Passive Wrist Research Articles

Multimodal Sensorimotor Integration of Visual and Kinaesthetic Afferents Modulates Motor Circuits in Humans.

Optimal motor control requires the effective integration of multi-modal information. Visual information of movement performed by others even enhances potentials in the upper motor neurons through the mirror-neuron system. On the other hand, it is known that motor control is intimately associated with afferent proprioceptive information. Kinaesthetic information is also generated by passive, external-driven movements. In the context of sensory integration, it is an important question how such passive kinaesthetic information and visually perceived movements are integrated. We studied the effects of visual and kinaesthetic information in combination, as well as isolated, on sensorimotor integration, compared to a control condition. For this, we measured the change in the excitability of the motor cortex (M1) using low-intensity Transcranial magnetic stimulation (TMS). We hypothesised that both visual motoneurons and kinaesthetic motoneurons enhance the excitability of motor responses. We found that passive wrist movements increase the motor excitability, suggesting that kinaesthetic motoneurons do exist. The kinaesthetic influence on the motor threshold was even stronger than the visual information. Moreover, the simultaneous visual and passive kinaesthetic information increased the cortical excitability more than each of them independently. Thus, for the first time, we found evidence for the integration of passive kinaesthetic- and visual-sensory stimuli.

Abnormal microscale neuronal connectivity triggered by a proprioceptive stimulus in dystonia

We investigated modulation of functional neuronal connectivity by a proprioceptive stimulus in sixteen young people with dystonia and eight controls. A robotic wrist interface delivered controlled passive wrist extension movements, the onset of which was synchronised with scalp EEG recordings. Data were segmented into epochs around the stimulus and up to 160 epochs per subject were averaged to produce a Stretch Evoked Potential (StretchEP). Event-related network dynamics were estimated using a methodology that features Wavelet Transform Coherency (WTC). Global Microscale Nodal Strength (GMNS) was introduced to estimate overall engagement of areas into short-lived networks related to the StretchEP, and Global Connectedness (GC) estimated the spatial extent of the StretchEP networks. Dynamic Connectivity Maps showed a striking difference between dystonia and controls, with particularly strong theta band event-related connectivity in dystonia. GC also showed a trend towards higher values in dystonia than controls. In summary, we demonstrate the feasibility of this method to investigate event-related neuronal connectivity in relation to a proprioceptive stimulus in a paediatric patient population. Young people with dystonia show an exaggerated network response to a proprioceptive stimulus, displaying both excessive theta-band synchronisation across the sensorimotor network and widespread engagement of cortical regions in the activated network.

Cross-Modal Functional Connectivity of the Premotor Cortex Reflects Residual Motor Output After Stroke.

Stroke is known to cause widespread activation and connectivity changes resulting in different levels of functional impairment. Recovery of motor functions is thought to rely mainly on reorganizations within the sensorimotor cortex, but increasing attention is being paid to other cerebral regions. To investigate the motor task-related functional connectivity (FC) of the ipsilesional premotor cortex (PMC) and its relation to residual motor output after stroke in a population of mostly poorly recoverd patients. Twenty-four stroke patients (23 right handed, mean age = 52.4 ± 12.6 years) with varying levels of motor deficits underwent functional magnetic resonance imaging while performing different motor tasks (passive mobilization, motor execution, and motor imagery of an extension movement of the unaffected hand [UH] or affected hand [AH]). For the different motor tasks, analyses of cerebral activation and task-related FC of the ipsilesional lateral sensorimotor network (SMN), and particularly the premotor cortex (PMC), were performed. Compared with UH data, FC of the ipsilesional lateral SMN during the passive or active motor tasks involving the AH was decreased with regions of the ipsilesional SMN and was increased with regions of the bilateral frontal and the ipsilesional posterior parietal cortices such as the precuneus (Pcu). During passive wrist mobilization, FC between the ipsilesional PMC and the contralesional SMN was negatively correlated with residual motor function, whereas that with nonmotor regions such as the bilateral Pcu and the contralesional dorsolateral prefrontal cortex was positively correlated with the residual motor function. Cross-modal FC of the ipsilesional PMC may reflect compensation strategies after stroke. The results emphasize the importance of the PMC and other nonmotor regions as prominent nodes involved in reorganization processes after a stroke.

Autologous Mesenchymal Stem Cells Improve Motor Recovery in Subacute Ischemic Stroke: a Randomized Clinical Trial.

While preclinical stroke studies have shown that mesenchymal stem cells (MSCs) promote recovery, few randomized controlled trials (RCT) have assessed cell therapy in humans. In this RCT, we assessed the safety, feasibility, and efficacy of intravenous autologous bone marrow-derived MSCs in subacute stroke. ISIS-HERMES was a single-center, open-label RCT, with a 2-year follow-up. We enrolled patients aged 18-70years less than 2weeks following moderate-severe ischemic carotid stroke. Patients were randomized 2:1 to receive intravenous MSCs or not. Primary outcomes assessed feasibility and safety. Secondary outcomes assessed global and motor recovery. Passive wrist movement functional MRI (fMRI) activity in primary motor cortex (MI) was employed as a motor recovery biomarker. We compared "treated" and "control" groups using as-treated analyses. Of 31 enrolled patients, 16 patients received MSCs. Treatment feasibility was 80%, and there were 10 and 16 adverse events in treated patients, and 12 and 24 in controls at 6-month and 2-year follow-up, respectively. Using mixed modeling analyses, we observed no treatment effects on the Barthel Index, NIHSS, and modified-Rankin scores, but significant improvements in motor-NIHSS (p = 0.004), motor-Fugl-Meyer scores (p = 0.028), and task-related fMRI activity in MI-4a (p = 0.031) and MI-4p (p = 0.002). Intravenous autologous MSC treatment following stroke was safe and feasible. Motor performance and task-related MI activity results suggest that MSCs improve motor recovery through sensorimotor neuroplasticity. ClinicalTrials.gov Identifier NCT00875654.

Spatiotemporal patterns of sensorimotor fMRI activity influence hand motor recovery in subacute stroke: A longitudinal task-related fMRI study

Motor hand deficits impact autonomy in everyday life, and neuroplasticity processes of motor recovery can be explored using functional MRI (fMRI). However, few studies have used fMRI to explore the mechanisms underlying hand recovery following stroke. Based on the dual visuomotor model positing that two segregated dorsomedial and dorsolateral cerebral networks control reach and grasp movements, we explored the relationship between motor task-related activity in the sensorimotor network and hand recovery following stroke.Behavioral recovery was explored with a handgrip force task assessing simple grasp, and a visuomotor reaching and precise grasping task, the Purdue Pegboard Test (PPT). We used a passive wrist flexion-extension task to measure fMRI activity in 36 sensorimotor brain areas. Behavioral and fMRI measurements were performed in 27 patients (53.2 ± 9.5 years) 1-month following stroke, and then 6-month and 24-month later. The effects of sensorimotor activity on hand recovery were analyzed using correlations and linear mixed models (LMMs).PPT and handgrip force correlated with fMRI activity measures in the sensorimotor and parietal areas. PPT recovery was modeled by fMRI measures in the ipsilesional primary motor cortex (MI-4p), superior parietal lobule (SPL-7M) and parietal operculum OP1, and lesion side. Handgrip force was modeled by ipsilesional MI-4a, OP1, and contralesional inferior parietal lobule (IPL-PFt). Moreover, the relationship between fMRI activity and hand recovery was time-dependent, occurring in the early recovery period in SPL-BA-7M, and later in MI.These results suggest that areas of both dorsolateral and dorsomedial networks participate to visuomotor reach and grasp tasks (PPT), while dorsolateral network areas may control recovery of simple grasp (handgrip force), suggesting that the type of movement modulates network recruitment. We also found functional dissociations between MI-4p related to PPT that required independent finger movements and MI-4a related to simple grasp without independent finger movements. These findings need to be replicated in further studies.

Functional outcome of joint mobilization added to task-oriented training on hand function in chronic stroke patients

BackgroundApproximately half of stroke patients show impaired upper limb and hand function. Task-oriented training focuses on functional tasks, while joint mobilization technique aims to restore the accessory movements of the joints.ObjectiveTo investigate the effect of adding joint mobilization to task-oriented training to help the patients in reaching a satisfactory level of recovery for their hand function.Patients and methodsThirty chronic stroke patients with paretic hand participated in the study; they were divided equally into study and control groups. The study group received joint mobilization followed by task-oriented training for the affected hand. Meanwhile, the control group received task-oriented training only. Both groups received their treatment in the form of 3 sessions per week for 6 successive weeks. The primary outcome measures were hand function that was assessed by Jebsen-Taylor hand function test (JTT) and active and passive wrist extension range of motion (ROM) that was measured by a standard goniometer. The secondary outcome measure was the grip strength of the hand that was assessed by a JAMAR adjustable hand dynamometer.ResultsThere was a significant improvement in all the outcome measurements in both groups that were more evident in the study group.ConclusionCombining joint mobilization with task-oriented training had a highly significant effect in improving the hand function in chronic stroke patients compared to task-oriented training alone.

Effect of Neck Botulinum Neurotoxin Injection on Proprioception and Somatosensory-Motor Cortical Processing in Cervical Dystonia

Background. Cervical dystonia (CD) is a neurological movement disorder characterized by involuntary contractions of the cervical musculature and is known to be associated with proprioceptive dysfunction in dystonic/nondystonic limbs. Objectives. We examined how neck botulinum neurotoxin (BoNT) injection affects wrist proprioception and the corresponding sensorimotor cortical activity in CD. Method. Wrist position sense acuity of the dominant (right) hand was evaluated in 15 CD and 15 control participants. Acuity measures were a psychophysical position sense discrimination threshold (DT; based on passive joint displacement) and joint position matching error (based on active movement). Cortical activity during the motor preparation period of the active joint position matching was examined using electroencephalography. Results. In their symptomatic state, patients demonstrated a significantly higher wrist proprioceptive DT, indicating an abnormal passive wrist position sense. Yet BoNT injections had no significant effect on this threshold. During active joint position matching, errors were significantly larger in patients, but this difference vanished after the administration of BoNT. Motor preparation of active wrist position matching was associated with a significantly higher rise of β-band (13-30 Hz) power over contralateral somatosensory-motor cortical areas in patients. This excessive cortical activity significantly declined post-BoNT. Conclusion. Wrist proprioceptive perception during passive/active movements is abnormal in CD. An excessive rise of premotor/motor cortical β-oscillations during motor planning is associated with this proprioceptive dysfunction. Neck BoNT injections normalized the cortical processing of proprioceptive information from nonsymptomatic limbs, indicating that local injections may affect the central mechanisms of proprioceptive function in CD.

IHandU: A Novel Quantitative Wrist Rigidity Evaluation Device for Deep Brain Stimulation Surgery.

Deep brain stimulation (DBS) surgery is the gold standard therapeutic intervention in Parkinson’s disease (PD) with motor complications, notwithstanding drug therapy. In the intraoperative evaluation of DBS’s efficacy, neurologists impose a passive wrist flexion movement and qualitatively describe the perceived decrease in rigidity under different stimulation parameters and electrode positions. To tackle this subjectivity, we designed a wearable device to quantitatively evaluate the wrist rigidity changes during the neurosurgery procedure, supporting physicians in decision-making when setting the stimulation parameters and reducing surgery time. This system comprises a gyroscope sensor embedded in a textile band for patient’s hand, communicating to a smartphone via Bluetooth and has been evaluated on three datasets, showing an average accuracy of 80%. In this work, we present a system that has seen four iterations since 2015, improving on accuracy, usability and reliability. We aim to review the work done so far, outlining the iHandU system evolution, as well as the main challenges, lessons learned, and future steps to improve it. We also introduce the last version (iHandU 4.0), currently used in DBS surgeries at São João Hospital in Portugal.

Controlling for lesions, kinematics and physiological noise: impact on fMRI results of spastic post-stroke patients

Functional magnetic resonance imaging (fMRI) is a widely used technique for assessing brain function in both healthy and pathological populations. Some factors, such as motion, physiological noise and lesion presence, can contribute to signal change and confound the fMRI data, but fMRI data processing techniques have been developed to correct for these confounding effects. Fifteen spastic subacute stroke patients underwent fMRI while performing a highly controlled task (i.e. passive extension of their affected and unaffected wrists). We investigated the impact on activation maps of lesion masking during preprocessing and first- and second-level analyses, and of adding wrist extension amplitudes and physiological data as regressors using the Statistical Parametric Mapping toolbox (SPM12).We observed a significant decrease in sensorimotor region activation after the addition of lesion masks and movement/physiological regressors during the processing of stroke patients’ fMRI data. Our results demonstrate that:•The unified segmentation routine results in good normalization accuracy when dealing with stroke lesions regardless of their size;•Adding a group lesion mask during the second-level analysis seems to be a suitable option when none of the patients have lesions in target regions. Otherwise, no masking is acceptable;•Movement amplitude is a significant contributor to the sensorimotor activation observed during passive wrist extension in spastic stroke patients;•Movement features and physiological noise are relevant factors when interpreting for sensorimotor activation in studies of the motor system in patients with brain lesions. They can be added as nuisance covariates during large patient groups’ analyses.

Vascularized Bone Graft to the Lunate Combined with Shortening of the Capitate and Radius for Treatment of Advanced Kienböck Disease After a Follow-Up for More Than 10 Years

PurposeThis study aimed to report the outcomes of patients with stage III Kienböck disease after treatment with a vascularized bone graft (VBG) to the lunate combined with capitate shortening osteotomy (CS) after a more than 10-year follow-up.MethodsA VBG to the lunate was combined with CS in 10 patients with stage III Kienböck disease (6 patients with stage IIIA and 4 with stage IIIB). We performed VBG, CS, and radial shortening osteotomy (RS) on 7 patients. Among them, 4 had undergone RS previously. The passive wrist extension angle and wrist flexion angle, grip strength (GS), carpal height ratio, Stahl index, visual analog scale of wrist pain, and Mayo modified wrist score were assessed before surgery and at the final follow-up.ResultsThe flexion angle decreased markedly after surgery, when GS increased in all 10 patients. Radiographic examinations revealed that the carpal height ratio decreased in 9 of 10 patients, whereas the Stahl index increased in 8 patients and remained unchanged in 2. The oldest 3 of 7 patients who underwent VBG, CS, and RS exhibited fusion of the proximal carpals except the pisiform. The mean visual analog scale decreased from 27.6 before surgery to 5.7 afterward. The Mayo modified wrist score improved in 9 patients after surgery and remained unchanged in one.ConclusionsIn stage III Kienböck disease, VBG to the lunate combined with CS relieved wrist pain and increased GS and lunate height but was followed by severely restricted wrist motion. Fusion of the proximal carpals developed in 3 of 7 patients who received VBG with CS and RS.Type of study/level of evidenceTherapeutic Ⅳ.

Upper-extremity Spasticity-reducing Treatment in Adjunct to Movement Training and Orthoses in Children with Cerebral Palsy at Gross Motor Function- and Manual Ability Classification System Levels IV-V: A Descriptive Study

ABSTRACT Covering a 20-year period of work with children with severe cerebral palsy (CP) within a Swedish habilitation service, changes in passive wrist extension with fingers extended (PWE-FE) and current hand function are described and compared between children receiving systematic upper-extremity treatment with botulinum neurotoxin type A and intervention programs from before 7 years of age (Group 1, n = 7), those whom for various reasons did not undergo this treatment (Group 2, n = 10), and those not having the option to receive treatment until later during childhood/adolescence (Group 3, n = 8). Group 3 showed more critical and less normal PWE-FE values for both wrists, and poorer hand function scores, particularly compared with Group 1. Findings cautiously suggest that repeated upper-extremity spasticity-reducing treatment and movement training/orthoses from an early age may help prevent critical loss of passive range of motion of the wrist joint flexion/extension and promote hand function development in children with severe CP.

Alterations of Elastic Property of Spastic Muscle With Its Joint Resistance Evaluated From Shear Wave Elastography and Biomechanical Model.

This study aims to quantify passive muscle stiffness of spastic wrist flexors in stroke survivors using shear wave elastography (SWE) and to correlate with neural and non-neural contributors estimated from a biomechanical model to hyper-resistance measured during passive wrist extension. Fifteen hemiplegic individuals after stroke with Modified Ashworth Scale (MAS) score larger than one were recruited. SWE were used to measure Young's modulus of flexor carpi radialis muscle with joint from 0° (at rest) to 50° flexion (passive stretch condition), with 10° interval. The neural (NC) and non-neural components i.e., elasticity component (EC) and viscosity component (VC) of the wrist joint were analyzed from a motorized mechanical device NeuroFlexor® (NF). Combining with a validated biomechanical model, the neural reflex and muscle stiffness contribution to the increased resistance can be estimated. MAS and Fugl-Meyer upper limb score were also measured to evaluate the spasticity and motor function of paretic upper limb. Young's modulus was significantly higher in the paretic side of flexor carpi radialis than that of the non-paretic side (p < 0.001) and it increased significantly from 0° to 50° of the paretic side (p < 0.001). NC, EC, and VC on the paretic side were higher than the non-paretic side (p < 0.05). There was moderate significant positive correlation between the Young's Modulus and EC (r = 0.565, p = 0.028) and VC (r = 0.645, p = 0.009) of the paretic forearm flexor muscle. Fugl-Meyer of the paretic forearm flexor has a moderate significant negative correlation with NC (r = −0.578, p = 0.024). No significant correlation between MAS and shear elastic modulus or NF components was observed. This study demonstrated the feasibility of combining SWE and NF as a non-invasive approach to assess spasticity of paretic muscle and joint in stroke clinics. The neural and non-neural components analysis as well as correlation findings of muscle stiffness of SWE might provide understanding of mechanism behind the neuromuscular alterations in stroke survivors and facilitate the design of suitable intervention for them.

Development and Evaluation of a Novel Passive Wrist Bilateral Rehabilitation Device paired with Virtual Reality: A Feasibility Study.

This paper introduces a novel passive wrist bilateral rehabilitation device coupled with a new Virtual Reality (VR) platform. This is the first work to have adapted three-link coaxial spherical parallel manipulator (SPM) to wrist rehabilitation. The device comprises a coaxial SPM and cross-connected cable system. The coaxial SPM facilitates 3 degrees of freedom (DOFs) spherical wrist orientation and singularity-free motion within its workspace. The cross-connected cable system enables bilateral symmetrical exercises in passive mode training. A VR platform with activities of daily living (ADL) task was developed and coupled with the device to increase the adherence of the users to the device. Experiments were conducted with fifteen healthy right-handed individuals with no history of wrist or hand injury to evaluate the feasibility of the system for providing passive bilateral training as well as the effectiveness of the VR platform. Subjects were asked to use their right arms to move the left arms passively through the device to perform four wrist movements, flexion, extension, radial deviation, and ulnar deviation. EMG activations on the left arm were observed when the right arm passively moved the left arm. The results showed that the device was capable of inducing the muscle activation of the left arm and the VR platform increased the motivation to continue the exercises. This demonstrates that this study can serve as the fundamental for larger clinical trials.

A Prospective Evaluation of the Anatomy of the First Dorsal Compartment in Patients Requiring Surgery for De Quervain's Tenosynovitis.

Background We prospectively evaluated the surgical anatomy during first dorsal compartment release for De Quervain's tenosynovitis, with special attention to the superficial branch of the radial nerve (SBRN). Additionally, the incidence of tendon instability during surgery was assessed. Methods This prospective cohort study consisted of 130 De Quervain's patients undergoing first dorsal compartment release. The treating surgeons recorded the type of incision used, the number of abductor pollicis longus (APL) and extensor pollicis brevis (EPB) tendon slips, the number of SBRN branches encountered, additional subcompartments created by any septations, and active/passive tendon stability. Results A singular first dorsal compartment was found in 37% of cases, whereas 55% of patients had two subcompartments and 8% had three. Multiple APL tendon slips (range: 1-4) were identified in 78% of patients. In contrast, a single EPB tendon was found in 92% of patients (range: 0-2). At least one SBRN was encountered in 61% of cases. Following surgery, instability was evident in 9% of patients, who had tendons perch with passive wrist flexion. In one of these patients (<1%), the tendons dislocated volarly out of the first dorsal compartment during active flexion. Conclusions The anatomical findings in our relatively large, prospective study of De Quervain's patients undergoing first dorsal compartment release are consistent with previous smaller and/or retrospective studies. Overall, we expect to encounter the SBRN during first dorsal compartment release in more than 50% of patients but are unconcerned if it is not visualized during a careful approach. Tendon instability has an incidence of 9%; however, dislocation is rare (<1%).

The Impact of Aging and Hand Dominance on the Passive Wrist Stiffness of Squash Players: Pilot Study

Background: Passive joint stiffness can influence the risk of injury and the ability to participate in sports and activities of daily living. However, little is known about how passive joint stiffness changes over time with intensive repetitive exercise, particularly when performing unilateral activities using the dominant upper limb.

Validity and reliability of a smartphone inclinometer app for measuring passive upper limb range of motion in a stroke population*

Purpose: To demonstrate the validity and reliability of a smartphone app to measure ROM after stroke.Materials and methods: Twenty-one stroke survivors with a diagnosis of stroke that affected the motor cortex or subcortical motor pathways and were hospital inpatients at one of two metropolitan hospitals were recruited. A within-session test-retest design was used to compare ROM measurements taken using the GetMyROM app for iPhone to those taken by a digital inclinometer. Torque-controlled passive elbow and wrist extension were collected and statistical analysis of concurrent validity and test-retest reliability performed.Results: GetMyROM app was valid when compared to the digital inclinometer for measuring passive ROM of the elbow (r = .98, p = .0001, ICC = 0.97) and wrist (r = .97, p = .0001, ICC = 0.96) in individuals with acute stroke. Both the GetMyROM app and inclinometer demonstrated excellent test-retest reliability: ICC values are 0.84 to 0.93, and standard error of measurement between 6° to 10°.Conclusion: The GetMyROM app may be implemented in a clinical setting similar to that where the study was conducted, enabling rehabilitation physicians and therapists to use a smartphone to take precise measurements of ROM in daily clinical practice.Implications for rehabilitationApproximately half of all stroke survivors experience reduced passive upper limb range of movement.Accurate measurement of passive upper limb range of movement using validated assessments and/or instruments is paramount.This study demonstrates that the GetMyROM app is valid and reliable compared to the gold standard comparison (digital inclinometer), and is therefore appropriate to use in clinical settings to take precise measurements.

Design of a robot-assisted exoskeleton for passive wrist and forearm rehabilitation

Abstract. This paper presents a new exoskeleton design for wrist and forearm rehabilitation. The contribution of this study is to offer a methodology which shows how to adapt a serial manipulator that reduces the number of actuators used on exoskeleton design for the rehabilitation. The system offered is a combination of end-effector- and exoskeleton-based devices. The passive exoskeleton is attached to the end effector of the manipulator, which provides motion for the purpose of rehabilitation process. The Denso VP 6-Axis Articulated Robot is used to control motion of the exoskeleton during the rehabilitation process. The exoskeleton is designed to be used for both wrist and forearm motions. The desired moving capabilities of the exoskeleton are flexion–extension (FE) and adduction–abduction (AA) motions for the wrist and pronation–supination (PS) motion for the forearm. The anatomical structure of a human limb is taken as a constraint during the design. The joints on the exoskeleton can be locked or unlocked manually in order to restrict or enable the movements. The parts of the exoskeleton include mechanical stoppers to prevent the excessive motion. One passive degree of freedom (DOF) is added in order to prevent misalignment problems between the axes of FE and AA motions. Kinematic feedback of the experiments is performed by using a wireless motion tracker assembled on the exoskeleton. The results proved that motion transmission from robot to exoskeleton is satisfactorily achieved. Instead of different exoskeletons in which each axis is driven and controlled separately, one serial robot with adaptable passive exoskeletons is adequate to facilitate rehabilitation exercises.

Model-Based Analysis of the Stiffness of the Wrist Joint in Active and Passive Conditions

The control of joint stiffness is a fundamental mechanism used to control human movements. While many studies have observed how stiffness is modulated for tasks involving shoulder and elbow motion, a limited amount of knowledge is available for wrist movements, though the wrist plays a crucial role in manipulation. We have developed a computational framework based on a realistic musculoskeletal model, which allows one to calculate the passive and active components of the wrist joint stiffness. We first used the framework to validate the musculoskeletal model against experimental measurements of the wrist joint stiffness, and then to study the contribution of different muscle groups to the passive joint stiffness. We finally used the framework to study the effect of muscle cocontraction on the active joint stiffness. The results show that thumb and finger muscles play a crucial role in determining the passive wrist joint stiffness: in the neutral posture, the direction of maximum stiffness aligns with the experimental measurements, and the magnitude increases by 113% when they are included. Moreover, the analysis of the controllability of joint stiffness showed that muscle cocontraction positively correlates with the stiffness magnitude and negatively correlates with the variability of the stiffness orientation (p < 0.01 in both cases). Finally, an exhaustive search showed that with appropriate selection of a muscle activation strategy, the joint stiffness orientation can be arbitrarily modulated. This observation suggests the absence of biomechanical constraints on the controllability of the orientation of the wrist joint stiffness.

State of the Art in Artificial Wrists: A Review of Prosthetic and Robotic Wrist Design

The human wrist contributes greatly to the mobility of the arm/hand system, empowering dexterity and manipulation capabilities. However, both robotic and prosthetic research communities tend to favor the study and development of end-effectors/terminal devices (hands, grippers, etc.) over wrists. Wrists can improve manipulation capabilities, as they can orient the end-effector of a system without imparting significant translational motion. In this paper, we review the current state of the art of wrist devices, ranging from passive wrist prostheses to actuated robotic wrist devices. We focus on the mechanical design and kinematic arrangements of said devices and provide specifications when available.

Peg-in-hole operation robust to position error by peg rotation using passive wrist joint

Peg-in-hole operation robust to position error by peg rotation using passive wrist joint