Leg Joints Research Articles

Friction Coefficient Evolution of Drying Lubricant in the Joints of Beetles by Friction Force Microscopy

Recent studies suggest that the joints of beetles and other insects comprise micro-structured surfaces in combination with lubricants. Here, we utilize friction force microscopy (FFM) to analyse the tribological properties of the femoro-tibial leg joints by the example of Coelorrhina aurata (metallic green flower beetle) and Otiorhynchus sulcatus (black vine weevil). To preserve the original state of the lubricant as well as the microstructures, the FFM measurements were conducted in silicone oil, which satisfies our requirements of transparency, customizable viscosity, absent health risks and lower density compared to the expected density of the lubricant. Microscopic friction was measured on fresh and air-dried samples to stress the change of the lubricant properties over time. Despite the similarity of the two beetle joints, the FFM measurements reveal different frictional properties of the respective lubricants.

Design and Experimental Study of Special Elastic Leg Joint for Quadruped Robots

Design and Experimental Study of Special Elastic Leg Joint for Quadruped Robots

Anti-arthritic Effects of Undifferentiated and Chondrogenic Differentiated MSCs in MIA-induced Osteoarthritis in Wistar Rats: Involvement of Oxidative Stress and Immune Modulation.

Osteoarthritis (OA) is a degenerative joint disease that can affect the many tissues of the joint. There are no officially recognized disease-modifying therapies for clinical use at this time probably due to a lack of complete comprehension of the pathogenesis of the disease. In recent years, emerging regenerative therapy and treatments with stem cells both undifferentiated and differentiated cells have gained much attention as they can efficiently promote tissue repair and regeneration. To determine how bone marrow-derived mesenchymal stem cells (BM-MSCs) and chondrogenic differentiated MSCs (CD-MSCs) can treat OA in rats, OA was induced in Wistar rats by injecting three doses of 100 μL physiological saline containing 1 mg of MIA into rat ankle joint of the right hind leg for three consecutive days. Following the induction, the osteoarthritic rats were injected weekly with BM-MSCs or CD-MSCs at a dose of 1x106 cells/rat/dose for three weeks. In addition to morphological and histological investigations of the ankle, spectrophotometric, ELISA, and Western blot analyses were applied to detect various immunological and molecular parameters in serum and ankle. The results of the study showed that in osteoarthritic rats, BM-MSCs and CD-MSCs significantly reduced right hind paw circumference, total leucocyte count (TLC), differential leukocyte count (DLC) of neutrophils, monocytes, lymphocytes, and eosinophils, serum rheumatoid factor (RF), prostaglandin E2 (PGE2) and interleukin (IL-) 1β levels, while they elevated serum IL-10 level. Additionally, BM-MSCs and CD-MSCs markedly reduced lipid peroxides (LPO) levels while they elevated superoxide dismutase (SOD) and glutathione-S-transferase (GST) activities. The monocyte chemoattractant protein-1 (MCP-1) level was significantly downregulated in ankle joint articular tissues by treatment with BM-MSCs or CD-MSCs while nuclear factor erythroid 2-related factor 2 (Nrf2) was upregulated; CD-MSCs treatment was more effective. According to these findings, it can be inferred that BM-MSCs and CD-MSCs have anti-arthritic potential in MIA-induced OA; CD-MSCs therapy is more effective than MSCs. The ameliorative anti-arthritic effects may be mediated by suppressing inflammation and oxidative stress through the downregulation of MCP-1 and upregulation of Nrf2. Based on the obtained results, BM-MSCs and CD-MSCs therapies are promising new options that can be associated with other clinical treatments to improve cartilage regeneration and joint healing. However, more preclinical and clinical research is required to assess the benefits and safety of treating osteoarthritic patients with BM-MSCs and CD-MSCs.

Assessment of four sterilization techniques for meniscal allograft transplantation in rabbits.

This study aimed to compare the effects of four sterilization techniques on meniscal allograft transplantation (MAT) in rabbits. In total, 85 medial or lateral meniscuses were obtained from 22 adult New Zealand white rabbits. These 85 meniscal allografts were seeded with Staphylococcus aureus (S. aureus) and randomly divided into five groups (n = 17): iodine group, Cobalt-60 group, glutaraldehyde group, ethylene oxide group and control group. Bacterial colonies of the allografts were determined before (n = 7) and after (n = 7) sterilization. Histological features were analyzed using haematoxylin and eosin (H&E) staining (n = 3). An additional 50 medial or lateral meniscuses were taken from 13 adult New Zealand white rabbits, and they were kept fresh-frozen (-40°C) for 1 month. Subsequently, these 50 meniscuses were randomly divided into five groups, which were treated with iodine, Cobalt-60, glutaraldehyde, ethylene oxide and normal saline, separately (n = 10), and stored at -20°C before MAT. MAT was given to the knee joints of the right hind legs of 50 adult Japanese white rabbits. After 6 weeks of MAT, the transplanted meniscal allografts were taken for biomechanical test (n = 7) and H&E staining (n = 3). The results of the bacterial count indicated that the number of S. aureus colonies was less than 1 colony-forming unit (CFU)/allograft in all five groups after sterilization, except for the control group (415 CFU/allograft). H&E staining revealed that allografts in the iodine group presented the complete structure; allografts in the Cobalt-60 and glutaraldehyde groups were preserved relatively well; and allografts in the control and ethylene oxide groups were severely destructed, especially in the ethylene oxide group. Using the transplanted allografts, the biomechanical test showed that the maximum load of allografts in each group was significantly different, with ethylene oxide effective sterilization agents being used for disinfecting meniscal grafts (iodine group: 270.71 ± 62.81 N, Cobalt-60 group: 182.14 ± 71.29 N, glutaraldehyde group: 254.29 ± 31.55 N, ethylene oxide group: 40.00 ± 22.73 N and control group: 183.14 ± 76.40) (p ≤ 0.001). H&E staining with transplanted allografts revealed that allografts in the iodine group had the most intact structure; allografts in the Cobalt-60 and glutaraldehyde groups presented a relatively intact structure; and allografts in the control and ethylene oxide groups were seriously damaged, especially in the ethylene oxide group. It was found that iodine, Cobalt-60, glutaraldehyde and ethylene oxide are effective sterilization agents for disinfecting meniscal grafts. Iodine exhibited superior preservation of both the biomechanics and structural integrity of the meniscal allografts, whereas ethylene oxide caused the most severe destruction to the meniscal allografts. Not applicable because this is an animal study.

Support leg joint kinetic determinants of maximal speed sprint performance

ABSTRACT This study aimed to comprehensively demonstrate support leg joint kinetic determinants of maximal speed sprint performance. Ground reaction forces and marker coordinates attached to the body were measured in the maximal speed phase from 44 male sprinters. Then, three-dimensional leg joint torque, angular velocity and power were calculated. Greater maximal running speed (9.47 ± 0.32 m/s) was correlated with greater mean hip extension (r = 0.354, p = 0.018) and flexion (r = −0.322, p = 0.033) and ankle plantar flexion torques (r = 0.464, p = 0.002), as well as greater ankle plantar flexion torque from 30% to 70% of the support phase (p < 0.001). Greater maximal running speed was associated with greater mean hip extension (r = 0.386, p = 0.010) and smaller knee extension velocities (r = −0.426, p = 0.004). Regarding joint torque power, greater maximal running speed was associated with greater mean positive (r = 0.416, p = 0.005) and negative (r = −0.390, p = 0.009) hip flexion – extension powers and positive (r = 0.642, p < 0.001) and negative (r = −0.512, p < 0.001) ankle plantar – dorsi flexion powers. Moreover, greater maximal speed was correlated with greater positive and negative ankle plantar – dorsi flexion powers from 21% to 39% (p < 0.001) and from 56% to 80% (p < 0.001), respectively, during the support phase. Understanding the joint kinetics related to maximal running speed will improve technical considerations and strength training direction for sprinters.

The metabolic cost of producing joint moments is greater at the hip than at the ankle.

Older adults walk using their hips relatively more and their ankles relatively less than young adults. This 'distal-to-proximal redistribution' in leg joint mechanics is thought to drive the age-related increase in metabolic rate during walking. However, many morphological differences between hip and ankle joints make it difficult to predict how, or whether, the distal-to-proximal redistribution affects metabolic rate during walking. To address this uncertainty, we compared the metabolic rate of participants while they repeatedly produced isolated hip and ankle moment cycles on a dynamometer following biofeedback. Overall, participants produced greater joint moments at their ankle versus hip and correspondingly activated their largest ankle extensor muscle more than their largest hip extensor muscle. Cycle average muscle activation across other hip and ankle extensors was nondifferent. Despite producing greater joint moments using slightly more relative muscle activation at the ankle, participants expended more net metabolic power while producing moments at the hip. Therefore, producing joint extension moments at the hip requires more metabolic energy than that at the ankle. Our results support the notion that the distal-to-proximal redistribution of joint mechanics contribute to greater metabolic rate during walking in older versus young adults.

Analysis of symptomatic differences in 391 patients with Brucella infections in different age groups

In order to investigate the clinical manifestations and laboratory findings associated with brucellosis for the purpose of facilitating prompt clinical diagnosis and effective treatment, as well as to offer a laboratory reference for the prevention of brucellosis outbreaks. In this study, a retrospective cohort design was employed to gather epidemiological characteristics, clinical symptoms, and associated laboratory data from 391 patients diagnosed with bacterial culture-positive brucellosis at the People's Hospital of Ningxia Hui Autonomous Region between 2019 and 2023. The patients were categorized into four age groups, with each group representing a 20 years age interval. Statistical analyses were conducted to examine the differences between these age groups using R version 4.3.2 and SPSS version 24.0 software. The results showed that among the 391 cases of brucellosis patients, fever (241 cases, 61.64%), lumbar and leg joint pain (225 cases, 57.54%), abnormal liver function (124 cases, 31.71%), spleen enlargement (78 cases, 19.95%), and cholecystitis (75 cases, 19.18%) were identified as the most prevalent clinical symptoms. Furthermore, the presence of clinical symptoms such as fever, lumbar and leg joint pain, abdominal pain and distension, headache, dizziness, rash, and complications including abnormal liver function, cholecystitis, spleen enlargement, exhibited statistical significance across four distinct age groups (P<0.05). The initial presentation of acute fever and rash was more pronounced in the pediatric cohort. In contrast, the youth group exhibited a higher prevalence of acute fever, liver function abnormalities, dizziness, headache, and splenomegaly. Furthermore, the strong-age group and the older age group more frequently experienced lumbar and leg joint pain, and symptoms related to the liver, gallbladder, spleen, and digestive system. In terms of laboratory examination, the rates of decreased white blood cell count (WBC), red blood cell count (RBC) and platelet count (PLT) were 18.91% (73 cases), 28.94% (112 cases) and 22.34% (86 cases), respectively. C-reactive protein (CRP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), total biluric acid (TBA), adenosine deaminase (ADA), alkaline phosphatase (ALP), glutamyl transpeptidase (GGT), procalcitonin (PCT), and D-Dimer (D-Dimer). The proportion of patients with elevated quantitative test results was 88.56% (271 cases), 50.90% (197 cases), 52.20% (202 cases), 23.82% (91 cases), 75.72% (290 cases), 23.06% (89 cases), 40.89% (157 cases), 68.34% (218 cases) and 73.33% (209 cases), respectively. Among them, the quantitative detection results of CPR, ALP and D-Dimer had statistical significance among the 4 age groups (χ2=16.366,28.089,7.880,P<0.05). Abnormally elevated laboratory parameters, including C-reactive protein (CRP), alkaline phosphatase (ALP), and D-dimer, were more pronounced in middle-aged and older cohorts, with a positive correlation to advancing age. Among the 391 brucella culture positive specimens, the top three departments with the highest number of isolations were infectious disease (52.4%, 204 cases), emergency (9.5%, 37 cases) and orthopedics (8.4%, 33 cases). In conclusion, the clinical manifestations of brucellosis are multifaceted and heterogeneous, frequently involving multiple organ systems, and the laboratory test results exhibit considerable variability. These findings indicate that clinicians should integrate clinical features of brucellosis with laboratory test results, considering the patient's age group, to enhance diagnostic accuracy and triage efficiency in suspected cases. Improving relevant diagnostic examinations can thereby aid in the effective control and prevention of the disease.

Design of 3 DOF hexapod leg movement using inverse kinematics: bridging gaps in multilegged robot kinematics literature

Designing the motion of a hexapod robot with 3 Degrees of Freedom (DOF) using the Inverse Kinematics method allows the robot to move by adjusting the angles of its leg joints according to the desired position and direction. This research involves the geometric and structural design of the hexapod robot and the development of an Inverse Kinematics algorithm to calculate the leg joint angles based on the target pose. The study uses the Inverse Kinematics method to design a hexapod robot for movement with 3 DOF. The testing results show an average Inverse Kinematics error of 1.56 mm on the X-axis, 0.88 mm on the Y-axis, and 0.78 mm on the Z-axis. During the forward and backward movement tests covering a distance of 100 cm, the average error was 2.58 cm and 12.38 cm, respectively. For the rotation tests, the average error was 3.6° for a 90° rotation to the right, 3° for a 90° rotation to the left, 13.2° for a 180° rotation to the right, and 3.8° for a 180° rotation to the left. The results indicate that the design of the 3DOF hexapod robot using the Inverse Kinematics method provides a sufficient level of accuracy in controlling movements along the X, Y, and Z axes. Despite some errors, the robot is capable of moving fairly accurately during forward, backward, and rotational movements.

Comparative Morphology of the Extrinsic and Intrinsic Leg Musculature in Dictyoptera (Insecta: Blattodea, Mantodea).

Insect legs, as primarily locomotory devices, can show a tremendous variety of morphological modifications providing a multitude of usages. The prehensile raptorial forelegs of praying mantises (Mantodea) are a prominent example of true multifunctionality since they are used for walking while being efficient prey-capturing and grasping devices. Although being mostly generalist arthropod predators, various morphological adaptations due to different environmental conditions occur across Mantodea. Recently, the general mantodean morphology, and particularly their raptorial forelegs, received an increased interest. Yet, knowledge about the evolutionary transition from walking to prey-grasping legs is still scarce. From evolutionary and functional perspectives, the question arises: what changes were necessary to achieve the strongly modified raptorial forelegs-while keeping walking ability-and how does the foreleg morphology differ from the remaining four walking legs? In this context, we investigated the musculature of the raptorial forelegs in seven phylogenetically distant mantodeans, including pterothoracic legs in four of them, using high-resolution microcomputed tomography and dissection. To understand the results from an evolutionary perspective, we additionally examined all three pairs of unmodified walking legs of the closest sister group-Blattodea. We updated the knowledge of blattodean morphology, revealing differences in cuticle structures of the coxal articulation of the first pair of legs between the two orders and a shared musculature set-up in all pairs of legs among later-branching mantodeans. Interestingly, the early branching species Metallyticus splendidus and Chaeteessa sp. show several muscular characteristics, otherwise found exclusively in one or the other order, with a few procoxal muscles showing an intermediate state between the two orders. Studying the evolutionary transition from a walking leg to a raptorial leg will help to understand the character evolution of this highly specialized biomechanical system from a purely locomotory appendage to a multi-functional device with all related amenities and constraints.

Inertial One-Leg Squat Training and Drop Jump Biomechanics in Athletes With Anterior Cruciate Ligament Reconstruction After Return to Sport.

Henderson, FJ and Shimokochi, Y. Inertial one-leg squat training and drop jump biomechanics in athletes with anterior cruciate ligament reconstruction after return to sport. J Strength Cond Res XX(X): 000-000, 2024-Athletes with anterior cruciate ligament reconstruction (ACLR) display altered jumping mechanics persisting long after returning to sport (RTS). We investigated the effects of flywheel rear leg elevated (Bulgarian) split squat (RLESS) training on single-leg drop jump (SLDJ) biomechanics in athletes with ACLR after RTS. Eleven competitive athletes with unilateral ACLR (546 ± 270 days postsurgery) performed 16 sessions of 1 set of deep knee flexion RLESS until failure in the reconstructed leg (REC) using a flywheel. Using motion capture and force plates, jump height and leg joint contribution were calculated during a 30-cm SLDJ, alongside peak vertical ground reaction force (vGRF), lower extremity joint peak angle, displacement, work, peak internal moment, and peak power. After training, the jump height increased in REC (p < 0.05) but not the intact leg (INT), although the jump height in REC remained lower than that in INT. Reconstructed leg knee contribution increased, whereas REC hip contribution decreased, so no bilateral difference remained after training. Although jump height remained unchanged in INT, several kinematic and kinetic variables changed significantly. Vertical ground reaction force showed no significant difference while asymmetry in internal knee varus moment disappeared, suggesting that some risk factors of ACL injury were reduced. Therefore, athletes with ACLR show persistent deficits in jumping performance, but adding 8 weeks of flywheel RLESS in REC can safely improve performance and restore normal joint contribution. Besides, coaches should be aware of possible changes in jumping mechanics in INT despite unchanged jumping performance when monitoring athletes with ACLR.

Impacts of mesenchymal stem cells and hyaluronic acid on inflammatory indicators and antioxidant defense in experimental ankle osteoarthritis.

No effective treatment guarantees full recovery from osteoarthritis (OA), and few therapies have disadvantages. To determine if bone marrow mesenchymal stem cells (BMMSCs) and hyaluronic acid (HA) treat ankle OA in Wistar rats. BMMSCs were characterized using flow cytometry with detection of surface markers [cluster of differentiation 90 (CD90), CD105, CD34, and CD45]. Fifty male Wistar rats were divided into five groups of 10 rats each: Group I, saline into the right tibiotarsal joint for 2 days; Group II, monosodium iodate (MIA) into the same joint; Groups III, MIA + BMMSCs; Group IV, MIA + HA; and Group V, MIA + BMMSCs + HA. BMMSCs (1 × 106 cells/rat), HA (75 µg/rat), and BMMSCs (1 × 106 cells/rat) alongside HA (75 µg/rat) were injected intra-articularly into the tibiotarsal joint of the right hind leg at the end of weeks 2, 3, and 4 after the MIA injection. The elevated right hind leg circumference values in the paw and arthritis clinical score of osteoarthritic rats were significantly ameliorated at weeks 4, 5, and 6. Lipid peroxide significantly increased in the serum of osteoarthritic rats, whereas reduced serum glutathione and glutathione transferase levels were decreased. BMMSCs and HA significantly improved OA. The significantly elevated ankle matrix metalloproteinase 13 (MMP-13) mRNA and transforming growth factor beta 1 (TGF-β1) protein expression, and tumor necrosis factor alpha (TNF-α) and interleukin-17 (IL-17) serum levels in osteoarthritic rats were significantly downregulated by BMMSCs and HA. The effects of BMMSCs and HA on serum TNF-α and IL-17 were more potent than their combination. The lowered serum IL-4 levels in osteoarthritic rats were significantly upregulated by BMMSCs and HA. Additionally, BMMSCs and HA caused a steady decrease in joint injury and cartilage degradation. BMMSCs and/or HA have anti-arthritic effects mediated by antioxidant and anti-inflammatory effects on MIA-induced OA. MMP-13 and TGF-β1 expression improves BMMSCs and/or HA effects on OA in Wistar rats.

Joint kinetic demand for performance in high jump

ABSTRACT High jump is a power-demanding motor task. Jumpers extend the take-off leg joints with maximum effort, but kinetic requirements (i.e. torque/power) for each joint are unclear. Here we show the inter-joint differences in the kinetic exertion related to the flight height in high jump trials by 16 male high jumpers (personal best record: 1.90–2.35 m). For the knee joint, both maximum net power and maximum norm of torque were significantly and positively correlated with flight height, with a stronger correlation for maximum net power (r = 0.70) than for maximum norm of torque (r = 0.52). For the hip joint, maximum norm of torque was significantly correlated with flight height (r = 0.62), but maximum net power (r = 0.36) was not. Both torque and power exhibited the proximal-to-distal sequence (from hip to ankle). The norm of ground reaction force peaked almost simultaneously with the hip torque while external net power peaked with knee power. We suggest that the required musculoskeletal function of each joint differs even in the same task. We suggest that it may be effective to adapt the different training programme between joints to improve performance. Jumpers should prioritise torque exertion for the hip and power exertion for the knee.

OA24 Extended oligoarthritis with proximal muscle weakness and antinuclear antibody positivity associated with a novel genetic variant of uncertain significance in lipopolysaccharide-responsive and beige-like anchor protein (LRBA) gene

Abstract Introduction LRBA deficiency is associated with recurrent infections and immune dysregulation, particularly autoimmune cytopenias, enteropathy and intestitial lung disease, and in a few cases chronic polyarthritis and uveitis. Case description A girl presented at three years old with history of not walking for two months with no history of trauma or fever. Examination revealed arthritis in her ankles and knees. Ultrasound showed synovial thickening in both knees and small effusion to hips. There was no evidence of uveitis at presentation. Her bloods showed raised C-Reactive Protein (CRP) 33 mg/L and Erythrocyte Sedimentation rate (ESR) 45 mm/h. Anti-nuclear and anti-centromere antibodies were positive. Diagnosis was made of oligoarticular JIA and she was treated with intra-articular steroids in both knees and ankles and was started on oral prednisolone, weekly oral methotrexate. On subsequent clinic review, she had started to walk with mild restriction to internal rotation of hips and difficulty in getting up from sitting. She was started on regular hydrotherapy, physiotherapy and occupational therapy. From five to 11 years old, she had four flares of uveitis, treated with prednisolone eye drops; and two flares of arthritis, treated with steroids. Her methotrexate was changed to subcutaneous and at eight years of age she was also started on subcutaneous adalimumab fortnightly. Due to prolonged proximal muscle weakness, abnormal gait and chronic pain in leg joints without clinical or radiological evidence of synovitis during clinic reviews, she underwent thorough neurological work up which was inconclusive for myopathies. Her creatinine kinase levels, thyroid profile, MRI brain and spine were normal. Genetic work up showed two variants in the LRBA gene, one pathogenic and the other was variant of uncertain significance (VUS). Her CTLA4 expression was normal by flow cytometry. Discussion Three case reports have previously associated homozygous LRBA deficiency with polyarthritis. Compound heterozygous LRBA deficiency may present with various phenotypes including autoimmune disease affecting multiple organs, immune cytopenia and immune dysregulations including CTLA-4 expression. This report potentially widens the clinical spectrum of LRBA deficiency and given that it is a novel variant, prompts us to screen for this gene mutation in patients with JIA where remission is challenging and there is a need for continuous immunosuppressive or immune-modulatory therapy. Three case reports have previously associated homozygous LRBA deficiency with polyarthritis. Compound heterozygous LRBA deficiency may present with various phenotypes including autoimmune disease affecting multiple organs, immune cytopenia and immune dysregulations including CTLA-4 expression. This report potentially widens the clinical spectrum of LRBA deficiency and given that it is a novel variant, prompts us to screen for this gene mutation in patients with JIA where remission is challenging and there is a need for continuous immunosuppressive or immune-modulatory therapy. Three case reports have previously associated homozygous LRBA deficiency with polyarthritis. Compound heterozygous LRBA deficiency may present with various phenotypes including autoimmune disease affecting multiple organs, immune cytopenia and immune dysregulations including CTLA-4 expression. This report potentially widens the clinical spectrum of LRBA deficiency and given that it is a novel variant, prompts us to screen for this gene mutation in patients with JIA where remission is challenging and there is a need for continuous immunosuppressive or immune-modulatory therapy. Key learning points • There is no single diagnostic investigation for JIA as the aetiology is complex and there are currently no specific clinical guidelines of when to consider genetic testing in patients with JIA. With the mainstreaming of genetic services and improved access to cheaper, advanced next-generation sequencing, we should consider looking into monogenic conditions that mimic JIA. • The case illustrates the challenges of determining whether VUS are pathogenic in causing arthritis, or just incidental findings. Compound heterozygous LRBA may present within a spectrum of clinical features, further analysis with CTLA4 expression by flow cytometry and genetic analysis of siblings and parents will be helpful. • Compound heterozygous LRBA variation has different clinical manifestation which needs personalised treatment. Treatment with abatacept (a soluble CTLA4 immunoglobulin fusion protein) which is reported in a case series of LRBA deficiency. Risks of continuous immunosuppressive treatment need to be balanced with more definitive hematopoietic stem cell transplantation (HSCT) previously used to achieved complete remission in LRBA deficiency.

Mediolateral Margin of Stability highlights motor strategies for maintaining dynamic balance in older adults.

The dynamical nature of gait increases fall risk for older adults as the Center of Mass (COM) is constantly displaced inside and outside the Base of Support (BOS). Foot placement and leg joint moments are the primary mechanisms controlling dynamic balance. The Margin of Stability (MOS) quantifies the distance between the COM dynamical state and the BOS. While research examined how aging affects the relationship between foot placement and MOS, the relationship to leg moments is unexamined. Examining this relationship would elucidate whether aging increases fall risk from changes in the joint moments controlling the COM. Fourteen older (66.9 ± 4.3 years) and sixteen young (26.3 ± 3.6 years) adults walked along a 12m path for three trials. The MOS, hip and ankle moments in sagittal and frontal planes were analyzed. For the knee, only the sagittal plane was analyzed. MOS was calculated as the distance between the extrapolated-COM and the Center of Pressure per step. Statistical Parametric Mapping independent t-tests assessed group differences. Cross-correlation quantified MOS and joint moment relationships per plane during single-stance. No group differences in walking speed were observed. A larger frontal plane MOS, hip abduction and ankle eversion moment occurred for older adults. Cross-correlation demonstrated moderate and strong relationships for the hip-MOS for both groups in the sagittal plane. Older adults had a larger sagittal plane hip-MOS correlation than young adults. The larger mediolateral MOS in older adults may indicate attempts to avoid lateral balance loss by shifting their COM away from their BOS lateral boundaries during single-stance. However, this strategy moves the COM toward the BOS medial borders potentially pre-maturely terminating the contralateral swing phase during medial destabilization. The stronger sagittal plane hip-MOS relationship in older adults may reflect increased coupling between hip moments and the COM to control dynamic balance.

Study of Self-Locking Structure Based on Surface Microstructure of Dung Beetle Leg Joint.

Dung beetle leg joints exhibit a remarkable capacity to support substantial loads, which is a capability significantly influenced by their surface microstructure. The exploration of biomimetic designs inspired by the surface microstructure of these joints holds potential for the development of efficient self-locking structures. However, there is a notable absence of research focused on the surface microstructure of dung beetle leg joints. In this study, we investigated the structural characteristics of the surface microstructures present in dung beetle leg joints, identifying the presence of fish-scale-like, brush-like, and spike-like microstructures on the tibia and femur. Utilizing these surface microstructural characteristics, we designed a self-locking structure that successfully demonstrated functionality in both the rotational direction of the structure and self-locking in the reverse direction. At a temperature of 20 °C, the biomimetic closure featuring a self-locking mechanism was capable of generating a self-locking force of 18 N. The bionic intelligent joint, characterized by its unique surface microstructure, presents significant potential applications in aerospace and various engineering domains, particularly as a critical component in folding mechanisms. This research offers innovative design concepts for folding mechanisms, such as those utilized in satellite solar panels and solar panels for asteroid probes.

Neural circuit mechanisms underlying context-specific halting in Drosophila

Walking is a complex motor programme involving coordinated and distributed activity across the brain and the spinal cord. Halting appropriately at the correct time is a critical component of walking control. Despite progress in identifying neurons driving halting1–6, the underlying neural circuit mechanisms responsible for overruling the competing walking state remain unclear. Here, using connectome-informed models7–9 and functional studies, we explain two fundamental mechanisms by which Drosophila implement context-appropriate halting. The first mechanism (‘walk-OFF’) relies on GABAergic neurons that inhibit specific descending walking commands in the brain, whereas the second mechanism (‘brake’) relies on excitatory cholinergic neurons in the nerve cord that lead to an active arrest of stepping movements. We show that two neurons that deploy the walk-OFF mechanism inhibit distinct populations of walking-promotion neurons, leading to differential halting of forward walking or turning. The brake neurons, by constrast, override all walking commands by simultaneously inhibiting descending walking-promotion neurons and increasing the resistance at the leg joints. We characterized two behavioural contexts in which the distinct halting mechanisms were used by the animal in a mutually exclusive manner: the walk-OFF mechanism was engaged for halting during feeding and the brake mechanism was engaged for halting and stability during grooming.

A Restriction Boundary-Based Coronal Plane Alignment of the Knee (CPAK) Classification for Restricted Kinematic Alignment Total Knee Arthroplasty.

Background Coronal plane alignment of the knee (CPAK) classification was proposed as a means of understanding the knee phenotype in leg alignment and joint line obliquity (JLO). However, when it is adapted to restricted kinematic alignment total knee arthroplasty (rKA-TKA), the boundaries of CPAK and those of rKA-TKA phenotype are different. We therefore reappraise the boundary between the CPAK classification and restriction protocol and propose a restriction boundary-based CPAK (Rb-CPAK). Methods Between May 2020 and March 2022, 143 knees in 95 patients underwent rKA at our institution and were included in this study. In Rb-CPAK, we set the following ranges: 6° varus to 3° valgus for arithmetic hip-knee-ankle angle (aHKA), 0° to 6° varus for the medial proximal tibial angle (MPTA), 0° to 5° valgus for the lateral distal femoral angle (LDFA), and 169° to 180° for JLO. The pre- and postoperative alignments were classified using the original CPAK and Rb-CPAK. Results There were significant differences in pre- and postoperative distributions between original CPAK and Rb-CPAK (p < 0.0001). Postoperative Rb-CPAK primarily led to neutral aHKA (116 of 143 knees), and decreased MPTA varus (pre: 83.9 ± 3.4, post: 87.0 ± 2.3, p < 0.0001) and stable LDFA values (pre: 88.7 ± 3.1, post: 88.5 ± 2.7, p = 0.4) were observed. Among cases with neutral JLO, 78 knees required MPTA or LDFA corrections. Postoperatively, 67 (64%) out of 119 knees categorized as neutral JLO fell within MPTA and LDFA ranges. Conclusion The Rb-CPAK modification more effectively outlined knees that required restriction, and the restriction was properly performed compared with the original CPAK. However, JLO does not effectively indicate if a knee requires restriction or not, and thus individual evaluation of LDFA and MPTA might be necessary.

Epoxy resin gel particles with adjustable stickiness and deformability for pesticide delivery

It is essential to develop a pesticide delivery system with a simple preparation process and strong leaf retention capability. In this study, epoxy resin (ER) was modified with alcohols with different carbon chain lengths through a one-step reaction to synthesize modified prepolymers (ModER). Among these, the ER modified by dodecanol (ER/Dodecanol) exhibited high flexibility, exceptional stickiness and the highest surface free energy. Subsequently, the organic phase containing emamectin benzoate (EB) and ModER was directly mixed with the aqueous phase containing sodium lignosulfonate (SL) to instantaneously obtain pesticide-loaded epoxy resin gel particles (ModERMP) through self-emulsification and electrostatic interaction. ER/Dodecanol loaded with EB (EB@ER/Dodecanol) had excellent flexibility. The particles underwent significant flattening, transitioning from micron-sized spherical particles to “biscuit-type” particles with nanoscale thickness. EB@ER/Dodecanol exhibited outstanding stickiness, enabling it to adhere to the mouthparts and legs of insects, thereby impacting their feeding behavior. Compared with that of the control, the leaf feeding rate for the experimental group was decreased by 9.36%. EB@ER/Dodecanol also had affinity for foliar micro/nanostructures while displaying excellent washout resistance. Following washing, the residue rate increased by 33.7% compared to that of the emulsifiable concentrate (EC). Furthermore, EB@ER/Dodecanol had excellent insecticidal activity both before and after washout. ModERMP represents a simple preparation process with robust washout resistance, thereby enhancing pesticide utilization rates.

Gait planning based on bionic quadruped robot

Based on the ankylosaurus, a four-legged robot structure with 14 degrees of freedom was designed in this study. The kinematic model was established using the Denavit-Hartenberg (D-H) method. The inverse kinematics of the robot was analyzed, and the angle equations of each leg joint were obtained. In order to reduce the kinetic energy generated when leaving the ground and landing, the compound cycloid was modified. The modified foot curve effectively reduces energy and meets the kinematic requirements. On the basis of the foot trajectory, the diagonal leg phase difference was set to 0.5, and the diagonal gait was adopted as the gait of the bionic quadrupled robot. Simulink software was used to construct the simulation environment, and the maximum error of the simulation results and the theoretical step height was 2.05%, and the step length maximum error was 2.39%. During walking, the thigh joint angle was −92.82° to −80.21°, and the hip joint angle was 22.23° to 43.83°. Compared with the simulation trajectory and the theoretical curve, because the experiment did not consider the balance of the fuselage, there was a certain error when the leg was raised to the highest point. Overall, the gait planning strategy designed in this study basically achieves the expected effect, lays a certain foundation for the practical application of the bionic quadruped dinosaur robot, and also provides a reference for the subsequent research.

Tribological properties of the beetle leg joints

Tribological properties of femoro-tibial leg joints in two beetles, darkling beetle Zophobas morio and Congo rose chafer Pachnoda marginata were studied. Very low friction of 0.004 was revealed by the direct measurements in the joint. It is assumed that semi-solid lubricant functioning as in technical bearings is one of the leading factors of the friction minimization. Dependence of the surface texture and physical chemical properties (hydrophobicity) on the cuticle friction was analysed. Contribution of the surface texture to the tribological properties of contacting surfaces was examined by the measurement in the tribosystem “contacting surface/glass”. It is supposed that coefficient of friction (COF) decreases with decrease of surface roughness. At the same time, no statistically significant correlation was found between the hydrophobicity of the surface and the value of the friction coefficient.