Kinematic Evaluation Research Articles

The accuracy of planar parallel manipulators (PPMs) is heavily affected by the clearances present in their joints. Wear is inevitable in the joint during the operation of the manipulators, which results in non-uniform clearances. Previous research has been confined to examining the precision of planar parallel manipulators under the assumption of consistent joint clearances. Therefore, this research undertakes a kinematic reliability assessment of planar parallel manipulators, considering the presence of non-uniform clearances in their joints. Initially, the non-uniform clearances are characterized using a B-spline curve for their parametric representation. Then, the position error model of a planar parallel manipulator is established considering non-uniform joint clearances, uncertainty of input data, and errors of linkage dimensions. The matrix of the mean and covariance of the distribution of the position error are analytically derived. The probability density function (PDF) of the distribution of position error is calculated using the central limit theorem. Subsequently, the kinematic reliability in the workspace can be calculated by a direct integral over the obtained PDF. The proposed method is available for a mechanism with any irregular joint clearance when wear occurs. The efficacy and precision of proposed method are confirmed through a comparison against Monte Carlo simulation.

Evaluation of different hindfoot kinematics according to various shoe types during walking using biplanar fluoroscopy.

Segmental trunk control is indispensable to achieve upright posture, attenuate movement-related oscillations, and maintain postural stability during activities of daily living including walking. Yet, its role in postural control is incompletely understood because it is seldom measured. Yoga is known to improve postural control in the elderly and people with various neuromuscular disorders; however, its influence on segmental trunk control is unexplored. The present study reports the influence of yoga on segmental trunk control in trained yoga practitioners using 3D kinematic evaluation. Ten yoga practitioners, practicing advanced yoga (>5years), and 10 age-matched healthy adults were studied after ethical approval and informed consent. Segmental trunk control was described as motion of the trunk with respect to the pelvis, which was computed as the difference between displacement of sternum and pelvic marker in the sagittal and frontal planes. Yoga practitioners demonstrated less variability in the displacement of sternum, pelvis, and ankle markers and greater segmental trunk control compared to controls (p < 0.001). Segmental trunk movement of yoga practitioners was 50% lower in the frontal plane (p < 0.001). Preliminary findings suggest that regular mind-body exercise in the form of yoga practice holds therapeutic potential to achieve greater segmental trunk control, which is essential to attenuate perturbations and negotiate challenges to develop postural stability. Regular yoga practice demonstrated a positive influence on segmental trunk control and total body sway resulting in enhanced postural control. Therefore, yoga practice can be recommended to achieve greater trunk segmental control in patients with impaired ability to dissociate trunk over pelvis such as Parkinson's disease, stroke, cerebral palsy, and balance disorders including vestibular and neuro-musculoskeletal disorders.

Ankle rehabilitation is an important indicator of walking ability recovery because it is used as a marker of early recovery of mobility function in post-stroke patients. Robot-assisted ankle rehabilitation has been proven to be more optimal for restoring range of motion, balance, and gait proprioception in patients. This study aims to optimize the design of an ankle rehabilitation exoskeleton through structural simulation, biomechanical alignment, and efficiency based on several alternative actuator designs. Alternative exoskeleton designs are focused on the rehabilitation of dorsiflexion-plantar flexion and inversion-eversion movements. The analysis method for assessing the best exoskeleton design alternatives uses an engineering design methodology approach based on static and dynamic test parameters, namely kinematics and FEA. The results of the design engineering implementation show that the exoskeleton design with Concept B is more efficient based on several mechanical test parameters compared to Concept A. Simulation results show that Design B alternative is superior in all test parameters with a value of (4.22 versus 3.68) in the safety factor, a lower peak stress of (30.43 MPa versus 39.15 MPa), and produces energy efficiency with lower torque requirements. The mechanical stability of Concept B is characterized by using a more efficient actuator design with superior safety improvements for users. Based on the parameters and characteristics of the simulation test using design engineering, Design B is more feasible to be developed as a robotic mechanical system for the needs of post-stroke patient ankle rehabilitation.

The arthroscopic repair with biceps rerouting (BR) technique has been determined with promising clinical and biomechanical outcomes for treating large-to-massive rotator cuff tears (LMRCTs). However, the in vivo effects of BR on glenohumeral kinematics during functional shoulder movement have not been fully elucidated.To investigate whether BR provides better restoration of shoulder kinematics as compared with conventional rotator cuff repair (RCR).Cohort study; Level of evidence, 3.Patients who underwent either repair with the BR technique (BR group) or RCR alone (RCR group) for treating LMRCTs between January 2021 and May 2022 were enrolled. They underwent 1-year postoperative kinematic evaluation of bilateral shoulders by performing scapular plane abduction within a dual-fluoroscopic imaging system. The glenohumeral translations in the superior-inferior (S-I) and anterior-posterior (A-P) directions were assessed at each 10° shoulder abduction angle. Moreover, the mean, maximum, minimum, and range of glenohumeral translations were calculated throughout the entire movement.A total of 18 patients were included in the final analysis, comprising 9 undergoing BR and 9 undergoing RCR. In the RCR group, as compared with contralateral shoulders, the operative shoulders showed increased superior humeral head translations during lower abduction angles of 30° to 50° (all P &lt; 0.004), with a greater maximum (P = 0.014) and a larger range (P = 0.002) for S-I translations throughout the entire movement. In the BR group, no significant differences between operative and contralateral shoulders were detected in any kinematic variables for the S-I direction (all P &gt; 0.132); however, the operative shoulders exhibited a larger maximum (P = 0.031), a smaller minimum (P = 0.008), and a larger range (P &lt; 0.001) for the A-P translations throughout the entire motion compared with contralateral shoulders.BR successfully reduced residual superior humeral translation compared to conventional RCR and restored normal S-I glenohumeral kinematic in the treatment of LMRCTs. However, the A-P glenohumeral kinematics were not fully restored after BR and its effect on the long-term clinical outcomes required further investigation.BR can be a promising technique to treat LMRCTs while its potential adverse effects on the A-P glenohumeral kinematics should not be ignored, which still required further clinical evidence to determine the long-term outcomes.

Nail-patella syndrome is a genetic disease with different phenotypes often affecting nails and knees. We present a woman with nail-patella syndrome with instability and dysfunction of the distal radioulnar joint. This is a trait which, to our knowledge, has not previously been described in nail-patella syndrome. In the clinical examination, the ulna head subluxed from the distal radioulnar joint when the wrist was fully supinated, creating a dorsal visible indentation and a volar protrusion of the ulnar head. The distal radioulnar joint instability of the case patient was quantified with a 3D visualisation and kinematic evaluation using dynamic radiostereometry analysis during a forearm rotation test and a press test. The investigation revealed limited pronation and hyper-supination during the forearm rotation compared with a healthy control. The dynamic radiostereometry analysis enabled a better understanding of the pathomechanics behind the instability. Patient-specific CT-derived bone models of ulna and radius revealed flat end dysplastic joint surfaces. The dynamic radiostereometry analysis proved to be a useful tool to describe, visualise and understand the pathomechanics of the case patient's distal radioulnar joint.

Task-specific differentiation of patellofemoral pain in women using a neural network analysis of joint angle subsets.

HighlightsThis work presents a low-cost 3D videogrammetry system of high applicability. The system has been validated against Vicon®, a widely used commercial solution in mus-culoskeletal kinematics analysis, demonstrating comparable accuracy and repeatabil-ity. Its accessible design makes it a practical alternative for motion analysis applica-tions, with potential use in both musculoskeletal studies and general kinematic evalua-tions.What are the main findings?It is a low-cost, high precision 3D videogrammetry system.It has similar accuracy and repeatability to Vicon®, a commercial system for kinematic analysis of musculoskeletal models.What is the implication of the main finding?It has increased accessibility to vision systems for kinematic analysis with high accuracy for research and clinical applications.It has greater modularity than commercial systems.(1) Background: Image acquisition systems based on videogrammetry principles are widely used across various research fields, particularly in mechanics, with applications ranging from civil engineering to biomechanics and kinematic analysis. This study presents the design, development, and validation of a low-cost, two-camera 3D videogrammetry system for the kinematic analysis of human motion. (2) Materials and Methods: Built using commercially available components and custom MATLAB® (version 2019b) software, the system captures synchronized video streams and extracts precise 3D coordinates of markers. Its performance was validated against the Vicon® (Vicon Nexus 1.7.1) system, a gold standard in musculoskeletal motion analysis. Comparative tests were conducted under static and dynamic conditions at varying working distances and velocities. (3) Results: Results demonstrate that the proposed system achieves high accuracy, with maximum measurement errors below 0.3% relative to Vicon®, and similar repeatability (SD of approximately 0.02 mm in static conditions). Compared to manual caliper measurements, both vision systems yielded similar results, with errors ranging between 0.01% and 0.82%. (4) Conclusions: A low-cost, two-camera videogrametric system was validated, offering full transparency, flexibility, and affordability, making it a practical alternative for both clinical and research settings in biomechanics and human movement analysis, with potential to be extended to general kinematic analysis.

Low back pain among athletes varies by sport, age, and sex, affecting performance and contributing to sports retirement. Recently, there has been an increasing focus on chronic primary low back pain (CPLBP) in athletes. The aim of this scoping review is to examine the existing literature on CPLBP, focusing on the physical and psychological differences between athletes with and without CPLBP. A systematic search across MEDLINE, CINAHL, SportDiscus, and PsycINFO, guided by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Guidelines (PRISMA), identified 11 relevant studies. Three key concepts guided the search: "chronic low back pain", "physical and psychological characteristics", and "athletes". From 1,767 screened articles, 11 studies involving 717 athletes (301 with CPLBP and 416 without) met the inclusion criteria. Most studies showed that athletes with CPLBP had significantly lower trunk muscle activation amplitudes and delayed onset. One study found that athletes with CPLBP had significantly reduced trunk extension strength. Kinematic evaluations showed a significant increase in trunk damping and lumbar extension in athletes with CPLBP compared to athletes without CPLBP. However, other studies reported no significant differences in trunk muscle activity, kinetic and kinematic variables. Finally, athletes with CPLBP reported significantly higher kinesiophobia, anxiety and pain catastrophizing scores. This review shows significant physiological and psychological differences between athletes with and without CPLBP. Future research should focus on sport-specific assessments of CPLBP and its impact on performance.

Knee hyperextension in chronic stroke: Associated biomechanical and neuromuscular factors.

Abstract. The Global Navigation Satellite System (GNSS) has become an integral component in various applications, offering differing levels of accuracy that span from several dozen meters to mere millimeters. While achieving high precision in positioning is essential, an equally important aspect that must be taken into consideration is the reliability of these results, particularly for applications that demand real-time data processing. Various environments can negatively impact the quality of positioning signals, highlighting the necessity for users to be cognizant of these challenging conditions. In particular, low-latitude regions experience significant interference due to the ionosphere, which plays a pivotal role in determining the effectiveness of GNSS signals. This interference is predominantly attributed to the occurrence of plasma bubbles, which induce scintillation, leading to a noticeable degradation in the quality of GNSS signals. Such conditions can hinder the capability to track certain satellites, potentially resulting in multiple cycle slips that compromise positional accuracy. Therefore, it is crucial to develop and implement strategies that ensure robust GNSS positioning in these affected environments. This paper aims to present a comprehensive analysis of several GNSS Real-Time Kinematic (RTK) evaluations conducted in Brazil, where the impact of scintillation will be systematically assessed alongside positioning results. The study relies on data gathered in both static and kinematic modes to draw conclusions. Furthermore, it will discuss various strategies aimed at mitigating these issues, focusing on enhancing the reliability of GNSS results, which typically involve modifications to the underlying stochastic model used in positioning calculations.

In the modern sports environment, pole sport is becoming increasingly popular. It combines elements of gymnastics, acrobatics, and dance techniques. Despite the growing interest in this sport, scientific research on its biomechanical aspects remains insufficiently studied. The peculiarities of performing acrobatic elements, the distribution of the load on the musculoskeletal system, and the risks of injury require a detailed analysis. The purpose of the article. This research aims to analyze the biomechanical features of acrobatic elements in pole sport, define key factors influencing exercises' technical performance, and estimate risks of injuries. The article discusses the main kinematic and kinetic parameters of movements and the influence of physical training on the efficiency of performing elements. Methodology. The research is based on a comprehensive analysis of literature, empirical data on athletes' movement patterns, and biomechanical characteristics of key element performance. Video analysis and three-dimensional kinematic evaluation were used, which allowed objective information about the distribution of load during the exercise. Scientific novelty. The work expands the scientific understanding of the influence of muscle activity and strength characteristics on the efficiency of performing elements in pole sport. For the first time, a detailed analysis of muscle symmetry and asymmetry in athletes was carried out, which allows the development of personalized training programs to correct imbalances. Conclusions. The study's results confirm the importance of an individual approach to the physical training athletes engaged in pole sport. Optimization of power balance and proper load distribution allows for improvement in performance techniques and reduces the risk of injury. Further research in this area can be aimed at improving training methods, using digital technologies for movement analysis, and integrating psychophysiological approaches to athletes' training.

BackgroundStroke is the leading cause of long-term disability with paucity of evidence-based interventions for individuals with severe upper extremity impairment in the affected arm. Loss of independent joint control limits reaching distance and velocity contributing to activity and participation limitations. Emerging evidence demonstrates improved independent upper extremity joint movement with training combining shoulder abduction loading during high repetition, task-specific reaching practice. The purpose of this study is to compare outcomes for one-year post-stroke for participants who receive reaching training with vs without progressive shoulder abduction loading during upper extremity reaching training using a standardized mechantronic device.MethodsThis is a phase II, double-blinded randomized clinical trial conducted at two inpatient rehabilitation hospitals. Eighty-six individuals will be recruited upon admission to acute inpatient rehabilitation and randomly allocated to either the experimental or active comparator intervention groups. Both groups will receive reaching training with the affected upper extremity in a standardized mechatronic device 4 days per week while in inpatient or day rehabilitation. Outcomes will be assessed at baseline, weekly while in inpatient and day rehabilitation, and every other month after discharge until one year post-stroke. Primary outcomes include change in reaching function of the affected upper extremity, measured by kinematic evaluation. This captures the loss of independent joint control due to flexion synergy expression. Secondary outcomes include measures of severity of flexion synergy motor impairment, Action Research Arm Test, Fugl-Meyer Assessment, and the Stroke Impact Scale.DiscussionThis study will test the efficacy of progressive shoulder abduction loading during reaching training using a mechatronic device. The results of this study have the potential to inform clinical practice for upper extremity reaching training for individuals with severe upper extremity impairment post-stroke to reduce flexion synergy expression.Trial registrationClinicaltrials.gov, NCT04118998. Registered on 8 October 2019.

BackgroundPulmonary arterial hypertension (PAH) is a severe condition characterized by elevated pulmonary arterial pressure, leading to significant morbidity and mortality. Despite ongoing research, its pathophysiology remains incompletely understood. Traditionally, PAH has been regarded as predominantly affecting the right ventricle (RV), often overlooking its potential impact on the left ventricle (LV), particularly in patients with preserved LV ejection fraction (EF).MethodsIn this study, we investigate the late-stage effects of PAH on both electrical and mechanical functions, as well as their coupling, in each ventricle using the monocrotaline-treated rat model. Specifically, an integrative approach combining in-vivo epicardial potential mapping, in-situ video kinematic evaluation, and transcriptomic analysis was performed on rats injected with monocrotaline (MCT, n = 22) or saline solution (Physio, n = 16).ResultsOur findings reveal that PAH induces global increases in refractoriness from 88.8 ± 1.9 ms to 152.7 ± 3.9 ms and reductions in conduction velocity in the RV from 0.59 ± 0.01 m/s to 0.55 ± 0.01 m/s and from 0.28 ± 0.01 m/s to 0.25 ± 0.01 m/s along and across the fiber orientation, respectively. Notably, a significant increase in electromechanical delay from 24.9 ± 1.2 ms to 35.8 ± 5.2 ms was also observed in the RV. In the LV, PAH also results in increased refractoriness from 95.4 ± 3.0 ms to 140.0 ± 11.5 ms and reduced transverse conduction velocity by 14%, despite preserved EF. Transcriptomic analysis indicates that while both ventricles exhibit upregulation of extracellular matrix remodeling-related genes, the RV primarily shows downregulation of electromechanical-related genes. On the contrary, an upregulation of the inflammatory pathways was detected mainly in the LV, alongside a downregulation of mitochondrial metabolism-related genes.ConclusionsOur findings revealed that both ventricles showed structural remodeling but only the RV underwent electromechanical alteration, while the LV displayed metabolic and inflammatory alteration. This was further validated by the preserved EF in the advanced stage of PAH. Our work highlights that a more comprehensive understanding of PAH pathophysiology can lead to targeted therapeutic strategies, challenging the conventional RV-centric perspective.

Evaluation of Equine Distal Limb Kinematics Before and After Administration of Analgesics for Treatment of Naturally Occurring Osteoarthritis

To meet the urgent market need for implementation of various heavy-load operations within complex and restricted underground environments, this paper proposes a new scientific structural development scheme for underground heavy-load robot. The scheme combines topology optimization and modular scale synthesis to achieve the optimal configuration for underground heavy-load robot. Firstly, orienting to the specific working environment and design requirements, a feasible configuration was deduced by the configuration synthesis method. Then, the topology optimization was carried out to output a new stable configuration for underground heavy-load robot with good flexibility and stability. Secondly, the modular design idea was applied to realize the optimal scale synthesis and function expansion of underground heavy-load robot. Finally, based on the kinematic analysis model, a reasonable and effective performance evaluation system was established to verify the performance of underground heavy-load robot. Simulation and experimental results indicated that the underground heavy-load robot developed in this paper had a more reasonable structure and more comprehensive functions. It can fully meet the design requirements of flexible operation and high carrying capacity in the confined underground space. The research in this paper provides new ideas for the structural development of heavy-load robot, effectively enhances the design efficiency of spatial multi-freedom degree industrial robot, and lays a foundation for the coordinated control of modern intelligent robots.

ABSTRACTAlthough it is well‐documented that robotic‐assisted total knee arthroplasty (TKA) can improve surgical precision, evaluations of the postoperative kinematics of patients implanted using robotics remain less common. The objective of this study is to analyze the weight‐bearing kinematics for multiple TKAs implanted using two different surgical robots. In vivo knee kinematics were assessed using fluoroscopy for 28 subjects implanted with a Bi‐Cruciate Stabilized (BCS) TKA, 23 with a Bi‐Cruciate Retaining (BCR) TKA, 13 with a posterior stabilized (PS) TKA, and 22 with a cruciate retaining (CR) TKA. All subjects were implanted by the same surgeon using the respective company's surgical robot. All subjects performed a weight‐bearing deep knee bend. Parameters of interest include the femoral condylar anterior/posterior motion, femorotibial axial rotation, and weight‐bearing range‐of‐motion. The BCS TKA experienced the most posterior rollback, 13.4 ± 4.4 mm for the lateral condyle and 5.8 ± 2.5 mm for the medial condyle. These subjects also experienced the most femorotibial axial rotation, +9.3 ± 5.3°. Conversely, CR subjects experienced the least overall rollback and most anterior sliding, 0.4 ± 3.8 mm of lateral rollback and 1.9 ± 4.1 mm of medial anterior sliding. Implant design appears to play a significant role in postoperative kinematics. Improved stability is evident in TKAs that account for the ACL. However, no system behaved significantly better nor worse than previously published literature evaluating standard instrumentation.Level of Evidence: Level 3, retrospective cohort study.

Peripheral nerve injuries remain a significant clinical challenge, particularly in severe neurotmesis injuries requiring complex therapeutic interventions to restore functionality. This study aimed to evaluate the pro-regenerative potential of combining neural guide conduits with conditioned medium from olfactory mucosa mesenchymal stem cells, compared to gold-standard surgical techniques. The study was conducted using a validated ovine model of common peroneal nerve injury. Recovery was assessed over 24 weeks through functional, kinematic, ultrasonographic, and electrophysiological evaluations, complemented by post-mortem nerve stereology and muscle histomorphometry. All therapeutic approaches promoted nerve and muscle regeneration, resulting in notable functional and structural improvements. However, irregularities were observed, as neural guide conduits and conditioned medium did not consistently outperform standard techniques. Additionally, recovery often fell short of normal values in the control group. These findings highlight the complexity of peripheral nerve regeneration in challenging surgical scenarios and underscore the translational potential of biomaterials and cell conditioned medium-based therapies. However, the observed irregularities emphasize the need for further research in complex animal models before application in real clinical cases. Such studies are essential to refine therapeutic strategies, address inconsistencies, and establish cell conditioned medium as a viable tool in peripheral nerve regeneration and repair.

BackgroundRapid real-time magnetic resonance (MR) sequences enable dynamic articular kinematic assessment. The abduction-external rotation (ABER) position has long been used to characterize glenohumeral pathology.PurposeTo evaluate a dynamic gradient recall echo (GRE) sequence for ABER-positioned glenohumeral joint kinematic assessment correlating with subjective instability and clinical apprehension testing.Material and MethodsSymptomatic patients were scanned using a routine MR arthrogram protocol supplemented by an additional "dynamic ABER" GRE technique acquired with the arm abducted and then internally-externally rotated in real time. Dynamic motion of the humeral head between the extremes of motion in the abducted and externally rotated positions was evaluated. The cohort was followed for 3 years.ResultsA total of 15 dynamic ABER studies in 15 different patients were evaluated by three readers (right: n=9; left: n=6), with a mean age of 30 years (range=19-45 years). Good accuracy of the humeral head excursion between the abducted and externally-internally rotated positions (AUC=0.88) was observed as a test for positively detecting instability. An association was detected between clinical instability and mean humeral head excursion as measured by all three readers (P = 0.026), although no association between positive apprehension testing and mean humeral head excursion was detected. There was a trend towards surgery-naïve patients with higher mean humeral head excursion subsequently undergoing surgical management (P=0.088), although this did not reach statistical significance.ConclusionCorrelation between subjective instability and humeral head translation demonstrated on a dynamic ABER sequence added to MR shoulder arthrograms was observed but without association with clinical apprehension testing.

Abstract This study focuses on the comparative evaluation of self-aligned (S-A) and alignment-free (A-F) mechanisms for upper limb rehabilitation robots, aiming to improve comfort and adaptability in rehabilitation exercises. The manuscript introduces a detailed analysis of the kinematic adaptability and interaction forces and torques associated with the 3Ra3P and 3Ra2R1P configurations, providing critical insights into their respective strengths and limitations. The methods include kinematic modeling and experimental evaluation of interaction forces during rehabilitation tasks, specifically “eating” and “combing” movements. Key findings reveal that the alignment-free design demonstrated superior adaptability to complex movement trajectories, allowing greater joint displacement and enhanced flexibility. However, this increased adaptability was associated with higher interaction forces and torques, indicating increased resistance and reduced compatibility. Conversely, the self-aligned design exhibited lower interaction forces, suggesting a smoother and more controlled rehabilitation experience, but with reduced flexibility. These insights emphasize the importance of selecting the appropriate design based on specific rehabilitation objectives. The implications of this work are significant for the development of personalized rehabilitation systems, as it highlights the trade-offs between adaptability and resistance in robotic assistance, guiding clinicians in optimizing rehabilitation protocols for individual patient needs.