Finger Joints 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.

Patterns of osteoarthritis in long finger joints: an observational cadaveric study with potential biomechanical considerations

PurposeTo explore the distribution and prevalence of osteoarthritis in metacarpophalangeal, proximal interphalangeal and distal interphalangeal joints in long fingers in a cadaveric study, and to discuss potential biomechanical influences on these patterns. MethodsThis cadaveric study evaluated 144 metacarpophalangeal, proximal interphalangeal and distal interphalangeal joints from 12 embalmed cadaver hands. A dorsal dissection approach was used to expose the joints, which were then marked with color-coded pegs for consistent orientation during imaging. High-resolution digital images of the distal articular surfaces were captured for analysis. The images were analyzed using custom software to quantify osteoarthritic areas, distinguishing between radial and ulnar aspects. Percentage affected joint surface was calculated using pixel-based measurements. Statistical analysis was used the Student t-test and ANOVA, with the significance threshold set at p < 0.05 and 95% confidence intervals ResultsThe ulnar side of the proximal interphalangeal joint in digits 2 and 3 showed higher prevalence of osteoarthritis (59.31% ± 15.48%) than the radial side (40.68% ± 15.48%), p = 0.007; in contrast, for digits 4 and 5, prevalence was greater on the radial (54.3% ± 10.99%) than the ulnar side (45.7% ± 10.99%), p = 0.007. No significant differences were noted in osteoarthritis distribution between the radial and ulnar aspects of the metacarpophalangeal and distal interphalangeal joints. ConclusionsThis study identified distinct patterns of osteoarthritis distribution in long-finger joints, with greater prevalence in the proximal interphalangeal joints. Although there were differences between stable (digits 2 and 3) and mobile (digits 4 and 5) fingers, further research is necessary to conclusively determine the role of biomechanical forces in the development of osteoarthritis. These findings lay the groundwork for future studies of the pathophysiology of osteoarthritis in the hand, and could guide the development of preventive and therapeutic interventions.

Theoretical and experimental studies on the bending properties of glued laminated timber manufactured with Chinese fir

China has been increasingly promoting the use of prefabricated timber structure buildings in recent years. However, unlike other countries, China lacks a diverse range of local tree species and engineered wood products suitable for load-bearing components in timber structures. This shortage poses a risk to the sustainable development of timber structures in China. This issue is addressed in this study, which focuses on the development and manufacture of glued laminated timber (GLT) using Chinese fir from plantation forests. The dynamic elastic modulus of 549 laminae was evaluated using the FAKOPP stress wave approach. A total of 28 laminae were randomly selected from Classes I, II, and III to assess the influence of stress grading on bending performance. This study included an analysis of failure modes, bending capacity, and the prediction model for bending stiffness of GLT with different layups and cross-sectional heights. The findings showed that the dynamic elastic modulus of the laminae followed a normal distribution. The bending strength and modulus of elasticity of finger-jointed laminae across different grades were 29.59 MPa to 37.05 MPa and 8.13 GPa to 10.94 GPa, respectively. The mechanical properties of both same-grade and mixed-grade composition GLT manufactured from Chinese fir met the TCT28 (MOR≥28 MPa, MOE≥8000 MPa) and TCYD24 (MOR ≥ 24 MPa, MOE ≥ 8000 MPa) garde requirements in GB/T26889, respectively. Failure modes in the GLT specimens typically began at the knots or finger joints of the bottom layer laminae. The cross-sectional height had no significant effect on the modulus of elasticity of GLT but exerted a significant effect on bending strength. The prediction model for bending stiffness, developed using the transformed section method, agreed with the experimental results. The outcome of this research provides a scientific and data-driven foundation for the application of Chinese fir in the field of structural materials.

Reconstruction of Chronic Soft Tissue Mallet Fingers: Outcomes of Step-Plasty vs. Purse-String Suture.

After failed conservative therapy or in the absence of any intervention, a rupture of the digital subcutaneous extensor tendon at the distal interphalangeal (DIP) joint, known as mallet finger, may lead to a chronic extension deficit due to excessive scarring and tendon elongation. Various surgical techniques to restore the extension of the distal phalanx have been proposed, but an optimal approach has not yet been established. To tighten the extensor tendon, a purse-string suture can be applied. Although it has shown efficacy, it can result in significant bulging and scar formation. Using the "abbreviato" technique, the elongated part of the extensor tendon is excised, and the tendon is re-sutured. Also, tenodesis has been described, particularly in pediatric cases. In this retrospective follow-up study, we aimed to investigate if the step-plasty procedure previously described by Baumeister provides comparable, if not superior, functional and aesthetic outcomes compared to existing techniques for patients with chronic mallet finger. In this retrospective study, a consecutive series of 68 patients with chronic mallet fingers was enrolled. Patients were treated surgically using step-plasty of the respective extensor tendon. After skin incision and tenolysis, the elongated extensor tendon was incised in a Z-like fashion and stepwise resected in the transverse portion of the Z. The functional and aesthetic effects of this step-plasty technique were compared with results of 44 patients previously treated using purse-string sutures of the extensor tendon and evaluated using Crawford's and Levante's criteria. In all patients undergoing the step-plasty procedure, the extension deficit was significantly reduced from an average of 42 degrees preoperatively to 11 degrees postoperatively. In contrast, the control group treated by purse-string sutures showed a slightly higher postoperative extension deficit of 15 degrees. According to Levante's criteria, the results of our step-plasty procedure were significantly better than those achieved with purse-string sutures. Our study demonstrated that the treatment of older or chronic subcutaneous extensor tendon ruptures using the step-plasty technique led to a significant reduction in extension deficits. According to Levante's criteria, the postoperative outcome was significantly better in comparison to the purse-string suture technique. Additionally, no skin resection was required to improve the extension capability of the distal finger joint, compared to established surgical procedures.

The Adhesion Performance in Green-Glued Finger Joints Using Different Wood Ring Orientations

Structural lumber is designed to meet the technical standards that ensure safety, cost-effectiveness, and sustainability. However, some tree species face limitations in their growth, which restricts their widespread use. An example of this is Nothofagus alpina, which has excellent mechanical properties but is not utilized much due to the challenges in extracting its timber and poor utilization, mainly because of the length of the wood. There is little information concerned with the uses and better management of small pieces using Nothofagus species, but it is still insufficient. This study investigates the adhesion performance of green-glued finger joints with varying wood ring orientations and moisture contents ranging from 21% to 25% using Nothofagus alpina. The primary aim is to assess how ring orientation and wet timber affect the green gluing process for creating larger wood pieces than sawn wood. The resulting products could meet the standards for wood serviceability number three for native Chilean wood. The findings indicate that finger joint performance improves with higher timber moisture levels. However, the orientation of the wood fibers did not significantly affect the performance under the tested conditions. It is important to note that this effect may become more significant near the fiber saturation point. These findings emphasize the need for a detailed protocol on the green gluing technique for Nothofagus alpina and the associated drying and surface processes in finger joint construction.

SCTNET: Shifted Windows and Convolution Layers Transformer for Continuous Angle Estimation of Finger Joints Using sEMG

SCTNET: Shifted Windows and Convolution Layers Transformer for Continuous Angle Estimation of Finger Joints Using sEMG

Effectiveness of mixed reality-based rehabilitation on hands and fingers by individual finger-movement tracking in patients with stroke

BackgroundMixed reality (MR) is helpful in hand training for patients with stroke, allowing them to fully submerge in a virtual space while interacting with real objects. The recognition of individual finger movements is required for MR rehabilitation. This study aimed to assess the effectiveness of updated MR-board 2, adding finger training for patients with stroke.MethodsTwenty-one participants with hemiplegic stroke (10 with left hemiplegia and 11 with right hemiplegia; nine female patients; 56.7 ± 14.2 years of age; and onset of stroke 32.7 ± 34.8 months) participated in this study. MR-board 2 comprised a board plate, a depth camera, plastic-shaped objects, a monitor, a palm-worn camera, and seven gamified training programs. All participants performed 20 self-training sessions involving 30-min training using MR-board 2. The outcome measurements for upper extremity function were the Fugl–Meyer assessment (FMA) upper extremity score, repeated number of finger flexion and extension (Repeat-FE), the thumb opposition test (TOT), Box and Block Test score (BBT), Wolf Motor Function Test score (WMFT), and Stroke Impact Scale (SIS). One-way repeated measures analysis of variance and the post hoc test were applied for the measurements. MR-board 2 recorded the fingers’ active range of motion (AROM) and Dunnett’s test was used for pairwise comparisons.ResultsExcept for the FMA-proximal score (p = 0.617) and TOT (p = 0.005), other FMA scores, BBT score, Repeat-FE, WMFT score, and SIS stroke recovery improved significantly (p < 0.001) during MR-board 2 training and were maintained until follow-up. All AROM values of the finger joints changed significantly during training (p < 0.001).ConclusionsMR-board 2 self-training, which includes natural interactions between humans and computers using a tangible user interface and real-time tracking of the fingers, improved upper limb function across impairment, activity, and participation. MR-board 2 could be used as a self-training tool for patients with stroke, improving their quality of life.Trial registration number: This study was registered with the Clinical Research Information Service (CRIS: KCT0004167).

A home-based hand rehabilitation platform for hemiplegic patients after stroke: A feasibility study

BackgroundPatients with stroke often experience weakened upper limbs, making daily tasks difficult to perform. Although rehabilitation devices are available, patients often relapse post-discharge due to insufficient practice. We present a home-based hand telerehabilitation intervention using the iManus™ platform comprising a sensorized glove, a mobile app for the patients, and a therapist portal for monitoring patient progress. ObjectivesThis research aimed to examine the feasibility, safety, and effectiveness of a home-based telerehabilitation intervention in improving hand function for individuals with mild stroke. A qualitative approach was also used to explore users' experiences, perceived benefits, and challenges associated with using the platform in a home setting. MethodsIn this single-case study, we delivered a hand telerehabilitation intervention to a chronic stroke patient with impaired hand function using the iManus™ platform. The intervention consisted of 40 home sessions over eight weeks. We assessed feasibility through user adherence and feedback obtained using a System Usability Scale (SUS) and a semi-structured interview with the participant and their informal caregiver. Safety was evaluated by monitoring pain levels using the Visual Analog Scale (VAS), and efficacy was determined by observing the changes in the fingers’ range of motion using the iManus™ platform and clinical outcomes measures, namely the Fugl-Meyer Assessment (FMA) and Jebsen Taylor Hand Function Test (JTHFT). ResultsOur participant completed all the assigned sessions, with each averaging 20 min. Usability scored 77.5 out of 100 on the SUS. User feedback from the interviews revealed improved mobility and control over therapy as benefits, indicating room for improvement in the intervention's adaptability and functionality. During the intervention, the participant noted no pain increase, and the telerehabilitation platform recorded range of motion improvements for all finger and wrist joints, excluding wrist extension. The FMA scores were 43 at T0, 53 at T1, and 56 at T2, while the JTHFT scores were 223 at T0, 188 at T1, and 240 at T2. ConclusionsThis single case study demonstrated the preliminary feasibility, safety, and efficacy of a novel home-based hand intervention for stroke survivors. The participant showed improved hand functions, good adherence to the program, and reported satisfaction with the intervention. However, these results are based on a single-case study, and further large-scale studies are needed before any generalization is recommended.

Bio-Inspired Photoelectric Dual-Mode Sensor Based on Photonic Crystals for Human Motion Sensing and Monitoring.

Photoelectric dual-mode sensors, which respond to strain signal through photoelectric dual-signals, hold great promise as wearable sensors in human motion monitoring. In this work, a photoelectric dual-mode sensor based on photonic crystals hydrogel was developed for human joint motion detection. The optical signal of the sensor originated from the structural color of photonic crystals, which was achieved by tuning the polymethyl methacrylate (PMMA) microspheres diameter. The reflective peak of the sensor, based on 250 nm PMMA PCs, shifted from 623 nm to 492 nm with 100% strain. Graphene was employed to enhance the electrical signal of the sensor, resulting in a conductivity increase from 9.33 × 10-4 S/m to 2 × 10-3 S/m with an increase in graphene from 0 to 8 mg·mL-1. Concurrently, the resistance of the hydrogel with 8 mg·mL-1 graphene increased from 160 kΩ to 485 kΩ with a gauge factor (GF) = 0.02 under 100% strain, while maintaining a good cyclic stability. The results of the sensing and monitoring of finger joint bending revealed a significant shift in the reflective peak of the photoelectric dual-mode sensor from 624 nm to 526 nm. Additionally, its resistance change rate was measured at 1.72 with a 90° bending angle. These findings suggest that the photoelectric dual-mode sensor had the capability to detect the strain signal with photoelectric dual-mode signals, and indicates its great potential for the sensing and monitoring of joint motion.

Machine-Learning-Based Accurate Finger Joint Stiffness Estimation With Joint Modular Soft Actuators

Machine-Learning-Based Accurate Finger Joint Stiffness Estimation With Joint Modular Soft Actuators

The Normal Active Range of Motion of the Index, Middle, Ring, and Little Fingers in a Sample of Indian Population.

Background The normative data for finger range of motion (ROM) are not available for the Indian population. The aim of our study was to measure the active ROM of finger joints in normal healthy volunteers in a sample of Indian population. Materials and Methods This is a prospective observational study conducted as a part of the Indian normative data project of the Indian Society for Surgery of the Hand (ISSH). The study included one participating center from four geographical regions of the country. Certified goniometers were used to measure the ROM of fingers in all centers. A standardized methodology was devised. A pilot study was done to assess the interobserver and intraobserver reliability, following which data were collected by one measurement. Results This pilot study was performed in 20 hands that showed good interobserver and intraobserver reliability correlation. A total of 390 hands were measured in four participating centers. Active flexion of metacarpophalangeal (MCP) joint was the highest in the middle finger (86.6 ± 10.4 degrees) followed by the index finger (86.0 ± 9.2 degrees), little finger (85.0 ± 8.4 degrees), and ring finger (84.2 ± 8.6 degrees). The index finger (97.2 ± 16.9 degrees) showed maximum proximal interphalangeal (PIP) joint flexion followed by the middle finger (96.2 ± 15.8 degrees), ring finger (96.0 ± 15.9 degrees), and little finger (91.8 ± 12.7 degrees). Distal interphalangeal (DIP) joint flexion increased from the index finger (81.6 ± 13.9 degrees) to the little finger (84.6 ± 12.9 degrees). The little finger MCP joint (26.3 ± 6.2 degrees) showed maximum extension followed by the index finger (25.7 ± 6.8 degrees), middle finger (24.7 ± 6.7 degrees) and ring finger (22.3 ± 7.1 degrees). The middle finger (15.6 ± 8.1 degrees) and ring finger (16.2 ± 8 degrees) had more PIP joint extension when compared to the index (13.7 ± 7.8 degrees) and little finger (13.2 ± 8.4 degrees). The ring finger (8.1 ± 6.8 degrees) and the middle finger (8.4 ± 6.9 degrees) had more DIP joint extension when compared with the index finger (6.0 ± 6.0 degrees) and the little finger (6.8 ± 6.7 degrees). Total active motion (TAM) of the middle finger (315.9 ± 31.0 degrees) was the maximum followed by the index finger (310.2 ± 27.3 degrees), ring finger (308.8 ± 29.1 degrees), and little finger (307.8 ± 25.2 degrees). Gender, body mass index (BMI), mother tongue, geographical location, and occupation were factors that had significant correlation, while no significant differences based on side, hand dominance, and age were noted. Conclusion We have reported normative data of finger ROM and TAM for the index, middle, ring, and little fingers in the Indian population. Finger ROM in the Indian population is highly variable. The observed TAM in the Indian population is higher than what is reported earlier.

Verification of grip strength as an evaluation tool for locomotive syndrome in rheumatoid arthritis

ObjectivesLocomotive syndrome (LS) leads to reduced physical function and a high risk of becoming bedridden. Grip strength serves as an indicator of upper limb and overall physical function. Rheumatoid arthritis (RA) patients with reduced grip strength frequently show finger and wrist joint inflammation. The purpose of this study was to verify grip strength as an evaluation tool for physical function and LS in RA patients. MethodsAs part of an ongoing multicenter observational study, 591 consecutive RA patients whose background information was available, including data for the 25-question Geriatric Locomotive Function Scale (GLFS-25) and grip strength, were examined. LS was defined as a GLFS-25 score ≥ 16 points. Finger and wrist joint inflammation were defined as tender or swollen joints. ResultsAmong the 591 patients, 244 (41.3%) patients had LS, and 167 (28.3%) were male. Receiver operating characteristic curve analysis yielded cut-off values of grip strength for LS of 24 kg (specificity 72.2%; sensitivity 62.7%) for males and 17 kg (specificity 65.7%; sensitivity 67.6%) for females. Multivariable logistic regression analysis revealed a significant association of grip strength with LS, even after adjusting for finger and wrist joint inflammation. ConclusionsLS was significantly associated with grip strength, even after adjusting for the presence of finger and wrist joint inflammation. We recommend adopting grip strength measurement as a screening tool for evaluating LS and guiding interventions.

Results of Tendon Transfers in Radial Nerve Palsies: A New Evaluation Protocol.

Radial nerve palsies present a challenging clinical scenario, often leading to substantial functional impairment. This study focuses on evaluating the outcomes of tendon transfer surgeries in patients with post-traumatic radial nerve injuries. The radial nerve, vital for upper limb movements, faces various etiologies, such as trauma, compression, or idiopathy. Patients with radial nerve palsy encounter difficulties in daily activities, emphasizing the need for effective management strategies. The research introduces a novel evaluation protocol, aiming to comprehensively assess tendon transfer outcomes. This protocol incorporates functional movements of wrist and finger joints, encompassing both objective and subjective parameters. The retrospective study includes eleven patients treated between 2010 and 2022, with a minimum follow-up of one year post-surgery. Tendon transfers demonstrated positive results. The evaluation protocol covers a wide range of parameters, including wrist and finger mobility, thumb function, grip strength, and patient satisfaction. The results indicate successful restoration of motor function, with an average grip strength of 70% compared to the healthy arm. The proposed evaluation protocol facilitates standardized and reproducible assessment, minimizing subjective errors in clinical evaluations. Despite the study's limitations, such as a relatively small sample size, the findings underscore the effectiveness of tendon transfers in treating radial nerve palsies. The introduced evaluation scheme provides a comprehensive and reproducible approach to assess outcomes, contributing to the global standardization of tendon transfer assessments in radial nerve injuries.

Ultrasonographic findings in diabetic cheiroarthropathy: a pilot study

Objective Diabetic cheiroarthropathy (DCA) is one of the musculoskeletal manifestations of diabetes mellitus. It is clinically diagnosed using the prayer and tabletop signs. The clinical appearance, however, mimics autoimmune-mediated polyarthritis of the hands and fingers. It is therefore crucial to positively identify DCA patients. Method We used high-frequency B-mode ultrasound to investigate 14 patients with DCA and seven non-DCA diabetics with anti-cyclic citrullinated peptide antibody-positive rheumatoid arthritis (RA). We recorded the frequency of synovitis in radiocarpal, metacarpophalangeal, and proximal interphalangeal joints, the presence of tenosynovitis of the finger flexor tendons, echogenicity of the synovia and the flexor tendon sheaths, and soft tissue alterations in the digits. We compared our findings between groups to determine sonographic characteristics of DCA. Results A low rate of small finger joint involvement in the presence of a high rate of finger flexor tendinopathy showed a high association with DCA in correlation (p = 0.002) and regression analysis (p < 0.001). Tendon sheaths were significantly more often hyperechoic and proliferative in DCA compared to RA (p = 0.008), and hypoechoic soft tissue alterations were almost exclusively seen in DCA patients (p = 0.003). Radiocarpal joint involvement and its echogenicity did not differ between groups. Conclusion Ultrasonography shows typical features in DCA, and is capable of discriminating DCA from non-DCA patients with RA and diabetes.

Adjuvant Treatment with Celecoxib after Collagenase Injection for Dupuytren Contracture: A Double-Blind Randomised Controlled Trial.

Background: In patients with a high recurrence risk after treatment for Dupuytren contracture (DC) by Collagenase Clostridium histolyticum (CCH), adjuvant medical therapy may improve the outcome. Non-steroidal anti-inflammatory drugs have been used in the treatment of similar fibroproliferative processes. The aim of this study was to investigate if adjuvant anti-inflammatory medication could improve the outcome of CCH treatment for DC. Methods: In a prospective double blinded randomised trial, the effect of adjuvant peroral celecoxib on the outcome of DC treated with CCH was investigated in 32 patients with a high fibrosis diathesis. Primary outcome was the increase in Total Passive Extension Deficit (TPED)/ray. Secondary outcomes were the TPED of the individual finger joints, Tubiana index, Disability of Arm, Shoulder and Hand score (DASH) and visual analogue scale (VAS) for pain and satisfaction. Results: A significantly greater improvement in the celecoxib group for TPED and metacarpophalangeal contracture was found. For the proximal interphalangeal joint, the effect was much less pronounced. The VAS for pain and satisfaction were better at 6 and 12 weeks in the celecoxib group. The other outcome parameters did not significantly differ between both groups. Conclusions: Adjuvant peroral administration of celecoxib might improve the gain in TPED after treatment with CCH in patients with DC and a high fibrosis diathesis, with a beneficial effect up to 24 months. Level of Evidence: Level II (Therapeutic).

Stretchable glove for accurate and robust hand pose reconstruction based on comprehensive motion data

We propose a compact wearable glove capable of estimating both the finger bone lengths and the joint angles of the wearer with a simple stretch-based sensing mechanism. The soft sensing glove is designed to easily stretch and to be one-size-fits-all, both measuring the size of the hand and estimating the finger joint motions of the thumb, index, and middle fingers. The system was calibrated and evaluated using comprehensive hand motion data that reflect the extensive range of natural human hand motions and various anatomical structures. The data were collected with a custom motion-capture setup and transformed into the joint angles through our post-processing method. The glove system is capable of reconstructing arbitrary and even unconventional hand poses with accuracy and robustness, confirmed by evaluations on the estimation of bone lengths (mean error: 2.1 mm), joint angles (mean error: 4.16°), and fingertip positions (mean 3D error: 4.02 mm), and on overall hand pose reconstructions in various applications. The proposed glove allows us to take advantage of the dexterity of the human hand with potential applications, including but not limited to teleoperation of anthropomorphic robot hands or surgical robots, virtual and augmented reality, and collection of human motion data.

Influence of finger joint length on the elastic modulus of reconstituted wood from Pinus taeda L.

The aim of this study was to evaluate the influence of three finger joint splice lengths on the dynamic modulus of elasticity of pieces of reconstituted wood from Pinus taeda L. Wooden specimens had finger joint splices of 5, 7 and 15 mm in length and were evaluated using the Stress Wave Time equipment, to analyze the wave propagation speed and dynamic modulus of elasticity, as well as the density of the pieces. As a result, increasing the finger joint’s length did not reduce the wave propagation speed through the wooden specimen. On the other hand, there was a reduction in the strength of the spliced wood as the much as the length of the finger joint increased. The density of the material may have influenced the reduction in the modulus of elasticity, even if it did not interfere with the wave propagation speed through the specimen.

An atlas of causal association between micronutrients and osteoarthritis

ObjectiveThis study examines the causal relationships between serum micronutrients and site-specific osteoarthritis (OA) using Mendelian Randomization (MR). MethodsThis study performed a two-sample MR analysis to explore causal links between 21 micronutrients and 11 OA outcomes. These outcomes encompass overall OA, seven site-specific manifestations, and three joint replacement subtypes. Sensitivity analyses using MR methods, such as the weighted median, MR-Egger, and MR-PRESSO, assessed potential horizontal pleiotropy and heterogeneity. Genome-wide association summary statistical data were utilized for both exposure and outcome data, including up to 826,690 participants with 177,517 OA cases. All data was sourced from Genome-wide association studies datasets from 2009 to 2023. ResultsIn the analysis of associations between 21 micronutrients and 11 OA outcomes, 15 showed Bonferroni-corrected significance (P < 0.000216), without significant heterogeneity or horizontal pleiotropy. Key findings include strong links between gamma-tocopherol and spine OA (OR = 1.70), and folate with hand OA in finger joints (OR = 1.15). For joint replacements, calcium showed a notable association with a reduced likelihood of total knee replacement (TKR) (OR = 0.52) and total joint replacement (TJR) (OR = 0.56). Serum iron was significantly associated with an increased risk of total hip replacement (THR) (OR = 1.23), while folate indicated a protective effect (OR = 0.95). Various sex-specific associations were also uncovered. ConclusionThese findings underscore the critical role of micronutrients in osteoarthritis, providing valuable insights for preventive care and potential enhancement of treatment outcomes.

A tendon-driven actuator with cantilever initiated variable stiffness used for robotic fingers

Variable stiffness actuators (VSAs) have emerged as a key actuation technology known for their bionic performance and task adaptability. However, current VSAs often exhibit relatively large sizes, making them possible for use in robotic arms and legs but less convenient for integrations into robotic hands. This paper introduces a compact design of a tendon-driven variable stiffness actuator (TVSA) based on an adjustable cantilever mechanism, which can be embedded into a robotic finger. This implementation endows the robotic finger with the independent regulation of joint position and stiffness. A concise and computationally efficient stiffness mapping model from the TVSA to the finger joints is then established, providing a theoretical foundation for the stiffness regulation of the tendon-driven fingers. A prototype of a robotic hand equipped with the presented TVSA demonstrates safe interactions with various objects of diverse shapes, weights and stiffness.