Movable surface models of hand joints using visible korean / Modelos de superficies móviles de articulaciones de manos utilizando visible Korean

SUMMARY: The human hand can make precise movements utilizing several joints of various articular types. To understand hand movements more accurately, it is essential to view the actual movements of bones and muscles considering the X, Y, and Z axes in the joints. This study aimed to investigate the joint movements in a hand using movable surface models, including these axes. These movable surface models of the hand will improve medical students' understanding of hand movements around the joints. To achieve this aim, 70 surface models were adopted from a Visible Korean model. Using Maya software, 20 virtual joints with X, Y, and Z axes included nine distal and proximal interphalangeal joints, five metacarpophalangeal joints, five carpometacarpal joints, and one wrist joint were created. Bone surface models were elaborately polished to maintain their original shape during movement. Muscle surface models were also processed to display the deformation of the muscle shape during movement. The surface models of the hand joints were moved by virtual control of the joints. We saved 87 movable surface models of the hand, including bones, muscles, and joint axes in stereolithography format, and compiled a Portable Document Format (PDF) file. Using the PDF file, the joint movements in a hand could be observed considering the X, Y, and Z axes alongside the stereoscopic shapes of the bones and muscles. These movable surface models of the hand will improve medical students' understanding of hand movements around the joints.

RESUMEN: La mano humana puede realizar movimientos precisos utilizando varias articulaciones de diferentes tipos articulares. Para comprender los movimientos de las manos con mayor precisión, es esencial ver los movimientos reales de los huesos y los músculos considerando los ejes X, Y y Z de las articulaciones. Este estudio tuvo como objetivo investigar los movimientos articulares en una mano utilizando modelos de superficies móviles, incluidos estos ejes. Estos modelos de superficie móvil de la mano mejorarán la comprensión de los estudiantes de medicina de los movimientos de la mano alrededor de las articulaciones. Para lograr este objetivo, se adoptaron 70 modelos de superficie de un modelo coreano visible. Con el software Maya, se crearon 20 articulaciones virtuales con ejes X, Y y Z que incluyeron nueve articulaciones interfalángicas distales y proximales, cinco articulaciones metacarpofalángicas, cinco articulaciones carpometacarpianas y una articulación de muñeca. Los modelos de superficie ósea se pulieron minuciosamente para mantener su forma original durante el movimiento. También se procesaron modelos de superficie muscular para mostrar la deformación de la forma del músculo durante el movimiento. Los modelos de superficie de las articulaciones de las manos se movieron mediante el control virtual de las articulaciones. Guardamos 87 modelos de superficies móviles de la mano, incluidos huesos, músculos y ejes articulares en formato de estereolitografía, y compilamos un archivo en formato de documento portátil (PDF). Usando el archivo PDF, los movimientos de las articulaciones en una mano se pueden observar considerando los ejes X, Y y Z junto con las formas estereoscópicas de los huesos y músculos. Estos modelos de superficie móvil de la mano mejorarán la comprensión de los estudiantes de medicina sobre los movimientos de la mano alrededor de las articulaciones.

Integrated linkage-driven dexterous anthropomorphic robotic hand.

Robotic hands perform several amazing functions similar to the human hands, thereby offering high flexibility in terms of the tasks performed. However, developing integrated hands without additional actuation parts while maintaining important functions such as human-level dexterity and grasping force is challenging. The actuation parts make it difficult to integrate these hands into existing robotic arms, thus limiting their applicability. Based on a linkage-driven mechanism, an integrated linkage-driven dexterous anthropomorphic robotic hand called ILDA hand, which integrates all the components required for actuation and sensing and possesses high dexterity, is developed. It has the following features: 15-degree-of-freedom (20 joints), a fingertip force of 34N, compact size (maximum length: 218 mm) without additional parts, low weight of 1.1 kg, and tactile sensing capabilities. Actual manipulation tasks involving tools used in everyday life are performed with the hand mounted on a commercial robot arm.

Gaze facilitates responsivity during hand coordinated joint attention.

The coordination of attention between individuals is a fundamental part of everyday human social interaction. Previous work has focused on the role of gaze information for guiding responses during joint attention episodes. However, in many contexts, hand gestures such as pointing provide another valuable source of information about the locus of attention. The current study developed a novel virtual reality paradigm to investigate the extent to which initiator gaze information is used by responders to guide joint attention responses in the presence of more visually salient and spatially precise pointing gestures. Dyads were instructed to use pointing gestures to complete a cooperative joint attention task in a virtual environment. Eye and hand tracking enabled real-time interaction and provided objective measures of gaze and pointing behaviours. Initiators displayed gaze behaviours that were spatially congruent with the subsequent pointing gestures. Responders overtly attended to the initiator's gaze during the joint attention episode. However, both these initiator and responder behaviours were highly variable across individuals. Critically, when responders did overtly attend to their partner's face, their saccadic reaction times were faster when the initiator's gaze was also congruent with the pointing gesture, and thus predictive of the joint attention location. These results indicate that humans attend to and process gaze information to facilitate joint attention responsivity, even in contexts where gaze information is implicit to the task and joint attention is explicitly cued by more spatially precise and visually salient pointing gestures.

Reliability of quantitative ultrasound measurement of flexor digitorum superficialis and profundus muscles in stroke.

Aim: This study aims to investigate reliability of quantitative ultrasound measurement of the flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP) muscles in stroke. Materials & methods: Patients with a history of stroke were recruited. FDP and FDS muscles on both upper extremities were investigated with ultrasound. Two independent assessors acquired images and analyzed them using a program and Heckmatt scale. Results: Forty-eight patients were included. The inter-rater intraclass correlation coefficient for echo intensities was calculated as 0.91 while intrarater intraclass correlation coefficient as 0.80. For Heckmatt scale, the inter-rater reliability for FDS was Kw = 0.74 (p < 0.0005) and for FDP it was Kw = 0.73 (p < 0.0005). Mean echo intensity values showed significant strong correlations with Heckmatt scores (r = 0.663 and r = 0.633 with both p values <0.001). Conclusion: Quantitative ultrasound imaging of FDS and FDP is a reliable method to demonstrate echo intensity changes of muscles in stroke.

Jerk Decomposition during Bimanual Independent Arm Cranking.

The relationship between the smoothness of the upper limb endpoint movement and multi joint angular motion is a function of the individual joint angular velocities, accelerations, and jerks as well as the instantaneous arm configuration and its rate of change during movement execution. We compared the contribution of jerk components to the total endpoint jerk in able bodied participants who performed arm cranking movements on an arm cranking device where the two arms could crank independently. The results of this investigation suggest that the most dominant components of the end effector jerk are related to both the angular jerks and to the change of arm configuration pose. This jerk partitioning is much stronger as it was found previously for both reaching arm movements and single hand cranking. This shows the task specificity of the decomposition of endpoint jerk and the effect that bi-manual tasks can have on the smoothness of movements. The proposed decomposition may give useful information in why certain bi-manual rehabilitation processes are more useful than others.

In Vivo Measurement of Thumb Joint Reaction Forces During Smartphone Manipulation: A Biomechanical Analysis.

The relationship between arthritis or repetitive stress injuries (RSIs) in thumbs and rapidly increasing hours of smartphone usage is not fully elucidated. We evaluated axial joint reaction forces (AJRFs) and thumb torques in 19 healthy subjects performing typical smartphone tasks, which included tapping, tap game, and swiping. We measured force and torque when a subject tapped or swiped the panel of the smartphone and analyzed the motions of each joint using surface markers and motion capture systems. We calculated AJRFs and torques on each thumb joint using inverse dynamics. The results were then compared with representative activities such as computer keyboard typing and handwriting. The mean AJRFs/torques at the thumb carpometacarpal joint (CMCJ) while tapping the smartphone and tap gaming were 12.5 N/95.5 N mm and 21.1 N/187.21 N mm, respectively. AJRFs and torques were significantly higher during tap gaming activities than during simple tapping subtasks (p = 0.003 and p < 0.001, respectively). Compared with those during computer keyboard typing, the mean AJRFs and torques at the CMCJ during smartphone tapping was 3 (p = 0.075) and 1.4 times (p = 0.680) larger, respectively. Considering the rapidly increasing dependency on smartphones in our daily lives, long-term exposure of the thumb to repetitive AJRFs and torques may lead to an acceleration of arthritis or aggravation of RSIs in thumbs. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2437-2444, 2019.

Role of Active Range of Motion in Hand and Wrist Joint Photography: A Preliminary Analysis.

INTRODUCTION: Hand photography is effective and advantageous for assessing functional deficits and improvements related to surgery. In this study, it is aimed to investigate whether the correct active range of motion (ROM) is masked by the passive ROM in a wrist joint. METHOD: Eleven patients who were treated for unilateral wrist fractures were included in the study. Photography was performed in all patients by the same surgeon according to the conventional hand surgery photography approach and the active ROM photography approach. Differences between the noninjured side and injured side were assessed. RESULTS: No differences were found between the active ROM and passive ROM during the extension and flexion movements in the noninjured side group. However, in the injured side group, the results from the photographs obtained with the conventional method were significantly better than the results from the photographs obtained when the wrist was actively moved. CONCLUSION: These findings suggest that photographs of wrists during passive motion may affect the results of a treatment or study by showing false positivity. We propose obtaining images of active ROM instead of passive ROM in hand photography.

Hand Gesture Recognition and Finger Angle Estimation via Wrist-Worn Modified Barometric Pressure Sensing.

This paper presents a new approach to wearable hand gesture recognition and finger angle estimation based on the modified barometric pressure sensing. Barometric pressure sensors were encased and injected with VytaFlex rubber such that the rubber directly contacted the sensing element allowing pressure change detection when the encasing rubber was pressed. A wearable prototype consisting of an array of ten modified barometric pressure sensors around the wrist was developed and validated with experimental testing for three different hand gesture sets and finger flexion/extension trials for each of the five fingers. The overall hand gesture recognition classification accuracy was 94%. Further analysis revealed that the most important sensor location was the underside of the wrist and that when reducing the sensor number to only five optimally placed sensors, classification accuracy was still 90%. For continuous finger angle estimation, aggregate R2 values between actual and predicted angles were thumb: 0.81 ± 0.10, index finger: 0.85±0.06, middle finger: 0.77±0.08, ring finger: 0.77 ± 0.12, and pinkie finger: 0.75 ± 0.10, and the overall average was 0.79 ± 0.05. These results demonstrate that a modified barometric pressure wristband can be used to classify hand gestures and to estimate individual finger joint angles. This approach could serve to improve the clinical treatment for upper extremity deficiencies, such as for stroke rehabilitation, by providing objective patient motor control metrics to inform and aid physicians and therapists throughout the rehabilitation process.

Improved Hand Function, Self-Rated Health, and Decreased Activity Limitations: Results After a Two-Month Hand Osteoarthritis Group Intervention.

OBJECTIVE: To evaluate the effects on hand function, activity limitations, and self-rated health of a primary care hand osteoarthritis (OA) group intervention. Hand OA causes pain, impaired mobility, and reduced grip force, which cause activity limitations. OA group interventions in primary care settings are sparsely reported. METHODS: Sixty-four individuals with hand OA agreed to participate; 15 were excluded due to not fulfilling the inclusion criteria. The 49 remaining (90% female) participated in an OA group intervention at a primary care unit with education, paraffin wax bath, and hand exercise over a 6-week period. Data were collected at baseline, end of intervention, and after 1 year. Instruments used were the Grip Ability Test (GAT), the Signals of Functional Impairment (SOFI), dynamometry (grip force), hand pain at rest using a visual analog scale (VAS), the Patient-Specific Functional Scale (PSFS), the Quick Disabilities of the Arm, Shoulder, and Hand (Quick-DASH), and the EuroQol VAS (EQ VAS). Data were analyzed using nonparametric statistics. RESULTS: Hand function, activity limitation, and self-rated health significantly improved from baseline to end of intervention, grip force (right hand: P < 0.001; left hand: P = 0.008), SOFI (P = 0.011), GAT (P < 0.001), hand pain at rest (P < 0.001), PSFS (1: P = 0.008, 2: P < 0.001, and 3: P = 0.004), Quick-DASH (P = 0.001), and EQ VAS (P = 0.039), and the effects were sustained after 1 year. CONCLUSION: The hand OA group intervention in primary care improves hand function, activity limitation, and self-rated health. The benefits are sustained 1 year after completion of the intervention.

Viability of Hand and Wrist Photogoniometry.

BACKGROUND: No goniometric technique is both maximally convenient and completely accurate, although photogoniometry (ie, picture taking to facilitate digital angle measurement) shows promise in this regard. Our purpose was to test the feasibility and reliability of a photogoniometric protocol designed to measure wrist and digit range of motion in general. METHODS: Two independent observers examined a sample of joints in both normal and abnormal hands according to a photogoniometric protocol. Interrater and intrarater correlation were calculated, and these measurements were compared with measurements made by a third independent examiner with a manual goniometer. RESULTS: The photo-based measurements were reliable within and between observers; however, only a minority of these measurements were in agreement with manually collected values. CONCLUSIONS: At present, photogoniometry is not an acceptable alternative to manual goniometry for determining wrist and digit range of motion in general. Joint-specific photogoniometry should be the subject of future study, as should relevant imaging and software technology.

Flash-lag effects in biological motion interact with body orientation and action familiarity.

The ability to localize moving joints of a person in action is crucial for interacting with other people in the environment. However, it remains unclear how the visual system encodes the position of joints in a moving body. We used a paradigm based on a well-known phenomenon, the flash-lag effect, to investigate the mechanisms underlying joint localization in bodily movements. We first found that observers perceived a strong flash-lag effect in biological motion: when a briefly-flashed dot was presented physically in perfect alignment with a continuously moving limb, the flash dot was perceived to lag behind the position of the moving joint. Importantly, our study revealed that for familiar forward walking actions, the strength of the flash-lag effect for a joint depends on body orientation. Specifically, observing a walker with a natural body orientation (i.e., upright) yielded a significantly stronger flash-lag effect for the critical foot joint than did viewing an inverted walker. In contrast, the hand joint showed a weaker flash-lag effect in the upright walker than the inverted walker. These findings suggest that the impact of body orientation on encoding joint locations depended on body part. Furthermore, we found that action familiarity modulates the impact of body orientation on the flash-lag effect. Body orientation impacted location encoding in familiar forward walking actions, but not in unfamiliar actions (e.g., backward walking, jumping-jack). Simulation results showed that generic motion mechanisms, such as the temporal averaging model, cannot fully account for these empirical findings regarding the flash-lag effect in biological motion. The present study provides compelling evidence that action processing interacts with position processing to localize the moving joints in whole-body actions, and that this influence depends on body orientation and familiarity of actions.

Estimation of distal arm joint angles from EMG and shoulder orientation for transhumeral prostheses.

In this paper, we quantify the extent to which shoulder orientation, upper-arm electromyography (EMG), and forearm EMG are predictors of distal arm joint angles during reaching in eight subjects without disability as well as three subjects with a unilateral transhumeral amputation and targeted reinnervation. Prior studies have shown that shoulder orientation and upper-arm EMG, taken separately, are predictors of both elbow flexion/extension and forearm pronation/supination. We show that, for eight subjects without disability, shoulder orientation and upper-arm EMG together are a significantly better predictor of both elbow flexion/extension during unilateral (R2=0.72) and mirrored bilateral (R2=0.72) reaches and of forearm pronation/supination during unilateral (R2=0.77) and mirrored bilateral (R2=0.70) reaches. We also show that adding forearm EMG further improves the prediction of forearm pronation/supination during unilateral (R2=0.82) and mirrored bilateral (R2=0.75) reaches. In principle, these results provide the basis for choosing inputs for control of transhumeral prostheses, both by subjects with targeted motor reinnervation (when forearm EMG is available) and by subjects without target motor reinnervation (when forearm EMG is not available). In particular, we confirm that shoulder orientation and upper-arm EMG together best predict elbow flexion/extension (R2=0.72) for three subjects with unilateral transhumeral amputations and targeted motor reinnervation. However, shoulder orientation alone best predicts forearm pronation/supination (R2=0.88) for these subjects, a contradictory result that merits further study.

In vivo kinematics of the thumb during flexion and adduction motion: Evidence for a screw-home mechanism.

The thumb plays a crucial role in basic hand function. However, the kinematics of its entire articular chain have not yet been quantified. Such investigation is essential to improve our understanding of thumb function and to develop better strategies to treat thumb joint pathologies. The primary objective of this study is to quantify the in vivo kinematics of the trapeziometacarpal (TMC) and scaphotrapezial (ST) joints during flexion and adduction of the thumb. In addition, we want to evaluate the potential coupling between the TMC and ST joints during these tasks. The hand of 16 asymptomatic women without signs of thumb osteoarthritis were CT scanned in positions of maximal thumb extension, flexion, abduction, and adduction. The CT images were segmented and three-dimensional surface models of the radius, scaphoid, trapezium, and the first metacarpal were created for each thumb motion. The corresponding rotations angles, translations, and helical axes were calculated for each sequence. The analysis shows that flexion and adduction of the thumb result in a three-dimensional rotation and translation of the entire articular chain, including the trapezium and scaphoid. A wider range of motion is observed for the first metacarpal, which displays a clear axial rotation. The coupling of axial rotation of the first metacarpal with flexion and abduction during thumb flexion supports the existence of a screw-home mechanism in the TMC joint. In addition, our results point to a potential motion coupling between the TMC and ST joints and underline the complexity of thumb kinematics. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1556-1564, 2017.

Evaluation of joint type modelling in the human hand.

This short communication presents preliminary results from an extensive investigation of joint modelling for the human hand. We use finger and hand movement data recorded from both hands of 110 subjects using passive reflective markers on the skin. Furthermore, we use data which was recorded from a single Thiel-fixated cadaver hand using also passive reflective markers but fixed to the bone. Our data clearly demonstrate that, for wrist and finger joints, hinge joint models are sufficiently accurate to describe their movement in Cartesian space.

Accuracy and Validity of Goniometer and Visual Assessments of Angular Joint Positions of the Hand and Wrist.

PURPOSE: To compare goniometric and visual assessments of angular hand joint and wrist joint positions measured by board-certified hand surgeons and certified hand therapists. We hypothesized that visual estimation would be similar to the goniometric measurement accuracy of digital and wrist joint positions. METHODS: The wrist, index finger metacarpophalangeal (MCP) joint, and index finger proximal interphalangeal (PIP) joint were evaluated in different positions by 40 observers: 20 board-certified hand surgeons and 20 certified hand therapists. Each observer estimated the position of the wrist, index MCP joint, and index PIP joint of the same volunteer, who was positioned in low-profile orthoses to reproduce predetermined positions. Following visual estimation, the participants measured the same joint positions using a goniometer. The control measurement was digitally determined by a radiologist who obtained radiographs of the hand and wrist positions in each orthosis. Observers were blinded to the results of control measurements. RESULTS: When considering all joints at all positions, neither visual assessments nor goniometer assessments were consistently within ± 5° of the measurements obtained on control radiographs. When considering individual joints, goniometer measurements were significantly closer to control radiograph measurements than the visual assessments for all 3 PIP joint positions. There was no difference for the measurements at the wrist or for 2 of the 3 MCP joint positions. Significant differences between surgeon and therapist joint angle measurements were not observed when comparing visual and goniometer assessments to radiograph controls. CONCLUSIONS: Compared with radiograph measurements, neither visual nor goniometer assessment displayed high levels of accuracy. On average, visual assessment of the angular positions of the index MCP and wrist joint were as accurate as the goniometer assessment, whereas goniometer assessment of the angular position of the PIP joint was more accurate than visual assessment. There was a relatively high degree of between-observer variability in measurements, and therefore, no one person's measurements could be consistently relied upon to be accurate. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic II.

Bilateral Asymmetry in Upper Extremities Is More Pronounced in Distal Compared to Proximal Joints.

The authors' aim was to compare spatial and temporal accuracy in proximal versus distal joints in upper extremities. Given the morphological differences in corticospinal and corticomotoneuronal projections for proximal and distal muscles, they hypothesized that bilateral asymmetry would be larger for distal than for proximal joints. Twelve participants performed isolated flexion-extension movements with the shoulders and index fingers. Angular range of motion of finger and shoulder movements was kept constant. The results showed significant bilateral asymmetry for both proximal and distal joints for both spatial and temporal accuracy. More importantly, bilateral asymmetry was significantly larger for the index fingers than for the shoulders for both spatial and temporal variables, as hypothesized. These results at the behavioral level pave the way for further studies that combine direct measures of neural activation with behavioral measures to further illuminate the potential link between bilateral communication and laterality effects in motor performance.

Early osteoarthritis of the trapeziometacarpal joint is not associated with joint instability during typical isometric loading.

The saddle-shaped trapeziometacarpal (TMC) joint contributes importantly to the function of the human thumb. A balance between mobility and stability is essential in this joint, which experiences high loads and is prone to osteoarthritis (OA). Since instability is considered a risk factor for TMC OA, we assessed TMC joint instability during the execution of three isometric functional tasks (key pinch, jar grasp, and jar twist) in 76 patients with early TMC OA and 44 asymptomatic controls. Computed tomography images were acquired while subjects held their hands relaxed and while they applied 80% of their maximum effort for each task. Six degree-of-freedom rigid body kinematics of the metacarpal with respect to the trapezium from the unloaded to the loaded task positions were computed in terms of a TMC joint coordinate system. Joint instability was expressed as a function of the metacarpal translation and the applied force. We found that the TMC joint was more unstable during a key pinch task than during a jar grasp or a jar twist task. Sex, age, and early OA did not have an effect on TMC joint instability, suggesting that instability during these three tasks is not a predisposing factor in TMC OA.

Effects of different extents of pulley release on tendon excursion efficiency and tendon moment arms.

To compare the excursion efficiency and moment arms of flexor digitorum superficialis (FDS) and profundus (FDP) among different conditions of pulley integrity related to trigger finger treatment, cadaveric fingers were first tested with an intact pulley system, and then the first (A1) and second (A2) annular pulleys were released gradually from the proximal to distal part. Linear position sensors and a motion capture system were used to measure the tendon excursion and joint rotation simultaneously. The tendon excursion efficiency was defined as the range of motion of the involved joints per unit of tendon excursion, and the tendon moment arm was determined by the slope of the linear fitting result of tendon excursion versus metacarpophalangeal (MCP) joint rotation. No significant differences were found between the release of the A1 pulley and the release extending to half the proximal part of the A2 pulley in the FDP excursion efficiency and the moment arms of FDS and FDP with respect to the MCP joint. These results imply that the release could extend to half the proximal A2 pulley, if necessary, without significantly decreasing the FDP excursion efficiency and increasing the moment arms of FDS and FDP with respect to the MCP joint.

Upper limb joint kinetics of three sitting pivot wheelchair transfer techniques in individuals with spinal cord injury.

STUDY DESIGN: Repeated measures design. OBJECTIVE: This study compared the upper extremity (UE) joint kinetics between three transfer techniques. SETTING: Research laboratory. METHODS: Twenty individuals with spinal cord injury performed three transfer techniques from their wheelchair to a level tub bench. Two of the techniques involved a head-hips method with leading hand position close (HH-I) and far (HH-A) from the body, and the third technique with the trunk upright (TU) and hand far from body. Motion analysis equipment recorded upper body movements and force sensors recorded their hand and feet reaction forces during the transfers. RESULTS: Several significant differences were found between HH-A and HH-I and TU and HH-I transfers indicating that hand placement was a key factor influencing the UE joint kinetics. Peak resultant hand, elbow, and shoulder joint forces were significantly higher for the HH-A and TU techniques at the trailing arm (P < 0.036) and lower at the leading arm (P < 0.021), compared to the HH-I technique. CONCLUSION: Always trailing with the same arm if using HH-A or TU could predispose that arm to overuse related pain and injuries. Technique training should focus on initial hand placement close to the body followed by the amount of trunk flexion needed to facilitate movement.

Joint angles and angular velocities and relevance of eigenvectors during prehension in the monkey.

Hand shaping during prehension involves intricate coordination of a complex system of bones, joints, and muscles. It is widely hypothesized that the motor system uses strategies to reduce the degrees of independent control. Both biomechanical constraints that result in coupling of the fingers and joints and neural synergies act to simplify the control problem. Synergies in hand shaping are typically defined using principal component-like analyses to define orthogonal patterns of movement. Although much less examined, joint angle velocities are also important parameters governing prehension. The primary goal of this study was to evaluate joint angles and joint angle velocities during prehension in monkeys. Fourteen joint angles and angular velocities were measured as monkeys reached to and grasped a set of objects designed to systematically vary hand shapes. Hand shaping patterns in joint angles and velocities were examined using singular value decomposition (SVD). Highly correlated patterns of movements were observed in both joint angles and joint angle velocities, but there was little correlation between the two, suggesting that velocities are controlled separately. Joint angles and velocities can be defined by a small number of eigenvectors by SVD. The unresolved question of the functional relevance of higher-order eigenvectors was also evaluated. Results support that higher-order components are not easily distinguished from noise and are likely not of physiological significance.