Biomechanical Methods Research Articles

WEIGHTLIFTING SPORTS SPECIAL PREPARATORU EXERCISES OF BARBEL LIFTING FOR INCREASING WEIGHTLIFTING CLEAN EXERCISE RESULTS

Improvement of weightlifters technical skills and special physical qualities involves use of different instrumental control methods, which are necessary for obtaining biomechanically accurate quantitative parameters of the athlete's movement structure. Such control, using biomechanical methods, allows us to substantiate the parameters of the exercise techniques for competitions and to identify factors that affect the effectiveness of the movement activity. Our research aim was to evaluate the effect of non-standard barbell lifting exercises on results of weightlifting competition. The study subjects were healthy 15 weightlifters. The assessment of dynamic parameters was done before and after the set of exercises by using non-standard weightlifting bar using FITRO Dyne Premium (Slovakia). The maximum muscle strength dynamics was performed by the REV 9000 Technogym (Italy) isokinetic dynamometer, along with the registration of muscle biopotentials (EMG). Data was analyzed using Excel statistics 3.1. After ascertaining experiment with a set of exercises with an non-standard barbell lifting on clean exercise, the dynamic parameters of the controlled barbell lifting on weightlifting clean exercise (standard performance) were improved.

RETRACTED ARTICLE: Pressure sore prevention in vet medicine: importance of the supports

(2019). RETRACTED ARTICLE: Pressure sore prevention in vet medicine: importance of the supports. Computer Methods in Biomechanics and Biomedical Engineering: Vol. 22, 44th Congress of the Societe de Biomecanique, pp. S538-S539.

ERGONOMIC RISK FACTORS ANALYSIS WITH MULTI-METHODOLOGICAL APPROACH: ASSESSING WORKERS’ ACTIVITIES IN BUILDINGS UNDER CONSTRUCTION

The aim of this article is to determinate a biomechanical risk analysis method based on a multi-methodological study for high-buildings under construction. This aim bases on the discussion related to the discrepancies about the risk analysis technique applied due to the differences in terms of risk types and levels of risk that different methods provide. The research analyzes the known musculoskeletal disorders, injuries, damages and the biomechanical risk factors of workers in high-buildings under construction. The data collected covers a sample of 150 workers in a high building under construction in Spain over a 12-months period. The research strategy consists in the following five stages: Firstly, tasks and task groups were identified and classified in five working groups of activities. Secondly, the study applies techniques of direct observation to calculate the level of biomechanical risk. Thirdly, the semi-structured interview conveyed approaches to obtain specific data about signs of Work-Related Musculoskeletal Disorders (WRMSDs). Fourthly, the study discusses the occupational registered injuries by analysis of medical diagnoses. Fifthly, the software tools tested provide more details of direct observation techniques as the traditional forms to calculate the levels of biomechanical risk. The results of the multi-methodological research design illustrate a phased approach may be contrasted between the stages and it allows a more complete analysis in order to compare the results. The research findings indicate that activities in buildings have a strong need to improve the analysis of designing processes in order to determinate tailored tasks and lessening bodily injuries and damages. Keywords: Ergonomics, methodology, Work-related musculoskeletal disorders, activities in buildings

Expert consensus on biomechanical research of dental implant

Current biomechanical research of dental implants focuses on the mechanical damage and enhancement mechanism of the implant-abutment interface as well as how to obtain better mechanical strength and longer fatigue life of dental implants. The mechanical properties of implants can be comprehensively evaluated by strain gauge analysis, photo elastic stress analysis, digital image correlation, finite element analysis, implant bone bonding strength test, and measurement of mechanical properties. Finite element analysis is the most common method for evaluating stress distribution in dental implants, and static pressure and fatigue tests are commonly used in mechanical strength test. This article reviews biomechanical research methods and evaluation indices of dental implants. Results provide methodology guidelines in the field of biomechanics by introducing principles, ranges of application, advantages, and limitations, thereby benefitting researchers in selecting suitable methods. The influencing factors of the experimental results are presented and discussed to provide implant design ideas for researchers.

Finite element analysis for blood accumulation in intracerebral hemorrhage.

Biomechanical methods may provide a novel way to understand blood accumulation in intracerebral hemorrhage (ICH). The current study presents the results of a biomechanical analysis of blood accumulation in ICH using a finite element analysis, with an emphasis on the pressure exerted by the mass effect of blood in early ICH. A two-dimensional finite model of the human brain parenchyma and the human ventricular system was developed and analyzed under two preloading conditions. The material properties of the human parenchyma were derived from previous reports. Ogden's theory was applied to describe the stress-strain association in soft tissue. The results of the present study indicated that maximal stress was located at the two ends of the hemorrhage cavity, with the majority of stresses distributed on the zone surrounding the bleed. The two load environments demonstrated similar stress distributions. The loads put on the detached edges were not less than the intracranial pressure (ICP) when the stress threshold was reached. The results of the present study suggest that the direction of blood accumulation can be determined by the shape of the initial blood mass. Mechanical factors (blood pressure and ICP) did not serve a definitive role in preventing blood from accumulating in the early stages of ICH. The present study may aid in understanding the effects of mechanical factors in blood accumulation and hemostasis in patients with early ICH.

Surgical tactics for elderly patients with deforming arthrosis of first metatarsophalangeal joint of foot

Aim. To analyze the results of various types of surgical interventions, used in elderly patients with deforming arthrosis of the first metatarsophalangeal joint of the foot.
 Materials and methods. The long-term results of treatment of osteoarthrosis of the first metatarsophalangeal joint of the foot were analyzed in 70 elderly persons depending on the stage of disease. Clinical, roentgenological investigation, biomechanical and statistical methods were used for diagnosis and treatment. Results. Surgical tactics of treatment for elderly patients depending on the stage of disease was developed, outcomes of surgical treatment were followed up in 55 patients. Good results were reached in 47 (85.4 %) patients, satisfactory – in 8 (15.6 %) patients, no unsatisfactory results were noted.
 Conclusions. Differentiated approach to treatment depends on the choice of optimal method in each concrete case taking into account the stage of disease, character of deformity; early complex postoperative rehabilitation permits to obtain favorable cosmetic and functional outcome, improve patients’ quality of life.

Modeling Judges’ Scores in Artistic Gymnastics

Background: In artistic gymnastics, performance is observed and evaluated by judges based on criteria defined in the code of points. However, there is a manifold of influences discussed in the literature that could potentially bias the judges’ evaluations in artistic gymnastics. In this context, several authors claim the necessity for alternative approaches to judging gymnastics utilizing biomechanical methods. Objective: The aim of this study was to develop and evaluate a model-based approach to judge gymnastics performance based on quantitative kinematic data of the performed skills. Methods: Four different model variants based on kinematic similarity calculated by a multivariate exploratory approach and the Recurrent Neural Network method were used to evaluate the relationship between the movement kinematics and the judges’ scores. The complete dataset consisted of movement kinematic data and judgment scores of a total of N = 173 trials of three different skills and routines from women’s artistic gymnastics. Results: The results exhibit a significant relationship between the predicted score and the actual score for six of the twelve model calculations. The different model variants yielded a different prediction performance in general across all skills and also in terms of the different skills. In particular, only the Recurrent Neural Network model exhibited significant correlation values between the actual and the predicted scores for all three investigated skills. Conclusion: The results were discussed in terms of the differences of the models as well as the various factors that might play a role in the evaluation process.

Recent Advance in Evaluation Methods for Characterizing Mechanical Properties of Bone

Skeletal biomechanics focuses on both transient and long-term effects of bone stress, using the basic theory and method of material mechanics, elasto-plasticity theory, and fracture mechanics,is considered to be one of the most important branches in biomechanics. In order to achieve complete and comprehensive evaluation of skeletal biomechanics, researchers developed a variety of levels of skeletal biomechanical evaluation methods, including mechanical testing, theoretical research, microstructure research and finite element analyses. At present, most of the mechanical evaluation methods were performed by a combination of mechanical tests and finite element (FE) simulation studies for the evaluation of mechanical properties. This study summerized the research in multi-level mechanical test methods, different research methods of microstructure, and the reconstruction of various FE skeletal models to study bone mechanics. The mentioned methods and techniques can be served as the basis for systematic studies of the biomechanical properties of bones.

Wound healing properties, antimicrobial and antioxidant activities of Salvia kronenburgii Rech. f. and Salvia euphratica Montbret, Aucher & Rech. f. var. euphratica on excision and incision wound models in diabetic rats

Diabetic patients suffer from persistent and non-healing wounds. Salvia species are traditionally used for the treatment of wounds and colds. The aims of the present study were to evaluate the in vivo wound healing potential, in vitro antimicrobial and antioxidant activities, and total phenolic and flavonoid contents of the aerial parts of two endemic taxa, Salvia kronenburgii Rech. f. (SK) and Salvia euphratica Montbret, Aucher & Rech. f. var. euphratica (SE). Two different concentrations (0.5% and 1% (w/w)) of ethanol extracts were investigated in incision and excision wound models on Streptozotocin-induced diabetic rats using biomechanical, biochemical, histopathological, macroscopic, and genotoxic methods for 7 and 14 days. Antimicrobial activity was evaluated against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Acinetobacter baumannii, Aeromonas hydrophila, Mycobacterium tuberculosis, Candida glabrata, Candida parapsilosis, and Candida tropicalis using the broth microdilution and the resazurin microtiter assay plate methods. Fito®, Ampicillin, Ethambutol, Isoniazid, and Fluconazole were used as reference drugs. Antioxidant capacities and total phenolic and flavonoid contents of both extracts were detected using DPPH free radical scavenging assay, Folin-Ciocalteu, and Al(NO3)3 methods, respectively. SK ointment at 0.5% and 1% (w/w) concentrations and SE ointment at 1% (w/w) concentration showed 99.9%, 99.5%, and 99.7% contraction, respectively for excision wounds, and SK and SE ointments at 1% (w/w) concentration showed 99.4% and 99.2% contraction for incision wounds while Fito® showed 98.9% and 98.5% contraction, respectively. Increased re-epithelialization (P < 0.01 and P < 0.001), angiogenesis, and decreased dermal inflammation (P < 0.001) were determined for SK and SE ointments at both 7 and 14 days. SE ointment on day 7 and SK ointment on day 14 reduced oxidative damage to DNA when compared to control (P < 0.01 and P < 0.001). Both tested plants had greater antibacterial activity against A. baumannii (62.5 μg/mL MIC value) and SE had greater antimycobacterial activity against M. tuberculosis (0.24 μg/mL MIC value) when compared to reference drugs Ampicillin, Isoniazid, and Ethambutol (125, 0.97, and 1.95 μg/mL MIC values, respectively). Antioxidant capacities, total phenolic and flavonoid contents of SE and SK were 87.08%, 76.21 μg GAE/mg, 43.43 μg QE/mg and 72.17%, 41.81 μg GAE/mg, 33.62 μg QE/mg, respectively. SK and SE had strong wound healing effects while SK found to be more effective than SE at both 7 and 14 days.

Feasibility of Incorporating Test-Retest Reliability and Model Diversity in Identification of Key Neuromuscular Pathways During Head Position Tracking.

To study the complex neuromuscular control pathways in human movement, biomechanical parametric models and system identification methods are employed. Although test-retest reliability is widely used to validate the outcomes of motor control tasks, it was not incorporated in system identification methods. This study investigates the feasibility of incorporating test-retest reliability in our previously published method of selecting sensitive parameters. We consider the selected parameters via this novel approach to be the key neuromuscular parameters, because they meet three criteria: reduced variability, improved goodness of fit, and excellent reliability. These criteria ensure that the parameter variability is below a user-defined value, the number of these parameters is maximized to enhance goodness of fit, and their test-retest reliability is above a user-defined value. We measured variability, the goodness of fit, and reliability using Fisher information matrix, variance accounted for, and intraclass correlation, respectively. We also incorporated model diversity as a fourth optional criterion to narrow down the solution space of key parameters. We applied this approach to the head position tracking tasks in axial rotation and flexion/extension. A total of forty healthy subjects performed the tasks during two visits. With variability and reliability measures ≤0.35 and ≥0.75, respectively, we selected three key parameters out of twelve with the goodness of fit >69%. The key parameters were associated with at least two neuromuscular pathways out of four modeled pathways (visual, proprioceptive, vestibular, and intrinsic), which is a measure of model diversity. Therefore, it is feasible to incorporate reliability and diversity in system identification of key neuromuscular pathways in our application.

In memorium Christopher Rae Jacobs

Dr Christopher Rae Jacobs 1965–2018 (Editor Journal of Computer Methods in Biomechanics and Biomedical Engineering)Dr Christopher Jacobs was an acclaimed Scientist and Academic who was recognised a...

Meshless Methods in Computational Biomechanics for Medicine

Meshless Methods in Computational Biomechanics for Medicine

Live human assessment of depth-dependent corneal displacements with swept-source optical coherence elastography.

PurposeTo assess depth-dependent corneal displacements in live normal subjects using optical coherence elastography (OCE).MethodsA corneal elastography method based on swept-source optical coherence tomography (OCT) was implemented in a clinical prototype. Low amplitude corneal deformation was produced during OCT imaging with a linear actuator-driven lens coupled to force transducers. A cross-correlation algorithm was applied to track frame-by-frame speckle displacement across horizontal meridian scans. Intra-measurement force and displacement data series were plotted against each other to produce local axial stiffness approximations, k, defined by the slope of a linear fit to the force/displacement data (ignoring non-axial contributions from corneal bending). Elastographic maps displaying local k values across the cornea were generated, and the ratio of mean axial stiffness approximations for adjacent anterior and posterior stromal regions, ka/kp, was calculated. Intraclass correlation coefficients (ICC) were used to estimate repeatability.ResultsSeventeen eyes (ten subjects) were included in this prospective first-in-humans translational study. The ICC was 0.84. Graphs of force vs. displacement demonstrated that, for simultaneously acquired measurements involving the same applied force, anterior stromal displacements were lower (suggesting stiffer behavior) than posterior stromal displacements. Mean ka was 0.016±0.004 g/mm and mean kp was 0.014±0.004 g/mm, giving a mean ka/kp ratio of 1.123±0.062.ConclusionOCE is a clinically feasible, non-invasive corneal biomechanical characterization method capable of resolving depth-dependent differences in corneal deformation behavior. The anterior stroma demonstrated responses consistent with stiffer properties in compression than the posterior stroma, but to a degree that varied across normal eyes. The clinical capability to measure these differences has implications for assessing the biomechanical impact of corneal refractive surgeries and for ectasia risk screening applications.

Comparative analysis for five fixations of Pauwels-I by the biomechanical finite-element method

Background: Little is known about how biomechanics govern the five fixtures such as DHS, MLS, DHS + LS, LP, and HA are accepted as common therapeutic techniques. Aims and objectives: A series of numerical models for a femoral neck fracture of Pauwels-I will be constructed by innovative approach of finite element in order to determine the most optimized option in comparison with biomechanical performance. Method: Twenty sets of computer tomography scanned femora were imported onto Mimics to extract 3 D models; these specimens were transferred to Geomagic-Studio for a simulative osteotomy and kyrtograph; then, they underwent UG to fit simulative solid models; 5 sorts of fixture were then expressed by Pro-Engineer virtually. After processing with HyperMesh, all compartments (fracture model + internal implant) were assembled onto 5 systems: “Dynamic Hip Screw (DHS), Multiple Lag screw (MLS), DHS + LS, femoral Locking Plate (LP) and HemiArthroplasty (HA).” Eventually, numerical models of the finite-elemental analysis were exported to AnSys to determine the solution. Result: Four models of fixation and a simulation of HA for Pauwels-I were established, validated, and analyzed with the following findings: In term of displacement, these 5 fixtures ranged between 0.3801 and 0.7536 mm have no significant difference; in term of stress, the averages of peaks for integral assemblage are b(MLS) = 43.5766 ≈< d(LP) = 43.6657 ≈< e(Ha) = 43.6657 < c(DHS + LS) = 66.5494 < a(DHS) = 105.617 in MPa indicate that MLS, LP and HA are not significantly different, but less than DHS + LS or DHS in each. Conclusion: A fixture of MLS or LP with optional HA should be recommended to clinically optimize a Pauwels-I facture.

BIOMECHANICAL MODELING IN SURGICAL TREATMENT OF A PATIENT WITH TRUE LUMBAR SPONDYLOLISTHESIS

Objective. To assess the results of clinical approbation of individual finite-element biomechanical model of a patient’s spino-pelvic complex with subsequent modeling of the best option of surgical treatment. Material and Methods. A biomechanical modeling of changes in the sagittal profile of a patient with degenerative disease of the lumbosacral spine, bilateral spondylolysis, and unstable grade 2 spondylolisthesis of the L4 vertebra was performed. The developed biomechanical model made it possible to assess the characteristics of the stress-strain state of the spinal motion segments aroused due to development of the disease. Within the built biomechanical model of the patient’s spino-pelvic complex, a corrective operation was further modeled that assumed a preservation of harmonious profile of sagittal spino-pelvic relationships. Post-correction characteristics of the stress-strain state of spinal motion segments were studied and compared with preoperative parameters of the biomechanical model. Results. Using methods of biomechanics and computer modeling allowed to calculate the stress-strain state of the lumbosacral spine under static load for two options of fixation and intervertebral cage implantation at the L4–L5 level: four transpedicular screws (L4–L5 vertebrae) and six transpedicular screws (L3–L4–L5 vertebrae). The simulation results showed that neither metal implants, nor elements of the lumbosacral spine experienced critical stresses and deformations that could lead to the destruction and instability of the implant. Conclusion. The developed individual biomechanical finite-element solid model of the spine and pelvis allowed for biomechanical justification of prerequisites for the formation and further progression of degenerative changes in spinal motion segments associated with violations of the sagittal profile due to grade 2 spondylolisthesis of the L4 vertebra. The model built on the results of radiological examination biomechanically substantiated the best option of corrective spine surgery allowing to minimize stresses and deformations by choosing reasonable magnitude of correction of sagittal spino-pelvic parameters and configuration of transpedicular system.

The evaluation of a hybrid biomechanical deformable registration method on a multistage physical phantom with reproducible deformation

BackgroundAdvanced clinical applications, such as dose accumulation and adaptive radiation therapy, require deformable image registration (DIR) algorithms capable of voxel-wise accurate mapping of treatment dose or functional imaging. By utilizing a multistage deformable phantom, the authors investigated scenarios where biomechanical refinement method (BM-DIR) may be better than the pure image intensity based deformable registration (IM-DIR).MethodsThe authors developed a biomechanical-model based DIR refinement method (BM-DIR) to refine the deformable vector field (DVF) from any initial intensity-based DIR (IM-DIR). The BM-DIR method was quantitatively evaluated on a novel phantom capable of ten reproducible gradually-increasing deformation stages using the urethra tube as a surrogate. The internal DIR accuracy was inspected in term of the Dice similarity coefficient (DSC), Hausdorff and mean surface distance as defined in of the urethra structure inside the phantom and compared with that of the initial IM-DIR under various stages of deformation. Voxel-wise deformation vector discrepancy and Jacobian regularity were also inspected to evaluate the output DVFs. In addition to phantom, two pairs of Head&Neck patient MR images with expert-defined landmarks inside parotids were utilized to evaluate the BM-DIR accuracy with target registration error (TRE).ResultsThe DSC and surface distance measures of the inner urethra tube indicated the BM-DIR method can improve the internal DVF accuracy on masked MR images for the phases of a large degree of deformation. The smoother Jacobian distribution from the BM-DIR suggests more physically-plausible internal deformation. For H&N cancer patients, the BM-DIR improved the TRE from 0.339 cm to 0.210 cm for the landmarks inside parotid on the masked MR images.ConclusionsWe have quantitatively demonstrated on a multi-stage physical phantom and limited patient data that the proposed BM-DIR can improve the accuracy inside solid organs with large deformation where distinctive image features are absent.

A novel approach to predict ingress/egress discomfort based on human motion and biomechanical analysis

This study proposes an ingress/egress discomfort prediction algorithm using an in-depth biomechanical method and motion capture database. The ingress/egress motion of the subject was captured using an optical motion capture system and physically adjustable vehicle mock-up. The subjective discomfort evaluation data were also recorded at the same time. The inverse kinematics and inverse dynamics were performed to analyze captured ingress/egress motion. These procedure provide motion and joint torque information on each subject. Based on the analysis results, this study proposes the following novel features: accumulated movement of joint and sum of rectified joint torque. This study conducted a feature selection procedure to identify a relevant feature subset. Recursive feature selection and optimal feature selection methods found the most relevant feature subset with collected subjective responses. Finally, we constructed the prediction model using support vector machine. The prediction model was evaluated through prediction accuracy and statistical analysis. For comparison with the previous study, this study implemented two representative models and compare the result with those of the previous studies using the identical dataset. The effectiveness of proposed algorithm was demonstrated in comparison with previous studies.

Shoulder biomechanics of RC repair and Instability: A systematic review of cadaveric methodology

BackgroundNumerous biomechanical studies have addressed normal shoulder function and the factors that affect it. While these investigations include a mix of in-vivo clinical reports, ex-vivo cadaveric studies, and computer-based simulations, each has its own strengths and limitations. A robust methodology is essential in cadaveric work but does not always come easily. Precise quantitative measurements are difficult in in-vivo studies, and simulation studies require validation steps. This review focuses on ex-vivo cadaveric studies to emphasize the best research methodologies available to simulate physiologically and clinically relevant shoulder motion. MethodsA PubMed and Web of Science search was conducted in March 2017 (and updated in May 2018) to identify the cadaveric studies focused on the shoulder and its function. The key words for this search included rotator cuff (RC) injuries, RC surgery, and their synonyms. The protocol of the study was registered on PROSPERO and is accessible at CRD42017068873. ResultsThirty one studies consisting of 167 specimens with various biomechanical methods met our inclusion criteria. All studies were level V cadaveric studies. Cadaveric biomechanical models are widely used to study shoulder instability and RC repair. These models are commonly limited to the glenohumeral joint by a fixed scapula, passively and discretely move the humerus, and statically load the RC without regard for the integrity of the glenohumeral capsule. ConclusionAll studies captured in this review evaluated shoulder biomechanics. Recent studies in patients suggest that some assumptions made in this space may not fully characterize motion of the human shoulder. With reproducible scapular positioning, dynamic RC activation, and preservation of glenohumeral capsule integrity, cadaveric studies can facilitate proper validation for simulation models and broaden our understanding of the shoulder environment during motion in healthy and disease states.

BIOMECHANICAL MODELING AND SIMULATION OF SUBCUTANEOUS ADIPOSE TISSUE BASED ON LINEAR ELASTIC AND HYPERELASTIC MODEL

The biomechanical modeling and simulation of human tissue are the basic part of virtual surgery system. As an important human soft tissue, the biomechanical modeling and simulation method of subcutaneous adipose tissue are urgent problems to be solved in virtual surgery system. In this paper, biomechanical modeling and simulation of subcutaneous adipose tissue were completed based on linear elastic and hyperelastic finite element model. First, the deformation process of subcutaneous adipose tissue was divided into two stages: Initial loading stage and later loading stage. Furthermore, the linear elastic model at initial loading stage and the nonlinear elastic model at later loading stage were established, respectively. Then, the biomechanical model of subcutaneous adipose tissue was solved based on the finite element method. Finally, the linear finite element calculation was included in nonlinear finite element calculations, and finite element simulation program of the subcutaneous adipose tissue was compiled in Visual Studio environment. The accuracy of the model was verified by comparing the simulation results with the experimental results. The efficiency of finite element simulation program of the linear and nonlinear hybrid model is evaluated by comparing the simulation time with the single linear model and the hyperelastic model.

Tendon stem progenitor cells: Understanding the biology to inform therapeutic strategies for tendon repair.

Tendon and ligament injuries are a leading cause of healthcare visits with significant impact in terms of economic cost and reduced quality of life. To date, reparative strategies remain largely restricted to conservative treatment or surgical repair. However, these therapies fail to restore native tendon structure and function; thus, the tissue may re-rupture or degenerate with time. To improve tendon healing, one promising strategy may be harnessing the innate potential of resident tendon stem/progenitor cells (TSPCs) to guide tenogenic regeneration. In this review, we outline recent advances in the identification and characterization of putative TSPC populations, and discuss biochemical, biomechanical, and biomaterial methods employed for their culture and differentiation. Finally, we identify limitations in our current understanding of TSPC biology, key challenges for their use, and potential therapeutic strategies to inform cell-based tendon repair. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1270-1280, 2019.