabilitation strategies

STUDY DESIGN

Invited review.

BACKGROUND

Shoulder osteoarthritis can result in significant functional deficits. To improve diagnosis and treatment, we must better understand the impact of osteoarthritis on shoulder biomechanics and the known mechanical benefits of currently available treatments.

PURPOSE

The purpose of this paper is to present up-to-date data on the effects of osteoarthritis and rehabilitation on the biomechanical parameters contributing to shoulder function. With this goal, we also reviewed the anatomy and the ranges of motion of the shoulder.

METHODS

A search of electronic databases was conducted. All study designs were included to inform this qualitative, narrative literature review.

RESULTS

This review describes the biomechanics of the shoulder, the impact of osteoarthritis on shoulder function, and the treatment of shoulder osteoarthritis with an emphasis on rehabilitation.

CONCLUSIONS

The shoulder is important for the completion of activities of daily living, and osteoarthritis of the shoulder can significantly reduce shoulder motion and arm function. Although shoulder rehabilitation is an integral treatment modality to improve pain and function in shoulder osteoarthritis, few high-quality studies have investigated the effects and benefits of shoulder physical and occupational therapies. To advance the fields of therapy and rehabilitation, future studies investigating the effects of therapy intensity, therapy duration, and the relative benefits of therapy subtypes on shoulder biomechanics and function are necessary.

Building FAIR Functionality: Annotating Events in Time Series Data Using Hierarchical Event Descriptors (HED)

Human electrophysiological and related time series data are often acquired in complex, event-rich environments. However, the resulting recorded brain or other dynamics are often interpreted in relation to more sparsely recorded or subsequently-noted events. Currently a substantial gap exists between the level of event description required by current digital data archiving standards and the level of annotation required for successful analysis of event-related data across studies, environments, and laboratories. Manifold challenges must be addressed, most prominently ontological clarity, vocabulary extensibility, annotation tool availability, and overall usability, to allow and promote sharing of data with an effective level of descriptive detail for labeled events. Motivating data authors to perform the work needed to adequately annotate their data is a key challenge. This paper describes new developments in the Hierarchical Event Descriptor (HED) system for addressing these issues. We recap the evolution of HED and its acceptance by the Brain Imaging Data Structure (BIDS) movement, describe the recent release of HED-3G, a third generation HED tools and design framework, and discuss directions for future development. Given consistent, sufficiently detailed, tool-enabled, field-relevant annotation of the nature of recorded events, prospects are bright for large-scale analysis and modeling of aggregated time series data, both in behavioral and brain imaging sciences and beyond.

Dynamic Analysis of a Spherical Parallel Robot Used for Brachial Monoparesis Rehabilitation

This paper presents studies on the dynamic analysis of the ASPIRE robot, which was designed for the medical recovery of brachial monoparesis. It starts from the virtual model of the existing version of the ASPIRE robot, which is analysed kinematically and dynamically by numerical simulations using the MSC.ADAMS software. For this purpose, this paper presents theoretical aspects regarding the kinematics and dynamics of the markers attached to the flexible bodies built in a specifically developed MSC.ADAMS model. Three simulation hypotheses are considered: (a) rigid kinematic elements without friction in couplings, (b) rigid kinematic elements with friction in couplings, and (c) kinematic elements as deformable solids with friction in couplings. Experimental results obtained by using the physical prototype of ASPIRE are presented. Results such as the connecting forces in the kinematic joints and the torques necessary to operate the ASPIRE robot modules have been obtained by dynamic simulation in MSC.ADAMS and compared with those determined experimentally. The comparison shows that the allure of the variation curve of the moment obtained by simulation is similar to that obtained experimentally. The difference between the maximum experimental value and that obtained by simulation is less than 1%. A finite element analysis (FEA) of the structurally optimized flexion/extension robot module is performed. The results demonstrate the operational safety of the ASPIRE robot, which is structurally capable of supporting the stresses to which it is subjected.

Effect of Rotation Sequence on Thoracohumeral Joint Kinematics during Various Shoulder Postures. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2021;2021:4912-4915. [PMID: 34892309 PMCID: PMC9817035 DOI: 10.1109/embc46164.2021.9629667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Current methods for selecting a rotation sequence to biomechanically model shoulder joint angles during motion assessment are challenging and controversial due to insufficient knowledge of their effect on the clinical interpretation of movement. Seven rotation sequences were examined by factors including incidences of gimbal lock and joint angle error in two healthy adults during 12 postures using right and left arms. This work was the first to explore the effects of each of the six Cardan angle sequences and the International Society of Biomechanics recommended YXY Euler sequence on the thoracohumeral joint in an array of postures. Results of this work show that there is not a "one size fits all" approach via rotation sequence selection for reliable and coherent expression of shoulder joint postures, particularly of the thoracohumeral joint. For best biomechanical modeling practice, it is recommended that researchers carefully consider the implications of a particular rotation sequence based on the posture or task of interest and resulting incidences of gimbal lock and joint angle error.Clinical Relevance- This work examines the effect of seven different mathematical computations for assessing shoulder joint angles in different postures for application of clinical movement analysis.

The Intra- and Inter-Rater Reliability of a Hip Rotation Range-of-Motion Measurement Using a Smartphone Application in Academy Football (Soccer) Players

The clinical assessment of hip rotation range-of-motion (ROM) is important for managing hip and groin injuries in footballers. Previously published reliability studies on hip ROM have employed protocols that are difficult to replicate under everyday clinical conditions. This single trial, intra- and inter-rater reliability study included 41 male academy football (soccer) players, aged 14–15 years, from one European football academy. Passive hip internal rotation (IR) and external rotation (ER) ROM were measured in supine with hip and knee flexed to 90°. The ROM was determined using a smartphone application, with the smartphone attached to the lower leg. The tests were performed on two separate occasions, one week apart, by two different physiotherapists and on both sides (left and right hips). Reliability was evaluated using Intra-Class Correlation Coefficients (ICCs) and Minimal Detectable Change (MDC). Hip IR and ER ROM displayed moderate to good intra-rater agreement (ICCs 0.54–0.75), with MDCs ranging from 10.9° to 16.4°. Inter-rater reliability displayed poor to moderate reliability (ICCs 0.33–0.75), with MDCs ranging from 11.7° to 16.5°. A hip rotation ROM test using a smartphone application and a protocol closely reflecting everyday clinical conditions displayed moderate to good intra-rater reliability and poor to moderate inter-rater reliability. Due to the high MDCs, the practical applicability of this test procedure is limited and further refinement is necessary.

Neurorobotic fusion of prosthetic touch, kinesthesia, and movement in bionic upper limbs promotes intrinsic brain behaviors

[Figure: see text].

Skin Strain Analysis of the Scapular Region and Wearables Design

Monitoring scapular movements is of relevance in the contexts of rehabilitation and clinical research. Among many technologies, wearable systems instrumented by strain sensors are emerging in these applications. An open challenge for the design of these systems is the optimal positioning of the sensing elements, since their response is related to the strain of the underlying substrates. This study aimed to provide a method to analyze the human skin strain of the scapular region. Experiments were conducted on five healthy volunteers to assess the skin strain during upper limb movements in the frontal, sagittal, and scapular planes at different degrees of elevation. A 6 × 5 grid of passive markers was placed posteriorly to cover the entire anatomic region of interest. Results showed that the maximum strain values, in percentage, were 28.26%, and 52.95%, 60.12% and 60.87%, 40.89%, and 48.20%, for elevation up to 90° and maximum elevation in the frontal, sagittal, and scapular planes, respectively. In all cases, the maximum extension is referred to the pair of markers placed horizontally near the axillary fold. Accordingly, this study suggests interesting insights for designing and positioning textile-based strain sensors in wearable systems for scapular movements monitoring.

Changes in kinematics and work physiology during progressive lifting in healthy adults

PURPOSE

To analyze progression of changes in kinematics and work physiology during progressive lifting in healthy adults.

METHODS

Healthy participants were recruited. A standardized lifting test from the WorkWell Functional Capacity Evaluation (FCE) was administered, with five progressive lifting low series of five repetitions. The criteria of the WorkWell observation protocol were studied: changes in muscle use (EMG), heart rate (heart rate monitor), base of support, posture and movement pattern (motion capture system). Repeated measures ANOVA's were used to analyze changes during progressive workloads.

RESULTS

18 healthy young adults participated (8 men, 10 women; mean age 22 years). Mean maximum weight lifted was 66 (±3.2) and 44 (±7.4) kg for men and women, respectively. With progressive loads, statistically significant (p < 0.01) differences were observed: increase in secondary muscle use at moderate lifting, increase of heart rate, increase of base of support and movement pattern changes were observed; differences in posture were not significant.

CONCLUSIONS

Changes in 4 out of 5 kinematic and work physiology parameters were objectively quantified using lab technology during progressive lifting in healthy adults. These changes appear in line with existing observation criteria.

How many trials are needed in kinematic analysis of reach-to-grasp?-A study of the drinking task in persons with stroke and non-disabled controls

Background

Kinematic analysis of the 3D reach-to-grasp drinking task is recommended in stroke rehabilitation research. The number of trials required to reach performance stability, as an important aspect of reliability, has not been investigated for this task. Thus, the aims of this study were to determine the number of trials needed for the drinking task to reach within-session performance stability and to investigate trends in performance over a set of trials in non-disabled people and in a sample of individuals with chronic stroke. In addition, the between-sessions test–retest reliability in persons with stroke was established.

Methods

The drinking task was performed at least 10 times, following a standardized protocol, in 44 non-disabled and 8 post-stroke individuals. A marker-based motion capture system registered arm and trunk movements during 5 pre-defined phases of the drinking task. Intra class correlation statistics were used to determine the number of trials needed to reach performance stability as well as to establish test–retest reliability. Systematic within-session trends over multiple trials were analyzed with a paired t-test.

Results

For most of the kinematic variables 2 to 3 trials were needed to reach good performance stability in both investigated groups. More trials were needed for movement times in reaching and returning phase, movement smoothness, time to peak velocity and inter-joint-coordination. A small but significant trend of improvement in movement time over multiple trials was demonstrated in the non-disabled group, but not in the stroke group. A mean of 3 trials was sufficient to reach good to excellent test–retest reliability for most of the kinematic variables in the stroke sample.

Conclusions

This is the first study that determines the number of trials needed for good performance stability (non-disabled and stroke) and test–retest reliability (stroke) for temporal, endpoint and angular metrics of the drinking task. For most kinematic variables, 3–5 trials are sufficient to reach good reliability. This knowledge can be used to guide future kinematic studies.

Sensor Network for Analyzing Upper Body Strategies in Parkinson's Disease versus Normative Kinematic Patterns

In rehabilitation, the upper limb function is generally assessed using clinical scales and functional motor tests. Although the Box and Block Test (BBT) is commonly used for its simplicity and ease of execution, it does not provide a quantitative measure of movement quality. This study proposes the integration of an ecological Inertial Measurement Units (IMUs) system for analysis of the upper body kinematics during the execution of a targeted version of BBT, by able-bodied persons with subjects with Parkinson's disease (PD). Joint angle parameters (mean angle and range of execution) and hand trajectory kinematic indices (mean velocity, mean acceleration, and dimensionless jerk) were calculated from the data acquired by a network of seven IMUs. The sensors were applied on the trunk, head, and upper limb in order to characterize the motor strategy used during the execution of BBT. Statistics revealed significant differences (p < 0.05) between the two groups, showing compensatory strategies in subjects with PD. The proposed IMU-based targeted BBT protocol allows to assess the upper limb function during manual dexterity tasks and could be used in the future for assessing the efficacy of rehabilitative treatments.

Metrological Evaluation of Human-Robot Collaborative Environments Based on Optical Motion Capture Systems

In the context of human-robot collaborative shared environments, there has been an increase in the use of optical motion capture (OMC) systems for human motion tracking. The accuracy and precision of OMC technology need to be assessed in order to ensure safe human-robot interactions, but the accuracy specifications provided by manufacturers are easily influenced by various factors affecting the measurements. This article describes a new methodology for the metrological evaluation of a human-robot collaborative environment based on optical motion capture (OMC) systems. Inspired by the ASTM E3064 test guide, and taking advantage of an existing industrial robot in the production cell, the system is evaluated for mean error, error spread, and repeatability. A detailed statistical study of the error distribution across the capture area is carried out, supported by a Mann-Whitney U-test for median comparisons. Based on the results, optimal capture areas for the use of the capture system are suggested. The results of the proposed method show that the metrological characteristics obtained are compatible and comparable in quality to other methods that do not require the intervention of an industrial robot.

Automatic Identification of Upper Extremity Rehabilitation Exercise Type and Dose Using Body-Worn Sensors and Machine Learning: A Pilot Study

BACKGROUND

Prior studies suggest that participation in rehabilitation exercises improves motor function poststroke; however, studies on optimal exercise dose and timing have been limited by the technical challenge of quantifying exercise activities over multiple days.

OBJECTIVES

The objectives of this study were to assess the feasibility of using body-worn sensors to track rehabilitation exercises in the inpatient setting and investigate which recording parameters and data analysis strategies are sufficient for accurately identifying and counting exercise repetitions.

METHODS

MC10 BioStampRC® sensors were used to measure accelerometer and gyroscope data from upper extremities of healthy controls (n = 13) and individuals with upper extremity weakness due to recent stroke (n = 13) while the subjects performed 3 preselected arm exercises. Sensor data were then labeled by exercise type and this labeled data set was used to train a machine learning classification algorithm for identifying exercise type. The machine learning algorithm and a peak-finding algorithm were used to count exercise repetitions in non-labeled data sets.

RESULTS

We achieved a repetition counting accuracy of 95.6% overall, and 95.0% in patients with upper extremity weakness due to stroke when using both accelerometer and gyroscope data. Accuracy was decreased when using fewer sensors or using accelerometer data alone.

CONCLUSIONS

Our exploratory study suggests that body-worn sensor systems are technically feasible, well tolerated in subjects with recent stroke, and may ultimately be useful for developing a system to measure total exercise "dose" in poststroke patients during clinical rehabilitation or clinical trials.

Myoelectric prosthesis users and non-disabled individuals wearing a simulated prosthesis exhibit similar compensatory movement strategies

Background

Research studies on upper limb prosthesis function often rely on the use of simulated myoelectric prostheses (attached to and operated by individuals with intact limbs), primarily to increase participant sample size. However, it is not known if these devices elicit the same movement strategies as myoelectric prostheses (operated by individuals with amputation). The objective of this study was to address the question of whether non-disabled individuals using simulated prostheses employ the same compensatory movements (measured by hand and upper body kinematics) as individuals who use actual myoelectric prostheses.

Methods

The upper limb movements of two participant groups were investigated: (1) twelve non-disabled individuals wearing a simulated prosthesis, and (2) three individuals with transradial amputation using their custom-fitted myoelectric devices. Motion capture was used for data collection while participants performed a standardized functional task. Performance metrics, hand movements, and upper body angular kinematics were calculated. For each participant group, these measures were compared to those from a normative baseline dataset. Each deviation from normative movement behaviour, by either participant group, indicated that compensatory movements were used during task performance.

Results

Results show that participants using either a simulated or actual myoelectric prosthesis exhibited similar deviations from normative behaviour in phase durations, hand velocities, hand trajectories, number of movement units, grip aperture plateaus, and trunk and shoulder ranges of motion.

Conclusions

This study suggests that the use of a simulated prosthetic device in upper limb research offers a reasonable approximation of compensatory movements employed by a low- to moderately-skilled transradial myoelectric prosthesis user.

Automatically Determining Lumbar Load during Physically Demanding Work: A Validation Study

A sensor-based system using inertial magnetic measurement units and surface electromyography is suitable for objectively and automatically monitoring the lumbar load during physically demanding work. The validity and usability of this system in the uncontrolled real-life working environment of physically active workers are still unknown. The objective of this study was to test the discriminant validity of an artificial neural network-based method for load assessment during actual work. Nine physically active workers performed work-related tasks while wearing the sensor system. The main measure representing lumbar load was the net moment around the L5/S1 intervertebral body, estimated using a method that was based on artificial neural network and perceived workload. The mean differences (MDs) were tested using a paired t-test. During heavy tasks, the net moment (MD = 64.3 ± 13.5%, p = 0.028) and the perceived workload (MD = 5.1 ± 2.1, p < 0.001) observed were significantly higher than during the light tasks. The lumbar load had significantly higher variances during the dynamic tasks (MD = 33.5 ± 36.8%, p = 0.026) and the perceived workload was significantly higher (MD = 2.2 ± 1.5, p = 0.002) than during static tasks. It was concluded that the validity of this sensor-based system was supported because the differences in the lumbar load were consistent with the perceived intensity levels and character of the work tasks.

Marker Placement Reliability and Objectivity for Biomechanical Cohort Study: Healthy Aging in Industrial Environment (HAIE-Program 4)

In large cohort studies, due to the time-consuming nature of the measurement of movement biomechanics, more than one evaluator needs to be involved. This may increase the potential occurrence of error due to inaccurate positioning of markers to the anatomical locations. The purpose of this study was to determine the reliability and objectivity of lower limb segments length by multiple evaluators in a large cohort study concerning healthy aging in an industrial environment. A total of eight evaluators performed marker placements on five participants on three different days. Evaluators placed markers bilaterally on specific anatomical locations of the pelvis, thigh, shank and foot. On the right foot, markers were placed in anatomical locations to define a multi-segmental foot model. The position of the marker at the anatomical locations was recorded by a motion capture system. The reliability and objectivity of lower limb segment lengths was determined by the intraclass correlation coefficient of a two-way random model and of the two-way mixed model, respectively. For all evaluators for all segments, the average reliability and objectivity was greater than 0.8, except for the metatarsus segment (0.683). Based on these results, we can conclude that multiple evaluators can be engaged in a large cohort study in the placement of anatomical markers.

Test-retest repeatability reveals a temporal kinematic signature for an upper limb precision grasping task in adults

Hand-eye coordination skills, such as reaching and grasping, are fundamentally important for the performance of most daily activities. Upper limb kinematics recorded by motion tracking systems provide detailed insight into the central nervous system control of movement planning and execution. For example, kinematic metrics can reveal deficits in control, and compensatory neuromotor strategies in individuals with neuropathologies. However, the clinical utility of kinematic metrics is currently limited because their psychometric properties, such as test-retest repeatability, have not been well characterized. Therefore, the purpose of this study was to examine the degree of repeatability of spatiotemporal kinematic metrics and determine which, if any, measures form a kinematic signature for a precision grasping task. Healthy adults (n = 40) were tested on two occasions separated by 5-10 days on a bead threading task consisting of reaching and precision grasping. Results showed good test-retest repeatability for reach peak velocity, reach and grasp durations, whereas poor to moderate reliability was observed for measures of spatial precision and maximum grip aperture. In addition, analysis showed that reliable estimates of kinematic metrics can be obtained using 10 trials. Overall, our results indicate that reach peak velocity and temporal metrics form a stable characteristic, or a kinematic signature, of individual performance on a standardized bead threading task. These findings suggest potential utility in applying kinematic metrics for clinical assessment of upper limb reaching tasks.

The development of a novel grip motion analysis technique using the Dartfish movement analysis software to evaluate hand movements during activities of daily living

Individuals with hand osteoarthritis (OA) have impairments in grip strength and range of motion (ROM). Obtaining quantitative joint angle measures of the hand is difficult. Without a complete understanding of the kinematics of the hand, the assessment of hand OA when performing activities of daily living (ADL) and recreational activities is not fully understood. The objectives of this study were to establish a simple measurement technique (Grip Configuration Model) describing an individual's grip ROM using the Dartfish Movement Analysis Software, and compare the joint angle measures during maximum flexion/extension and five ADL in people with/without hand OA. Forty participants (20 without hand OA, 20 with hand OA) thumb CMC and MCP, and index MCP and PIP joint angles were evaluated for each activity using the Dartfish Software and Grip Configuration Model. Significant limitations of 17.2% (p < 0.001) and 12.7% (p = 0.01) were seen in the group with hand OA for maximum flexion/extension, respectively. The spray bottle task demonstrated a significant difference of 14.7% (p = 0.001) between the two test groups. Measurements using the Dartfish Software were compared against a manual goniometer and electromagnetic tracking system. This study demonstrated the weakened ROM in individuals with hand OA is translated to ADL and how the Grip Configuration Model simplifies the evaluation of how people grasp objects.

An Asian-centric human movement database capturing activities of daily living

Assessment of human movement performance in activities of daily living (ADL) is a key component in clinical and rehabilitation settings. Motion capture technology is an effective method for objective assessment of human movement. Existing databases capture human movement and ADL performance primarily in the Western population, and there are no Asian databases to date. This is despite the fact that Asian anthropometrics influence movement kinematics and kinetics. This paper details the protocol in the first phase of the largest Asian normative human movement database. Data collection has commenced, and this paper reports 10 healthy participants. Twelve tasks were performed and data was collected using Qualisys motion capture system, force plates and instrumented table and chair. In phase two, human movement of individuals with stroke and knee osteoarthritis will be captured. This can have great potential for benchmarking with the normative human movement captured in phase one and predicting recovery and progression of movement for patients. With individualised progression, it will offer the development of personalised therapy protocols in rehabilitation.

Design and Initial Testing of an Affordable and Accessible Smart Compression Garment to Measure Physical Activity Using Conductive Paint Stretch Sensors

Motion capture and the measurement of physical activity are common practices in the fields of physical therapy, sports medicine, biomechanics, and kinesiology. The data collected by these systems can be very important to understand how someone is recovering or how effective various assistive devices may be. Traditional motion capture systems are very expensive and only allow for data collection to be performed in a lab environment. In our previous research, we have tested the validity of a novel stitched stretch sensor using conductive thread. This paper furthers that research by validating a smart compression garment with integrated conductive paint stretch sensors to measure movement. These sensors are very inexpensive to fabricate and, when paired with an open-sourced wireless microcontroller, can enable a more affordable, accessible, and comfortable form of motion capture. A wearable garment like the one tested in this study could allow us to understand how meaningful, functional activities are performed in a natural setting.