Article

An introductory study of common grasps used by adults during performance of activities of daily living

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Abstract

This paper presents the results of a descriptive survey on human grasps. Sixty-four videos were selected to represent tasks performed in the main areas of activities of daily living (ADL) (personal care, meal preparation, eating, housekeeping, etc.). All the participants were right-handed. Elementary grasps were identified for each hand, and the grasp type (from a 9-type classification), the hands involved, and the duration were registered for each case. The results show that the most commonly used grasps are: pinch, non-prehensile, cylindrical, lateral pinch and lumbrical. The presence of these grasps in the areas of ADL is, however, very different (e.g., pinch is widely used in food preparation and very little in driving). Some grasps were used more frequently with one hand or when both hands were used simultaneously (e.g., special pinch was hardly used by the left hand). Knowing the grasp types most frequently used in ADL is essential to be able to assess grasp rehabilitation processes or hand prostheses development.

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... Based on this comparison, nine hand postures were chosen as classes for the SVM to predict: cylindrical grasp (Cyl), pinch grasp (Pinch), lateral pinch (LatP), oblique palmar grasp (Obl), lumbrical grasp (Lum), hook grasp (Hook), intermediate power-precision grasp (intPP), special pinch/tripod (SpP), and pointing index (nonP). The non-prehensile grasp in [6] was not present in the NinaPro DB5 dataset, and thus it was replaced with the "pointing index" posture. These postures are described and represented in Table 2. reaction time. ...
... From the NinaPro DB5 dataset, only a subset of movements was selected for classification. The goal was to classify movements as described by Vergara et al. [6], so a comparison was made between the hand postures in NinaPro DB5 and those described by Vergara. Based on this comparison, nine hand postures were chosen as classes for the SVM to predict: cylindrical grasp (Cyl), pinch grasp (Pinch), lateral pinch (LatP), oblique palmar grasp (Obl), lumbrical grasp (Lum), hook grasp (Hook), intermediate power-precision grasp (intPP), special pinch/tripod (SpP), and pointing index (nonP). ...
... Based on this comparison, nine hand postures were chosen as classes for the SVM to predict: cylindrical grasp (Cyl), pinch grasp (Pinch), lateral pinch (LatP), oblique palmar grasp (Obl), lumbrical grasp (Lum), hook grasp (Hook), intermediate power-precision grasp (intPP), special pinch/tripod (SpP), and pointing index (nonP). The non-prehensile grasp in [6] was not present in the NinaPro DB5 dataset, and thus it was replaced with the "pointing index" posture. These postures are described and represented in Table 2. Thumb and proximal part of the fingers ...
Article
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Every year, thousands of people undergo amputations due to trauma or medical conditions. The loss of an upper limb, in particular, has profound physical and psychological consequences for patients. One potential solution is the use of externally powered prostheses equipped with motorized artificial hands. However, these commercially available prosthetic hands are prohibitively expensive for most users. In recent years, advancements in 3D printing and sensor technologies have enabled the design and production of low-cost, externally powered prostheses. This paper presents a pattern-recognition-based human–prosthesis interface that utilizes surface electromyography (sEMG) signals, captured by an affordable device, the Myo armband. A Support Vector Machine (SVM) algorithm, optimized using Bayesian techniques, is trained to classify the user’s intended grasp from among nine common grasping postures essential for daily life activities and functional prosthetic performance. The proposal is viable for real-time implementations on low-cost platforms with 85% accuracy in grasping posture recognition.
... Designs similar to the human hand are suitable for prosthetic use for obvious aesthetic reasons. Furthermore, they are a trend in robotics, where efforts are being made to develop adaptable end effectors that are capable of grasping a wide variety of objects, especially in assistive robotic arms like those attached to wheelchairs to support people with upper limb disabilities in performing activities of daily living (ADL) [1][2][3]. These devices increase the feeling of independence and the well-being of people with disabilities but are hardly found in commercial products due to their high associated costs and their technical requirements (battery, control, processing capacities, etc.), which constitute a drawback to their extensive use in society. ...
... However, only three grasp types were identified, with a mean classification accuracy lower than 80%, decreasing to 60% when trying to classify five grasp types. Still, these works do not identify some of the basic grasps used by the human hand in ADL [1], which are necessary for controlling a prosthetic hand in a natural way. ...
... On the contrary, in fields such as rehabilitation [35], the taxonomies are usually poor, with differences existing among digital/whole hand or lateral/cylindrical. For that reason, our research group identified a set of grasp types in [1] that were used in more than 90% of ADL. Based on these results and previous research, an assessment protocol (AHAP [2]) was developed for anthropomorphic hands, with eight grasping postures selected for the evaluation of artificial hands. ...
Article
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The design and control of artificial hands remains a challenge in engineering. Popular prostheses are bio-mechanically simple with restricted manipulation capabilities, as advanced devices are pricy or abandoned due to their difficult communication with the hand. For social robots, the interpretation of human intention is key for their integration in daily life. This can be achieved with machine learning (ML) algorithms, which are barely used for grasping posture recognition. This work proposes an ML approach to recognize nine hand postures, representing 90% of the activities of daily living in real time using an sEMG human–robot interface (HRI). Data from 20 subjects wearing a Myo armband (8 sEMG signals) were gathered from the NinaPro DS5 and from experimental tests with the YCB Object Set, and they were used jointly in the development of a simple multi-layer perceptron in MATLAB, with a global percentage success of 73% using only two features. GPU-based implementations were run to select the best architecture, with generalization capabilities, robustness-versus-electrode shift, low memory expense, and real-time performance. This architecture enables the implementation of grasping posture recognition in low-cost devices, aimed at the development of affordable functional prostheses and HRI for social robots.
... Previous research has identified essential grasp and pinch patterns for independence in ADLs (Gracia-Ibáñez et al., 2018). Vergara et al. (2014) analyzed videos of individuals performing different ADLs to identify different types of elementary grasp actions (EGAs) used during activities. According to Vergara et al., an EGA is "any complete action in which the hand performed a particular action using a fairly constant hand posture configuration" (p. ...
... Certain grasps were more commonly used in specific ADLs. For example, Pinch is frequently used in food preparation and leisure; Obl is widely used during driving and transport; and Cyl is a common grasp used during shopping, driving, and housekeeping (Vergara et al., 2014). Table 1 provides a summary of the grasps used in this study. ...
... The methods for this research study are based on the process followed by Vergara et al. (2014) and Gracia-Ibáñez et al. (2018). The university institutional review board approved the study, reference number: 19-320-H. ...
Article
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Background: : Occupation-based interventions are effective in hand rehabilitation. The purpose of this study was to identify the grasp and pinch patterns used during specific ceramic activities for rehabilitative interventions.
... In a comfortable sitting posture, all the participants were asked to exert maximum effort without the help of other muscles other than those of the forearm and hand while performing six representative ADL grasps ( Figure 1) based on the grasp taxonomy used in Vergara et al. [30], while recording muscular activity by means of sEMG: two-finger pad-to-pad pinch (P2D); cylindrical grasp (Cyl); lumbrical grasp (Lum); lateral pinch (LatP); oblique palmar grasp (Obl); and intermediate power-precision grasp (IntPP). ...
... Both depend on the grasp configuration [27,28], among other factors. Grasp configuration is determined by the type of applied grasp, and several grasp taxonomies have been reported in the literature in accordance with their purpose [29,30], such as the nine-type classification proposed in [30] for the commonest grasps used in activities of daily living (ADLs). This paper presents a study of the surface electromyography of forearm muscles (considering muscle activation, NZC, EWL and EMAV characteristics from seven representative forearm areas) while performing the commonest grasps used in day-to-day life with a twofold objective: (i) look for muscular forearm areas that are significantly affected or differently used by HOA in EMG terms; (ii) study if the affected EMG characteristics can be used as predictors to detect HOA in an early stage by using different combinations of them in discriminant analyses. ...
... Both depend on the grasp configuration [27,28], among other factors. Grasp configuration is determined by the type of applied grasp, and several grasp taxonomies have been reported in the literature in accordance with their purpose [29,30], such as the nine-type classification proposed in [30] for the commonest grasps used in activities of daily living (ADLs). This paper presents a study of the surface electromyography of forearm muscles (considering muscle activation, NZC, EWL and EMAV characteristics from seven representative forearm areas) while performing the commonest grasps used in day-to-day life with a twofold objective: (i) look for muscular forearm areas that are significantly affected or differently used by HOA in EMG terms; (ii) study if the affected EMG characteristics can be used as predictors to detect HOA in an early stage by using different combinations of them in discriminant analyses. ...
Article
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The early and objective detection of hand pathologies is a field that still requires more research. One of the main signs of hand osteoarthritis (HOA) is joint degeneration, which causes loss of strength, among other symptoms. HOA is usually diagnosed with imaging and radiography, but the disease is in an advanced stage when HOA is observable by these methods. Some authors suggest that muscle tissue changes seem to occur before joint degeneration. We propose recording muscular activity to look for indicators of these changes that might help in early diagnosis. Muscular activity is often measured using electromyography (EMG), which consists of recording electrical muscle activity. The aim of this study is to study whether different EMG characteristics (zero crossing, wavelength, mean absolute value, muscle activity) via collection of forearm and hand EMG signals are feasible alternatives to the existing methods of detecting HOA patients’ hand function. We used surface EMG to measure the electrical activity of the dominant hand’s forearm muscles with 22 healthy subjects and 20 HOA patients performing maximum force during six representative grasp types (the most commonly used in ADLs). The EMG characteristics were used to identify discriminant functions to detect HOA. The results show that forearm muscles are significantly affected by HOA in EMG terms, with very high success rates (between 93.3% and 100%) in the discriminant analyses, which suggest that EMG can be used as a preliminary step towards confirmation with current HOA diagnostic techniques. Digit flexors during cylindrical grasp, thumb muscles during oblique palmar grasp, and wrist extensors and radial deviators during the intermediate power–precision grasp are good candidates to help detect HOA.
... This was intended to support immersion into the story line and engagement in motor imagery. The actions completed within each scene were specifically developed to promote motor imagery of common hand grips used in activities of daily living (Kyberd et al., 2009;Vergara et al., 2014). These included an oblique palmar grasp when lifting the coffee plunger (making breakfast scene), a pinch grip while selecting marbles from a jar (packing bag scene) and a tripod grip while writing (writing plan scene) (Vergara et al., 2014). ...
... The actions completed within each scene were specifically developed to promote motor imagery of common hand grips used in activities of daily living (Kyberd et al., 2009;Vergara et al., 2014). These included an oblique palmar grasp when lifting the coffee plunger (making breakfast scene), a pinch grip while selecting marbles from a jar (packing bag scene) and a tripod grip while writing (writing plan scene) (Vergara et al., 2014). Additionally, standard hand and wrist range of motion exercises were included, with the participant imagining wrist flexion and extension, wrist rotation, and digit flexion and extension (warm-up exercises scene). ...
... Indeed, Mornieux et al. (2008) did not show any significant effect of pedal interface on pedaling force or on the amount of muscle activations during submaximal exercise, either in expert or in nonexpert population. Interestingly, upper limbs are particularly characterized by their adaptabilities to various functions in daily life (MacKenzie & Iberall, 1994;Vergara et al., 2014) and some examples showed a strong interaction between grip conditions' and upper limb muscles' coordination (Charissou et al., 2017;Vigouroux et al., 2019). This suggests a potential higher influence of pedal interface in the modulation of upper limb muscle synergies than for lower limbs. ...
... Based on the conclusions from Mornieux et al. (2008), we hypothesized that pedal interface will not influence muscle synergies and motor output on the lower limbs. Oppositely, based on the well-known capabilities of the hand to grip and hold and its influence upper limb muscle coordination (Charissou et al., 2017;MacKenzie & Iberall, 1994;Vergara et al., 2014;Vigouroux et al., 2019), we hypothesized that both torques and muscle synergies will be modulated in upper limbs. From a fundamental perspective, testing the impact of the interface during pedaling would enable us to observe the robustness of synergies when facing different movement constraints in the upper limbs. ...
Article
Pedaling is a physical exercise practiced with either the upper or the lower limbs. Muscle coordination during these exercises has been previously studied using electromyography and synergy analysis, and three to four synergies have been identified for the lower and upper limbs. The question of synergy adaptabilities has not been investigated during pedaling with the upper limbs, and the impact of various modalities is yet not known. This study investigates the effect of pedal type (either clipped/gripped or flat) on the torque performance and the synergy in both upper and lower limbs. Torques applied by six participants while pedaling at 30% of their maximal power have been recorded for both upper and lower limbs. Electromyographic data of 11 muscles on the upper limbs and 11 muscles on the lower limbs have been recorded and synergies extracted and compared between pedal types. Results showed that the torques were not modified by the pedal types for the lower limbs while a deep adaptation is observable for the upper limbs. Participants indeed used the additional holding possibility by pulling the pedals on top of the pushing action. Synergies were accordingly modified for upper limbs while they remain stable for the lower limbs. In both limbs, the synergies showed a good reproducibility even if larger variabilities were observed for the upper limbs. This pilot study highlights the adaptability of muscle synergies according to the condition of movement execution, especially observed for the upper limbs, and can bring some new insights for the rehabilitation exercises.
... Las implicaciones funcionales de este diagnóstico son vastas. Algunos de los efectos identificados incluyen dolor durante la actividad, pérdida de fuerza de la pinza (10, 11), disminución de la capacidad motora fina (12) y menor agarre cilíndrico (13). Se ha observado que algunos de estos déficits pueden ser identificados antes del diagnóstico en estudios de radiológicos (11)(12)(13). ...
... Algunos de los efectos identificados incluyen dolor durante la actividad, pérdida de fuerza de la pinza (10, 11), disminución de la capacidad motora fina (12) y menor agarre cilíndrico (13). Se ha observado que algunos de estos déficits pueden ser identificados antes del diagnóstico en estudios de radiológicos (11)(12)(13). La mayoría de los pacientes buscan atención médica debido al dolor. ...
Chapter
La terapia de mano es el tratamiento no quirúrgico de los trastornos y lesiones de la mano o de las extremidades superiores que afectan la función de la mano. Los terapeutas de mano son fisioterapeutas o terapeutas ocupacionales que se especializan en esta disciplina y tiene formación específica en anatomía, exploración, biomecánica, fisiología y técnicas de abordaje. Un terapeuta de mano generalmente pasa por una formación y capacitación extensa para convertirse en un “terapeuta de mano certificado”. La terapia de la mano, integrada dentro del equipo de cirugía de mano, tiene un papel crucial en la recuperación de las lesiones de la mano o muñeca. El objetivo de este libro es ofrecer un compendio en lengua castellana donde se aborden las patologías de la mano más frecuentes desde un punto de vista interdisciplinar, ayudando a los lectores a razonar las diferentes patologías y a afianzar los conocimientos de la terapia de mano basándonos en la evidencia científica. Partiendo de la base de una buena exploración y valoración, en cada uno de los capítulos se abordan los tratamientos de las lesiones más frecuentes acompañado de numerosas ilustraciones que facilitan su comprensión. Elaborado por los mejores expertos de España en la disciplina, estamos seguro de que este libro ayudará al lector a elaborar un razonamiento clínico basado en la evidencia científica que le permitirá comprender y aplicar los diferentes tratamientos específicos para cada una de las lesiones de la mano que se exponen.
... Performing activities of daily living (ADLs) requires grasping objects and applying forces on them to be able to do tasks. The applied grasping postures depend on the object to be grasped and on the task to be performed, and are often categorised using different taxonomies [11][12][13] . In this paper, the taxonomy of 13 is applied (Fig. 1): thumb-index pad-to-pad pinch (TIPinch), lateral pinch (LatP), cylindrical grasp (Cyl), lumbrical grasp (Lum), oblique palmar grasp (Obl) and intermediate OPEN 1 ...
... power-precision grasp (IntPP). The daily frequency of these grasp types has been analysed in a previous study 13 , as has their relevance for functionality 14 . In addition to the pad-on-pad pinch grasp, other types of grips were demonstrated to be important. ...
Article
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This work aims to: (1) Provide maximal hand force data on six different grasp types for healthy subjects; (2) detect grasp types with maximal force significantly affected by hand osteoarthritis (HOA) in women; (3) look for predictors to detect HOA from the maximal forces using discriminant analyses. Thirty-three healthy subjects (37 ± 17 years, 17 women, 16 men) and 30 HOA patients (72 ± 9 years, all women) participated in the experiment. Participants were asked to exert their maximal force while performing six different grasp types 3 times. Two MANOVAs were conducted to detect if force depended on gender in healthy participants and if force significantly diminished in women with HOA. Finally, a linear discriminant analysis for detecting HOA was performed using forces of the grasp types that were significantly affected by HOA. Gender-disaggregated statistics are provided for healthy participants. Significant differences are obtained for all grasp types per gender. The women with HOA exerted significantly lower force values (p < 0.001) for all the grasp types than healthy ones. The discriminant analysis revealed that oblique grasp was the most significant one for detecting HOA. A discrimination equation was obtained with a specificity of 88.2% and a sensitivity of 83.3%. This work provides grip force data on six grasp types for healthy participants and for women with HOA. HOA women present reduced strength in all grasps due to pathology. Three of these grasps are a novelty. Oblique grasp strength may suffice to discriminate a patient with HOA, which might help non-invasive HOA detection.
... Limited mobility is a prevalent dysfunction that is observed in patients suffering from neurological diseases such as Stroke, Epileptic Encephalopathy, Cerebral Palsy or Parkinson diseases [1,2,3,4]. The importance of upper limb function rehabilitation is emphasized since upper limbs are used to manipulate objects and to interact physically in Activities of Daily Living (ADL) [5,6]. ...
... Step 1: Identification of system quality attribute requirements. Upper limbs rehabilitation is important since it allows the use of hands to interact physically in ADL [5]. Sometimes different kinds of medical conditions do not allow the use of wearable devices for virtual rehabilitation. ...
... Then hand and all fingers rested relaxed and extended on the table at the beginning and end of each functional activity performed (Fig. 1). The index and middle fingers, as well as the thumb were analyzed as they are mostly used during grip and pinching (Arauz et al., 2017;Domalain et al., 2011;Tanashi et al., 2020), which represent a significant part of hand postures utilized during hand function (Vergara et al., 2014). Six functional activities utilizing precision grip and pinching (Gracia-Ibáñez et al., 2017;Tanashi et al., 2020;Vergara et al., 2014) were selected, as these allowed for the intended assessment and were the most suitable for the equipment available and measurement approach. ...
... The index and middle fingers, as well as the thumb were analyzed as they are mostly used during grip and pinching (Arauz et al., 2017;Domalain et al., 2011;Tanashi et al., 2020), which represent a significant part of hand postures utilized during hand function (Vergara et al., 2014). Six functional activities utilizing precision grip and pinching (Gracia-Ibáñez et al., 2017;Tanashi et al., 2020;Vergara et al., 2014) were selected, as these allowed for the intended assessment and were the most suitable for the equipment available and measurement approach. These activities are by no means a complete set of activities but are simply meant to underscore the relevance of the methods applied in the present study. ...
Article
This study aims at qualitatively and quantitatively evaluating the effects of simulated index finger proximal interphalangeal (PIP) joint fusion angles on hand kinematic function and performance. Although arthrodesis of the index finger PIP joint is an effective medical procedure that produces a durable, pain-free, and stable joint, it permanently immobilizes the joint. Twenty healthy subjects performed basic functional hand activities with the index finger PIP joint unconstrained (UC) and constrained to selected angles under surveillance of a motion capture system. Our results indicate differences in perceived difficulty, time performance, and the functional ROM of the hand joints when the index finger PIP joint is UC and constrained to 0, 20, and 40 degrees of flexion. The mean total perceived difficulty scores for all 6 tasks were higher for the PIP at 0 degrees than for the UC condition (p < 0.001) and for the PIP at 40 degrees (p = 0.048). The functional ROM presented a smaller total number of hand joints affected by the PIP at 20 degrees (25 in total) than the PIP at 0 (31 in total) and 40 (27 in total) degrees during execution of all 6 tasks tested. Therefore, the decision on the appropriate index finger PIP angle for arthrodesis may be between 20 and 40 degrees, as globally for all 6 tasks tested, 0 degrees exhibited the worst results regarding perceived difficulty, performance time, and number of joints with affected ROM. Selecting the appropriate angle for arthrodesis should consider a more complete set of functional activities.
... Regarding gripping, special attention has been paid to ensure that the system is able to identify most functional grips. For this purpose, both those involving the fingers, the palm of the hand or a combination of both have been considered [36]. In addition, along with the most commonly used grips, the so-called tenodesic grip, widely used in patients with cervical SCI, has been taken into account. ...
Article
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Rehabilitation is a critical routine in recovering mobility for individuals with motor limitations due to injury. Consistency in rehabilitation routines is essential for effective recovery, and it depends on the patient’s motivation and autonomy. This article introduces a serious game based on Virtual Reality (VR) that immerses the patient in a fully dynamic and engaging training environment for upper limb rehabilitation. It simulates the activity of a handball goalkeeper, compelling the patient to exercise their arms and hands to regain upper limb mobility and trunk inclination to enhance stability, particularly relevant for wheelchair users. The proposed system aims to simplify technology use, featuring a single VR headset integrating body tracking, and functional and spatial-temporal data analysis algorithms, without the need for additional tracking devices. An intuitive, hands-free interface makes the system adaptable to each patient’s specific limitations and safe by minimizing overexertion and compensatory actions. Moreover, the proposal allows for the logging of activity data and introduces a set of metrics enabling therapists to assess progress. This facilitates patient autonomy, enabling them to perform their routine in a medical center under professional supervision or at home without needing to commute to the rehabilitation centre. The experimentation focuses on a functional validation of the proposed system by patients and therapists at the Hospital Nacional de Parapléjicos de Toledo (HNPT), as a prerequisite to ensure patient safety and acceptance before undertaking long-term studies to measure the effectiveness and impact of using the proposed serious game on patient recovery and improvement.
... This study develops and validates a novel method for stiffness estimation at first contact using piezoelectric sensing, focusing on the previously unexplored period between the first and second finger contacts during a grasp. We demonstrate this approach in pinch grasps, a ubiquitous action in daily manipulation tasks [7]. Our dataset comprises silicone blocks with known stiffness properties, supplemented by validation on everyday objects. ...
Preprint
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Stiffness estimation is crucial for delicate object manipulation in robotic and prosthetic hands but remains challenging due to dependence on force and displacement measurement and real-time sensory integration. This study presents a piezoelectric sensing framework for stiffness estimation at first contact during pinch grasps, addressing the limitations of traditional force-based methods. Inspired by human skin, a multimodal tactile sensor that captures vibrational and force data is developed and integrated into a prosthetic hand's fingertip. Machine learning models, including support vector machines and convolutional neural networks, demonstrate that vibrational signals within the critical 15 ms after first contact reliably encode stiffness, achieving classification accuracies up to 98.6\% and regression errors as low as 2.39 Shore A on real-world objects of varying stiffness. Inference times of less than 1.5 ms are significantly faster than the average grasp closure time (16.65 ms in our dataset), enabling real-time stiffness estimation before the object is fully grasped. By leveraging the transient asymmetry in grasp dynamics, where one finger contacts the object before the others, this method enables early grasp modulation, enhancing safety and intuitiveness in prosthetic hands while offering broad applications in robotics.
... The main reason for the use of more DoF is to increase the number of possible grasps made by the prosthesis and, therefore, to increase its dexterity. It has been shown that the implementation of two grasp types (cylindrical and pulp pinch) would cover 50% of ADLs, and the expansion to eight grasp types would cover over 90% of ADLs [4]. ...
Article
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In the field of biomechanical modeling, the development of a prosthetic hand with dexterity comparable to the human hand is a multidisciplinary challenge involving complex mechatronic systems, intuitive control schemes, and effective body interfaces. Most current commercial prostheses offer limited functionality, typically only one or two degrees of freedom (DoF), resulting in reduced user adoption due to discomfort and lack of functionality. This research aims to design a computationally efficient low-level control algorithm for prosthetic hand fingers to be able to (a) accurately manage finger positions, (b) anticipate future information, and (c) minimize power consumption. The methodology employed is known as model-based predictive control (MBPC) and starts with the application of linear identification techniques to model the system dynamics. Then, the identified model is used to implement a generalized predictive control (GPC) algorithm, which optimizes the control effort and system performance. A test bench is used for experimental validation, and the results demonstrate that the proposed control scheme significantly improves the prosthesis’ dexterity and energy efficiency, enhancing its potential for daily use by people with hand loss.
... tip pinch [42]). This grasp has been documented as the most frequent in ADL [43,44]. The study focuses on six-bar mechanisms because this topology is of interest for the conception of RHEx to be placed either on the lateral or on the dorsal side of the index finger, partially mimicking the movement of the phalanges. ...
Article
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Stroke often causes neuromotor disabilities, impacting index finger function in daily activities. Due to the role of repetitive, even passive, finger movements in neuromuscular re-education and spasticity control, this study aims to design a rehabilitation exoskeleton based on the pulp pinch movement. The exoskeleton uses an underactuated RML topology with a single degree of mobility, customized from 3D scans of the patient's hand. It consists of eight links, incorporating two consecutive four-bar mechanisms and the third inversion of a crank-slider. A two-stage genetic optimization was applied, first to the location of the intermediate joint between the two four-bar mechanisms and later to the remaining dimensions. A targeted genetic optimization process monitored two quality metrics: average mechanical advantage from extension to flexion, and its variability. By analyzing the relationship between these metrics and key parameters at different synthesis stages, the population evaluated is reduced by up to 96.2%, compared to previous studies for the same problem. This custom-fit exoskeleton uses a small linear actuator to deliver a stable 12.45 N force to the fingertip with near-constant mechanical advantage during flexion. It enables repetitive pulp pinch movements in a flaccid finger, improving rehabilitation consistency and facilitating home-based therapy.
... Furthermore, the thumb pull direction, or lateral pinch position, is performed in many ADLs such as holding a cup or key. Thumb push is also performed in other ADL tasks such as typing on a keyboard or texting on a phone [53]. Restoring strength to this particular thumb posture is important for individuals who received CMC OA surgery to maintain independent living. ...
Article
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Thumb carpometacarpal (CMC) osteoarthritis (OA) is caused by the degeneration of joint surfaces at the base of the thumb. If conservative treatments have failed, surgery may be needed to improve symptoms. Typically, standard clinical tools, such as the pinch gauge, are used to measure thumb force. However, these devices have utilized multiple digits and do not represent forces specifically generated by the thumb. Therefore, different devices are necessary to accurately measure isolated thumb force. The primary objective was to research the effect of thumb force after ligament reconstruction with tendon interposition surgery. To accomplish this, several sub-objectives were implemented: (1) create a testing device to collect isolated thumb forces, (2) collect a normative thumb force data set of males and females to compare the impact of aging and surgery, (3) collect and compare clinical data to see if these data sets matched isolated thumb forces, (4) determine the effect of wrist position on isolated thumb force data in different wrist positions, and (5) collect thumb force in directions that mimic daily activities, a directional force downward (push) and inward (pull). On average, older participants generated statistically larger forces than younger participants. Additionally, only 50% of CMC OA participants showed greater than 5 N of improvement at 6-months post-surgery compared to pre-surgery, but did not reach healthy force levels. When evaluating wrist rotation, OA participants’ push and pull decreased by 8 N and 7 N in the horizontal wrist position, and their push and pull increased by 2 N and 5 N in the vertical wrist position. Evaluation and results with standard clinical tools showed different post-surgery trends than isolated force data, which suggested the clinical approach has mixed results and may be under- or over-estimating the recovery process. These data sets allow surgeons and hand therapists to identify changes in isolated thumb force generation to create specialized therapies and treatment options, which is an improvement upon current clinical measurement tools.
... Taking each hand individually, the task can be represented as 12 epochs of different %MVCs. MD and CV were calculated in all epochs, after removing the first second of acquisition (Right Hand: rMD 1-12 , rCV 1-12, Left Hand: lMD 1-12 , lCV [1][2][3][4][5][6][7][8][9][10][11][12]. Hence, the MD and CV for the BSC test were determined by calculating the mean unilateral values of MD and CV across the 12 epochs, averaged between both the hands. ...
... Grasping is present in most of the activities of daily living [5]. The estimated total of use of the hands in activities of daily living, during the day, is more than five hours, not counting work and sports activities [6]. ...
Article
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Background: Grasping is present in most of the activities of daily living. The estimated total use of the hands in activities of daily living is more than five hours a day, not counting work and sports activities. The hand grasp strength peak is only relevant for short durations of applied forces, in the activities. The sustained strength gives a more realistic assessment of strength capabilities, during daily tasks. Objective: To characterize the sustained grasp strength over 5 seconds, in different grasps configurations, and identify changes in these when a musculoskeletal injury is present. Patients: Thirty right-handed participants, fifteen healthy (Control Group), and fifteen injured (Experimental Group) with musculoskeletal hand conditions, on the right side, 18 men and 12 women, were integrated into this study. In both groups, there were 9 men and 6 women. Methods: The Biometrics E-link® Dynamometer G200, was used, being kilograms as the measurement unit. The test position, to assess the hand grasp sustained strength, was recommended by the American Society of Hand Therapists. The strength was collected for 5 seconds, in the right hand, on eight grasp configurations, which can be performed on the dynamometer. Results: Men have more sustained strength than women, in all the grasp configurations assessed. The Experimental Group has inferior results regarding the peak strength, and the behavior of the strength is less stable. The man obtains the maximum endurance, and it is always over zero. The Inferior Pincer and the Parallel Extension are the grasp configurations that require less strength, being both precision grasps. The Medium Wrap is the grasp configuration that requires more strength, and it is also the one that has more differences between groups, regarding the strength and the peak strength. The three strongest grasps have the same configuration being the difference in the diameter of the grabbed object. Conclusion: The strength behavior for 5 seconds is similar between participants, with or without musculoskeletal conditions, being less high, less regular, and decreasing faster when there is an injury.
... Even today, finger motions, such as writing and keyboarding, are fundamental to many productive activities. Margarita reported that pinching motion accounts for 38.3% of activities of daily living (ADL) [1], suggesting that it is an important movement for humans. Napier stated that human grasping movements can be divided into two types [2]. ...
Article
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Fine motor skills have been suggested to be related to human cognitive abilities. To develop an objective method for evaluating fine motor skills, we applied a flexible tactile sensor based on electrical impedance tomography (EIT) and the contact resistance principle to a cylinder designed to mimic the peg used in the Functional Dexterity Test. Six pinching motions were classified to confirm the feasibility of the prototype system. Two types of classification were performed: classification using reconstructed images and classification using measured voltage vectors. The feasibility of the classification method was evaluated using adult subjects, and it was demonstrated that the system can accurately classify various types of pinching motions. The results revealed that utilizing reconstructed images for classification achieved a discrimination accuracy of 79.4%, while employing measured voltage vectors for classification resulted in a discrimination accuracy of 91.4%. These findings underscore the potential for developing an automated finger motion analysis system using EIT-based tactile sensor.
... A trial capture began when the participant aligned their arm on the natural object or SPINDLE handle and was ready to move. From this instance until the next twenty-second period was considered a trial [50]. The details of the task protocol can be found in Appendix A. ...
Article
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Individuals with neurological disorders often exhibit altered manual dexterity and muscle weakness in their upper limbs. These motor impairments with tremor lead to severe difficulties in performing Activities of Daily Living (ADL). There is a critical need for ADL-focused robotic training that improves individual’s strength when engaging with dexterous ADL tasks. This research introduces a new approach to training ADLs by employing a novel robotic rehabilitation system, Spherical Parallel INstrument for Daily Living Emulation (SPINDLE), which incorporates Virtual Reality (VR) to simulate ADL tasks. The study results present the feasibility of training individuals with movements similar to ADLs while interacting with the SPINDLE. A new game-based robotic training paradigm is suggested to perform ADL tasks at various intensity levels of resistance as needed. The proposed system can facilitate the training of various ADLs requiring 3-dimensional rotational movements by providing optimal resistance and visual feedback. We envision this system can be utilized as a table-top home device by restoring the impaired motor function of individuals with tremor and muscle weakness, guiding to improved ADL performance and quality of life.
... Prior to participation, all subjects gave their informed written consent for the study, which was approved by the ethics committee of our university (reference number CD/31/2019). Participants performed seven representative grasps of ADL (Figure 1), based on the grasp taxonomy by Vergara et al. [27]: two and three fingers pad-to-pad pinch (PpP), cylindrical grasp (Cyl), lumbrical grasp (Lum), lateral pinch (LatP), oblique palmar grasp (Obl), and intermediate power-precision grasp (IntPP). ...
Article
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The specific role of forearm muscles in the development of activities of daily living (ADL) remains unknown. Consequently, studying forearm muscle activity during the most commonly used grasps in ADL would yield valuable insights for hand function evaluation, rehabilitation, and advancements in prosthetic control. In this study, forearm muscle activity was analyzed in 22 healthy subjects, examining seven representative forearm areas during the performance of seven types of grasps at 50% of maximum effort. A Scheirer–Ray–Hare test revealed significant differences for grasp, spot, and their interaction (α < 0.05), but not for repetition (and its interactions). Specific significant differences between grasps were found in specific spots by means of Bonferroni post hoc analyses, ensuring the possibility to discriminate between grasps, which is key to identifying the person’s intention to perform a particular grasp. The median values ranged from 4.4% to 32.8%, depending on the spot and grasp, with small 95% confidence intervals (0.5% to 5.5%). Cylindrical grasp requires the highest muscle activity among all spots, while lateral pinch demands the least. The findings elucidate the contribution, coordination, and function of each muscle in relation to each grasp, with implications for rehabilitation, prosthetics, and telerobotic and teleoperation systems.
... First, grasp configuration, determined by the employed grasp type, has already been extensively studied. Several grasp taxonomies have been reported depending on their purpose [27], [28], such as the 9-type classification applied in [5] to determine the frequency of use of grasps in activities of daily living (ADL). Second, very little is known about the different ways of performing the same grasp based on a subject's previous experience because the solution to this problem is not straightforward. ...
Article
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Surface Electromyography (sEMG) signals are widely used as input to control robotic devices, prosthetic limbs, exoskeletons, among other devices, and provide information about someone’s intention to perform a particular movement. However, the redundant action of 32 muscles in the forearm and hand means that the neuromotor system can select different combinations of muscular activities to perform the same grasp, and these combinations could differ among subjects, and even among the trials done by the same subject. In this work, 22 healthy subjects performed seven representative grasp types (the most commonly used). sEMG signals were recorded from seven representative forearm spots identified in a previous work. Intra- and intersubject variability are presented by using four sEMG characteristics: muscle activity, zero crossing, enhanced wavelength and enhanced mean absolute value. The results confirmed the presence of both intra- and intersubject variability, which evidences the existence of distinct, yet limited, muscle patterns while executing the same grasp. This work underscores the importance of utilizing diverse combinations of sEMG features or characteristics of various natures, such as time-domain or frequency-domain, and it is the first work to observe the effect of considering different muscular patterns during grasps execution. This approach is applicable for fine-tuning the control settings of current sEMG devices.
... Critical issues rarely occur; however, literature data report pad-to-pad (31.9%), lumbrical (15.4%), and cylindrical grasp (12%)-where the thumb is in opposition to the palm and adducted-together with the nonprehensile use (18.6%) of the hand, which are the most important and demanding everyday grasps in the healthy population. [35][36][37] These grasps represent almost 80% of autonomy patterns, which explains the difficulties that scleroderma patients encounter in ADLs. ...
Article
Background: Reports on hand dysfunction and rehabilitation in SSc are quite scarce in the literature and mainly focus on functional assessment tools, such as the Duruoz Hand Index and the HAMIS test for evaluating hand mobility by simulating specific grasps with nine different objects. Purpose of the study: This study aimed to provide an adequate assessment methodology for hand grasp dysfunctions in patients suffering from systemic sclerosis (SSc) through the 16-grasp test. Study design: Case-control study. Methods: Ninety-seven consecutive SSc patients were recruited at our Scleroderma Unit, where a 16-grasp test was performed by all patients and supervised by an experienced hand therapist. Sixteen different patterns of grasp have been divided into power grasps and precision pinch and two more modalities: static and dynamic prehension evaluation on scale from 0 to 4. We also compared previous evaluations on 19 of patients recruited. Results: The majority of SSc patients (84 females and 13 males; mean age 56.0 ± 12.0 years; mean disease duration 8.0 ± 6.0 years) displayed grasp dysfunctions; in particular 48% and 54% reported slight difficulty in the right and left grasps respectively, 6% medium difficulty in both hands, and only 3% and 1% experienced severe difficulty respectively, while 31.5% had no issues in either hand. Our results showed that the limited cutaneous subset (lcSSc) scored a lower deficit for either grasp compared to diffuse form (dcSSc). No statistically significant differences in total grasp deficit had been noticed when comparing patients having a disease duration < 5 years or longer. In the retrospective study on 19 of these patients, 8 out of 10 lcSSc patients showed no significant changes, while in 2 out of 10, slight improvements were observed in both hands. However, in the dcSSc group, 4 out of 9 worsened bilaterally while the grasp scores for 5 of them remained unchanged. Conclusion: Our study reported hand involvement in both lcSSc and dcSSc forms, more significantly in dcSSc patients. This test is intended to be a more objective means of assessing grasp alterations linked to scleroderma hand deformities. Furthermore, thanks to its intuitiveness, the test may be useful for engineers designing personalized ergonomic assistive devices.
... The Biopac 3 MP 36 amplifier also enabled electromyography (EMG) measures. The interactive objects represented the objects that were used in daily living [19,20]. ...
Preprint
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A system to evaluate several facets of hand function for neuroprostheses-mediated tasks is proposed. It includes a platform that serves as a test bench, sensors for dynamometry, electromyography, sensorized glove, and interactive objects. The system methodically locates and assesses the motor points along the forearm, evaluates stimulation-induced fatigue, measures digit motion and forces exerted during ADL grasps, and evaluates nerve excitability to advance electrode designs. While the system is exclusively designed for neuroprostheses-mediated grasp, it can also be extended to generic grasp and object manipulation-based research.
... We first assessed whether the test offered a holistic assessment by analyzing both dexterity (defined as inclusion of at least five common hand grasps) and control systems (defined as the test's ability to be sensitive in detecting performance variations due to different control systems) (Vergara et al., 2014). Next, we evaluated whether the manipulated test objects require the prosthesis to perform a range of grasping movements with varying degrees of hand closure and force, mirroring real-world applications. ...
Article
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This article provides a comprehensive narrative review of physical task-based assessments used to evaluate the multi-grasp dexterity and functional impact of varying control systems in pediatric and adult upper-limb prostheses. Our search returned 1,442 research articles from online databases, of which 25 tests—selected for their scientific rigor, evaluation metrics, and psychometric properties—met our review criteria. We observed that despite significant advancements in the mechatronics of upper-limb prostheses, these 25 assessments are the only validated evaluation methods that have emerged since the first measure in 1948. This not only underscores the lack of a consistently updated, standardized assessment protocol for new innovations, but also reveals an unsettling trend: as technology outpaces standardized evaluation measures, developers will often support their novel devices through custom, study-specific tests. These boutique assessments can potentially introduce bias and jeopardize validity. Furthermore, our analysis revealed that current validated evaluation methods often overlook the influence of competing interests on test success. Clinical settings and research laboratories differ in their time constraints, access to specialized equipment, and testing objectives, all of which significantly influence assessment selection and consistent use. Therefore, we propose a dual testing approach to address the varied demands of these distinct environments. Additionally, we found that almost all existing task-based assessments lack an integrated mechanism for collecting patient feedback, which we assert is essential for a holistic evaluation of upper-limb prostheses. Our review underscores the pressing need for a standardized evaluation protocol capable of objectively assessing the rapidly advancing prosthetic technologies across all testing domains.
... We have also performed a cross-sectional study of grasp forces with varying subjects and objects to understand the variation in force values across different variables. Cylindrical grasp is one among the most commonly used grasp types [6]. Additional experiments on cylindrical grasp types involving some of the common objects requiring cylindrical grasps during ADLs was conducted. ...
Conference Paper
Human grasps involved in activities of daily living rely on the correlation of multiple degrees of freedom in a hand. This correlation is called grasp synergies and holds promise for efficient control of robotic hands including prostheses and exoskeletons. A number of studies involving human grasping experiments have been reported. However, the approach, lift and hold phases which are intricately linked to the hand grasp for activities of daily living have hardly been part of such studies. We report a human grasping study which includes the approach, lift and hold phases. Grasp synergies in the force and posture space are identified. We have observed distinct force patterns while manipulating different objects. Additionally, our analysis of correlation coefficients between the pair of fingers highlights the cooperative behaviour and synergy between fingers while grasping. Our study contributes valuable insights into finger correlations, and synergies in terms of grasp postures and forces. CCS CONCEPTS • Human-centered computing → Empirical studies in HCI.
... A total of 27 degrees of freedom (DoFs) are involved in the mechanism of the hand, including 2 DoFs at the wrist and 25 DoFs on the linkages between the fingers [19]. Most hand functions are represented by six categories of movements: an opposing pinch, a spherical (span) grip, a hook (or snap), and a palmar grab (also called as a tip or precision pinch, a lateral (key) pinch) [20]. The kinematics of human hand movements may be tracked and studied using a variety of techniques, including Kinect system, optical motion capture and instrumented data gloves [21]. ...
Article
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The hand of a human being is the most commonly utilized body part in daily activities. Assessing the functional capability is highly challenging and important in medical applications purposes. This research aims to design and implement a sensor-based system for function assessment and movements analysis of the hand by calculating the angular velocity, acceleration and magnetic field for the joints of the fingers during the daily activities. The proposed system was applied to two groups of volunteers: The first group consisted of seven males, whereas the second group consisted of seven females, and the results were taken by calculating the acceleration, angular velocity, magnetic field during activities of daily living (ADL). This study showed the system is important in hand movement and control function evaluation. The thumb and index fingers have similar pitch orientations while interacting, while the middle finger employs a distinct range. Yaw variables are less noticeable, but the variation in roll angles between fingers is.
... In individuals without upper extremity neurological deficits, the time required for them to feed themselves involves roughly one hour of hand use per day. Pulp-to-pulp pinching is used for approximately 56 minutes, with cylindrical grasping used for about four minutes (e.g., drinking water from the bottle) and lateral pinch only for roughly 4:30 minutes [13]. ...
Article
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In tetraplegia, hand reconstruction is of high priority. Key pinch reconstruction has been advocated for tetraplegia hand reconstruction because of the lack of donors for nerve and tendon transfers. We report a patient with mid-cervical tetraplegia who underwent nerve and tendon transfers in the right and left upper limbs seven months post-injury to reconstruct hand function. The particularity of our case resides in the left-hand thumb and index pulp-to-pulp reconstruction. For this, we transferred the nerve to the supinator to the posterior interosseous nerve and the nerve to the extensor carpi radialis brevis to the anterior interosseous nerve. During a second surgery, we relieved clawing by transferring the split flexor digitorum superficialis of the middle and ring fingers, motored by the brachioradialis, to the extensor apparatus of all fingers. Finally, to achieve better thumb palmar abduction, we osteotomized the scaphoid tubercle and fixed it to the distal radius while maintaining thenar muscle attachments. Five years after surgery, the patient was able to grasp and release small objects placed on a table after becoming left-handed. Here, we demonstrated that pinch-to-pinch reconstruction is possible, which increased hand use in daily activities, especially during eating and grabbing small objects over the table.
... Nevertheless, such hypothesis was only observed for a power grip task and, thus, needs to be explored in other hand force production configuration such as pinch grip and non-prehensile tasks. Pinch grip is indeed also exposed to grip force loss with deviated wrist positions [6,12,15] and is among the most common used grip [26]. The influence of wrist posture on finger forces during non-prehensile tasks, such as four-finger pressing, is less studied whereas those tasks offer an interesting paradigm, with lesser co-contraction of wrist extensors [23] and specific wrist equilibrium constraints due to finger force sharing [18]. ...
Preprint
Grip strength loss in extended and flexed wrist postures has been explained by reduced force-generating capacities of extrinsic finger flexor resulting from non-optimal length, owing to the force-length relationship. Recent works suggested that other muscles, especially wrist extensors, participate in this grip strength loss. The objective of this study was to clarify the role of the force-length relationship in finger force production. 18 participants performed maximal isometric finger force production during pinch grip (Pinch) and four-finger pressing (Press) tasks in four different wrist postures (extended, flexed, neutral, spontaneous). The maximum finger force (MFF), finger and wrist joint angles, as well as activation of four muscles were determined using dynamometry, motion capture, and electromyography. The force and length of the four muscles were estimated from joint angles and muscle activation using a musculoskeletal model. MFF decreased for flexed wrist during Pinch but remained stable across wrist postures during Press. The results suggested that the loss of pinch grip force in deviated wrist posture is partially related to force-length relationship of finger extensors. In opposition, MFF during Press was not influenced by the modulation of muscle capacities but was probably first limited by mechanical and neural factors related to finger interdependence
... Nevertheless, such hypothesis was only observed for a power grip task and thus need to be explored in other hand force production configuration such as pinch grip and non-prehensile tasks. Pinch grip is indeed also exposed to grip force loss with deviated wrist positions 5,11,14 and is among the most common used grip 25 . The influence of wrist posture on finger forces during non-prehensile tasks, such as four-finger pressing, is less studied whereas those tasks offer an interesting paradigm, with lesser co-contraction of wrist extensors 22 and specific wrist equilibrium constraints due to finger force sharing 17 . ...
Article
Full-text available
Grip strength loss in extended and flexed wrist postures has been explained by reduced force-generating capacities of extrinsic finger flexor resulting from non-optimal length, owing to the force-length relationship. Recent works suggested that other muscles, especially wrist extensors, participate in this grip strength loss. The objective of this study was to clarify the role of the force-length relationship in finger force production. 18 participants performed maximal isometric finger force production during pinch grip (Pinch) and four-finger pressing (Press) tasks in four different wrist postures (extended, flexed, neutral, spontaneous). The maximum finger force (MFF), finger and wrist joint angles, as well as activation of four muscles were determined using dynamometry, motion capture, and electromyography. The force and length of the four muscles were estimated from joint angles and muscle activation using a musculoskeletal model. MFF decreased for flexed wrist during Pinch but remained stable across wrist postures during Press. The results suggested that the loss of pinch grip force in deviated wrist posture is partially related to force-length relationship of finger extensors. In opposition, MFF during Press was not influenced by the modulation of muscle capacities but was probably first limited by mechanical and neural factors related to finger interdependence.
... Frequency-related features are generally extracted using Fourier transform, wavelets or bandpass filtering, and it is common to see spatial features extracted through Laplacian filters, spatial patterns, principal component analysis and independent component analysis 78 . Sensorimotor-related rhythms commonly extracted are the mu band (8-12 Hz) and beta band (18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30), as these change in amplitude with overt movement, imagined movement and movement preparation. ...
... Other taxonomies mentioned in works of Kamakura et al. [47], Edwards et al. [10], Kapandji [45] are listed with 14, 20 and 21 grasps respectively. A similar study [51], that used a different categorization which incorporated non-prehensile grasps. Even though there has been a considerable effort in creating statistics of human hand use and grouping of hand grasps [11,12]. ...
Preprint
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Grasping is an incredible ability of animals using their arms and limbs in their daily life. The human hand is an especially astonishing multi-fingered tool for precise grasping, which helped humans to develop the modern world. The implementation of the human grasp to virtual reality and telerobotics is always interesting and challenging at the same time. In this work, authors surveyed, studied, and analyzed the human hand-grasping behavior for the possibilities of haptic grasping in the virtual and remote environment. This work is focused on the motion and force analysis of fingers in human hand grasping scenarios and the paper describes the transition of the human hand grasping towards a tripod haptic grasp model for effective interaction in virtual reality.
... Because the main role of the prosthetic hand is to pick up objects, its ADL is measured by the variety of gripping functions it provides. According to established studies, there are six representative prehensile patterns for measuring hand functionality in ADL: (1) lateral hold, (2) power hold, (3) tripod (triangular hold), (4) fingertip hold, (5) extension, and (6) spherical hold (Light et al., 2002;Massa et al., 2002;Vergara et al., 2014). Therefore, the level of dexterity of the prosthetic hand was set with these six grips as the criteria (refer to Appendix A Table A for details). ...
Article
Assistive technologies have been recognized as a particularly powerful aid for increasing the independence and social integration of the people with disabilities in an aging society, where the extent of acquired disability is significant. For the development of novel assistive technologies to be effective, it is necessary to properly understand the needs of consumers. Therefore, this study identifies the heterogeneous preference of potential users of 3D-printed prosthetic hands with regards to their daily lifestyle patterns using discrete choice experiment and latent class analysis. The results indicate that the consumers of prosthetic hands have varying group-wise preferences for different types of prosthetics based on their lifestyle patterns. Specifically, those who spend more time at home were less concerned about weight and dexterity than those who were younger and spent more time outside at work and leisure. In all, the development of 3D-printed prosthetic hands needs to be directed towards reducing weight and increasing functionality for further adoption. Our findings will enhance the understanding of assistive technologies adoption and provide important strategic implications by suggesting the required progress and development pathway of 3D-printed prosthetic hands to increase market penetration and satisfy unmet needs.
... The tasks consisted of the 20 ADLs proposed in the Sollerman Hand Function Test (SHFT) (Sollerman & Ejeskär, 1995) as being representative of the activities and grasp types performed by a healthy adult subject during daily life. Moreover, six additional ADLs were performed in order to include the grasp types under-represented in the SHFT (intermediate, special pinch and non-prehensile) according to the real frequency of grasps in ADLs (Vergara et al., 2014). All the subjects performed the tasks following the operator's instructions, which included whether subjects had to use both hands or only the dominant one according to SHFT instructions (Sollerman & Ejeskär, 1995) (see Table 2). ...
Article
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The recording of hand kinematics during product manipulation is challenging, and certain degrees of freedom such as distal interphalangeal (DIP) joints are difficult to record owing to limitations of the motion capture systems used. DIP joint kinematics could be estimated by taking advantage of its kinematic linkage with proximal interphalangeal (PIP) and metacarpophalangeal joints. This work analyses this linkage both in free motion conditions and during the performance of 26 activities of daily living. We have studied the appropriateness of different types of linear regressions (several combinations of independent variables and constant coefficients) and sets of data (free motion and manipulation data) to obtain equations to estimate DIP joints kinematics both in free motion and manipulation conditions. Errors that arise when estimating DIP joint angles assuming linear relationships using the equations obtained both from free motion data and from manipulation data are compared for each activity of daily living performed. Estimation using manipulation condition equations implies a lower mean absolute error per task (from 5.87° to 13.67°) than using the free motion ones (from 9° to 17.87°), but it fails to provide accurate estimations when passive extension of DIP joints occurs while PIP is flexed. This work provides evidence showing that estimating DIP joint angles is only recommended when studying free motion or grasps where both joints are highly flexed and when using linear relationships that consider only PIP joint angles.
Article
Background: In baseball pitches, the forkball requires a special grip, pinching the ball between the second and third fingers to achieve the resulting breaking ball trajectory. We hypothesized that the forkball grip would have a substantial impact on the hardness of the flexor digitorum superficialis. The aim was to quantify and clarify the change in the hardness of the flexor digitorum superficialis due to the forkball grip. Methods: Twenty-one adult male subjects were recruited and instructed to perform two baseball grips with the ball: fast and forkball, and the rest without the ball. The shear wave speeds of the pronator teres, flexor carpi radialis, flexor digitorum superficialis, and flexor carpi ulnaris were measured using shear wave elastography. Results: In the forkball grip, compared with the fastball grip and the rest without the ball, the shear wave speed of the flexor digitorum superficialis was significantly higher than those of the pronator teres, flexor carpi radialis, and flexor carpi ulnaris (P<0.001), indicating that muscle hardness increased due to the forkball grip. In contrast, no significant differences were found between the conditions for the other forearm flexor-pronator muscles. Conclusions: Quantification of muscle hardness using shear wave elastography showed that gripping a forked ball increased muscle hardness in the flexor digitorum superficialis.
Article
A stroke is a neurological disease that primarily causes paralysis. Besides paraplegia, all other types of paralysis affect the upper extremity. Advanced technologies, such as wearable devices and rehabilitation regimens, are also being developed to enhance the functional ability of a stroke person to grasp and release daily living objects. In this research, we developed a rehabilitation functional assist device combining a flexion and extension mechanism with suction cup technology (hybrid technology) to help post-stroke patients improve their hand grip strength in day-to-day grasping activities. Ten poststroke hemiplegia patients were studied to test the functional ability of the impaired hand by wearing and not wearing the device. The outcomes were validated by three standard clinical tests, such as the Toronto Rehabilitation Institute – Hand Functional Test (TRI-HFT), the Chedoke Arm Hand Activity Inventory (CAHAI-9), and the Fugl-Meyer Assessment (FMA) with overall score improvements of 14.5 ± 3.8–25 ± 2.2 ( p = 0.005), 5.4 ± 2.8–10 ± 1.6 ( p = 0.008), and 9.6 ± 2.6–17 ± 2.4 ( p = 0.005) respectively. The p-value for each of the three evaluations was less than 0.05, indicating significantly improved results and the average feedback score of the participants was 3.8 out of 5. The proposed device significantly increased impaired hand functionality in post-stroke patients. The subjects could complete some of the grasping tasks that they could not grasp without the device. Clinical trial registration The Clinical Trial Registry of India approved the work CTRI/2022/02/040495 described in this manuscript.
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There is a wide variety of tools and measures for rehabilitation outcomes in post-stroke patients with impairments in the upper limb and hand, such as paralysis, paresis, flaccidity, and spasticity. However, there is a lack of general recommendations for selecting the most appropriate scales, tests, and instruments to objectively evaluate therapy outcomes. Reviews on upper limb and hand measurements reveal that clinicians’ choices of tools and methods are highly varied. Some clinicians and medical teams continue to employ non-standard and unverified metrics in their research and measurements. This review article aims to identify the key parameters, assessed by outcome measures and instruments, that play a crucial role in upper limb and hand rehabilitation for post-stroke patients, specifically focusing on the recovery of hand function. The review seeks to assist researchers and medical teams in selecting appropriate outcome measures when evaluating post-stroke patients. We analyze the measured factors and skills found in these outcome measures and highlight useful tools that diversify assessments and enhance result objectivity through graphical representation. The paper also describes trends and new possibilities in hand outcome measures. Clinicians frequently use proven devices, such as EMG, goniometers, and hand dynamometers. Still, there is a growing trend towards incorporating technologies, such as pose and position estimation, using artificial intelligence, or custom hand grip measurement devices. Researchers are increasingly adopting scales previously successful in orthopedic and surgical patients, recognizing their potential for objectivizing outcomes in neurological patients with post-stroke hand complications. The review included only adults over the age of 18. Outcome measures were tested for usefulness in the rehabilitation of stroke patients.
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Obtaining large biomechanical datasets for machine learning is an ongoing challenge. Physics-based simulations offer one approach for generating large datasets, but many simulation methods, such as computed muscle control (CMC), are computationally costly. In contrast, interpolation methods, such as inverse distance weighting (IDW), are computationally fast. We examined whether IDW is a low-cost and accurate approach for interpolating muscle activations from CMC.IDW was evaluated using lateral pinch simulations in OpenSim. Simulated pinch data were organized into grids of varying sparsity (high, medium, and low density), where each grid point represented the muscle activations associated with a unique combination of mass and height of a young adult. For each grid, muscle activations were calculated via CMC and IDW for 108 random mass-height pairs that were not coincident with simulation grid vertices. We evaluated the interpolation errors from IDW for each grid, as well as the sensitivity of lateral pinch force to these errors. The root mean square error (RMSE) associated with interpolated muscle activations decreased with increasing grid density and never exceeded 4%. While CMC received a target thumb-tip force of 40 N, errors from the interpolated muscle activations never impacted the simulated force magnitude by more than 0.1 N. Furthermore, the computation time for CMC simulations averaged 4.22 core-minutes, while IDW averaged 0.95 core-seconds per mass-height pair.These results indicate IDW is a practical approach for rapidly estimating muscle activations from sparse CMC datasets. Future works could adapt our IDW approach to evaluate other tasks, biomechanical features, and/or populations.
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Background and objectives: Osteoarthritis at the base of the thumb (CMC-1 OA) is a pathology that mainly affects postmenopausal women. The main symptoms including pain, decreased hand-thumb strength and fine motor capacity. Although a proprioceptive deficit has already been demonstrated in people with CMC-1 OA, there is insufficient evidence regarding the effects of proprioceptive training. The main objective of this study is to determine the effectiveness of proprioceptive training in functional recovery. Materials and methods: A total of 57 patients were included in the study, 29 in the control group and 28 in the experimental group. Both groups underwent the same basic intervention programme, but the experimental group included a proprioceptive training protocol. Variables of the study were pain (VAS), perception of occupational performance (COMP), sense position (SP) and force sensation (FS). Results: Statistically significant improvement was observed in the experimental group in pain (p < .05) and occupational performance (p < .001) after 3 months of treatment. No statistical differences were found in sense position (SP) or sensation of force (FS). Discussion and conclusions: The results concord with previous studies focussing on proprioception training. The incorporation of a proprioceptive exercise protocol reduces pain and significantly improves occupational performance.
Article
Objective: The human hand is known to have excellent manipulation ability compared to other primate hands. Without the palm movements, the human hand would lose more than 40% of its functions. However, uncovering the constitution of palm movements is still a challenging problem involving kinesiology, physiology, and engineering science. Methods: By recording the palm joint angles during common grasping, gesturing, and manipulation tasks, we built a palm kinematic dataset. Then, a method for extracting the eigen-movements to characterize the common motion correlation relationships of palm joints was proposed to explore the palm movement constitution. Results: This study revealed a palm kinematic characteristic that we named the joint motion grouping coupling characteristic. During natural palm movements, there are several joint groups with a high degree of motor independence, while the movements of joints within each joint group are interdependent. Based on these characteristics, the palm movements can be decomposed into seven eigen-movements. The linear combinations of these eigen-movements can reconstruct more than 90% of palm movement ability. Moreover, combined with the palm musculoskeletal structures, we found that the revealed eigen-movements are associated with joint groups that are defined by muscular functions, which provided a meaningful context for palm movement decomposition. Conclusion: This paper suggests that some invariable characteristics underlie the variable palm motor behaviors and can be used to simplify palm movement generation. Significance: This paper provides important insights into palm kinematics, and helps facilitate motor function assessment and the development of better artificial hands.
Article
The modern human hand is an intriguing mix of primitive morphology and derived function. Traditionally, its form and function are explained as a functional “trade‐off” between the requirements of locomotion and manipulation, but recently acquired comparative, experimental and fossil evidence suggests that this functional trade‐off is more complex than conventional wisdom suggests. Moreover, when studying hand evolution within the hominin clade, the only morphological evidence comes from the hard‐tissues, and evidence about hand function must be inferred indirectly from the archaeological record. We lack information about critical aspects of hand form (e.g., soft tissues) and function (e.g., neurology) as well as non‐lithic evidence about behavior. Thus, comparative anatomical, experimental and ethological studies of modern humans and other primates are critical to making more informed inferences about hand use in the past. We review the relevant fossil and archaeological evidence within the relevant comparative context (e.g., other extant apes and dexterous monkeys) in an attempt to reconstruct hand evolution within the hominin clade. We conclude by summarizing our current understanding—or lack thereof—of the evolutionary history of the modern human hand.
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There are several causes that can lead to functional weakness in the hands or upper extremities (UE), such as stroke, trauma, or aging. Therefore, evaluation and monitoring of UE rehabilitation have become essential. However, most traditional evaluation tools (TETs) and assessments require clinicians to assist or are limited to specific clinical settings. Several novel assessments might apply to wearable devices, yet those devices will still need clinicians or caretakers to help with further tests. Thus, a novel UE assessment device that is user-friendly and requires minimal assistance would be needed. The cylindrical grasp is one of the common UE movements performed in daily life. Therefore, a cylindrical sensor-embedded holding device (SEHD) for training and monitoring was developed for a usability test within this research. The SEHD has 14 force sensors with an array designed to fit holding positions and a six-axis inertial measurement unit (IMU) to monitor grip strength, hand dexterity, acceleration, and angular velocity. Six young adults, six healthy elderly participants, and three stroke survivors had participated in this study to see if the SEHD could be used as a reference to TETs. During result analyses, where the correlation coefficient analyses were applied, forearm rotation smoothness and the Purdue Pegboard Test (PPT) showed a moderate negative correlation [r (16) = −0.724, p < 0.01], and the finger independence showed a moderate negative correlation with the PPT [r (10) = −0.615, p < 0.05]. There was also a highly positive correlation between the maximum pressing task and Jamar dynamometer in maximum grip strength [r (16) = 0.821, p < 0.01]. These outcomes suggest that the SEHD with simple movements could be applied as a reference for users to monitor their UE ability.
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In this paper, we present results from a study of prehensile human hand use during the daily work activities of four subjects: two housekeepers and two machinists. Subjects wore a head-mounted camera that recorded their hand usage during their daily work activities in their typical place of work. For each subject, 7.45 hours of video was analyzed, recording the type of grasp being used and its duration. From this data, we extracted overall grasp frequency, duration distributions for each grasp, and common transitions between grasps. The results show that for 80 percent of the study duration the housekeepers used just five grasps and the machinists used 10. The grasping patterns for the different subjects were compared, and the overall top 10 grasps are discussed in detail. The results of this study not only lend insight into how people use their hands during daily tasks, but can also inform the design of effective robotic and prosthetic hands.
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Background: This review aims to assess the efficacy of upper limb interventions on stroke survivors' health-related quality of life (QOL). Method: Published studies were identified following a systematic search of the literature from 10 electronic databases, 3 subject-relevant journals, a Web search via a popular search engine, and reference lists of the included articles. In total, 22 articles met the inclusion criteria and were subjected to data extraction to establish the effectiveness of the intervention on QOL scores. Interventions varied according to their content, including acupuncture treatment, botulinum toxin type A (BTX-A) injections, constraint-induced movement therapy (CIMT), task training, and therapeutic exercise. Studies were required to have at least 1 quantitative outcome QOL measure. Results: Of the 22 studies, 12 reported significant findings within groups and between control groups. Interventions including BTX-A injections, CIMT, exercise programs, baclofen pump, robotic-assisted therapy, electrical stimulation, and acupuncture were reported to significantly improve either overall health-related QOL or certain individual QOL domains, such as strength, hand function, memory, mood, activities of daily living, mobility, social participation, communication, energy, pain, and sleep. Conclusion: The review demonstrates the need for upper limb intervention studies to focus on QOL as a primary outcome measure in addition to the functional outcomes currently used.
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To assess prosthetic use by upper extremity amputees, and their difficulties with prostheses in activities of daily living and occupations. This study is based on a survey of 307 subjects, who were using prostheses manufactured in the Center of Prosthetics and Orthotics. The survey questionnaire included items about general demographic characteristics, side and level of amputation, type of prosthesis and its use, and difficulties in the activities of daily living, employment and driving. The most common type of prosthesis was the cosmetic hand type (80.2%). There were no statistically significant correlations between satisfaction with prosthesis and the amputation level or type of prosthesis. The most common difficulties in daily living activities experienced by amputees were lacing shoes, removing bottle-tops with a bottle opener, and using scissors. Only 7.3% of amputees received rehabilitation services. Less than half of the amputees (44.7%) used their prostheses for eight or more hours a day, and 76.9% used their prostheses for regular or irregular cosmetic purposes. After amputation, most of the respondents (69.0%) became unemployed or changed workplaces. In our study, respondents preferred cosmetic usage to functional usage. Only 30.0% of respondents reported satisfaction with their prostheses. Many of the amputees had difficulties in complex tasks and either changed jobs or became unemployed. Clerical workers were the occupation group, which was most likely to return to work. The development of a more functional prosthetic hand and additional rehabilitation services are required.
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In this paper, the influence of the finger posture on the subjective effort during pinching motion is investigated by using a tendon-skeletal finger model. The experimental results show that the subjective effort human feels is affected by the size of the object he/she pinches, and the subjective effort correlates with the finger length. The simulation results show that the pattern of the tendon forces is similar to that of the EMG activity measured in the experiment, and the positive correlation was observed between the finger length and the object size where the summation of the tendon forces becomes the minimum. These results suggest that the reason why subjective pinching effort is influenced by the finger posture is the difference in the efficiency of the force transmission from the muscles.
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Tetraplegic patients were tested for hand strength before and after hand surgery. They also answered questions about how they rated the results of surgery. Presentation of the efficacy of reconstruction of hand raising, lateral grip, and cylindrical grip in the tetraplegic hand. The study was conducted in the Werner Wicker Clinic, Bad Wildungen, Germany, from 1991 to 1998. The results of reconstruction surgery performed on 23 tetraplegic hands, as reflected in lifting the hand (n=3), lateral grip (n=21), and cylindrical grip (n=14), are presented. In a follow-up study in 22 patients, their management of activities of daily living 34.1 months (9-51 months) after the surgery is compared with the preoperative situation. Subjective satisfaction levels were elicited for each of the 22 patients by means of a questionnaire. The gain in force corresponded to 893 g (150-1500 g) for cyclindrical grip and 488 g (100-1200 g) for lateral grip, while they were able to develop grade 4 force for lifting the hand. After the operation 28 aids/appliances that patients had formerly used regularly were no longer necessary. There were 75 separate activities listed in the questionnaire, and on average the 22 patients were able to perform 8.7 (0-20) more of these. Most patients (19) said they would advise others to have the operation and 18, that they would have the operation again. There were 12 complications in nine patients. Reconstructive surgery on the hands of tetraplegic patients leads to gains in both cylindrical grip and lateral grip force and to increased manual dexterity. Patient satisfaction with the procedure is high.
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A three-dimensional scalable biomechanical model of the four fingers of the hand to evaluate power grip is proposed. The model has been validated by means of reproducing an experiment in which the subjects exerted the maximal voluntary grasping force over cylinders of different diameters. The model is used to simulate the cylinder grip for two hand sizes and for five different handle diameters. The reduction of the muscle forces using different handle diameters has been studied. The model can be applied to the design and evaluation of handles for power grip and to the study of power grasp for normal and abnormal hands.
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The exquisite mechanical functionality and versatility of the human hand emerges from complex neuro-musculo-skeletal interactions that are not completely understood. I have found it useful to work within a theoretical/experimental paradigm that outlines the fundamental neuro-musculo-skeletal components and their interactions. In this integrative paradigm, the laws of mechanics, the specifications of the manipulation task, and the sensorimotor signals define the interactions among hand anatomy, the nervous system, and manipulation function. Thus, our collaborative research activities emphasize a firm grounding in the mechanics of finger function, insistence on anatomical detail, and meticulous characterization of muscle activity. This overview of our work on precision pinch (i.e., the ability to produce and control fingertip forces) presents some of our findings around three Research Themes: Mechanics-based quantification of manipulation ability; Anatomically realistic musculoskeletal finger models; and Neural control of finger muscles. I conclude that (i) driving the fingers to some limit of sensorimotor performance is instrumental to elucidating motor control strategies; (ii) that the cross-over of tendons from flexors to extensors in the extensor mechanism is needed to produce force in every direction, and (iii) the anatomical routing of multiarticular muscles makes co-contraction unavoidable for many tasks. Moreover, creating realistic and clinically useful finger models still requires developing new computational means to simulate the viscoelastic tendinous networks of the extensor mechanism, and the muscle-bone-ligament interactions in complex articulations. Building upon this neuromuscular biomechanics paradigm is of immense clinical relevance: it will be instrumental to the development of clinical treatments to preserve and restore manual ability in people suffering from neurological and orthopedic conditions. This understanding will also advance the design and control of robotic hands whose performance lags far behind that of their biological counterparts.
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The aim of this study was to critically analyse the various outcome measures available for assessing wrist and hand function. To this end, an extensive literature search was performed on Medline, PubMed and the Science Citation Index, focusing on terms associated with the method of development of the outcome measures item generation, item reduction, validity, reliability, internal consistency and their strengths and weaknesses. The most commonly used outcome measures described in literature were the DASH score (disability of shoulder, arm and hand questionnaire), the PRWE score (patient-rated wrist evaluation questionnaire), the Brigham and Women's carpal tunnel questionnaire and the Gartland and Werley score. Our study provides very useful evidence to suggest that the PRWE score is the most responsive instrument for evaluating the outcome in patients with distal radius fractures, while the DASH score is the best instrument for evaluating patients with disorders involving multiple joints of the upper limb. The Brigham and Women's score is a disease-specific outcome instrument for carpal tunnel syndrome; it has been validated and demonstrated to show good responsiveness and reliability in evaluating outcome in patients with carpal tunnel release. The Gartland and Werley score, although the most commonly described instrument in the literature for evaluating outcome after wrist surgery, has not been validated so to date.
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Current analytical models of grasping and manipulation with robotic hands contain simplifications and assumptions that limit their application to manufacturing environments. To evaluate these models, a study was undertaken of the grasps used by machinists in a small batch manufacturing operation. Based on the study, a taxonomy of grasps was constructed. An expert system was also developed to clarify the issues involved in human grasp choice. Comparisons of the grasp taxonomy, the expert system, and grasp-quality measures derived from the analytic models reveal that the analytic measures are useful for describing grasps in manufacturing tasks despite the limitations in the models. In addition, the grasp taxonomy provides insights for the design of versatile robotic hands for manufacturing
Conference Paper
This paper presents a study on the usage frequency of different grasp types throughout the daily functions of a professional house maid and a machinist. Subjects wore a head-mounted camera that recorded their hand usage during their daily work activities. This video was then analyzed, recording grasp type and associated time stamps, as well as information related to the task and object. The results show that nearly 80% of the time the house maid used just six grasps and the machinist used nine. This data, in conjunction with established grasp taxonomies, will enable a better understanding of how people utilize different grasps to accomplish tasks throughout the day, as well as inform the design of robotic and prosthetic hands.
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Unlabelled: Upper limb (UL) impairments are the most common disabling deficits after stroke and have complex relationships with activity and participation domains. However, relatively few studies have applied the ICF model to identify the contributions of specific UL impairments, such as muscular weakness, pain, and sensory loss, as predictors of activity and participation. The purposes of this predictive study were to evaluate the relationships between UL variables related to body functions/structures, activity, and participation domains and to determine which would best explain activity and participation with 55 subjects with chronic stroke. Body functions/structures were assessed by measures of grip, pinch, and UL strength, finger tactile sensations, shoulder pain, and cognition (MMSE); activity domain by measures of observed performance (BBT, NHPT, and TEMPA); and participation by measures of quality of life (SSQOL). Upper-limb and grip strength were related to all activity measures (0.52 <r < 0.82, p < .0001). Shoulder pain (r = -.39,p < .001) was the variable which was mostly related to participation. Grip strength alone accounted for 62%, 54%, and 36% of the variance in the activity measures (respectively TEMPA, BBT and NHPT). Shoulder pain accounted for 30% of the participation measure. Strength deficits and shoulder pain of the paretic UL demonstrated to be important targets for clinical interventions to improve activity and participation with chronic stroke subjects. Level of evidence: 2c.
Article
The development of a biomechanical model for a human finger is faced with many challenges, such as extensor mechanism complexity, statistical indeterminacy and suitability of computational processes. Motivation for this work was to develop a computer model that is able to predict the internal loading patterns of tendons and joint surfaces experienced by the human finger, while mitigating these challenges. Proposed methodology was based on a non-linear optimising mathematical technique with a criterion of boundary conditions and equality equations, maximised against unknown parameters to reduce statistical indeterminacy. Initial validation was performed via the simulation of one dynamic and two static postures case studies. Past models and experiments were used, based on published literature, to verify the proposed model's methodology and results. The feasibility of the proposed methodology was deemed satisfactory as the simulated results were concordant with in-vivo results for the extrinsic flexors.
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The DASH (Disability of Arm, Shoulder and Hand) score is being used increasingly as an outcome measure for upper limb pathology. In our clinical practice the DASH score has been used to study the outcome of several common upper limb disorders. We reviewed the literature and applied the principles of the World Health Organization on this scoring system.
Article
The purpose of this study was to test the utility of the 10% rule in hand rehabilitation. The 10% rule states that the dominant hand possesses a 10% greater grip strength than the nondominant hand. This rule has been used for many years to assist therapists in setting strength goals for patients with injured hands. The sample for this study consisted of 310 male and female students, faculty, and staff from a small, private liberal arts college located in Pennsylvania. Grip strength was measured with a factory-calibrated Jamar dynamometer. Results showed an overall 10.74% grip strength difference between dominant and nondominant hands. This finding verified the 10% rule. However, when the data were separated into left-handed and right-handed subjects, a 12.72% difference for right-handed subjects and a -0.08% difference for left-handed subjects was found. In conclusion, this study showed that the 10% rule is valid for right-handed persons only; for left-handed persons, grip strength should be considered equivalent in both hands.
Article
A standardised hand function test based on seven of the eight most common hand grips is reported. The test consists of 20 activities of daily living. The test procedure and the method of scoring are described as is our evaluation of the validity and reliability of the test. Fifty-nine tetraplegic patients were evaluated using the test before reconstructive surgery to their hands. The test score correlated well with the accepted international functional classification of the patient's arm (r = 0.76, p < 0.001). The mean test score in the arms of patients lacking sensation was significantly lower than in those with tactile gnosis (O:1-3 compared with OCu:1-3, p < 0.001).
Article
Seventy Australian upper limb amputees responded to a detailed postal questionnaire asking how often they wore their prostheses and their level of satisfaction with both their prostheses and their functional abilities. Fifty-six percent of amputees wore their limbs "once in a while" or "never." Prostheses were most often worn "all the time" for work and social activities. The amount of time amputees wore their prostheses was moderately associated with their level of satisfaction with their prostheses. The association between the amount of time amputees wore their prostheses and their level of satisfaction with their functional abilities was very low. Their prostheses were rated as "fair" or "not acceptable" by 64% of amputees. Sweating was rated as "not acceptable" by 55%. This may well be a significant contributing factor to the low prosthetic use. The amputees who did not wear prostheses did not have any greater satisfaction with their ability to do the tasks they want to do than the amputees who wore prostheses.
Article
The authors discuss the difficulties and limitations in functional evaluation of the hand and wrist. Assessment should be done prospectively by independent observers. The evaluation tests should be relevant to the patient's problem. Difficulties in interpretation of the results and in the choice of an adequate score are discussed. The authors present new techniques of functional evaluation used in Brussels: quantitative global functional evaluation using the 400-points score, electrogoniometric evaluation of the wrist, isokinetic and isometric wrist dynamometry, biomechanic evaluation of fracture healing using instrumented external fixation, and use of the DASH questionnaire.
Article
The ideal diameter for a tool handle for males and females has been determined using an existing biomechanical model of the hand validated in previous works. The model estimates a 33-mm optimum diameter tool handle for the general population (males and females). When the optimum diameter for a tool handle is selected, the muscles exert the minimum force needed to hold the tool and perform gripping activities. Optimal handle design reduces the force required for gripping a tool, protects the underlying joint structures, and reduces the risk of developing cumulative trauma associated with repetitive task requiring high grip forces and awkward postures. This article provides a design parameter for optimal tool diameter to aid the therapist in the selection of assistive devices, built-up handles, or for the fabrication of a tool handle.
Article
The aim of this study was to describe the type and frequency of hand use in healthy older adults. Observational studies were conducted involving structured observations at five-minute intervals on 15 healthy older adults as they went about their normal daily routine between 10.00 am and 2.00 pm. Overall, the dominant hand was used more frequently than the non-dominant hand. Subjects used their hands predominantly to hold and manipulate objects, and not for balance. There was no significant difference between the frequency of manipulating objects with the fingers and the frequency of use of the whole hand. Subjects used their hands significantly more often in bimanual activities than in unimanual activities or in no activity. Although subjects usually stood while they held or manipulated objects, they also sat or walked while manipulating them. The present study provides insights into how healthy older adults naturally use their hands in performing everyday activities. While the dominant hand is used more than the non-dominant hand, the hands are used predominantly together to perform bimanual tasks.
Article
The purpose of this study was to measure dexterity in children aged 4-19 years using the Nine-hole Peg Test. Four hundred and six children were tested with their dominant hand and then their nondominant hand. A commercial version of the Nine-hole Peg Test was used. An analysis of variance showed a main effect for age, gender, and hand dominance. Speed of dexterity improved with age. In all age groups, females performed faster than males. Participants performed faster with the dominant hand than the nondominant hand. The normative data collected provide information for comparing scores to children with different diagnostic categories to screen for fine motor difficulties.
Article
The present work displayed the first quantitative data of forces acting on tendons and pulleys during specific sport-climbing grip techniques. A three-dimensional static biomechanical model was used to estimate finger muscle tendon and pulley forces during the "slope" and the "crimp" grip. In the slope grip the finger joints are flexed, and in the crimp grip the distal interphalangeal (DIP) joint is hyperextended while the other joints are flexed. The tendons of the flexor digitorum profundus and superficialis (FDP and FDS), the extensor digitorum communis (EDC), the ulnar and radial interosseus (UI and RI), the lumbrical muscle (LU) and two annular pulleys (A2 and A4) were considered in the model. For the crimp grip in equilibrium conditions, a passive moment for the DIP joint was taken into account in the biomechanical model. This moment was quantified by relating the FDP intramuscular electromyogram (EMG) to the DIP joint external moment. Its intensity was estimated at a quarter of the external moment. The involvement of this parameter in the moment equilibrium equation for the DIP joint is thus essential. The FDP-to-FDS tendon-force ratio was 1.75:1 in the crimp grip and 0.88:1 in the slope grip. This result showed that the FDP was the prime finger flexor in the crimp grip, whereas the tendon tensions were equally distributed between the FDP and FDS tendons in the slope grip. The forces acting on the pulleys were 36 times lower for A2 in the slope grip than in the crimp grip, while the forces acting on A4 were 4 times lower. This current work provides both an experimental procedure and a biomechanical model that allows estimation of tendon tensions and pulley forces crucial for the knowledge about finger injuries in sport climbing.
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