Plane Joint Research Articles

Deep Temporal Clustering of Pathological Gait Patterns in Post-Stroke Patients Using Joint Angle Trajectories: A Cross-Sectional Study

Rehabilitation of gait function in post-stroke hemiplegic patients is critical for improving mobility and quality of life, requiring a comprehensive understanding of individual gait patterns. Previous studies on gait analysis using unsupervised clustering often involve manual feature extraction, which introduces limitations such as low accuracy, low consistency, and potential bias due to human intervention. This cross-sectional study aimed to identify and cluster gait patterns using an end-to-end deep learning approach that autonomously extracts features from joint angle trajectories for a gait cycle, minimizing human intervention. A total of 74 sub-acute post-stroke hemiplegic patients with lower limb impairments were included in the analysis. The dataset comprised 219 sagittal plane joint angle and angular velocity trajectories from the hip, knee, and ankle joints during gait cycles. Deep temporal clustering was employed to cluster them in an end-to-end manner by simultaneously optimizing feature extraction and clustering, with hyperparameter tuning tailored for kinematic gait cycle data. Through this method, six optimal clusters were selected with a silhouette score of 0.2831, which is a relatively higher value compared to other clustering algorithms. To clarify the characteristics of the selected groups, in-depth statistics of spatiotemporal, kinematic, and clinical features are presented in the results. The results demonstrate the effectiveness of end-to-end deep learning-based clustering, yielding significant performance improvements without the need for manual feature extraction. While this study primarily utilizes sagittal plane data, future analysis incorporating coronal and transverse planes as well as muscle activity and gait symmetry could provide a more comprehensive understanding of gait patterns.

Gait asymmetry assessment through Eigen-Gait components on dissimilarity maps

Motor impairments caused by neurological diseases have an important impact on gait, particularly on the coordination between left and right lower limbs. Deviation from normal gait is often measured to assess this impact on gross motor functions, and to monitor the progress of patients during rehabilitation. The concept of gait dissimilarity map is introduced to represent bilateral raw gait signals, while accounting for their respective spatiotemporal dynamics. A model of gait for the healthy population is constructed through Singular Value Decomposition, considering both lower limbs. The obtained eigenvectors synthesize the symmetry present in gait. Then, by projecting the dissimilarity maps of patients with gait disorders on the space formed by such eigenvectors, we compute their associated Eigen-Gait Asymmetry Index (EGAI) relatively to an average normal gait reference vector. For the knee joint in the sagittal plane, EGAI values of patients are higher (9.73 ±2.16) than those of healthy controls (3.86 ±0.9), reflecting the asymmetry induced by neurological diseases. Patients with hemiparesis show the highest EGAI (10.4 ±1.8), followed by patients with paraparesis (9.9 ±1.8) and patients with tetraparesis (8.6 ±2.5). Indeed, patients with hemiparesis show a more asymmetrical gait since only one side of the body is affected. EGAI for hip, ankle and pelvis joints in the sagittal plane show similar trends. Our innovative method characterizes bilateral gait, enriching traditional unilateral assessments. Our method yields a comprehensive score reflecting both asymmetry and gait deviations, aiming to provide clinicians with an effective and precise monitoring tool.

Influence of rock bolt reinforcement on shear behaviour of a nonpersistent joint plane

The impact of rock bolts on the mechanical behavior of nonpersistent joints, including the intricate interactions between the joints, rock bridges, and rock bolts, has received limited investigation despite their effectiveness in reinforcing rock mass discontinuities. In order to tackle this issue, a variety of normal stresses were applied during direct shear tests conducted on artificial rock-like specimens with nonpersistent joints, both bolted and unbolted. Meanwhile, to measure the deformation in the rock bridge and joint plane region, a set of strain gauges were implemented. The findings indicated that the local shear deformation-shear displacement curves, whether with or without rock bolts, can be categorized into five distinct stages. Application of the rock bolts on the nonpersistent joint plane resulted in making the following two important statements: (a) The rock bolts delay the shear stress transmission along the joint plane from the joint parts to the rock bridge area; (b) The rock bolts limit the dilatancy occurring in both the joint parts and at the rock bridge area. Furthermore, the shear displacement of the bolted nonpersistent joint specimen at the peak shear strength was found to be greater than that of the unbolted nonpersistent joint specimen indicating protection of the rock bridge by the rock bolts. Whether bolted or unbolted, the stiffness values seem to be the same for the nonpersistent joint plane for a selected normal stress; this observation is significantly different from that observed for the persistent joint plane.

Polyaxial Stress-Dependent Tensorial Permeability Variations of a Columnar Jointed Rock Mass: Insights from 3D Distinct Element Method

AbstractStress-induced permeability changes in geological formations have implications for various geo-engineering applications. Fractures are the predominant fluid flow pathways within tight geological formations such as jointed basaltic rock mass. Three-dimensional permeability variations of a columnar jointed rock mass using the three-dimensional block distinct element method are investigated. First, a permeability tensor is constructed by simulating fluid flow through joint sets using cubic law and determining its principal components through eigenvector analysis. Subsequently, numerical simulations are conducted to gain insights into the impact of principal stresses on joint deformation and fluid flow. Joint deformation is controlled by the joint’s mechanical properties, contact models, and stress state. Different isotropic and anisotropic stress loading scenarios on the permeability tensor evolution are investigated. The research findings indicate that isotropic stress loading led to uniform normal compression on fractures, resulting in a monotonic reduction of all permeability tensor components and increased permeability anisotropy. Anisotropic stress loading, particularly the intermediate stress, often neglected, significantly influenced the rock’s overall permeability. While the directions of the principal components remained consistent during isotropic loading, they exhibited changes in both direction and magnitude during anisotropic loading. The relative angle between the joint plane and the principal stresses was crucial in controlling joint behavior, including normal compression, shear failure, and dilation. Additionally, data analysis revealed that the exponential empirical model provided an excellent fit for permeability–stress data.

Penatalaksanaan Fisioterapi pada Kasus Sprain Ankle Dekstra dengan Modalitas Ultrasound Therapy dan Terapi Latihan di RSUD Bandung Kiwari

ankle sprain is an injury that occurs to the lateral complex ligaments due to excessive stretching accompanied by inversion and plantar flexion which occurs suddenly when the foot does not rest perfectly on an uneven floor/ground surface. To determine the implementation of Physiotherapy in reducing pain, increasing muscle strength, increasing the Scope of Joint Movement and preventing re-injury in cases of right ankle sprains using Ultrasound therapy and Exercise Therapy modalities. After undergoing therapy 6 times, the results using VAS showed a decrease in pain in silent pain, obtained a value of 2 at T1 & T2, a value of 1 at T3 - T5 and a value of 0 at T6. Pressure pain was obtained with a value of 3 at T1 - T3, a value of 2 at T4 and a value of 1 at T5 & T6. Movement pain was obtained with a value of 6 on T1 & T2, a value of 5 on T3 then a value of 4 on T4 4. On T5 & T6, the pain value was reduced to 3. There was an increase in the range of motion of the joint in the right Ankle joint in the sagittal plane, the results of T1 & T2 were obtained (S = 10ᴼ – 00ᴼ – 30ᴼ) T3 & T4 (S = 15ᴼ - 00ᴼ - 35ᴼ) and T5 & T6 there is an increase in the range of motion of the joints in the sagittal plane, namely (S = 20ᴼ - 00ᴼ - 35ᴼ ). In the Value Rotation field at T1 (R = 25ᴼ - 00ᴼ - 10ᴼ) then at T2 (R = 30ᴼ - 00ᴼ - 10ᴼ) at T3 (R = 30ᴼ - 00ᴼ - 15ᴼ) The value of T4 - T6 has an increase in value to (R = 30ᴼ - 00ᴼ - 20ᴼ). There was an increase in muscle strength by using MMT in the dorsiflexion plane of motion, a value of 4+ was obtained at T1-T3, a value of 5 at T4 - T6. Plantar flexion obtained a value of 4- at T1 & T2, a value of 4 at T3 & T4 and a value of 4+ at T5 and at T6 a value of 5. Inversion obtained a value of 4 at T1 & T2, a value of 4+ at T3 – T5 and a value of 5 at T6 . Eversion was obtained with a value of 4 at T1 & T2, a value of 4+ at T3 and an increase in value to 5 at T4 - T6. Ultrasound can reduce pain and reduce muscle tension, Theraband Exercise can increase the range of motion of joints, and Calf raises can increase muscle strength.

Evaluation of Lower Limb Angular Acceleration in Healthy and Hallux Valgus Young and Older Women During Gait

Objectives: To comprehend the kinematic effects of hallux valgus (HV) deformity on young and older people, we assessed the angular acceleration of the joints in the lower limbs of these women. Methods: Forty-eight women in two groups, young adults (20-30 years old) and older adults (50-60 years old), participated in this study (12 healthy and 12 with HV). We used an inertial measurement unit (IMU)-based motion capture system to measure the kinematics of motion. Biomechanical variables were assessed at an ideal speed during gait (stance and swing phases). All modules were calibrated in advance and then attached to the right thigh, shank, and foot. Results: The results showed that in the young group, angular acceleration was significantly different during gait in all planes of the ankle joint, the sagittal plane of the knee joint, and the horizontal and frontal planes of the hip joint. In the older group, it was significantly different in the sagittal plane of the ankle and knee and the sagittal and frontal planes of the hip joint. Discussion: It appears that the angular acceleration of the lower limb joints was affected by HV, especially in the young group. Additionally, the angular acceleration of the knee joint was less affected in both groups.

Double-spiral as a bio-inspired functional element in engineering design

Spiral, one of the most well-known functional patterns in nature that can be observed in structures such as the proboscis of lepidoptera and snail shells or as vortices forming in flowing fluids, has long served as a source of inspiration for humans in the creation of numerous spiral-based designs. Double-spiral is a design derived from spirals, which has been previously presented and utilized as a compliant joint. Advantageous properties of double-spirals, such as easily adjustable design, multiple degrees of freedom, reversible extensibility, and tunable deformability make them promising candidates for the development of mechanically intelligent structures that exhibit unique behavior and reach desired functions, such as soft grippers, continuum manipulators, energy-dissipative structures, and foldable metamaterials. In this article, we first develop the Double-Spiral Design software to facilitate the design and modeling of double-spirals. We then design and manufacture five different spiral-based structures using three-dimensional (3D) printing, including (1) a freeform passive gripper, (2) a highly extensible enveloping gripper, (3) a mechanical interlocking structure, (4) an adaptive energy-dissipative structure, and (5) a compliant planar joint. Through practical experimentation, we test the functionality of the developed structures and showcase the potential of double-spirals for being used in various technical applications. This study represents a significant step towards a better understanding of double-spirals and demonstrates their broad but unexplored potential in engineering design.

Comparison of Electromigration in Tin-Bismuth Planar and Bottom Terminated Component Solder Joints

Electromigration monitoring of bottom terminated component (BTC) solder joints is limited to electrical resistance measurements of the solder balls. Tracking the microstructural evolution such as bismuth segregation in tin-bismuth solder ball, is typically via metallurgical cross sectioning, a destructive technique. Once cross sectioned, the solder ball is not available for further electromigration current stressing. A novel planar solder geometry has been invented and developed that allows real-time, non-destructive monitoring of solder microstructure, while the progress of electromigration can be concurrently tracked via electrical resistance means. Planar solder joints are easy to fabricate in a typical metallurgical laboratory. If the electromigration behavior of the planar and the BTC solder joints happen to be similar, the planar solder joint approach could greatly aid in the quick development of solder alloys by comparing the rates of electromigration and the metallurgical changes in planar solders of various compositions. In this paper, the electromigration rates and behavior of eutectic Sn-Bi alloy in planar and in BTC solder joints were compared and shown to be similar. This important finding opens the use of planar solder joints for the quick and low-cost development of low-temperature solder alloys.

Cross-sectional analysis of speed-up mechanism in normal gait among healthy older adults with and without falls – Results from the Baltimore Longitudinal Study of Aging

BackgroundFalls in older adults increase the risk of mobility loss. Proper understanding of gait mechanisms related to falls may provide novel solutions for maintaining mobility in older adults. Research questionIdentify fall-related gait patterns through analyzing alterations in gait parameters to walk faster than usual pace in older adults. MethodsA Total of 519 participants (mean age = 73.12 years; 51.05 % female), including non-fallers (n = 396) and fallers (n = 123), aged 60–96 years were assessed in the Baltimore Longitudinal Study of Aging. Participants completed gait assessments at both usual and fast paces. Range of motions (ROM) for the hip, knee, and ankle joint in the sagittal plane and hip abductor ROM during normal and fast pace gait were measured by 3D motion capture system (Vicon 612). For all gait variables, percentage-changes (PC; (((fast-walking_parameter – usual-walking_parameter) /usual-walking_parameter)*100)) was calculated. Associations of PC for gait speed and PC for other gait parameters were compared between fallers and non-fallers. ResultsCompared to non-fallers, fallers walked with shorter stride, elongated double support time and shorter knee ROM in the faster pace walk (p = 0.044, p = 0.019, and p = 0.036, respectively). PCs of all gait related variables were significantly associated with PC of gait speed in non-fallers (ps < 0.005), while in the fallers, only PC for stride length, cadence, and hip ROM were associated with PC for gait speed (ps < 0.001). SignificanceAmong non-fallers related PC for gait speed was associated with PC across gait parameters suggesting the use of similar biomechanical approaches in usual and fast gait. Compared to non-fallers, fallers demonstrated different mechanisms of transition from usual to fast gait. Evaluating speed-up strategies could provide insight into subtle yet important gait modifications in apparently well-functioning older adults that would help identify individuals at high risk of falling.

A DEVICE-BASED (GAITON) SAGITTAL PLANE KINEMATICS ANALYSIS OF LOWER EXTREMITY JOINTS AMONG PATIENTS WITH KNEE OSTEOARTHRITIS – A METHODOLOGICAL APPROACH.

Background: Gait assessment is an effective method for identifying functional limitations associated with knee Osteoarthritis and understanding the relationship between disease symptoms and gait quality. Objective: To evaluate the mean difference in the kinematics of lower extremity joints among patients with knee osteoarthritis. Methods: A total of 20 people living with Knee OA were recruited as of 25th September 2024 in this prospective cross-sectional design study. The eligible participants were conveniently recruited from the SRM physiotherapy OPD based on voluntary participation after signing the informed consent. Adult participants aged 18 years and above, both sexes and able to walk independently without mobility aids were recruited and the joint kinematics were measured using the GaitOn Software, 2-dimensional analysis, and sagittal kinematic parameters of stance phase. Results: The mean age of the patients was 53.6 ± 7.3, and the mean BMI was 29.1±4.6. The one sample t-test demonstrated a statistically significant difference between kinematic angles of the lower extremity joint in sagittal plane of population mean (reference value) and sample mean (measured by GaitOn); Initial contact phase (hip: mean diff -4.06, p&lt;0.01, ankle: mean diff 34.1, p &lt; 0.0001), Loading response (hip: mean diff -5.8. p &lt;0.001, knee: mean diff 9.6, p &lt; 0.001, ankle: mean diff 32.4, p &lt; 0.001). Midstance (hip: mean diff 11.06, p &lt;0.001, ankle: 31.4, p&lt; 0.001). Terminal stance (hip: mean diff 28.3, p&lt; 0.004, ankle: mean diff 31.4, p&lt; 0.001) and Pre-swing (hip: mean diff 16.5, p&lt; 0.001, ankle: mean diff 31.4, p&lt; 0.001). Conclusions: The hip and ankle joints equally share knee kinematic compensations. By acknowledging the complex interactions between the hip, ankle, and knee joints, healthcare providers can develop more comprehensive and effective treatment plans for individuals with knee OA.

Study on the Mechanical Properties and Failure Characteristics of Heterogenous Shale Based on CT Scanning

Summary Shale reservoirs, as a significant type of unconventional reservoir, have always been a focal point in oil and gas exploration and development. The precise determination of shale mechanical properties is fundamental to the stimulation of shale oil and gas reservoirs. The heterogeneity of rock has a significant impact on its mechanical properties. Computed tomography (CT) scanning technology is an important method for observing the internal microstructure of rocks, and digital cores constructed based on CT scans can truly reflect the heterogeneity of shale. Numerical models of shale were established using image processing technology; the basic mechanical parameters of minerals were obtained through nanoindentation experiments; and mineral content was determined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Uniaxial and triaxial compression simulations were conducted to study the impact of mineral composition and porosity on shale mechanical performance. The results indicate that the mechanical properties of shale are the outcome of the combined effects of pore distribution, mineral arrangement, and porosity. Initial natural pores significantly influence the initiation and expansion of fractures during the loading process. For models with obvious through-going joints, fractures mainly expand along the joint planes. For models with uneven pore distribution, fractures start at the pores and expand along the loading direction, eventually connecting different pores, leading to failure. In cases where a certain type of mineral is abundant or concentrated in the mineral composition, its mechanical properties will be significantly influenced by that type of mineral. In this simulation model with a high quartz content, the direction of fracture propagation during fracture was altered by the quartz. Porosity also has a significant impact on mechanical properties. As porosity increases, the model’s compressive strength decreases. Under triaxial loading conditions, at lower confining pressures, the model primarily fails due to tensile stresses; as the confining pressure increases, the proportion of tensile failures decreases, while the proportion of compressive failures increases. Models with a high content of quartz maintain a relatively stable proportion of tensile failures under different confining pressures. Meanwhile, dolomite in the model, due to its strong deformation capability, is better able to withstand tensile stress initially, but as loading continues, the proportion of tensile failures gradually increases. The composition of shale plays a crucial role in determining its mechanical properties, serving as a key reference for analyzing the mechanical behavior of shale.

Experimental and numerical simulation study of rough jointed rock samples under triaxial compression conditions

The presence of joint planes significantly affects the mechanical properties of rock and poses a threat to the safety of engineering construction. To examine the influence of Joint Roughness Coefficient (JRC) and joint plane inclination on the mechanical behavior of jointed rock masses, this research employed 3D printing technology to fabricate jointed rock samples with varying JRC and joint inclination angles. Triaxial compression tests were then conducted on these samples in the laboratory. The results indicate that an increase in JRC strengthens the serrated interlocking effect of joint planes, leading to a corresponding increase in both the peak failure strength and elastic modulus of samples with different inclination angles. For samples with the same JRC, the peak strength initially decreases with increasing inclination angle, followed by a subsequent rise. The variation trend of Poisson’s ratio, however, shows the opposite pattern. The joint inclination significantly impacts the failure mode of the samples. However, as JRC changes, the failure mode does not show significant variation. Furthermore, drawing from the laboratory test results, numerical simulations were performed using the Particle Flow Code in 2 Dimensions (PFC2D) to analyze mesoscopic crack propagation mechanisms in jointed rock models subjected to triaxial compression. Finally, this research discusses the effects of JRC and joint plane inclination on the anisotropic characteristics of jointed samples and offers a detailed analysis of the failure mechanisms.

Design and optimization of a planar anti-buckling compliant rotational joint with a remote center of motion

Compliant mechanisms (CMs) exhibit some excellent mechanical properties and provide numerous innovative solutions for many existing mechanical applications. Among them, planar compliant rotational joints have made substantial contributions to precision engineering. To achieve high-precision positioning with a compliant rotational joint, it is essential to study characteristics such as anti-buckling and constant stiffness. The remote center of motion (RCM) mechanism, with its compact structure and ease of precise control, is expected to enhance overall rigidity and reduce parasitic displacements. Here, we propose a planar anti-buckling compliant rotational joint with a RCM. Static modeling and model validation are conducted for different geometric configurations, including single and combined structures. A distributed configuration with bidirectional anti-buckling properties is selected for optimization. Using a global parameter optimization model, single-objective optimization studies are conducted for three distinct characteristics. Subsequently, a multi-objective optimization model for constant stiffness and high precision is established. Based on the optimization results, a compliant rotational joint with bidirectional anti-buckling, constant rotational stiffness, and high precision is designed. Finally, the effectiveness of the optimization method is validated through physical experiments.

Suppressed Arm Swing While Running: No Change In Sagittal Plane Joint Kinetics

Suppressed Arm Swing While Running: No Change In Sagittal Plane Joint Kinetics

Feasibility and usefulness of video-based markerless two-dimensional automated gait analysis, in providing objective quantification of gait and complementing the evaluation of gait in children with cerebral palsy

BackgroundGait analysis aids in evaluation, classification, and follow-up of gait pattern over time in children with cerebral palsy (CP). The analysis of sagittal plane joint kinematics is of special interest to assess flexed knee gait and ankle joint deviations that commonly progress with age and indicate deterioration of gait. Although most children with CP are ambulatory, no objective quantification of gait is currently included in any of the known international follow-up programs. Is video-based 2-dimensional markerless (2D ML) gait analysis with automated processing a feasible and useful tool to quantify deviations, evaluate and classify gait, in children with CP?MethodsTwenty children with bilateral CP with Gross Motor Function Classification Scale (GMFCS) levels I–III, from five regions in Sweden, were included from the national CP registry. A single RGB-Depth video camera, sensitive to depth and contrast, was positioned laterally to a green walkway and background, with four light sources. A previously validated markerless method was employed to estimate sagittal plane hip, knee, ankle kinematics, foot orientation and spatio-temporal parameters including gait speed and step length.ResultsMean age was 10.4 (range 6.8–16.1) years. Eight children were classified as GMFCS level I, eight as II and four as III. Setup of the measurement system took 15 min, acquisition 5–15 min and processing 50 min per child. Using the 2D ML method kinematic deviations from normal could be determined and used to implement the classification of gait pattern, proposed by Rodda et al. 2001.Conclusion2D ML assessment is feasible, since it is accessible, easy to perform and well tolerated by the children. The 2D ML adds consistency and quantifies objectively important gait variables. It is both relevant and reasonable to include 2D ML gait assessment in the evaluation of children with CP.

Experimental and Numerical Study of Steel-Concrete Composite Beams Strengthened under Load.

This study analysed the strengthening process of a classical steel-concrete composite beam. The beam consisted of a reinforced concrete slab connected by shear studs to an IPE steel profile. The key idea was that the composite beam was strengthened under load. This process simulated an actual reinforced structure that is always subjected to dead loads, with possible service loads. This study assumed that strengthening was implemented to increase the load-carrying capacity and stiffness, not as a way for simulation a repair. The strengthening consisted of expanding the steel part of the beam by welding an additional plate to the bottom flange of the IPE profile. This study included the results of numerical analyses conducted in Abaqus software and lab results. A three-dimensional numerical model was created, taking into account the non-linear behaviour of concrete and steel, the susceptibility of the composite at the joint plane, and the residual stresses created during welding. A full-scale strengthening of the composite beams under load was carried out. Comparison of the results obtained in the experimental tests and numerical analyses showed a very high convergence of the results, as well as in terms of the non-linear operation of steel and concrete. This confirmed the validity of the created numerical model, which can be the basis for further research into the process of optimal strengthening of composite elements.

Validity of Valor Inertial Measurement Unit for Upper and Lower Extremity Joint Angles.

Inertial measurement units (IMU) are increasingly utilized to capture biomechanical measures such as joint kinematics outside traditional biomechanics laboratories. These wearable sensors have been proven to help clinicians and engineers monitor rehabilitation progress, improve prosthesis development, and record human performance in a variety of settings. The Valor IMU aims to offer a portable motion capture alternative to provide reliable and accurate joint kinematics when compared to industry gold standard optical motion capture cameras. However, IMUs can have disturbances in their measurements caused by magnetic fields, drift, and inappropriate calibration routines. Therefore, the purpose of this investigation is to validate the joint angles captured by the Valor IMU in comparison to an optical motion capture system across a variety of movements. Our findings showed mean absolute differences between Valor IMU and Vicon motion capture across all subjects' joint angles. The tasks ranged from 1.81 degrees to 17.46 degrees, the root mean squared errors ranged from 1.89 degrees to 16.62 degrees, and interclass correlation coefficient agreements ranged from 0.57 to 0.99. The results in the current paper further promote the usage of the IMU system outside traditional biomechanical laboratories. Future examinations of this IMU should include smaller, modular IMUs with non-slip Velcro bands and further validation regarding transverse plane joint kinematics such as joint internal/external rotations.

Managing lower extremity loading in distance running by altering sagittal plane trunk leaning

BackgroundTrunk lean angle is an underrepresented biomechanical variable for modulating and redistributing lower extremity joint loading and potentially reducing the risk of running-related overuse injuries. The purpose of this study was to systematically alter the trunk lean angle in distance running using an auditory real-time feedback approach and to derive dose–response relationships between sagittal plane trunk lean angle and lower extremity (cumulative) joint loading to guide overuse load management in clinical practice. MethodsThirty recreational runners (15 males and 15 females) ran at a constant speed of 2.5 m/s at 5 systematically varied trunk lean conditions on a force-instrumented treadmill while kinematic and kinetic data were captured. ResultsA change in trunk lean angle from –2° (extension) to 28° (flexion) resulted in a systematic increase in stance phase angular impulse, cumulative impulse, and peak moment at the hip joint in the sagittal and transversal plane. In contrast, a systematic decrease in these parameters at the knee joint in the sagittal plane and the hip joint in the frontal plane was found (p < 0.001). Linear fitting revealed that with every degree of anterior trunk leaning, the cumulative hip joint extension loading increases by 3.26 Nm·s/kg/1000 m, while simultaneously decreasing knee joint extension loading by 1.08 Nm·s/kg/1000 m. ConclusionTrunk leaning can reduce knee joint loading and hip joint abduction loading, at the cost of hip joint loading in the sagittal and transversal planes during distance running. Modulating lower extremity joint loading by altering trunk lean angle is an effective strategy to redistribute joint load between/within the knee and hip joints. When implementing anterior trunk leaning in clinical practice, the increased demands on the hip musculature, dynamic stability, and the potential trade-off with running economy should be considered.

Head-Shaft Angle Influences Isometric Shoulder Strength Levels after Intramedullary Nailing of Proximal Humerus Fractures: A Pilot Study.

Proximal humerus fractures are common fractures of the elderly population which can lead to long-term compromise of a patient's shoulder function. Closed reduction and internal fixation with intramedullary nailing is a well-established surgical technique yielding good outcomes, as perceived by patients, obtained via Patient-Reported Outcome Measures, and objectified by clinical shoulder testing. Apart from conventional range-of-motion testing and clinical shoulder tests, strength testing of the shoulder is a yet-neglected but meaningful and standardizable outcome parameter. In this study, isometric shoulder strength is evaluated in relation to fracture morphology/postoperative reduction quality as well as with patient-reported outcomes. 25 patients (mean age 73.2 ± 10.5 years) underwent isometrics strength-testing of the shoulder joint in the scapular plane (abduction) as well as in the sagittal plane (flexion) as well as hand-grip strength-testing at 4.5 ± 1.88 years follow-up. Pre- and postoperative radiographs were analysed. Patients completed ASES and CMS questionnaires. Patients exhibited a decrease in abduction and flexion force (-24.47% and -25.30%, respectively, p < 0.001) using the contralateral, uninjured arm as reference. Abduction force tended to be decreased in three- and four-part fractures. Patient satisfaction correlated negatively with the relatively reduced force of the affected arm. Varus-angulated humeral heads produced significantly lower abduction force output than valgus- or physiologic angulation (p = 0.014), whereas flexion force was unaffected (p = 0.468). The anatomical reduction had no influence on shoulder strength. Proximal humerus fractures may cause a significant reduction in shoulder function, both reported by patients and objectified by shoulder strength testing. Varus head angulation demonstrated the greatest loss of shoulder strength and should be avoided to ensure proper functioning. Further, strength testing seems a valuable outcome parameter for a thorough shoulder examination with easy obtainability.

Gait signature changes with walking speed are similar among able-bodied young adults despite persistent individual-specific differences

Understanding individuals’ distinct movement patterns is crucial for health, rehabilitation, and sports. Recently, we developed a machine learning-based framework to show that “gait signatures” describing the neuromechanical dynamics governing able-bodied and post-stroke gait kinematics remain individual-specific across speeds. However, we only evaluated gait signatures within a limited speed range and number of participants, using only sagittal plane (i.e., 2D) joint angles. Here we characterized changes in gait signatures across a wide range of speeds, from very slow (0.3 m/s) to exceptionally fast (above the walk-to-run transition speed) in 17 able-bodied young adults. We further assessed whether 3D kinematic and/or kinetic (ground reaction forces, joint moments, and powers) data would improve the discrimination of gait signatures. Our study showed that gait signatures remained individual-specific across walking speeds: Notably, 3D kinematic signatures achieved exceptional accuracy (99.8%, confidence interval (CI) 99.1–100%) in classifying individuals, surpassing both 2D kinematics and 3D kinetics. Moreover, participants exhibited consistent, predictable linear changes in their gait signatures across the entire speed range. These changes were associated with participants’ preferred walking speeds, balance ability, cadence, and step length. These findings support gait signatures as a tool to characterize individual differences in gait and predict speed-induced changes in gait dynamics.