The three-dimensional analysis of three thumb joints coordination in activities of daily living

Kinematic Investigation of Healthy, Arthritic, and Postsurgery Thumbs: Is the Metacarpophalangeal Joint the Gateway to Carpometacarpal Arthritis?

The thumb carpometacarpal (CMC) joint is one of the most likely joints to develop osteoarthritis (OA). If conservative treatments fail to alleviate symptoms, surgery may be pursued. Kinematic outcomes of CMC surgery techniques have been described, but current tools have limitations in capturing motion abilities. The goals of this study were (1) develop a new and robust set of kinematic outcome measures, and apply them to (2) a cohort of younger and older control individuals without CMC OA to determine age and sex-related changes, and (3) a cohort of participants with CMC OA before, 3 months, and 6 months after undergoing thumb ligament reconstruction with tendon interposition surgery to detect the impacts of surgery. 52 (26 males, 26 females) control and 18 (3 males, 15 females) surgical participants were tested. Kinematics were investigated using motion capture by mapping the three-dimensional motion space of the whole thumb, and two-dimensional motion boundaries of the metacarpal (MC) and proximal phalange (PP). Visual analog pain score was recorded. Older control participants had shifted regions of motion compared to younger participants (p ≤ 0.027), suggesting asymptomatic CMC wear. Control females had 31% more metacarpophalangeal (MCP) motion than control males (p = 0.013), which could alter loading paths through the CMC joint and increase OA risk. Pain at 6 months postsurgery was 72% less than presurgery (p < 0.001), but motion abilities were 20-28% less than presurgery (p ≤ 0.074) and 24-40% less than control participants (p ≤ 0.066). These techniques have the possibility of identifying presymptomatic motion changes, including those at the metacarpophalangeal joint in CMC OA progression.

Association between three-dimensional motion analysis of the thumb and clinical parameters in patients with carpal tunnel syndrome

We analysed the relationship between motor dysfunction of the thumb and the clinical parameters of carpal tunnel syndrome using three-dimensional motion analysis. This single-centred, prospective study included 65 hands in 51 patients with idiopathic carpal tunnel syndrome and 30 healthy hands. Three-dimensional thumb kinematics were acquired using a motion capture system with a retroreflective surface-based marker method. The trajectory area of thumb tip, adduction and abduction of the trapeziometacarpal joints and metacarpophalangeal joints were correlated with the clinical parameters. There was no significant correlation between the results of motion analysis values and patient-reported outcomes measures. Thumb movement disorder associated with carpal tunnel syndrome affected specific activities of daily living based on the pinching movements, such as 'writing' and 'buttoning clothes' among the patient-reported outcome measure items.Level of evidence: III.

Rapid online correction of reach-to-manipulate movements in children with developmental coordination disorder: A pilot kinematic comparison study

BACKGROUND

Children with developmental coordination disorder show difficulties in making rapid online corrections, and this has been demonstrated in experiments where reaching/pointing movements were employed. However, typical hand movements in real-life contexts involve subsequent movements, such as grasping and manipulating objects after reaching. This study aimed to reinvestigate online correction of reaching movements that were connected with grasping and object manipulation and to explore its impact on the coordination of subsequent hand movements in children with developmental coordination disorder.

METHODS

Five children with developmental coordination disorder and five children with typical development were recruited. Their reach-to-manipulate movements in a double-step task were recorded using motion analysis. The manipulative movements included simple and complex forms of pencil rotation. Movement time, movement velocity, and correlation coefficients between finger joints were derived to quantify their motor performances.

FINDINGS

Children with developmental coordination disorder showed longer movement time and deceleration phases during online correction of reaching movement than children without developmental coordination disorder. In subsequent grasping and manipulation movements after online correction, they also exhibited lower correlation coefficients in four to five finger joint couplings that are essential for movement completion, compared to children without developmental coordination disorder.

INTERPRETATION

Our findings from the current pilot study suggest that children with developmental coordination disorder have impairments in online correction when reaching for objects and may also have reduced coordination of some finger movements that are important for subsequent grasping and object manipulation. Future studies with larger sample sizes are warranted to confirm these findings.

Measurement of the lumbrical muscle activity of the hand using electromyography supported by the ultrasound imaging technique with string navigation

Although placing surface electrodes on small muscles by palpation is difficult, ultrasound guidance may enable electrode placement on the small muscles. This study aimed to examine whether ultrasound guidance is helpful for placement of electrodes on a small muscle, such as the hand lumbrical muscle. Twelve dominant hands of 12 healthy right-handed adults were included in this study. The first lumbrical muscle belly of the hands was identified using ultrasound guidance with a string navigation technique for placing surface electrodes. This technique was designed to identify the location of the center of the muscle belly under ultrasound imaging using a string. After the electrodes were placed on the muscle belly using this technique, the surface electromyographic signals of the first lumbrical, first dorsal interosseous, and adductor pollicis muscles were recorded. The activity of the lumbrical muscle could be separately measured of the first dorsal interosseous and adductor pollicis muscles. This technique has the potential to enable surface electromyography of small muscles for which placement of surface electrodes by palpation is challenging.

Innovative Quantitative Assessment of Hand Function in Carpal Tunnel Syndrome

BACKGROUND

Carpal tunnel syndrome (CTS) compromises fine sensorimotor function during activities of daily living and affects a large number of individuals with high burden costs for society. The purpose of this study was to quantitatively characterize fine movement skills in CTS patients preoperatively and at 1 month postoperatively by means of a sensor-engineered glove, in order to provide new insights for evaluative and finally therapeutic purposes.

METHODS

Forty-one CTS patients and 41 age- and gender-matched healthy controls (HC) were analyzed by adopting the engineered glove Hand Test System (HTS), which previously demonstrated its reliability and sensitivity to detect hands dysfunction in several neurological diseases. A sub-group of 11 CTS subjects was re-tested 1 month after surgery. Three parameters-touch duration (TD), inter-tapping interval (ITI), and movement rate (MR)-were considered to characterize hand function.

RESULTS

The affected hand of CTS patients generally showed worst finger opposition performances than HC. Comparing the dominant hand, all parameters were able to significantly discriminate CTS patients from HC. Considering the nondominant hand, the best performing parameter in discriminating CTS from HC was TD. The follow-up assessment at 1 month after surgery showed that considered parameters were able to monitor patients' recovery. In particular, the TD parameter recorded at the 3 different assigned task modalities resulted significantly enhanced.

CONCLUSIONS

Results of this pilot study proved the validity of the parameters obtained through the sensor-engineered glove to assess objectively hand functional status and surgical outcomes in CTS.

The effect of rheumatoid arthritis on upper extremity functions: A kinematic perspective

AIM

To examine the global upper extremity kinematics in 3D while performing "jar opening motion" in Rheumatoid Arthritis (RA) and to compare these with healthy individuals.

METHOD

Twenty-four women (12 healthy, 12 RA) were included. Evaluations were made with a JAMAR dynamometer, Health Assessment Questionnaire, and 3D kinematic analysis of global upper extremity during "jar opening motion." The time taken during "jar opening motion" was analyzed in 2 parts (Part 1, Part 2), with total time: part 1 + part 2. In addition, shoulder-to-table distance; elbow flexion angle; wrist extension angle; the area scanned and angular rotation by arm, forearm and hand were used in the analysis.

RESULTS

Between groups, there was a statistical difference in: bilateral hand grip strength; part 1, part 2, total time; shoulder-to-table distance; elbow flexion angle; the area scanned by hand; angular rotation of arm and hand in favor of the healthy group (P < .05). In stepwise multiple regression analysis, the most predictive variable for disability was elbow flexion, explaining 53.9% of disability.

CONCLUSION

Compared to healthy individuals, individuals with RA have slower motion, more elbow flexion, less hand grip strength, circular pattern in hand, rotation in arm and hand. Increased disability may result in greater load on elbow flexion.

Functional Assessment of 3D-Printed Multifunction Assistive Hand Device for Chronic Stroke Patients

Patients with chronic stroke often have difficulty opening their hands and performing grasping movements. Several passive hand orthoses for assisting hand rehabilitation have been developed and demonstrated to be clinically effective. However, current devices have several limitations, such as supporting only a single grasping motion and using an abnormal grasping posture. Therefore, this study developed a three-dimensional (3D)-printed multifunctional hand device (3DP-MFHD) to solve these problems and evaluated the feasibility of using the device during home rehabilitation. Six participants were enrolled, and each of them was provided with the 3DP-MFHD. In addition to a task-oriented training course, the participants were asked to train at home for 4 weeks for at least 5 days per week and 40 min per day. The results revealed that hand grip force increased by 36.1%, lateral pinch force increased by 17.6%, and the Action Research Arm Test score increased by 54.1%. The 3DP-MFHD is a promising means to facilitate hand rehabilitation and improve hand strength and function in patients with chronic stroke. The 3DP-MFHD can be used as part of home rehabilitation.

Effect of the position of the interphalangeal joint on movements of the trapeziometacarpal joint during thumb opposition

The Kapandji test is a simple method to score thumb opposition; however, the position of the interphalangeal joint of the thumb during this test has not been described. We aimed to quantitatively examine the effect of the thumb interphalangeal joint position on movements of the trapeziometacarpal joint during thumb opposition using the Kapandji test. The Kapandji test was carried out in 20 healthy participants during thumb interphalangeal joint extension and flexion. Movements of the joints and the activity of thenar muscles were recorded using motion capture and electromyography, respectively. We found that interphalangeal joint extension increased the trapeziometacarpal joint movement and thenar muscle activity compared with interphalangeal joint flexion, which contributed to thumb opposition at Kapandji Positions 0-6. These findings suggest the position of the thumb interphalangeal joint affects the trapeziometacarpal joint during thumb opposition, and assessment of thumb opposition using the Kapandji test is best done with the thumb interphalangeal joint in extension.

The Influence of the Abduction Joints of Four Fingers to Grasp: Experimental and Simulated Verification

The thumb is the most important finger of the human hand and has a great influence on grasp manipulations. However, the extent to which joints other than the thumb joints affect the grasp, and thus, which joints should be included in a prosthetic hand, remains an open issue. In this paper, we focus on the metacarpophalangeal joints of the four fingers, except the thumb, which can generate flexion/extension and abduction/adduction motions. The contribution of these joints to grasping was evaluated in four aspects: grasp size, grasp force, grasp quality and grasp success rate. Six subjects participated in experiments with respect to the maximum grasp size and grasp force. The results show that possessing abduction mobility of the metacarpophalangeal joints can increase the grasp size by 4.67 ± 1.93 mm and the grasp force by 5.27 ± 4.25 N. Then, the grasping quality and success rate were tested in a simulation platform and using a robotic hand, respectively. The results show that grasp quality was promoted by 76.7% in the simulated environment with abduction mobility compared to without abduction mobility, whereas the grasp success rate was promoted by 68.3%. We believe that the results of this work can benefit the understanding of hand function and prosthetic hand design.

Three-dimensional analysis of thumb motion recovery after carpal tunnel release

This study quantified recovery of thumb motion in patients with carpal tunnel syndrome after carpal tunnel release using three-dimensional motion analysis with a retroreflective surface-based marker method. Eighteen hands from 14 patients who underwent carpal tunnel release for idiopathic carpal tunnel syndrome were included. The angular movements of the three joints of the thumb, the path length of the thumb tip and the area enclosed by the perimeter path of the thumb tip were measured during circumduction. The range of joint movement, including abduction/adduction of the trapeziometacarpal joint, and flexion/extension of the interphalangeal and metacarpophalangeal joints and the path length of the thumb tips, improved significantly 1 year after surgery. The quantification of thumb kinematics helps to better understand motor dysfunction in carpal tunnel syndrome, assess the severity of the condition and decide on treatment.Level of evidence: IV.

Anatomy and biomechanics of healthy and arthritic trapeziometacarpal joints

Understanding the biomechanics of the trapeziometacarpal (TMC) or first carpometacarpal (CMC1) joint, the pathophysiology of basal thumb arthritis, the design and performance of surgical procedures require a solid anatomical basis. This review of literature summarizes the most recent data on the descriptive, functional, and comparative anatomy of healthy and arthritic TMC joints.

Transfer of the Distal Anterior Interosseous Nerve for Thumb Motion Reconstruction in Radial Nerve Paralysis

PURPOSE

With nerve or tendon surgery, the results of thumb reconstruction to treat radial nerve paralysis are suboptimal. The goals of this study were to describe the anatomy of the deep branch of the posterior interosseous nerve (PIN) to the thumb extensor muscles (DBPIN), and to report the clinical results of transferring the distal anterior interosseous nerve (DAIN) to the DBPIN.

METHODS

The PIN was dissected in 12 fresh upper limbs. Myelinated nerve fibers in the DBPIN and DAIN were counted. Five patients with radial nerve paralysis underwent transfer of the motor branch to the flexor carpi radialis to the PIN and a motor branch of the pronator teres to the extensor carpi radialis brevis. In addition, these patients had selective reconstruction of thumb motion by transferring the DAIN to the DBPIN, through either a combined volar and dorsal approach (n = 2) or a single dorsal approach (n = 3) with division of the interosseous membrane.

RESULTS

At the origin of the abductor pollicis longus, the DBPIN divided into a lateral branch that innervated the abductor pollicis longus and extensor pollicis brevis, and a medial branch that innervated the extensor pollicis longus and extensor index proprius. The number of myelinated nerve fibers in the DAIN corresponded to 65% of that of the DBPIN. In each of the 5 patients, full thumb motion at the trapeziometacarpal joint was restored with no, or minimal, extension lag at the metacarpophalangeal (MCP) joint.

CONCLUSIONS

The anatomy of the DBPIN is predictable. Transferring the DAIN to the DBPIN is feasible through a single dorsal approach, allowing full recovery of thumb motion.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic V.

Fully Wearable Actuated Soft Exoskeleton for Grasping Assistance in Everyday Activities

Worldwide, over 50 million people suffer from persistent hand impairments after stroke or spinal cord injury (SCI). This results in major loss of independence and quality of life. Robotic hand exoskeletons can compensate for lost motor function and assist in grasping tasks performed in everyday activities. Several recent prototypes can partially provide this assistance. However, it remains challenging to integrate the dexterity required for daily tasks in a safe and user-friendly design that is acceptable for daily use in subjects with neuromotor hand impairments. We present the design of RELab tenoexo; a fully wearable assistive soft hand exoskeleton for daily activities. We present sleek mechanisms for a hand module that generates the four most frequently used grasp types, employing a remote actuation system that reduces weight on the hand. For optimal assistance and highest adaptability, we present various design and control options to customize the modular device, along with an automated tailoring algorithm that allows automatically generated hand modules for individual users. Mechanical evaluation shows that RELab tenoexo covers the range of motion and the fingertip forces required to assist users in up to 80% of all grasping activities. In user tests, we find that the low weight, unintrusive size, high wearing comfort, and appealing appearance are beneficial for user acceptance and usability in daily life. Finally, we demonstrate that RELab tenoexo leads to an immediate improvement of the functional grasping ability in a subject with SCI.

Thumb Interphalangeal Joint Replacement as an Alternative to Joint Fusion

Arthrodesis is the generally accepted treatment for symptomatic osteoarthritis of the interphalangeal (IP) joint of the thumb. For 7 thumbs in 5 patients, an IP joint replacement was offered as a pain alleviating and motion conserving treatment option for osteoarthritis. In these cases, an offlabel use of the SR-PIP prosthesis was performed. All patients did well postoperatively with reasonable pain-free range of motion of the interphalangeal joint except one patient who required further surgeries for recurring joint instability. Radiologically, though, an osteolysis around the stems that could lead to loosening of the prosthesis and progressing periarticular ossifications that might cause a blockage of the joint were observed. IP joint arthroplasty represents a viable option on the short term; however, further studies should be conducted to ensure their long-term sustainability.

Complex thumb motions and their potential clinical value in identifying early changes in function

BACKGROUND

Early diagnosis and treatment of osteoarthritis of the thumb allows for early interventions that may mitigate osteoarthritis progression and decrease severity later in life. Early identification of motion changes is limited by the clinical reliance on single planar measurements using goniometry. Multi-planar measurements using motion capture can provide insights into joint function and pathophysiology that cannot be obtained from single-plane goniometry measurements. Thus, the goals of this research were 1) to determine differences in thumb motions across three groups of participants (young healthy (n = 23), older healthy (n = 11), and those with carpometacarpal osteoarthritis (n = 24)) and 2) to determine if multi-planar motions provided additional movement information in comparison to standard planar measures.

METHODS

In this study, a motion capture system was used to collect standard clinical ranges of motion and complex multi-planar tasks. Differences in motion patterns due to aging and osteoarthritis were identified. Motions tested included palmar adduction-abduction, radial adduction-abduction, metacarpophalangeal flexion-extension, interphalangeal flexion-extension, functional adduction-abduction, opposition, and circumduction.

FINDINGS

Results indicated that motion capture was capable of detecting changes in carpometacarpal mobility that were not detected using standard approaches. Our results suggested that use of multi-planar measurements have the potential to identify changes that are indicators of early stages of osteoarthritis.

INTERPRETATION

Early indicators are clinically useful as they will enhance patient treatment by permitting the application of treatment approaches sooner, potentially leading to reduced overall functional deficits.

Methods for Congenital Thumb Hypoplasia Reconstruction. A Review of the Outcomes for Ten Years of Surgical Treatment

BACKGROUND AND OBJECTIVES

Congenital thumb hypoplasia is a rare deformity of upper extremity. The incidence for thumb hypoplasia grade II-V is 1:10,000 newborns per year in Latvia. A technique for extensor indicis proprius (EIP) tendon transfer with subperiosteal fixation was developed and used for thumb hypoplasia grades II and IIIa. Pollicization or second-toe-to-hand transplantation with metatarsophalangeal (MTP) joint arthrodesis was used for the reconstruction of hypoplasia grade IIIb-V. The aim of this retrospective cohort study is to evaluate the outcomes for reconstruction techniques used in one surgical center during a ten-year period by one surgeon to evaluate functional and aesthetical outcomes for new techniques.

MATERIALS AND METHODS

In total, 21 patients were operated on during 2007-2017, and 18 of these patients were involved in this study. Long-term follow-up was completed to evaluate the functions and aesthetics of the hands.

RESULTS

disabilities of the arm, shoulder and hand (DASH) was 9.35 (8-10.7) for the second-toe-to-hand with MTP joint arthrodesis transplantation method for pollicization method 19.8 (6-26.7), and for the EIP tendon transposition, 14.54 (0.9-56.3).

CONCLUSIONS

The postoperative functional parameters of congenital hand hypoplasia patients, regardless of the surgical method, are worse than the functional results of healthy patients. The use of the second-toe-to-hand with MTP joint arthrodesis transplantation method provides patients with congenital hand IIIb-V hypoplasia a stable and functional first finger formation. The functional results are comparable to the clinical results of the pollicization method while ensuring the creation of a five-digit hand.

Assessment of hand function during activities of daily living using motion tracking cameras: A systematic review

The human hand is the most frequently used body part in activities of daily living. With its complex anatomical structure and the small size compared to the body, assessing the functional capability is highly challenging. The aim of this review was to provide a systematic overview on currently available 3D motion analysis based on skin markers for the assessment of hand function during activities of daily living. It is focused on methodology rather than results. A systematic review according to the PRISMA guidelines was performed. The systematic search yielded 1349 discrete articles. Of 147 articles included on basis of title, 123 were excluded after abstract review, and 24 were included in the full-text analysis with 13 key articles. There is still limited knowledge about hand and finger kinematics during activities of daily living. A standardization of the task is required in order to overcome the nonrepetitive nature and high variability of upper limb motion and ensure repeatability of task performance. To yield a progress in the analysis of human hand movements, an assessment of human kinematics including fingers, wrist, and thumb and an identification of relevant parameters that characterize a healthy motion pattern during functional tasks are needed.

Three-dimensional functional workspace of thumb prehension

BACKGROUND

Clinical assessment of thumb motion is challenging, due to the complex anatomy and motion of the thumb. It is especially difficult to measure hand movement during activity, and to measure the effects of surgery that changes the morphology of the thumb. A three-dimensional model of the hand may enable clinicians to better assess prehension and thumb motion at baseline, and following surgical intervention.

METHODS

A kinematic model of the hand was developed to measure thumb and finger position during functional tasks, enabling the calculation of the volume of space in which prehension could occur. This method was validated by application to a mechanical model of the hand, and then applied to ten adult participants, using three-dimensional motion analysis with a marker array developed for the purpose of this study.

FINDINGS

This method can be used to accurately measure three-dimensional thumb joint range of motion (RoM) and predicted functional workspace during functional activities. The thumb carpometacarpal joint was predominantly responsible for thumb position during functional tasks. Predicted functional workspace is proportional to hand morphometric measurements.

INTERPRETATION

A kinematic model of the hand measures thumb RoM and predicts functional workspace during functional activities.

Distal upper limb kinematics during functional everyday tasks

Quantitative characterisation of upper limb motion allows the evaluation of the effect of pathology on functional task performance, potentially directing rehabilitation strategies. Movement patterns of the distal upper limb in healthy adults during functional tasks have not been extensively characterised. During five loaded functional tasks (drinking from a glass, pouring from a kettle, turning a handle, lifting a bag to a shelf, turning a key) the movement patterns were characterised using three-dimensional motion analysis with a minimal marker set in 16 healthy adults (10 M,6F, 27 (IQR:25-43)years). Joint angles reported include flexion/extension at the elbow and wrist, forearm supination/pronation and digits 2-5 metacarpophalangeal (MCP) joint flexion/extension. Additionally for the thumb the angle between the metacarpal of the thumb and the 2nd digit (Thumb base), the thumb MCP (Thumb MCP) and interphalangeal (Thumb IP) joint angles are presented. Durations of activities performed at self-selected comfortable speeds (3.36 (IQR:3.07,3.66)s turning a key to 6.20 (IQR:5.44,6.38)s drinking from a glass) are reported. The maximum joint angles used (median of participants' maxima) were 141° of elbow flexion, 116° forearm supination, 36° wrist extension, 56° Thumb base, 14° Thumb MCP flexion, 18° Thumb IP flexion, 85° MCP2-5 flexion. The tasks of drinking from a glass, lifting a bag to a shelf and turning a key appeared to have the least variation in performance, suggesting that these activities are better suited to be selected as standardized tasks for assessing the impact of pathology on movement than pouring from a kettle and turning a handle.

Inter-rater and inter-instrument reliability of goniometric thumb active and passive flexion range of motion measurements in healthy hands

Introduction

Goniometry is a common measure of range of motion and may be assessed by different therapists and goniometers. To date, there is limited psychometric data on active and passive range of motion measurements of individual thumb joints. The purpose of this study was to analyze inter-rater and inter-instrument reliability of passive and active flexion goniometric measures of thumb joints in healthy adults.

Methods

A within-subjects psychometric design was utilized. Two raters each used two goniometers (Baseline™ Flexion-Hyper Extension and Baseline™ 180 Degree Digit) to measure each participant’s (n = 48) thumb carpometacarpal, metacarpophalangeal, and interphalangeal flexion range of motion. Inter-rater and inter-instrument reliability and stability were evaluated through use of intraclass correlation coefficient, standard error of the measurement, and minimal detectable change test statistics.

Results

Inter-rater reliability was poor for carpometacarpal flexion and good-to-excellent for metacarpophalangeal and IP flexion. Between-rater error ranged between 3.9 and 6.3 degrees for active measurements and between 3.9 and 7.9 degrees for passive. Error was generally less when using the Baseline™ 180 Degree Digit goniometer. Inter-instrument reliability was excellent for all joints.

Discussion

These findings validate the concerns that thumb goniometry inter-rater reliability may differ in clinical and non-clinical populations, support further study in clinical populations, and support a common assumption that the same rater should test the same client with the same goniometer to minimize measurement error. When compared to the Baseline™ Flexion-Hyper Extension Goniometer, the Baseline™ 180 Degree Digit had higher repeatability across raters. Further research on within-rater reliability is required as is study on clinical populations.

Design, control, and testing of a thumb exoskeleton with series elastic actuation

We present an exoskeleton capable of assisting the human thumb through a large range of motion. Our novel thumb exoskeleton has the following unique features: (i) an underlying kinematic mechanism that is optimized to achieve a large range of motion, (ii) a design that actuates four degrees of freedom of the thumb, and (iii) a series elastic actuation based on a Bowden cable, allowing for bidirectional torque control of each thumb joint individually. We present a kinematic model of the coupled thumb exoskeleton system and use it to maximize the range of motion of the thumb. Finally, we carry out tests with the designed device on four subjects to evaluate its workspace and kinematic transparency using a motion capture system and torque control performance. Results show that the device allows for a large workspace with the thumb, is kinematically transparent to natural thumb motion to a high degree, and is capable of accurate torque control.

Quantifying the human finger reachable space

Describing the flexibility of the hand using the reachable space concept has drawn the attention of many researchers in recent years. Existing approaches involving numerical techniques to obtain the reachable space are generally computationally expensive. In this study, we propose a resource-friendly approach to determine and quantify the bidimensional reachable space of the finger. The fundamental idea of the approach connects to a set of arc formulae for the boundary of the reachable space. These formulae of the boundary result a unique description to calculate the area of the reachable space using Green's theorem. Adopting this novel approach, reachable spaces can be visualised and quantified to effectively evaluate the functionality of different subjects and their therapeutic conditions. We evaluated the performance of the proposed approach against the popular kinematic feedforward approach and Monte Carlo simulation separately. The exclusive description of the reachable space boundary resulted in significant improvement to the execution time while delivering more accurate quantification values.

Kinematic Analyses of the Thumb during Simulated Posteroanterior Glide Mobilization

Objective

Thumb problems are common in some health professionals such as physical therapists. The purpose of this case-control study is to investigate the influence of clinical experience and different mobilization techniques on the kinematics of the thumb.

Methods

Twenty-three participants without exposure to manual techniques (the Novice Group) and fifteen physical therapists with at least 3 years of orthopedic experience (the Experienced Group) participated. The kinematics of the thumb while performing 3 different simulated posteroanterior (PA) glide mobilization techniques on a load cell was monitored. These 3 techniques were: 1) unsupported, 2) with digital support and 3) with thumb interphalangeal joint supported by the index finger. The amount of forces exerted were 25% to 100% of maximum effort at 25% increments. The main effects of experience and technique on thumb kinematics were assessed.

Results

Both experience and technique had main effects on the flexion/extension angles of the thumb joints. Experienced participants assumed a more flexed position at the carpometacarpal (CMC) joint, and the novice participants performed with angles closer to the neutral position (F = 7.593, p = 0.010). Participants’ metacarpophalangeal (MCP) joints were in a more flexed position while performing PA glide with thumb interphalangeal (IP) joint supported by the index as compared to the other two techniques (p < .001).

Conclusions

Negative correlations were generally obtained between the sagittal plane angles of adjacent thumb joints during mobilization/manipulation. Therapists are recommended to treat patient with more stable PA glide mobilization techniques, such as PA glide with thumb interphalangeal joint supported by the index finger, to prevent potential mobilization-related thumb disorders.

Three-dimensional finger joint angles by hand posture and object properties

The objective of this study was to identify three-dimensional finger joint angles for various hand postures and object properties. Finger joint angles were measured using a VICON system for 10 participants while they pinched objects with two, three, four and five fingers and grasped them with five fingers. The objects were cylinders and square pillars with diameters of 2, 4, 6 and 8 cm and weights of 400, 800, 1400 and 1800 g. Hand posture and object size more significantly affected the joint flexion angles than did object shape and weight. Object shape affected only the metacarpophalangeal (MCP) joint angle of the index finger and the flexion angle of the MCP joint of the little finger. Larger flexion angles resulted when the hand posture was grasping with five fingers. The joint angle increased linearly as the object size decreased. This report provides fundamental information about the specific joint angles of the thumb and fingers. Practitioner Summary: Three-dimensional finger joint angles are of special interest in ergonomics because of their importance in handheld devices and musculoskeletal hand disorders. In this study, the finger joint angles corresponding to various hand postures and objects with different properties were determined.

How kinematic disturbance in the deformed rheumatoid thumb impacts on hand function: a biomechanical and functional perspective

Purpose This study investigates the effects of kinematic disturbances in rheumatoid thumb on patient's hand functions via objective and patient-perceived measurements. Method Twenty-one patients with rheumatoid arthritis (RA) and 21 healthy age- and gender-matched individuals were recruited to receive the objective evaluations, including the Purdue Pegboard Test, Jamar dynamometer, pinch-meter, Permanent Impairment Scale and self-administrated measurements, including the Health Assessment Questionnaire (HAQ) and Manual Ability Measure-36 (MAM-36). An electromagnetic tracking system was used to measure thumb kinematics. The differences in the measures between the RA and control groups and the dominant and non-dominant hands of the RA group were examined. The relationships between the thumb kinematics and hand functional capabilities, as well as impairment levels, were also explored. Results The RA group showed significantly smaller thumb movement capabilities and hand strength, as well as worse scores in hand dexterity, MAM-36 and HAQ than healthy controls. The movement workspace of the RA thumb showed moderate correlations with the factors of hand strength, dexterity, impairment scale, MAM-36 and HAQ scores. Conclusions The findings indicate deficits related to the movement capability of the RA thumb may negatively influence hand dexterity and functional hand performance, as well as life quality, for the patients with RA. Implications for Rehabilitation A deformed rheumatoid thumb might limit the movement workspace of the thumb and consequently impair the hand performance as well as the life quality. The dominant thumb of the RA patients might have greater structural and functional deterioration than the non-dominant side. Suitable joint protection strategies, exercises and orthotics should be early applied to the RA patients for preserving hand functions.

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.

Analysis of surface EMG activation in hand percussion playing depending on the grasping type and the tempo

Although instrument playing-based training has been repeatedly reported to improve functional hand movements including grasping, the attempts to present quantitative information on physiological mechanism of grasping have been relatively insufficient to determine the type and the intensity of the exercises involved. This study aimed to examine the muscle activation during hand percussion playing depending on the grasping type and the playing tempo. A total of twelve healthy older adults with a mean age of 71.5 years participated in this study. Surface electrodes were placed on three grasping-related muscles: Flexor digitorum superficialis, extensor digitorum, and flexor pollicis brevis. Participants were instructed to play with the egg shaker, paddle drum mallet and clave involving different types of grasp at three different tempi (i.e., 80, 100, and 120 bpm) and sEMG data were collected during each playing. Significantly greater muscle activation was generated with the small sphere type of egg shaker, compared to the handle type of paddle drum mallet and the small cylinder type of clave. Playing at faster tempo also elicited significantly greater muscle activation than at slower tempo. With regard to the rise time of muscle activation, while tempo significantly affected the rise time, the time to peak muscle did not significantly change depending on the grasping type. This study confirmed that grasping pattern and the tempo of movement significantly influence the muscular activation of grasping involved in instrument playing. Based on these results, clinical implication for instrument selection and structured instrument playing would be suggested.

Robotic thumb grasp-based range of motion optimisation

With the thumb serving an important role in the function of the human hand, improving robotic prosthetic thumb functionality will have a direct impact on the prosthesis itself. So far, no significant work exists that examines the ranges of motion a prosthetic thumb should exhibit; many myoelectric prostheses arbitrarily select them. We question this design practice as we expect a significant functional volume reduction for performing certain activities vs. the maximum obtainable workspace. To this end, we compare and contrast four anatomically-accurate thumb models. We quantify their angular ranges of motion by generating point clouds of end-effector positions, and by computing their alpha-shape bounded volumes. Examining the function of the thumb for several grasps, we identify a 76% reduction of the required workspace volume vis-a-vis the maximum volume of a "'generic'" human thumb.

Analysis of the Constraint Joint Loading in the Thumb During Pipetting

Dynamic loading on articular joints is essential for the evaluation of the risk of the articulation degeneration associated with occupational activities. In the current study, we analyzed the dynamic constraint loading for the thumb during pipetting. The constraint loading is considered as the loading that has to be carried by the connective tissues of the joints (i.e., the cartilage layer and the ligaments) to maintain the kinematic constraints of the system. The joint loadings are solved using a classic free-body approach, using the external loading and muscle forces, which were obtained in an inverse dynamic approach combined with an optimization procedure in anybody. The constraint forces in the thumb joint obtained in the current study are compared with those obtained in the pinch and grasp tests in a previous study (Cooney and Chao, 1977, "Biomechanical Analysis of Static Forces in the Thumb During Hand Function," J. Bone Joint Surg. Am., 59(1), pp. 27-36). The maximal compression force during pipetting is approximately 83% and 60% greater than those obtained in the tip pinch and key pinch, respectively, while substantially smaller than that obtained during grasping. The maximal lateral shear force is approximately six times, 32 times, and 90% greater than those obtained in the tip pinch, key pinch, and grasp, respectively. The maximal dorsal shear force during pipetting is approximately 3.2 and 1.4 times greater than those obtained in the tip pinch and key pinch, respectively, while substantially smaller than that obtained during grasping. Our analysis indicated that the thumb joints are subjected to repetitive, intensive loading during pipetting, compared to other daily activities.

Stabilization effectiveness and functionality of different thumb orthoses in female patients with first carpometacarpal joint osteoarthritis

BACKGROUND

Thumb orthoses have to reconcile and satisfy competing goals: stability and mobility. The purpose of the study was to characterize the stabilization effectiveness and functionality of different thumb carpometacarpal osteoarthritis orthoses.

METHODS

Eighteen female carpometacarpal osteoarthritis subjects were included. Four orthoses were compared: BSN medical (BSN); Push braces (PUSH); Sporlastic (SPOR); and medi (MEDI). Three-dimensional thumb kinematics during active opposition-reposition with and without orthosis was quantified. Ranges-of-motion of the carpometacarpal and metacarpophalangeal joint in x- (flexion-extension), y- (adduction-abduction) and z-direction (pronation-supination) were determined. Hand functionality was examined by Sollerman test.

FINDINGS

All orthoses restricted carpometacarpal range-of-motion in all directions. In x-direction carpometacarpal range-of-motion was smallest with MEDI and BSN, in y-direction largest with PUSH compared to all other orthoses, in z-direction smaller with BSN and MEDI compared to PUSH, but similar to SPOR. All orthoses restricted metacarpophalangeal range-of-motion in x-direction, except PUSH. In x-direction metacarpophalangeal range-of-motion was smallest with MEDI compared to all other orthoses. In y-direction and z-direction only BSN and MEDI restricted metacarpophalangeal range-of-motion. Sollerman score was highest with PUSH, lowest with MEDI and both differed from other orthoses. Values for BSN and SPOR were similar and lay between PUSH and MEDI.

INTERPRETATION

Stabilization is borne by functionality. The high stabilization effectiveness provided by MEDI resulted in lowest hand functionality. PUSH, which partially stabilized the CMC joint and allowed large motions in the MCP joint, afforded largest hand functionality. Best compromise of stability and functionality could be reached with BSN. Long-term studies are needed to monitor clinical efficacy.

Effect of carpometacarpal joint osteoarthritis, sex, and handedness on thumb in vivo kinematics

PURPOSE

To investigate the influence of trapeziometacarpal (TMC) osteoarthritis (OA) on the 3-dimensional motion capability of the TMC and thumb metacarpophalangeal (MCP) joints. In order to examine other factors affecting the thumb's motion kinematics, we further aimed to address the influence of sex and handedness on the motion capability of normal TMC and MCP joints.

METHODS

We included 18 healthy subjects (9 women, 9 men; 8 dominant hands, 10 nondominant hands) and 18 women with stage II/III TMC OA. A motion analysis system using surface markers was used to quantify the thumb's 3-dimensional opposition-reposition kinematics. The range of motion of the thumb's TMC and MCP joints in flexion-extension, abduction-adduction, and pronation-supination were determined.

RESULTS

TMC OA led to a loss in abduction-adduction in the TMC joint (38° in controls, 26° in TMC OA subjects), although neither flexion-extension nor pronation-supination were affected. At the MCP joint, the TMC OA subjects showed a 48% reduction in abduction-adduction (32° controls, 16° TMC OA subjects) and 42% reduction in pronation-supination (34° in controls, 20° in TMC OA subjects) than the healthy controls. Ranges of motion of the healthy TMC and MCP joints were similar in dominant and nondominant hands as well as in women and men.

DISCUSSION

The study demonstrated that stage II/III TMC OA restricts the motion of the TMC joint in abduction-adduction and of the MCP joint in abduction-adduction and pronation-supination. Thumb motion capability was unaffected by sex and handedness.

CLINICAL RELEVANCE

Osteoarthritis-induced loss of TMC motion did not reflect a generalizable clinical parameter, rather, it seemed to distinctly affect the TMC and the MCP joints and their motion planes and directions. As neither sex nor handedness influenced the motion capabilities of the healthy thumb, kinematic factors contributing to TMC OA may develop at a later age.

In vivo analysis of trapeziometacarpal joint arthrokinematics during multi-directional thumb motions

BACKGROUND

The investigation of the joint arthrokinematics of the trapeziometacarpal joint is critical to comprehend the causative mechanism underlying this common form of osteoarthritis. Therefore, the purpose of this study is to evaluate the arthrokinematics of the trapeziometacarpal joint during thumb postures in vivo.

METHODS

Fifteen healthy participants were enrolled in this study. Static computed tomography images of the 1st metacarpal bone and trapezium were taken at specific thumb postures during thumb flexion-extension, abduction-adduction, and circumduction motions. Images were analyzed to examine the joint gliding, expressed as displacement of the centroid of the articular surface of the 1st metacarpal bone, relative to the trapezium. The gliding ratio, defined as joint gliding in each direction normalized to the dimension of the trapezium joint surface in the given direction, was computed and compared between different thumb motions.

FINDINGS

The results indicate that thumb motions influenced joint gliding. The centroids of the articular surface of the 1st metacarpal bone were primarily located at the central and dorsal-radial regions while executing these motions. The maximum joint gliding of the 1st metacarpal bone occurred in the radial-ulnar direction when performing abduction-adduction, and in the dorsal-volar direction while performing flexion-extension and circumduction, with the gliding ratio values of 42.35%, 51.65%, and 51.85%, respectively.

INTERPRETATION

Activities that involved abduction-adduction in the trapeziometacarpal joint caused greater joint gliding in the ulnar-radial direction, while flexion-extension resulted in greater joint gliding in the dorsal-volar and distal-proximal directions. Understanding normal joint kinematics in vivo may provide insights into the possible mechanism leading to osteoarthritis of the trapeziometacarpal joint, and help to improve the design of implants.

Carpal tunnel syndrome impairs thumb opposition and circumduction motion

BACKGROUND

Carpal tunnel syndrome is associated with sensory and motor impairments resulting from the compressed and malfunctioning median nerve. The thumb is critical to hand function, yet the pathokinematics of the thumb associated with carpal tunnel syndrome are not well understood.

QUESTIONS/PURPOSES

The purpose of this study was to evaluate thumb motion abnormalities associated with carpal tunnel syndrome. We hypothesized that the ranges of translational and angular motion of the thumb would be reduced as a result of carpal tunnel syndrome.

METHODS

Eleven patients with carpal tunnel syndrome and 11 healthy control subjects voluntarily participated in this study. Translational and angular kinematics of the thumb were obtained using marker-based video motion analysis during thumb opposition and circumduction movements.

RESULTS

Motion deficits were observed for patients with carpal tunnel syndrome even though maximum pinch strength was similar. The path length, normalized by palm width of the thumb tip for the patients with carpal tunnel syndrome was less than for control participants (opposition: 2.2 palm width [95% CI, 1.8-2.6 palm width] versus 3.1 palm width [95% CI, 2.8-3.4 palm width], p < 0.001; circumduction: 2.2 palm width [95% CI, 1.9-2.5 palm width] versus 2.9 palm width [95% CI, 2.7-3.2 palm width], p < 0.001). Specifically, patients with carpal tunnel syndrome had a deficit of 0.3 palm width (95% CI, 0.04-0.52 palm width; p = 0.022) in the maximum position of their thumb tip ulnarly across the palm during opposition relative to control participants. The angular ROM also was reduced for the patients with carpal tunnel syndrome compared with the control participants in extension/flexion for the metacarpophalangeal (opposition: 34° versus 58°, p = .004; circumduction: 33° versus 58°, p < 0.001) and interphalangeal (opposition: 37° versus 62°, p = .028; circumduction: 41° versus 63°, p = .025) joints.

CONCLUSIONS

Carpal tunnel syndrome disrupts kinematics of the thumb during opposition and circumduction despite normal pinch strength.

CLINICAL RELEVANCE

Improving understanding of thumb pathokinematics associated with carpal tunnel syndrome may help clarify hand function impairment associated with the syndrome given the critical role of the thumb in dexterous manipulation.

Increased range of motion and decreased strength of the thumb in massage practitioners with thumb pain

The purpose of this study was to compare the range of motion (ROM) and strength of the metacarpophalangeal (MP) and interphalangeal (IP) joints among massage practitioners with and without thumb pain and control subjects. Sixteen massage practitioners with thumb pain, 16 practitioners without thumb pain, and 16 control subjects participated in this study. ROM of flexion, extension, and abduction in the MP joint; ROM of flexion and extension in the IP joint of the thumb; strength of the flexor pollicis brevis (FPB), extensor pollicis brevis (EPB), abductor pollicis brevis, flexor pollicis longus (FPL), and extensor pollicis longus measured in all subjects. ROM of extension and abduction in the MP joint were significantly increased in massage practitioners with and without thumb pain compared with control subjects. ROM of extension in the IP joint was significantly increased in massage practitioners with thumb pain compared with those without thumb pain. The strength of the EPB and FPL muscle was significantly decreased in massage practitioners with thumb pain compared with those without thumb pain and control subjects, respectively. In addition, there was significantly increased EPB/FPB strength in massage practitioners without thumb pain compared to those with thumb pain and control subjects.

In vivo analysis of trapeziometacarpal joint kinematics during pinch tasks

This study investigated how the posture of the thumb while performing common pinch movements and the levels of pinch force applied by the thumb affect the arthrokinematics of the trapeziometacarpal joint in vivo. Fifteen subjects performed the pinch tasks at the distal phalange (DP), proximal interphalangeal (PIP) joint, and metacarpophalangeal (MP) joint of the index finger with 0%, 50%, and 80% of maximal pinch forces by a single-axis load cell. 3D images of the thumb were obtained using the computed tomography. The results show that the reference points moved from the central region to the dorsal-radial region when changing from pinching the DP to the MP joint without pinching force being applied. Pinching with 80% of the maximum pinching force resulted in reference points being the closest to the volar-ulnar direction. Significant differences were seen between 0% and 50% of maximum pinch force, as well as between 0% and 80%, when pinching the MP joint in the distal-proximal direction. The effects of posture of the thumb and applied pinch force on the arthrokinematics of the joint were investigated with a 3D model of the trapeziometacarpal joint. Pinching with more than 50% of maximum pinch force might subject this joint to extreme displacement.

In vivo kinematics of the thumb carpometacarpal joint during three isometric functional tasks

BACKGROUND

The thumb carpometacarpal (CMC) joint is often affected by osteoarthritis--a mechanically mediated disease. Pathomechanics of the CMC joint, however, are not thoroughly understood due to a paucity of in vivo data.

QUESTIONS/PURPOSES

We documented normal, in vivo CMC joint kinematics during isometric functional tasks. We hypothesized there would be motion of the CMC joint during these tasks and that this motion would differ with sex and age group. We also sought to determine whether the rotations at the CMC joint were coupled and whether the trapezium moved with respect to the third metacarpal.

METHODS

Forty-six asymptomatic subjects were CT-scanned in a neutral position and during three functional tasks (key pinch, jar grasp, jar twist), in an unloaded and a loaded position. Kinematics of the first metacarpal, third metacarpal, and the trapezium were then computed.

RESULTS

Significant motion was identified in the CMC joint during all tasks. Sex did not have an effect on CMC joint kinematics. Motion patterns differed with age group, but these differences were not systematic across the tasks. Rotation at the CMC joint was generally coupled and posture of the trapezium relative to the third metacarpal changed significantly with thumb position.

CONCLUSIONS

The healthy CMC joint is relatively stable during key pinch, jar grasp, and jar twist tasks, despite sex and age group.

CLINICAL RELEVANCE

Our findings indicate that directionally coupled motion patterns in the CMC joint, which lead to a specific loading profile, are similar in men and women. These patterns, in addition to other, nonkinematic influences, especially in the female population, may contribute to the pathomechanics of the osteoarthritic joint.

Identification of three movement phases of the hand during lateral and pulp pinches using video motion capture

BACKGROUND

Hand injuries affect a person's ability to engage successfully in activities of daily living (ADLs). Video motion capture (VMC) facilitates measurement of dynamic movement. No study to date has used VMC as a means of quantifying the simultaneous movement patterns of all joints of all digits of the hand during active purposeful movement.

METHOD

The purpose of this study was to analyze all joints of all five digits during active completion of the lateral and pulp pinches. VMC data were collected from four participants during completion of two pinches. Joint angles were plotted to facilitate identification of movement patterns.

RESULTS

Range of motion recorded in all joints with VMC, excluding flexion of the thumb carpometacarpal of both pinches, coincided with the normative goniometric data. Three phases were observed: initiation, preshaping, and pinch phases. Patterns of movement in all digits were identified for the two pinches.

CONCLUSION

VMC is a feasible and valid method for objectively quantifying dynamic movement of multiple joints simultaneously. The results provide new insight to the dynamics of hand movement as well as a basis for subsequent evaluations of movement patterns performed in ADLs and instrumental ADLs.

The range of movement of the thumb

PURPOSE

The movements at each thumb joint are flexion and extension (called radial abduction in the CMCJ) and additional movements of anteposition, retroposition and opposition at the CMCJ, due to the saddle shape of the articulation. Our study was designed to provide a means of thumb movement measurement and provide a range for each.

METHODS

A prospective cohort study was performed looking at 100 consecutive individuals without thumb pathology to determine thumb joint range of movements and evaluate the reliability of such measurements.

RESULTS

The mean age was 26 (range of 18-37) with 62 female individuals. The mean range of movement of the IPJ was flexion of 88 ° (80-90 °) and extension of 12 ° (0-45 °). That of the MCPJ was flexion of 60 ° (43-70 °) and extension of 8.1 ° (0-15 °). That of the CMCJ was anteposition of 61.2 ° (50-71 °), retroposition of 31.1 mm (25-38 mm), radial abduction of 62.9 ° (53-71 °), opposition Kapandji grade 9 (grades 9-10) and adduction of 10.2 ± 4 ° (5-20 °). CMC adduction was difficult to measure with a poor intra- and inter-observer correlation (inter-reliability correlation coefficient of 0.02 and intra-reliability coefficient of 0.04). For the remaining measurements, the mean inter-reliability correlation coefficient was 0.82 (p < 0.01) while the mean intra-reliability correlation coefficient was 0.93 (p < 0.01). There was negative correlation identified between IPJ extension and MCPJ extension (-0.50) and between CMCJ radial abduction and MCPJ extension (-0.60).

CONCLUSIONS

Having established the normal ranges of movements for the thumb joints and shown that our measurement methods are reliable and reproducible, we have identified that a reduction in certain thumb joint movements appears to be compensated for by an increased movement range in the other joints.

Manipulability analysis of human thumb, index and middle fingers in cooperative 3D rotational movements of a small object

The combined motion of the human thumb, index and middle fingers while rotating a small object across the extended, intermediate and flexed planes with respect to the fingers was analyzed. Auto reflective markers were attached on the fingers to track their motion across three postures and planes via a 3D motion capture system. Central, right and left rotation postures were considered in each plane for investigation and the rotation experiments were performed with 30 healthy subjects. The obtained data were used to compute the finger joint angles. Based on the three criteria of (i) manipulability measure, (ii) major axis direction angle of the manipulability ellipsoid and (iii) ratio of the minor over major axis lengths, the collective behavior of the fingers was studied. It has been found after analysis that the thumb and middle finger were active, while the index finger operated passively when manipulating small objects in cooperative rotational motion across the three planes. Activeness refers to the independence of a digit in controlling the motion of an object whereas passiveness denotes its dependence on other digits. An active finger governs the motion of an object whereas a passive finger simply supports it. The results of this investigation are of great importance in planning treatment for rehabilitation and for designing controllers for robotic therapists, finger exoskeletons and prostheses.

Inverse dynamic analysis of the biomechanics of the thumb while pipetting: a case study

Thumb-push manual pipettes are commonly used tools in many medical, biological, and chemical laboratories. Epidemiological studies indicate that the use of thumb-push mechanical pipettes is associated with musculoskeletal disorders in the hand. The goal of the current study was to evaluate the kinematics and joint loading of the thumb during pipetting. The time-histories of joint angles and the interface contact force between the thumb and plunger during the pipetting action were determined experimentally, and the joint loadings and joint power in the thumb were calculated via an inverse dynamic approach. The moment, power, and energy absorption in each joint of the thumb during the extraction and dispensing actions were analyzed. The results indicate that the majority of the power is generated in the interphalangeal (IP) and carpometacarpal (CMC) joints for the pipetting action. The analysis method and results in the current study will be helpful in exploring the mechanism for musculoskeletal injuries of the hand associated with pipetting, providing a preliminary foundation for ergonomic design of the pipette.