Wrist Position Research Articles

Identification of prevalence of musculoskeletal disorders and various risk factors in dentists

PurposeThe awkward and repetitive movements lead to tissue straining, potentially leading to painful musculoskeletal disorders (MSDs). MSDs in dentists result in work inefficiency and a reduction in work hours. A survey was conducted to assess the prevalence of MSDs amongst the dental population of interest. MethodsCustomized individual detail questionnaires, Standard Nordic Musculoskeletal questionnaires, and Level of Pain estimation using the Likert Scale were used to deduce the various responsible risk factors for the occurrence of MSDs in dentists. Inferential statistical analysis was done to identify the prevalence and severity of the MSDs. The Chi-Square test (95 % confidence interval) was used to identify and compare the association of risk factors involved in MSDs with the occurrence of the Effect of MSDs, the presence of MSDs, and the severity of the MSDs. ResultsThe results of the study deduced that the dentists followed the sedentary work practices. The dentists experienced maximum discomfort in the neck region, which was accompanied by the discomfort experienced in the lower back, hands and wrists, making the upper extremity being more susceptible to the MSDs. Gender risk factors the, the prevalence of MSDs in the dentist's upper back, and the severity of pain in the upper back region showed a significant association level. ConclusionThe wrist posture, the prevalence of MSDs and the severity of pain in the dentists' neck, shoulder and upper back showed a significant association level.

Carpal instability after partial trapeziectomy, total trapeziectomy and the resection of the distal scaphoid pole: a cadaveric study.

Non-dissociative carpal instability (CIND) may lead to severe functional impairment. Destabilisation of the scapho-trapezial-trapezoidal (STT) ligament complex seems to result in a CIND. In one group with eight cadaver arms, distal scaphoid pole was resected with the adjacent ligaments. In the other eight cadavers, hemitrapeziectomy was performed followed by total trapeziectomy. CT scans were performed in different wrist positions, and the changed positions of the scaphoid, lunate and capitate were measured in comparison to non-operated wrists. Mainly in clenched fist position, dissociation between proximal and distal row can be determined after total trapeziectomy and resection of distal scaphoid pole. Capitate rotates dorsally up to 24°, the scaphoid up to 17° and the lunate up to 7° compared to the non-operated wrists. Resection of the distal scaphoid pole results in dorsal rotation of capitate and scaphoid of about 14° and the lunate 8°. Relative scapholunate and capitolunate angle increased significantly after total trapeziectomy, especially in clenched fist position. After scaphoid pole resection, significant SL and CL angles changescould be seen in almost every wrist position. Destabilisation of the STT ligament complex by total trapeziectomy or distal scaphoid pole resection results in dissociation of the proximal and distal carpal row without instability within the proximal or distal row, corresponding to a CIND. III.

Effect of mount location on the quantification of light intensity in myopia study

PurposeTo investigate how the mounting location of wearable devices affects the measurement of light intensity.MethodsTwo commercially available wearable devices, HOBO and Clouclip, were used to compare the effects of different...

Comparison of the validity and reliability of three different methods used for wrist proprioception measurement

Backgroundː Early detection of loss of proprioception is essential to prevent injury and maintain professional work activities. However, although many different methods are present for wrist proprioception measurement, these methods' validity and reliability studies are quite limited. ObjectiveTo compare the validity and reliability of the goniometer, inclinometer, and joint position sense goniometer methods used in measuring wrist active joint position sense (AJPS). Methodsː Thirty-two volunteer healthy participants (64 wrists) between the ages of 19–31 (mean age:23,34 ± 3,84) were included in the study. Wrist AJPS was assessed with an isokinetic dynamometer as a reference standard in addition to an inclinometer, goniometer, and joint position sense goniometer (JPSG). Spearman's Correlation Coefficient was used for validity analysis, and Intraclass Correlation Coefficient (ICC3,1) was used to analyze test-retest reliability. Resultsː It was found that the goniometer (p < 0.001, r = 0.529) is a moderately valid method to assess active wrist joint position sense. The JPSG (p < 0.001, r = 0.432) and inclinometer (p = 0.005, r = 0.350) have weak validity. According to the results of ICC3,1 analysis, the goniometer (p < 0.001, ICC3,1 = 0.422) and JPSG (p < 0.001, ICC3,1 = 0.369) were found to have poor reliability in assessing wrist AJPS, and the inclinometer (p = 0,183, ICC3,1 = 0,114) was not found as a reliable method. Conclusionsː Our results suggest that the JPSG and inclinometer should not be used in the wrist active joint position sense evaluation because of weak validity and poor reliability. The goniometer can be used in clinics and academic research to evaluate wrist joint position sense if the rater lacks a reliable and valid measurement tool.

PREVALENCE OF MUSCULOSKELETAL DISCOMFORTS AMONG RURAL FARMERS IN NORTH-WESTERN NIGERIA

Agricultural tasks can be considered some of the most demanding and hazardous, especially in developing countries where crop production relies heavily on manual implements. Weeding, one of the common agricultural activities performed by farmers, requires a significant amount of physical effort and often involves awkward wrist and trunk postures, subjecting farmers to multiple risk factors that can result in musculoskeletal discomfort. In this study, a combination of qualitative and quantitative approaches is used to examine the prevalence of musculoskeletal conditions among rural peasant farmers in Jigawa, a state in northwestern Nigeria. The results of this study indicate that lower back pain, upper back pain, and wrist/hand pain are the most prevalent musculoskeletal conditions experienced by peasant farmers who are exposed to intensive manual farming operations.

Investigating the influence of keyboard inclinations on sitting and standing workstations

Given the growing global computer workforce, concerns exist about the escalation of computer related injury with Carpal tunnel syndrome (CTS) being one of the most reported work-related musculoskeletal disorders (WMSDs) among office workers. The optimal range of keyboard angles for sitting and standing positions based on wrist posture, forearm muscle activities and user preference as well as the keyboard location in relation to user position were analysed. 30 volunteers with an above 40 words per minute typing speed participated in this study. Result show that, although user prefer to use positive keyboard angle, the negatively tilted keyboard is more ergonomically friendly at both sitting and standing workstations, reducing muscle activity and awkward wrist posture while maintaining performance. The findings indicate that negative sloped keyboard might have the possibility to reduce the risk of developing CTS in office workers. Practitioner summary: This study determines the range of optimal slope of keyboard angle in a sit and stand workstation. Our results indicate a trend in the negative slope keyboard as an ergonomically friendly option for the intervention to Carpal tunnel pressure.

Abstract 18245: ViTrack™ : A Computer Vision Technology for Continuous Blood Pressure and Advanced Cardio Hemodynamics

Introduction: There is an unmet need for a wearable device for accurate and continuous non-invasive blood pressure (BP) and other cardio-hemodynamic parameters in real-world situations. Methods: To address the need, we have developed ViTrack™, a wrist wearable optomechanical sensor capable of 3D contact sensing at the microscale. ViTrack, based on a fundamentally new method, utilizes pressure-dependent spatiotemporal skin displacement to directly measure beat-to-beat SBP and DBP. ViTrack also measures heart rate and respiratory parameters, and advanced hemodynamic parameters. In real-world settings, patient activities such as body or arm movements introduce motion artifacts that interfere with BP measurement. To address this, ViTrack’s 3D imaging system has been enhanced with advanced computer vision and AI/ML techniques to ensure precise and consistent measurements, regardless of patient movement or wrist position relative to the heart (hydrostatic pressure change). Methods: We have built a minimum viable product. Animal studies (n = 12) showed that the device correlates well (R2 value = 0.958) with invasive arterial pressure (IAP). In outpatient settings, in more than 120 subjects, both male and female, with a wide range of BP (86-180 SBP; 60-110 DBP), when compared to the auscultatory method, ViTrack measures BP in accordance with FDA standards (Association for the Advancement of Medical Instrumentation [AAMI] standard: mean offset &lt; 5mmHg; standard deviation &lt;8 mmHg). Subsequently, in unconstrained patients (n=14), we compared the ViTrack continuously over 2 hours against IAP in real-life ICU conditions. The arm with ViTrack was unconstrained, while the opposite arm was constrained because of the IAP line. With the implementation of the computer vision and AI/ML algorithms, when beat-to-beat measures were averaged across 20 seconds and compared to IAP, ViTrack demonstrated excellent accuracy for both DBP (mean error = -1.37 mmHg [SD = 3.8 mmHg]) and SBP (mean error = -2.69 mmHg [SD = 5.99 mmHg]). Conclusions: Studies show that ViTrack, a wearable device, can accurately and continuously measure BP in real-world settings. The technology could disrupt the way we measure and manage BP. A multi-center trial is further validating the technology.

Use it or lose it: The relationship between two image-based biomarkers in better understanding osteoarthritis progression in the wrist

Bone tissue is influenced by its mechanical environment and adapts in response to its mechanical load. This is supported by studies analyzing bone adaptation in the knee and hip. Changes to the bone have also been found to precede cartilage degeneration in diseases such as osteoarthritis (OA). Our objective was to demonstrate the relationship between joint contact and bone density in the wrists of healthy adults. Static CT scans with a calibration phantom were taken to obtain measures of bone mineral density (vBMD) in 3 normalized depths; 0 – 2.5, 2.5 – 5, and 5 – 7.5 mm. Participants underwent a four-dimensional CT scan (4DCT) while performing maximum wrist extension to maximum wrist flexion. 3D bone models of the distal radius, scaphoid, and lunate were made, and analyzed vBMD and joint contact area (JCA) in the radiolunate (RL) and radioscaphoid (RS) joints separately. Correlation coefficients were calculated where vBMD was the dependent variable, and kinematic JCA throughout every 10 degrees of motion were the independent variables. Statistically significant independent variables associated with vBMD were assessed using a regression model and were entered in steps; (1) significant correlations, (2) sex, and (3) age.An increase in vBMD was significantly, positively associated with an increase in JCa. Notably, in the deeper regions (5 – 7.5 mm) of the radius that is primarily composed of trabecular bone. Sex contributed to the variance in vBMD, while age did not. Subchondral bone changes are influenced by wrist position, demonstrating that the wrist serves to bear load similar to the knee and hip.

Individual Muscle Force Estimation in the Human Forearm Using Multi-Muscle MR Elastography (MM-MRE).

To establish the sensitivity of magnetic resonance elastography (MRE) to active muscle contraction in multiple muscles of the forearm. We combined MRE of forearm muscles with an MRI-compatible device, the MREbot, to simultaneously measure the mechanical properties of tissues in the forearm and the torque applied by the wrist joint during isometric tasks. We measured shear wave speed of thirteen forearm muscles via MRE in a series of contractile states and wrist postures and fit these outputs to a force estimation algorithm based on a musculoskeletal model. Shear wave speed changed significantly upon several factors, including whether the muscle was recruited as an agonist or antagonist (p = 0.0019), torque amplitude (p = <0.0001), and wrist posture (p = 0.0002). Shear wave speed increased significantly during both agonist (p = <0.0001) and antagonist (p = 0.0448) contraction. Additionally, there was a greater increase in shear wave speed at greater levels of loading. The variations due to these factors indicate the sensitivity to functional loading of muscle. Under the assumption of a quadratic relationship between shear wave speed and muscle force, MRE measurements accounted for an average of 70% of the variance in the measured joint torque. This study shows the ability of MM-MRE to capture variations in individual muscle shear wave speed due to muscle activation and presents a method to estimate individual muscle force through MM-MRE derived measurements of shear wave speed. MM-MRE could be used to establish normal and abnormal muscle co-contraction patterns in muscles of the forearm controlling hand and wrist function.

The Green Transfer—Long-Term Results

The purpose of this study was to determine the long-term results of the Green transfer (flexor carpi ulnaris to extensor carpi radialis brevis) for patient-reported outcomes, wrist position, and range of motion. We re-examined 13 patients from a previous prospective study involving surgery for hemiplegia that included a Green transfer. The average follow-up was 8 years with the range from 5 to 11 years. The wrist range of motion and the postoperative position of the wrists were measured. The surgical outcomes were measured via the Pediatric Orthopedic Data Collection Instrument, the Shriner's Hospital Upper Extremity Evaluation, Pediatric Quality of Life, and visual analog score for appearance from the patient and the parent. At this follow-up, only 7 of the 13 patients had a wrist position near neutral with the ability to flex and extend the wrist. Wrist range of motion was improved in four, decreased in four, and stayed the same in five patients. In contrast to these positional wrist results, statistically significant improvements were noted in several aspects of the Pediatric Orthopedic Data Collection Instrument, visual analog scores, and Shriner's Hospital Upper Extremity Evaluation scores. Long-term follow-up of the flexor carpi ulnaris to extensor carpi radialis brevis tendon transfer in hemiplegic patients reveals the results to be variable but favorable from a patient-reported outcome standpoint. Therapeutic IV.

Altered Ulnar Variance With Full-Body Weight-bearing During Handstands With Upper Extremity Weight-bearing CT.

Ulnar variance (UV) is a radiographic measurement relating the articular surface heights of the distal radius and ulna. Abnormal UV increases the risk for wrist pathology; however, it only provides a static measurement of an inherently dynamic bony relationship that changes with wrist position and loading. The purpose of this study was to investigate how full-body weight-bearing affects UV using weight-bearing computed tomography (WBCT). Ten gymnasts completed two 45-second scans inside a WBCT machine while performing a handstand on a flat platform (H) and parallettes (P). A non-weight-bearing CT scan was collected to match clinical practice (N). Differences in UV between weight-bearing conditions were evaluated separately for dominant and nondominant sides, and then, UV was compared between weight-bearing conditions on pooled dominant/nondominant data. Pooled analyses comparing weight-bearing conditions revealed a significant increase in UV for H versus N (0.58 mm) and P versus N (1.00 mm), but no significant change in UV for H versus P (0.43 mm). Significant differences in UV were detected for H versus N, P versus N, and H versus P for dominant and nondominant extremities. The change from N to H was significantly greater in the dominant versus nondominant side, but greater in the nondominant side from N to P. Ulnar variance changed with the application of load and position of the wrist. Differences in UV were found between dominant and nondominant extremities. Upper extremity loading patterns are affected by hand dominance as defined by a cartwheel and suggest skeletal consequences from repetitive load on a dominantly used wrist. Although statistically significant, subtle changes detected in this investigational study do not necessarily bear clinical significance. Future WBCT research can lead to improved diagnostic measures for wrist pathologies affected by active loading and rotational wrist behavior.

Deformation of palmar hand measurements in a power grip by wrist ulnar/radial deviation

ObjectivesThe present study analyzed changes in palmar hand measurements during power grip by wrist radial/ulnar deviation for an ergonomic grip design. MethodTwelve palmar dimensions (Tip-to-PTC/DTC distances, Tip-to-MMC distances, and Tip-to-MMC surface lengths) of digits 2 to 5 were measured for 30 Koreans with various hand sizes (15 males and 15 females; hand length = 177.9 ± 12.3 mm) at three wrist postures (neutral, 20° of radial deviation, and 30° of ulnar deviation) using 3D scanning and casting methods. ResultsAs the hand changed from the straight neutral posture to the power grip posture, the Tip-to-PTC/DTC distances (related to grip widths), Tip-to-MMC distances (related to grip heights), and Tip-to-MMC surface lengths (related to grip circumferences) decreased to 30%–65% compared to corresponding original lengths. Wrist posture also had significant effects on the Tip-to-PTC/DTC and Tip-to-MMC distances by 6.5%–9.0%, while finger position significantly affected all the measurements by 8.2%–22.3%. Practitioner summaryThe measurement protocol of palmar hand dimensions and the changes in palmar hand measurements by wrist posture are of use to develop an ergonomic handle design for comfort and prevention of musculoskeletal disorders.

A robot-aided visuomotor wrist training induces motor and proprioceptive learning that transfers to the untrained ipsilateral elbow

BackgroundLearning of a visuomotor task not only leads to changes in motor performance but also improves proprioceptive function of the trained joint/limb system. Such sensorimotor learning may show intra-joint transfer that is observable at a previously untrained degrees of freedom of the trained joint.ObjectiveHere, we examined if and to what extent such learning transfers to neighboring joints of the same limb and whether such transfer is observable in the motor as well as in the proprioceptive domain. Documenting such intra-limb transfer of sensorimotor learning holds promise for the neurorehabilitation of an impaired joint by training the neighboring joints.MethodsUsing a robotic exoskeleton, 15 healthy young adults (18–35 years) underwent a visuomotor training that required them to make continuous, increasingly precise, small amplitude wrist movements. Wrist and elbow position sense just-noticeable‐difference (JND) thresholds and spatial movement accuracy error (MAE) at wrist and elbow in an untrained pointing task were assessed before and immediately after, as well as 24 h after training.ResultsFirst, all participants showed evidence of proprioceptive and motor learning in both trained and untrained joints. The mean JND threshold decreased significantly by 30% in trained wrist (M: 1.26° to 0.88°) and by 35% in untrained elbow (M: 1.96° to 1.28°). Second, mean MAE in untrained pointing task reduced by 20% in trained wrist and the untrained elbow. Third, after 24 h the gains in proprioceptive learning persisted at both joints, while transferred motor learning gains had decayed to such extent that they were no longer significant at the group level.ConclusionOur findings document that a one-time sensorimotor training induces rapid learning gains in proprioceptive acuity and untrained sensorimotor performance at the practiced joint. Importantly, these gains transfer almost fully to the neighboring, proximal joint/limb system.

Wrist position affects muscle fatigue during isometric contractions of wrist flexors: An exploratory study

ObjectiveTo investigate the influence of wrist position and torque level on lower arm flexor muscle fatigue. BackgroundWork-related musculoskeletal health risks at the wrist joint may depend on joint position and torque level, as proposed by ergonomic workplace assessment tools. As empirical data are scarce, muscle fatigue, as proxy of work-related musculoskeletal health risks, can be used to explore this assumption. Method18 healthy participants performed fatiguing isometric wrist flexion contractions in three wrist positions (40° flexion, 0° neutral position, and 40° extension) and torque levels (10, 20, 40% of the maximum voluntary contraction). Electromyographic signs of fatigue were analyzed in the flexor carpi radialis (FCR) and flexor digitorum superficialis (FDS) muscles. ResultsMuscle fatigue was dependent on torque level and wrist position and differed between muscles. Signs of fatigue were more evident at higher torque levels for both muscles. While fatigue signs in FCR were not clearly associated with wrist position, the FDS fatigued more during wrist flexion. An interaction effect between torque level and wrist position was not observed. ConclusionHigher torque levels induce greater signs of local muscle fatigue in wrist flexor muscles, and a 40° wrist flexion triggers fatigue, while 40° wrist extension does not. Our data do not support the assumption of increased risk in greater wrist angles in any direction by prevailing ergonomic risk assessments. Relevance to industryPeople with work-related wrist flexor effort may be at increased risk of musculoskeletal disorders when higher torques are applied and flexed wrist positions are required.

Association of ulnar variance with three-dimensional carpal alignment and demographics in asymptomatic volunteers.

Several carpal pathologies are considered to be related to ulnar variance. Recently, computer-aided computed tomography (CT) analysis software was introduced to quantify three-dimensional (3D) carpal alignment with high accuracy and reliability. To determine the association of ulnar variance with 3D carpal alignment and demographics. A wrist of 121 asymptomatic volunteers (69 men, 52 women; mean age = 38 ± 10.4 years) was imaged in the neutral wrist position with cone-beam CT. Computer-aided CT analysis software (Bonelogic), based on segmentation and numerical modelling, was used to define ulnar variance and standardized 3D axes for all carpal bones. The association of ulnar variance with 3D carpal alignment, age of the volunteer, and side and dominance of the imaged wrist was assessed. The mean ulnar variance was -1.6 ± 1.5 mm (range = -5.3 to 2.4 mm). The mean ulnar variance was -1.9 mm and -1.1 mm in men and women (P = 0.007), respectively. Of the imaged 121 wrists, 18 (15%) had positive and 103 (85%) negative ulnar variance. There was no association between ulnar variance and any of the radio- or intercarpal angle values in either the sagittal or coronal plane (ρ = -0.16…0.17, r = -0.13….0.12). The ulnar variance showed no association with side (P = 0.51) or dominance (P = 0.27) of the imaged wrist. 3D carpal alignment is not affected by ulnar variance. The association of ulnar variance with sex may in part explain the difference in reported prevalence of some carpal pathologies, such as ulnar impaction syndrome and Kienböck's disease.

Effect of upper extremity kinesio tape application on hand function, wrist joint position and grip strength in children with hemiparetic cerebral palsy

Abstract Although kinesio taping (KT) is frequently used in musculoskeletal disorders, there is not enough data on the effectiveness of holistic KT application on the upper extremity in spastic hemiparetic children. Our study aims to evaluate the effect of KT application on spasticity, range of motion, dexterity and hand grip strength in these patients. Twenty patients diagnosed with spastic hemiparetic cerebral palsy, aged 5-17 years, who were trained and treated in a private educational institution, were included in the study. Between November 2021 and January 2022, in addition to neurodevelopmental therapy for 12 weeks, KT was applied from the lateral epicondyle region to the end of the metacarpals, with 15-25% tension, to the dorsal face of the hand, with the taping direction facilitation technique (starting direction is the origin of the muscle). Spasticity, range of motion, dexterity and hand grip strength were evaluated as pre-test and post-test. It was determined that the mean score difference between the pre-test and post-test range of motion (ROM) shoulder abduction, ROM supination, ROM wrist flexion, ROM wrist extension and hand grip strength of the individuals was statistically significant (). It was determined that the individuals’ pre-test-post-test Jebsen hand function test (JHFT) Writing, JHFT card flipping, JHFT small objects, JHFT nutrition simulation, JHFT backgammon checkers stamps, JHFT large light objects, JHFT total score average difference was statistically significant (). These results indicate that KT application positively affects upper extremity functions in the rehabilitation of hemiparetic cerebral palsy. Longitudinal studies are recommended in patients with hemiparetic cerebral palsy.

Effect of muscle length in a handgrip task on corticomotor excitability of extrinsic and intrinsic hand muscles under resting and submaximal contraction conditions.

The neurophysiological mechanisms underlying muscle force control for different wrist postures still need to be better understood. To further elucidate these mechanisms, the present study aimed to investigate the effects of wrist posture on the corticospinal excitability by transcranial magnetic stimulation (TMS) of extrinsic (flexor [FCR] and extensor carpi radialis [ECR]) and intrinsic (flexor pollicis brevis (FPB)) muscles at rest and during a submaximal handgrip strength task. Fourteen subjects (24.06 ± 2.28 years) without neurological or motor disorders were included. We assessed how the wrist posture (neutral: 0°; flexed: +45°; extended: -45°) affects maximal handgrip strength (HGSmax ) and the motor evoked potentials (MEP) amplitudes during rest and active muscle contractions. HGSmax was higher at 0° (133%) than at -45° (93.6%; p < 0.001) and +45° (73.9%; p < 0.001). MEP amplitudes were higher for the FCR at +45° (83.6%) than at -45° (45.2%; p = 0.019) and at +45° (156%; p < 0.001) and 0° (146%; p = 0.014) than at -45° (106%) at rest and active condition, respectively. Regarding the ECR, the MEP amplitudes were higher at -45° (113%) than at +45° (60.8%; p < 0.001) and 0° (72.6%; p = 0.008), and at -45° (138%) than +45° (96.7%; p = 0.007) also at rest and active conditions, respectively. In contrast, the FPB did not reveal any difference among wrist postures and conditions. Although extrinsic and intrinsic hand muscles exhibit overlapping cortical representations and partially share the same innervation, they can be modulated differently depending on the biomechanical constraints.

Profiling Somatosensory Impairment after Stroke: Characterizing Common "Fingerprints" of Impairment Using Unsupervised Machine Learning-Based Cluster Analysis of Quantitative Measures of the Upper Limb.

Altered somatosensory function is common among stroke survivors, yet is often poorly characterized. Methods of profiling somatosensation that illustrate the variability in impairment within and across different modalities remain limited. We aimed to characterize post-stroke somatosensation profiles ("fingerprints") of the upper limb using an unsupervised machine learning cluster analysis to capture hidden relationships between measures of touch, proprioception, and haptic object recognition. Raw data were pooled from six studies where multiple quantitative measures of upper limb somatosensation were collected from stroke survivors (n = 207) using the Tactile Discrimination Test (TDT), Wrist Position Sense Test (WPST) and functional Tactile Object Recognition Test (fTORT) on the contralesional and ipsilesional upper limbs. The Growing Self Organizing Map (GSOM) unsupervised machine learning algorithm was used to generate a topology-preserving two-dimensional mapping of the pooled data and then separate it into clusters. Signature profiles of somatosensory impairment across two modalities (TDT and WPST; n = 203) and three modalities (TDT, WPST, and fTORT; n = 141) were characterized for both hands. Distinct impairment subgroups were identified. The influence of background and clinical variables was also modelled. The study provided evidence of the utility of unsupervised cluster analysis that can profile stroke survivor signatures of somatosensory impairment, which may inform improved diagnosis and characterization of impairment patterns.

Analysis of ANN and Fuzzy Logic Dynamic Modelling to Control the Wrist Exoskeleton

Human intention has long been a primary emphasis in the field of electromyography (EMG) research. This being considered, the movement of the exoskeleton hand can be accurately predicted based on the user's preferences. The EMG is a nonlinear signal formed by muscle contractions as the human hand moves and easily captured noise signal from its surroundings. Due to this fact, this study aims to estimate wrist desired velocity based on EMG signals using ANN and FL mapping methods. The output was derived using EMG signals and wrist position were directly proportional to control wrist desired velocity. Ten male subjects, ranging in age from 21 to 40, supplied EMG signal data set used for estimating the output in single and double muscles experiments. To validate the performance, a physical model of an exoskeleton hand was created using Sim-mechanics program tool. The ANN used Levenberg training method with 1 hidden layer and 10 neurons, while FL used a triangular membership function to represent muscles contraction signals amplitude at different MVC levels for each wrist position. As a result, PID was substituted to compensate fluctuation of mapping outputs, resulting in a smoother signal reading while improving the estimation of wrist desired velocity performance. As a conclusion, ANN compensates for complex nonlinear input to estimate output, but it works best with large data sets. FL allowed designers to design rules based on their knowledge, but the system will struggle due to the large number of inputs. Based on the results achieved, FL was able to show a distinct separation of wrist desired velocity hand movement when compared to ANN for similar testing datasets due to the decision making based on rules setting setup by the designer.

Effects of wrist posture and stabilization on precision grip force production and muscle activation patterns.

Most of the power for generating forces in the fingers arises from muscles located in the forearm. This configuration maximizes finger joint range of motion while minimizing finger mass and inertia. The resulting multiarticular arrangement of the tendons, however, complicates independent control of the wrist and the digits. Actuating the wrist impacts sensorimotor control of the fingers and vice versa. The goal of this study was to systematically investigate interactions between isometric wrist and digit control. Specifically, we examined how the need to maintain a specified wrist posture influences precision grip. Fifteen healthy adults produced maximum precision grip force at 11 different wrist flexion/extension angles, with the arm supported, under two conditions: 1) the participant maintained the desired wrist angle while performing the precision grip and 2) a robot maintained the specified wrist angle. Wrist flexion/extension posture significantly impacted maximum precision grip force (P < 0.001), with the greatest grip force achieved when the wrist was extended 30° from neutral. External wrist stabilization by the robot led to a 20% increase in precision grip force across wrist postures. Increased force was accompanied by increased muscle activation but with an activation pattern similar to the one used when the participant had to stabilize their wrist. Thus, simultaneous wrist and finger requirements impacted performance of an isometric finger task. External wrist stabilization can promote increased precision grip force resulting from increased muscle activation. These findings have potential clinical significance for individuals with neurologically driven finger weakness, such as stroke survivors.NEW & NOTEWORTHY We explored the interdependence between wrist and fingers by assessing the influence of wrist posture and external stabilization on precision grip force generation. We found that maximum precision grip force occurred at an extended wrist posture and was 20% greater when the wrist was Externally Stabilized. The latter resulted from amplification of muscle activation patterns from the Self-Stabilized condition rather than adoption of new patterns exploiting external wrist stabilization.