Biomechanics

Biomechanics is a vast discipline within the field of Biomedical Engineering. It explores the underlying mechanics of how biological and physiological systems move. It encompasses important clinical applications to address questions related to medicine using engineering mechanics principles. Biomechanics includes interdisciplinary concepts from engineers, physicians, therapists, biologists, physicists, and mathematicians. Through their collaborative efforts, biomechanics research is ever changing and expanding, explaining new mechanisms and principles for dynamic human systems. Biomechanics is used to describe how the human body moves, walks, and breathes, in addition to how it responds to injury and rehabilitation. Advanced biomechanical modeling methods, such as inverse dynamics, finite element analysis, and musculoskeletal modeling are used to simulate and investigate human situations in regard to movement and injury. Biomechanical technologies are progressing to answer contemporary medical questions. The future of biomechanics is dependent on interdisciplinary research efforts and the education of tomorrow’s scientists

IDENTIFICATION OF FATIGUE-RELATED KINEMATIC CHANGES IN ELITE RUNNERS USING A SUPPORT VECTOR MACHINE APPROACH

Understanding the kinematic changes underlying fatigue is essential in running biomechanics. The aim of this study was to identify fatigue-related kinematic changes in elite runners using a support vector machine approach. Full-body kinematics of thirteen trained runners were recorded in a non-fatigued and a fatigued state during treadmill running at their individual fatigue-speed. A support vector machine was trained and used to identify kinematic differences between the non-fatigued and fatigued state based on principal component scores. Strides during non-fatigued and fatigued running could be separated with 99.4% classification accuracy. Four upper limb (two shoulder and two elbow), four lower limb (one ankle, two knee and one hip) and two trunk (one thoracic and one lumbar spine) principal component scores were identified as most discriminative kinematic features between non-fatigued and fatigued running. The findings of the study suggest the feasibility of a support vector machine approach to identify subtle fatigue-related kinematic changes in elite runners

IS PRINCIPAL COMPONENT ANALYSIS MORE EFFICIENT TO DETECT DIFFERENCES ON BIOMECHANICAL VARIABLES BETWEEN GROUPS?

The biomechanical analysis investigates variables such as angles, inter-segmental forces and moments at the joints. When the relevant parameters (e.g., range of motion, peak values) are selected a priori from these variables, they could not perfectly represent the information content of the original dataset. Therefore, in this study we want to validate the efficacy of the Principal Component Analysis (PCA) in overcoming the limitations of the a priori selection of the parameters. An application study is reported; the lower-limb joint mechanics between patients operated with two different surgical techniques for a total hip arthroplasty are analyzed with both the traditional analysis and the PCA. The findings from the two methods converged, but the PCA identified new sources of variability not previously detected

Classification of forefoot plantar pressure distribution in persons with diabetes : a novel perspective for the mechanical management of diabetic foot?

Background: The aim of this study was to identify groups of subjects with similar patterns of forefoot loading and verify if specific groups of patients with diabetes could be isolated from non-diabetics. Methodology/Principal Findings: Ninety-seven patients with diabetes and 33 control participants between 45 and 70 years were prospectively recruited in two Belgian Diabetic Foot Clinics. Barefoot plantar pressure measurements were recorded and subsequently analysed using a semi-automatic total mapping technique. Kmeans cluster analysis was applied on relative regional impulses of six forefoot segments in order to pursue a classification for the control group separately, the diabetic group separately and both groups together. Cluster analysis led to identification of three distinct groups when considering only the control group. For the diabetic group, and the computation considering both groups together, four distinct groups were isolated. Compared to the cluster analysis of the control group an additional forefoot loading pattern was identified. This group comprised diabetic feet only. The relevance of the reported clusters was supported by ANOVA statistics indicating significant differences between different regions of interest and different clusters. Conclusion/s Significance: There seems to emerge a new era in diabetic foot medicine which embraces the classification of diabetic patients according to their biomechanical profile. Classification of the plantar pressure distribution has the potential to provide a means to determine mechanical interventions for the prevention and/or treatment of the diabetic foot

The influence of barefoot and barefoot inspired footwear on the kinetics and kinematics of running in comparison to conventional running shoes.

Barefoot running has experienced a resurgence in footwear biomechanics literature, based on the supposition that it serves to reduce the occurrence of overuse injuries in comparison to conventional shoe models. This consensus has lead footwear manufacturers to develop shoes which aim to mimic the mechanics of barefoot locomotion. This study compared the impact kinetics and 3-D joint angular kinematics observed whilst running: barefoot, in conventional cushioned running shoes and in shoes designed to integrate the perceived benefits of barefoot locomotion. The aim of the current investigation was therefore to determine whether differences in impact kinetics exist between the footwear conditions and whether shoes which aim to simulate barefoot movement patterns can closely mimic the 3-D kinematics of barefoot running. Twelve participants ran at 4.0 m.s-1±5% in each footwear condition. Angular joint kinematics from the hip, knee and ankle in the sagittal, coronal and transverse planes were measured using an eight camera motion analysis system. In addition simultaneous tibial acceleration and ground reaction forces were obtained. Impact parameters and joint kinematics were subsequently compared using repeated measures ANOVAs. The kinematic analysis indicates that in comparison to the conventional and barefoot inspired shoes that running barefoot was associated significantly greater plantar-flexion at footstrike and range of motion to peak dorsiflexion. Furthermore, the kinetic analysis revealed that compared to the conventional footwear impact parameters were significantly greater in the barefoot condition. Therefore this study suggests that barefoot running is associated with impact kinetics linked to an increased risk of overuse injury, when compared to conventional shod running. Furthermore, the mechanics of the shoes which aim to simulate barefoot movement patterns do not appear to closely mimic the kinematics of barefoot locomotion

Validation of an Inertial-Measurement-Unit System for Calculating Hip and Knee Flexion Angles During Gait

Technological advances regarding Inertial Measurements Units (IMUs) have positioned this type of sensor as an alternative for camera-based motion capture. This study introduces a new IMU based system (IMUsys) to measure hip and knee flexion angles. PURPOSE: To validate the use of a five-sensor IMUsys for the measurement of knee and hip flexion angles during gait in adults and pediatrics at two different time points. METHODS: Bilateral hip and knee flexion patterns (LH, RH, LK, and RK) of twenty-two healthy participants (12 adults and 10 pediatric) between the ages of 8 – 35 years were investigated. Participants performed two 1-min gait trials on a treadmill at self-selected speeds at two different time points. Data were analyzed using linear regression coefficients, the root mean square error (RMSE), the mean absolute error (MAE), and Bland & Altman plots. RESULTS: A strong relationship (r2\u3e 0.94) between the IMUsys and the camera-based system was found across all condition. RMSEs [LH \u3c 10°, RH \u3c 10°, LK \u3e 10°, RK \u3e 10°] were found across all condition. Repeatability coefficients [LH ≤ 5°, RH ≤ 5°, LK \u3e 10°, RK \u3c 10°] were found across all condition. CONCLUSION: The validity of the IMUsys was maintained across age groups with different segment proportion, and during prolonged use. However, the large errors observed for knee flexion measurements should be considered when using the IMUsys

Master of Science

thesisUnderstanding the quantitative aspects of kinematic and temporal parameters in fall-prone populations in natural environments is important, particularly in settings replicating hospital environments where patients are often impaired and less familiarized with the layout. Studies indicate fall rates are much higher in these settings than in comparable community settings. The aim of this study was to determine how bed height and side rail presence/type influence fall risk when patients get out of bed unassisted. Seventy-nine older adults with mobility impairments performed an unconstrained sit-to-walk movement at three randomized bed heights representing low, medium, and high bed conditions. Three side rail conditions were also studied. Temporal and kinematic parameters were obtained from key sit-to-walk movement events using 3D motion capture and ground reaction forces. There was no evidence that the presence of side rails influenced kinematics. Temporal parameters proved to be most affected by bed heights, particularly in the low bed condition. Velocity and momentum parameters were less significantly affected between conditions. Participants appeared to use similar momentum strategies to rise and initiate gait but altered their timing in order to accommodate their balance deficits. This study supports the model that suggests increased impairment leads to slower movement event timing during sit-to-walk transition. This study did not support other findings that mediolateral kinematics were higher in those with greater impairments, nor did bed height alter any of these kinematics at any event. Participants had statistically significant higher forward velocities when initiating gait from the medium bed condition, and they had statistically significant lower posterior momenta when exiting the high bed condition. These could be indications of increased mobility and improved use of generated kinetic energy. These represent potentially favorable results in light of reducing fall risk. Medium bed height appeared to produce the least significant differences in parameters when compared to the two other bed heights. This implies the most flexibility to prioritize postural stability or postural mobility. Low bed heights generated particular problems by reducing fluid motion and creating more impediments to postural stability. This suggests that low bed heights may not reduce fall rates during bed exit