Multiple Fingers Research Articles

Passive Realization of Object Spatial Compliance by a Hand Having Multiple Four-Joint Hard Fingers

Abstract This paper presents an approach to passively realize any specified object spatial compliance using the grasp of a robotic hand. The kinematically anthropomorphic hands considered have multiple 4-joint fingers making hard point contact with the held object, and the joints of each finger have selectable passive elastic behavior. It is shown that the space of passively realizable compliances is restricted by the kinematic structure of the anthropomorphic hand. To achieve an arbitrary compliant behavior, fingers must be able to adjust their orientation. Synthesis procedures for grasps having 3, 4, and 5 or more fingers are developed. These procedures identify the finger configurations and the individual finger joint compliances needed to passively achieve any specified spatial object compliance matrix in the 20-dimensional subspace of grasp-realizable behaviors.

Finger Multi-Joint Trajectory Measurement and Kinematics Analysis Based on Machine Vision

A method for measuring multi-joint finger trajectories is proposed using MediaPipe. In this method, a high-speed camera is used to record finger movements. Subsequently, the recorded finger movement data are input into MediaPipe, where the system automatically extracts the coordinate data of the key points in the finger movements. From this, we obtain data pertaining to the trajectory of the finger movements. In order to verify the accuracy and effectiveness of this experimental method, we compared it with the DH method and the Artificial keypoint alignment method in terms of metrics such as MAPE (Mean Absolute Percentage Error), maximum distance error, and the time taken to process 500 images. The results demonstrated that our method can detect multiple finger joints in a natural, efficient, and accurate manner. Then, we measured posture for three selected hand movements. We determined the position coordinates of the joints and calculated the angular acceleration of the joint rotation. We observed that the angular acceleration can fluctuate significantly over a very short period of time (less than 100 ms), in some cases increasing to more than ten times the initial acceleration. This finding underscores the complexity of finger joint movements. This study can provide support and reference for the design of finger rehabilitation robots and dexterous hands.

A Two-stage Surgery for Completely Degloving Injury of Multiple Fingers: a Retrospective Cohort Study

PurposeThe completely degloving injury of multiple fingers is a challenging clinical problem. Based on our technical experience, a novel two-stage surgery of abdominal hypodermal pocket followed by separation and full thickness skin grafting was conducted. MethodsFrom January 2017 to August 2020, 7 cases (17 fingers) of degloving injury of multiple whole fingers who were treated in a two-stage fashion; an emergency first stage surgery of abdominal hypodermal pocket embedding and a second stage surgery (4 weeks later) of full thickness skin grafting, were retrospectively studied. The results were evaluated according to the patient subjective evaluation, static two-point discrimination and disabilities of the arm, shoulder and hand (DASH) scores and active range of motion (ROM) of metacarpophalangeal (MP) and proximal interphalangeal (PIP) joints. ResultsAll seven cases healed successfully, although two cases experienced distal phalanx necrosis. The affected fingers recovered with a good appearance and soft texture and the results were either satisfying or acceptable for all participants. The active ROM of MP joint ranged from 55° to 64° with an average of 59.5° three months postoperatively and ranged from 70° to 81° with an average of 77.2° six months postoperatively, while the active ROM of PIP joint ranged from 58° to 69° with an average of 64.1° three months postoperatively and from 76° to 86° with an average of 81° six months postoperatively. One year postoperatively, the static two-point discrimination ranged from 7 to 10mm with an average of 8.6mm and DASH scores ranged from 25 to 42 with an average of 37. ConclusionA novel two-stage surgery of abdominal hypodermal separated pockets followed by full thickness is an effective and worthwhile option for treating the completely degloving injury of multiple fingers.

Video-based diagnosis support system for pianists with Musician's dystonia.

Musician's dystonia is a task-specific movement disorder that deteriorates fine motor control of skilled movements in musical performance. Although this disorder threatens professional careers, its diagnosis is challenging for clinicians who have no specialized knowledge of musical performance. To support diagnostic evaluation, the present study proposes a novel approach using a machine learning-based algorithm to identify the symptomatic movements of Musician's dystonia. We propose an algorithm that identifies the dystonic movements using the anomaly detection method with an autoencoder trained with the hand kinematics of healthy pianists. A unique feature of the algorithm is that it requires only the video image of the hand, which can be derived by a commercially available camera. We also measured the hand biomechanical functions to assess the contribution of peripheral factors and improve the identification of dystonic symptoms. The proposed algorithm successfully identified Musician's dystonia with an accuracy and specificity of 90% based only on video footages of the hands. In addition, we identified the degradation of biomechanical functions involved in controlling multiple fingers, which is not specific to musical performance. By contrast, there were no dystonia-specific malfunctions of hand biomechanics, including the strength and agility of individual digits. These findings demonstrate the effectiveness of the present technique in aiding in the accurate diagnosis of Musician's dystonia.

A multi-factor knuckle and nail bed verification tool for forensic imagery analysis

BackgroundThe grooming process involves sexually explicit images or videos sent by the offender to the minor. Although offenders may try to conceal their identity, these sexts often include hand, knuckle, and nail bed imagery. ObjectiveWe present a novel biometric hand verification tool designed to identify online child sexual exploitation offenders from images or videos based on biometric/forensic features extracted from hand regions. The system can match and authenticate hand component imagery against a constrained custody suite reference of a known subject by employing advanced image processing and machine learning techniques. DataWe conducted experiments on two hand datasets: Purdue University and Hong Kong. In particular, the Purdue dataset collected for this study allowed us to evaluate the system performance on various parameters, with specific emphasis on camera distance and orientation. MethodsTo explore the performance and reliability of the biometric verification models, we considered several parameters, including hand orientation, distance from the camera, single or multiple fingers, architecture of the models, and performance loss functions. ResultsResults showed the best performance for pictures sampled from the same database and with the same image capture conditions. ConclusionThe authors conclude the biometric hand verification tool offers a robust solution that will operationally impact law enforcement by allowing agencies to investigate and identify online child sexual exploitation offenders more effectively. We highlight the strength of the system and the current limitations.

Integrated photodetectors embedded within fiber laser based on hybrid rGO:ZnO nanostructures

Online power monitoring is helpful in fiber-optic communication applications. This report introduced an innovative all-fiber photodetector based on the polished side of an arc-shaped fiber for the optical signals’ in situ measurements. For this purpose, a metal-semiconductor–metal photodetector was designed with multiple interdigitated metal fingers of gold electrodes. A waveguide structure containing polymethyl methacrylate (PMMA), graphene layers, and zinc oxide nanostructures was developed and covered over the arc-shaped fiber. Due to the PMMA’s refractive index (n = 1.4905), the evanescent field of propagating mode was drawn out of the core, thus increasing the light interaction with semiconductor nanostructures. To study the influence of graphene flakes on the optoelectrical behavior of zinc oxide nanostructures, a suspension of graphene oxide (GO) and ZnO nanorods was synthesized and transferred onto the PMMA thin film, which was deposited on the polished side of the arc-shaped fiber. The morphological analysis indicates the formation of ZnO nanorods with different orientations, and these nanorods have the potential to enhance incident photon trapping greatly. Upon photon exposure, the guiding photons in the fiber evanescently coupled with the deposited nanostructures, and the photoexcited electron–hole pairs were generated in the semiconductor material. Using applied voltage across the interdigitated electrodes, the generated excitons were separated and increased the photocurrent, which was monitored precisely by source-measure equipment. The optoelectrical properties of fabricated devices showed that incorporating graphene layers can improve the photon detection performance of the fabricated all-fiber photodetectors based on ZnO nanostructures.

Multiple congenital bilateral trigger fingers in a 2-year-old child: A case report

BackgroundCongenital trigger finger is a rare pediatric condition characterized by a finger fixed in a flexed position due to tendon anomalies. This rare condition involves multiple trigger fingers in children and is not extensively covered in the medical literature. MethodsWe examined a 2-year-old boy with multiple trigger fingers present since birth. Surgical release of the A1 pulleys was performed. ResultsSurgery resulted in normal finger function at the one-year follow-up. ConclusionsAlthough rare, congenital trigger finger is treatable in children. Adaptive and timely interventions can significantly improve outcomes and reduce disability. This case highlights the importance of early and effective treatment strategies.

Towards Efficient Neural Decoder for Dexterous Finger Force Predictions.

Dexterous control of robot hands requires a robust neural-machine interface capable of accurately decoding multiple finger movements. Existing studies primarily focus on single-finger movement or rely heavily on multi-finger data for decoder training, which requires large datasets and high computation demand. In this study, we investigated the feasibility of using limited single-finger surface electromyogram (sEMG) data to train a neural decoder capable of predicting the forces of unseen multi-finger combinations. We developed a deep forest-based neural decoder to concurrently predict the extension and flexion forces of three fingers (index, middle, and ring-pinky). We trained the model using varying amounts of high-density EMG data in a limited condition (i.e., single-finger data). We showed that the deep forest decoder could achieve consistently commendable performance with 7.0% of force prediction errors and R2 value of 0.874, significantly surpassing the conventional EMG amplitude method and convolutional neural network approach. However, the deep forest decoder accuracy degraded when a smaller amount of data was used for training and when the testing data became noisy. The deep forest decoder shows accurate performance in multi-finger force prediction tasks. The efficiency aspect of the deep forest lies in the short training time and small volume of training data, which are two critical factors in current neural decoding applications. This study offers insights into efficient and accurate neural decoder training for advanced robotic hand control, which has the potential for real-life applications during human-machine interactions.

Nail growth disorder in multiple fingers following harvesting of radial forearm free flap for phalloplasty in gender-affirming surgery: a case report

Nail growth disturbance commonly takes place after trauma or relevant diseases, such as infections and tumors. However, abnormal growth of the nail plate sometimes occurs without an obvious causative factor. This report presents the case of a patient who underwent male genital reconstruction with a radial forearm free flap for gender affirmation. Although the entire process was smooth, with no accidental events, the second, third, and fourth phalangeal nail plates of the hand from which the flap was harvested showed no evident growth of the fingernail 2 months postoperatively. Nail production was preserved in the remaining fingernails. Typical symptoms, such as redness, swelling, and tenderness, were noted upon clinical observation. Eventually, nail production restarted 5 months after surgery. Steroid and antibiotic treatment was attempted to reduce periungual inflammation. Additionally, close observation with psychological support was conducted.

Flow-Through Procedure in Sequela After Complex Injuries of the Hand With Fingers’ Amputation

PurposeComplex injuries of the hand with finger amputation can result in important functional impairment. If the amputated fingers cannot be replanted, the developed sequelae should be further evaluated. Sometimes, in the presence of a few remaining local vascular resources, the use of the flow-through technique can help in solving the problem. MethodsThis study retrospectively reviews 4 cases who underwent single or multiple fingers reconstruction with toe transfers by using true flow-through or flow-through conduit flaps. A thorough description of the two methods is done, and the quality of the regained functionality of the hand is presented. ResultsAll the patients were males, aged between 21 and 45 (median age 31.75). One of them injured the left dominant hand, and the other three their right dominant hand. The median time between the accident and reconstructive surgery was 14.5 months (range, 3 months-36 months). All the initial lesions were work-related trauma. One patient had severe sequela after forearm compartment syndrome and amputation of the thumb and fifth finger; one patient had a metacarpal hand, one patient had amputation of two fingers (2nd and 4th); and one patient had three fingers amputated (2nd, 3rd, and 4th). In the first patient, a true flow-through flap and a second toe transfer was done, and in the other three patients multiple toe transfers by using the flow-through conduit technique were used. A good functionality of the reconstructed hand was obtained in all the patients. ConclusionsToe transfer remains one of the best methods in the reconstruction of hands with missing fingers. The use of both true flow-through flap and flow-through conduit methods are very useful, especially in cases with few vascular resources.

Syndactylized glabrous flaps for multiple finger palmar defects.

Palmar finger or pulp defects require coverage with glabrous tissue to achieve a good match with the lost tissue. The management of multiple finger palmar or pulp defects is challenging because these defects may not always be suitable for local or pedicled flaps. In such situations, syndactylizing free or pedicled flaps can be used. We evaluated the results of free glabrous flaps syndactylizing across multiple finger defects. The two flaps used were the superficial branch of the radial artery (SUPBRA) flap and hypothenar free flap. Seven syndactylized glabrous free flaps were used to cover the defects in 16 fingers. The functional results and complaints were also assessed. Mean flap size was 14.35 cm2. Six flaps survived. Postoperative evaluation data were obtained for the 13 fingers. All the patients returned to their previous work. All patients had a diminished protective sensation of at least 4.31 according to the SWM test. The mean two-point discrimination score of the patients was 9.9 mm (7-14). One finger had a PIP joint flexion contracture of 30°, no donor-site complaints were observed. The advantages of these flaps include single operation site, strong glabrous tissue coverage, low risk of flexion contracture, and adequate tissue size for large defects. Disadvantages include two-stage and complex microsurgical operations, prolonged treatment, and hospital stay.

Nonbacterial thrombotic endocarditis of mitral valve associated with a lymphoproliferative malignancy: case report and literature review

BackgroundNon-bacterial thrombotic endocarditis (NBTE) is a rare condition marked by sterile vegetations on cardiac valves, often linked to rheumatologic diseases, autoimmune disorders, and advanced solid malignancies. An early diagnosis and treatment of the associated clinical condition are mandatory, although they do not usually eliminate valvular vegetations, making anticoagulation essential to prevent embolic events. Despite variability, the prognosis of NBTE is usually unfavorable due to recurrent embolic events and the severity of the primary condition, typically advanced cancer.Case presentationWe present a case of a 57 years-old male who presented to the emergency department with a 5-day history of painful bilateral digital edema and color change episodes (from pallor to cyanosis). Physical examination revealed erythrocyanosis in the distal extremities, prompting consideration of secondary Raynaud syndrome.Despite medical therapy, progressive digital ischemia led to multiple finger amputations. During etiological investigation, anticoagulation tests and autoimmune analysis yielded negative results. A transesophageal echocardiogram was performed, revealing an irregular hyperechogenic mass on the anterior leaflet of the mitral valve without valve dysfunction, and a thoracic computed tomography scan with contrast showed an enlarged right paratracheal lymph node. Histopathological analysis from a transthoracic needle biopsy of the paratracheal lymph node revealed diffuse large B-cell lymphoma. The patient underwent aggressive R-CHOP chemotherapy, achieving a favorable complete response.ConclusionThis is a particular case involving the occurrence of NBTE and Raynaud phenomenon as the initial paraneoplastic manifestations in a previously healthy young man. Reports of NBTE associated with lymphoproliferative conditions are quite rare, with fewer than ten cases described in the literature. To our knowledge, this is the first case of NBTE specifically associated with diffuse large B-cell lymphoma.

Modulation of Motor Cortical Inhibition and Facilitation by Touch Sensation from the Glabrous Skin of the Human Hand.

Touch sensation from the glabrous skin of the hand is essential for precisely controlling dexterous movements, yet the neural mechanisms by which tactile inputs influence motor circuits remain largely unexplored. By pairing air-puff tactile stimulation on the hand's glabrous skin with transcranial magnetic stimulation (TMS) over the primary motor cortex (M1), we examined the effects of tactile stimuli from single or multiple fingers on corticospinal excitability and M1's intracortical circuits. Our results showed that when we targeted the hand's first dorsal interosseous (FDI) muscle with TMS, homotopic (index finger) tactile stimulation, regardless of its point (fingertip or base), reduced corticospinal excitability. Conversely, heterotopic (ring finger) tactile stimulation had no such effect. Notably, stimulating all five fingers simultaneously led to a more pronounced decrease in corticospinal excitability than stimulating individual fingers. Furthermore, tactile stimulation significantly increased intracortical facilitation (ICF) and decreased long-interval intracortical inhibition (LICI) but did not affect short-interval intracortical inhibition (SICI). Considering the significant role of the primary somatosensory cortex (S1) in tactile processing, we also examined the effects of downregulating S1 excitability via continuous theta burst stimulation (cTBS) on tactile-motor interactions. Following cTBS, the inhibitory influence of tactile inputs on corticospinal excitability was diminished. Our findings highlight the spatial specificity of tactile inputs in influencing corticospinal excitability. Moreover, we suggest that tactile inputs distinctly modulate M1's excitatory and inhibitory pathways, with S1 being crucial in facilitating tactile-motor integration.

A Comparison of Patient Characteristics and Outcomes Between Patients Receiving Flexor Digitorum Superficialis Slip Excision or Isolated A1 Pulley Release for Trigger Finger

Resection of the radial or ulnar slip of the flexor digitorum superficialis (FDS) tendon is a known treatment option for persistent trigger finger. Risk factors for undergoing FDS slip excision are unclear. We hypothesized that patients who underwent A1 pulley release with FDS slip excision secondary to persistent triggering would have a higher comorbidity burden compared to those receiving A1 pulley release alone. We identified all adult patients who underwent A1 pulley release with FDS slip excision because of persistent triggering either intraoperatively or postoperatively from 2018 to 2023. We selected a 3:1 age- and sex-matched control group who underwent isolated A1 pulley release. Charts were retrospectively reviewed for demographics, selected comorbidities, trigger finger history, and postoperative course. We performed multivariable logistic regression to assess the probability of FDS slip excision after adjusting for several variables that were significant in bivariate comparisons. We identified 48 patients who underwent A1 pulley release with FDS slip excision and 144 controls. Our multivariable model showed that patients with additional trigger fingers and a preoperative proximal interphalangeal (PIP) joint contracture were significantly more likely to undergo FDS slip excision. Patients who underwent A1 pulley release with FDS slip excision were significantly more likely to have multiple trigger fingers or a preoperative PIP joint contracture. Clinicians should counsel patients with these risk factors regarding the potential for FDS slip excision in addition to A1 pulley release to alleviate triggering of the affected digit. Therapeutic III.

Heart rate variability and cold-induced vascular dilation after stimulation of two different areas of the ear: a prospective, single-blinded, randomized crossover study

BackgroundBoth noninvasive transauricular vagus nerve stimulation (taVNS) and traditional medical practice (TMP), such as auriculotherapy, use the auricle as a starting point for stimulation, but with two different conceptual frameworks: taVNS depends on vagal afferences to account for its effects, whereas TMP requires stimulation of the ear with high topographical accuracy regardless of the afferent nerves. The aim of this study was to measure heart rate variability (HRV) and cold water–induced vasodilation (CIVD) after puncturing two different ear points with the same afference but that should have opposite effects according to TMP.MethodsTen healthy subjects were investigated in this single-blinded crossover study over three sessions. In the first session, sympathetic activation was performed via cold water immersion of the right hand, with recordings taken from multiple fingers. HRV was assessed in the time domain (square root of the mean squared differences of NN intervals (RMSSD)) and frequency domain (low (LF) and high frequencies (HF)). In the second and third sessions, the same skin immersion test was performed, and mechanical stimulation was applied to the ear at two different points on the internal surface of the antitragus, one with alleged parasympathetic activity and the other with alleged sympathetic activity. The stimulation was done with semipermanent needles.ResultsStimulation of the point with alleged parasympathetic activity immediately resulted in a significant decrease in RMSSD in 75% of the subjects and in LF in 50% of the subjects, while stimulation of the point with alleged sympathetic activity resulted in an increase in HF and RMSSD in 50% of the subjects. Stimulation of these points did not affect the CIVD reflex. The 20 min cold water immersion induced an immediate decrease in LF and the LF/HF ratio and an increase in HF. The skin temperature of the nonimmersed medius significantly decreased when the contralateral hand was immersed, from 34.4 °C to 31.8 °C.ConclusionsStimulation of two different ear points innervated by the same afferent nerves elicited different HRV responses, suggesting somatotopy and a vagal effect beyond vagal afferences. These results are not in accordance with the claims of TMP.Trial registrationNCT04130893 (18/10/2019) clinicaltrials.com.

Ultrasonographic Diagnosis of Finger Flexor Tendon Hypoplasia in a Child with Phalangeal Agenesis

Agenesis and hypoplasia affecting multiple flexor tendons within the same hand represent an exceedingly uncommon occurrence, with no previous studies addressing this condition. This report details a 4-year-old girl with agenesis of the right third and fourth fingers, who sought consultation due to the inability to flex her seemingly unaffected second and fifth fingers. Ultrasound examination revealed substantial thinning of the flexor tendons in the second to fifth digits, with a notable absence of attachment to the middle phalanx. In addition to flexor tendon hypoplasia, hypoplasia of the third and fourth middle phalanges was observed. Hand deformities featuring both finger agenesis and flexor tendon hypoplasia across multiple fingers were exceptionally rare. In such instances, ultrasound, in conjunction with radiography, emerges as the recommended initial imaging tool for comprehensive evaluation of both the phalangeal bones and flexor tendons.

Retrograde Percutaneous Release of Trigger Finger or Thumb Using Sono-Instruments®: Detailed Technique, Pearls, and Pitfalls.

Percutaneous release is a common treatment option for trigger finger stenosing tenosynovitis. While surgical and conservative treatments are available, percutaneous techniques offer several advantages, including faster recovery time, reduced complications, and simultaneous treatment of multiple trigger fingers. The sono-instrument is a minimally invasive device designed for surgical release of the A1 pulley in adults. The device is efficient and safe, and in addition, several design features enhance the visibility of the instrument under ultrasound imaging. The technique is truly percutaneous, as the whole operation is done through a single needle puncture. This minimizes postoperative discomfort and allows an immediate return to daily living and professional activities. The technique can be performed in an outpatient clinic under local anesthesia. The learning curve is quick; however, surgeons must acquire experience in hand sonography to master this new form of surgery. The aim of this article is to provide an in-depth exposition of the technical nuances, pearls, and pitfalls of this novel retrograde percutaneous release method. To our knowledge, this is the first retrograde truly percutaneous release technique yet described, facilitated by the novel Sono-Instruments®.

A smooth surface measurement method by flexible contact using multiple fingers device

Contact measurement technology is commonly used for analysis and modeling of three-dimensional (3D) object. This paper presents a contact measurement method, using a claw type probe based on a set of rotary encoders that can flexibly contact objects with efficiently multi-lines scanning. In this paper, a 3D measurement system by flexible contact of multiple fingers was built. The claw probe was set on a coordinate measurement machine. By moving the position of the claw for interpolation detection to improve the sampling rate, higher precision 3D reconstruction was achieved. Also, a compensation algorithm was proposed for this type detector to improve measuring accuracy. In the experiments, two surface models were produced by 3D printing as the test objects. By comparing the designed surface with the reconstructed surface, it is demonstrated that this system can effectively and softly measure smooth surface, like the back of human body, which is valuable for further study and use in rehabilitation massage, apparel design, and etc.

Two-finger Stiffness Discrimination with the Stochastic Resonance Effect

We investigated the ability of two fingers to discriminate stiffness with stochastic resonance. It is known that the haptic perception at the fingertip improves when vibrotactile noise propagates to the fingertip, which is a phenomenon called the stochastic resonance. The improvement in the haptic sensation of a fingertip depends on the intensity of the noise propagating to the fingertip. An improvement in the haptic sensation of multiple fingertips does not require multiple noise sources, such as vibrators, to be attached to multiple fingertips; i.e., even a single vibrator can propagate noise to multiple fingers. In this study, we focus on stiffness discrimination as a task using multiple fingers, in which the thumb and index finger are used to touch an object and perceive its stiffness. Subsequently, we demonstrate that the stiffness perception is improved by propagating sufficiently intense noise to the thumb and index finger using only a single vibrator. The findings indicate the possibility of improving the haptic sensation at multiple fingertips using one vibrator.

Continuous Kalman Estimation Method for Finger Kinematics Tracking from Surface Electromyography.

Deciphering hand motion intention from surface electromyography (sEMG) encounters challenges posed by the requisites of multiple degrees of freedom (DOFs) and adaptability. Unlike discrete action classification grounded in pattern recognition, the pursuit of continuous kinematics estimation is appreciated for its inherent naturalness and intuitiveness. However, prevailing estimation techniques contend with accuracy limitations and substantial computational demands. Kalman estimation technology, celebrated for its ease of implementation and real-time adaptability, finds extensive application across diverse domains. This study introduces a continuous Kalman estimation method, leveraging a system model with sEMG and joint angles as inputs and outputs. Facilitated by model parameter training methods, the approach deduces multiple DOF finger kinematics simultaneously. The method's efficacy is validated using a publicly accessible database, yielding a correlation coefficient (CC) of 0.73. With over 45,000 windows for training Kalman model parameters, the average computation time remains under 0.01 s. This pilot study amplifies its potential for further exploration and application within the realm of continuous finger motion estimation technology.