DISSERTATION ABSTRACT Li Jin Doctor of Philosophy Department of Human Physiology March 2018 Title: Kinematic and Kinetic Analysis of Walking and Running across Speeds and Transitions between Locomotion States Walking and running are general locomotion activities for human beings. Basic gait patterns and whole body center of mass (COM) dynamic patterns are distinctly different between them. Lower extremity joint mechanics patterns could reflect musculoskeletal coordination characteristics. Change of locomotion tasks and speeds can affect lower extremity joint kinematic and kinetic characteristics, and progression of age may also affect these characteristics. Little is known about change of locomotion tasks and speeds effects on lower extremity joint level kinetic characteristics, and whether there is a connection between COM system and lower extremity system. To address this, twenty healthy subjects were recruited to participate in a series of treadmill tests, including walking (0.8 – 2.0 m/s, with 0.2 m/s intervals), running (1.8 – 3.8 m/s, with 0.4 m/s intervals) and gait mode transition from walking to running, and from running to walking (between 1.8 – 2.4 m/s, 0.1 m/s2). Three-dimensional kinematic and kinetic data were collected in all locomotion tests and used to calculate and analyze outcome variables for lower extremity joints and the COM system across different conditions. Results indicate that change of locomotion speeds significantly affect joint level kinetic characteristics within both walking and running locomotion states. Different locomotion task demands (walking vs. running) require fundamental alteration of lower extremity joint level kinetic patterns, even at the same locomotion speed. Progression of age also affects lower extremity joint level kinematic and kinetic patterns in walking and running across speeds. Additionally, stance phase an energy generation and transfer phenomenon occurred between the distal and proximal joints of the lower extremity in both walk-to-run and run-to-walk transitions. Lastly, a connection exists between whole body COM oscillation patterns and lower extremity joint level kinetic characteristics in running. These findings serve to further clarify the mechanisms involved in change of locomotion tasks and speeds effects on lower extremity joint kinetic patterns, and further establish a connection between the COM system and the lower extremity system. These findings may be beneficial for future foot-ankle assistive device development, potential optimization of gait efficiency and performance enhancement. This dissertation includes previously published and unpublished coauthored material.

The anconeus, a small triangular muscle positioned on the posterolateral part of the elbow joint, has been the subject of considerable research without a satisfactory conclusion being reached regarding the role it plays during normal elbow kinematics. The aim of this investigation was to elucidate the function of the anconeus muscle and find the relative contribution that it makes to elbow kinematics by examining relative electrical muscle activity and elbow kinematics both before and after anconeus defunctioning carried out using a local anaesthetic (lidocaine). The study was performed through an examination of the myoelectric activity of the representative elbow flexor and extensor muscles (biceps brachii and triceps brachii) and the elbow kinematics and kinetics. Right-handed, healthy volunteers performed elbow flexion-extension and supination-pronation movements in both horizontal and sagittal planes before and after blocking of the anconeus. The kinematics and kinetics of the elbow were assessed using inertial sensors, and muscle electrical activity was recorded using surface electromyography. In the following stage of the study, the anconeus muscle was blocked through an injection of lidocaine and then the flexion-extension and pronation-supination movements were repeated. The relative electrical activity results from the anconeus before blocking clearly indicate that the activity of the muscle was higher during the extension portion of the flexion-extension cycle, suggesting that it behaves as an extensor muscle. However, from the paired sample t-test analysis, it was found that blocking of the anconeus had no effect on the kinematics and kinetics of the elbow, including the angular velocity, net torque, power and net joint work. Moreover, the angular velocity data for the elbow, before and after the blocking for all movements, showed a linear trend with slopes and Pearson's correlations close to unity, indicating no apparent difference on the elbow kinematics. In addition, the relative electrical activity of the biceps and triceps brachii muscles did not alter significantly following blocking of the anconeus. These findings suggest that the anconeus muscle is a relatively weak elbow extensor as it is likely that the small contribution that the anconeus provides during extension before blocking is compensated by the triceps brachii after the anconeus is deactivated. In order to provide additional weight and support to the findings of the experimental study, a computational model of the elbow joint was created in Abaqus CAE with the aim of investigating the contribution of the anconeus during the flexion-extension motion. In particular, the effect on the range of motion and contact area of the elbow joint was investigated both before and after anconeus blocking. The analysis was done in a range of motion of 90°, starting with the elbow extended 30° and ending flexed 120°. The elbow joint model considered cortical bone, trabecular bone, cartilage, collateral ligaments, the anconeus, biceps brachii and triceps brachii. The results of the investigation indicated that the anconeus muscle does not produce a significant change in the range of motion and contact area in the articulation, an outcome that supports the findings of the experimental investigation.

No description available.

Total knee arthroplasty has been effective in reducing pain, but less so in restoring function, especially for activities requiring deep knee flexion. The philosophy of this dissertation was that more functionally effective and optimally designed artificial knees could be created for high flexion activities, if the knee joint kinematics and joint contact forces applied during finite element testing, knee simulator testing, and fatigue testing were more physiologically accurate. The objective of this work was to determine knee joint kinematics and contact forces that could be used in high flexion total knee replacement design and pre-clinical testing. Knee kinematics were determined during high flexion activities for total knee replacement patients and asymptomatic subjects by tracking the motion of skin-mounted sensors. In addition, a protocol was developed to determine the effect of soft tissue artefact on the accuracy of the skin-mounted sensor system in high flexion. The ranges of motion determined for the studied activities can be used as a benchmark to measure the functional success of high flexion total knee replacements. Tibiofemoral joint contact forces were estimated during high flexion activities of daily living using a simple, non-invasive, inverse dynamics based model. The accuracy of the joint contact force estimates was investigated by comparing the estimated forces to in vivo forces measured directly using implanted instrumented tibial components. The comparison showed that the model underestimates the measured axial joint contact force, most likely because the model neglects antagonistic muscle co-contraction. The measured and modeled joint contact forces and the measured knee kinematics could be used to form industry standards for knee simulator and fatigue testing to ensure that the implants are being tested physiologically. Healthy target populations can be studied using the methods outlined in this thesis to define testing standards for target populations: Kinematics can be determined as they were in this work for a group of Middle Eastern subjects, and the non-invasive inverse dynamics based model (with some consideration for the underestimation of forces) could be used to determine the tibiofemoral joint contact forces that the implant might be subjected to during activities of daily living. / Thesis (Ph.D, Mechanical and Materials Engineering) -- Queen's University, 2010-10-25 11:33:06.162

No description available.

Yes / Background Walking down slopes and/or over uneven terrain is problematic for unilateral trans-tibial amputees. Accordingly, ‘ankle’ devices have been added to some dynamic-response feet. This study determined whether use of a microprocessor controlled passive-articulating hydraulic ankle–foot device improved the gait biomechanics of ramp descent in comparison to conventional ankle–foot mechanisms. Methods Nine active unilateral trans-tibial amputees repeatedly walked down a 5° ramp, using a hydraulic ankle–foot with microprocessor active or inactive or using a comparable foot with rubber ball-joint (elastic) ‘ankle’ device. When inactive the hydraulic unit's resistances were those deemed to be optimum for level-ground walking, and when active, the plantar- and dorsi-flexion resistances switched to a ramp-descent mode. Residual limb kinematics, joints moments/powers and prosthetic foot power absorption/return were compared across ankle types using ANOVA. Findings Foot-flat was attained fastest with the elastic foot and second fastest with the active hydraulic foot (P < 0.001). Prosthetic shank single-support mean rotation velocity (p = 0.006), and the flexion (P < 0.001) and negative work done at the residual knee (P = 0.08) were reduced, and negative work done by the ankle–foot increased (P < 0.001) when using the active hydraulic compared to the other two ankle types. Interpretation The greater negative ‘ankle’ work done when using the active hydraulic compared to other two ankle types, explains why there was a corresponding reduction in flexion and negative work at the residual knee. These findings suggest that use of a microprocessor controlled hydraulic foot will reduce the biomechanical compensations used to walk down slopes.

<p>Musculoskeletal degradation and musculoskeletal injuries place a substantial burden on the healthcare system. Advancing the understanding and prevention of the injury potential associated with these injuries in various demographics as well as advancing performance optimization requires knowledge of the loading distribution among the various musculoskeletal tissues at the joints. Accurate muscle force estimates are needed for characterizing these distributions due to their influence on the loading of the system. This dissertation discusses</p> <p>the development and validation of a physiologically-driven skeletal muscle force model that is suitable for application on an individualized level. The derivation of the skeletal muscle force model began with dimensional analysis and a selection of critical parameters that define muscle force generation. One of the key parameters included was measured muscle voltage using electromyography sensors. This provided the model with the ability to be easily used</p> <p>in application-based studies. It also incorporated the muscle force-length, force-velocity, and force-frequency curves, providing an even stronger physiological basis to the model. Validation was performed by multiple studies using experimental data from subjects conducting exercises chosen to target specific muscles of interest. Data was collected from a Vicon Vero motion capture system, an instrumented Bertec treadmill, and Delsys Trigno electromyography sensors. The first study analyzed the ankle joint of seventeen subjects using the two Newton-Euler equations of rigid body motion and the skeletal muscle force model. The average percent error across all subjects was 8.2% and ranged from 4.2% to 15.5%. The second study analyzed the sensitivity of two sets of parameters within the model. The first was conducted on a set of observed and fitted constants from the dimensionless pi terms and aimed to identify which, if any, could be excluded from an optimization routine. Results indicated that only two of the nine constant parameters needed to be optimized. The second sensitivity analysis focused on the anatomical kinematic parameters in order to identify the impact that the incorporation of MRI scans for subject-specific anatomical models would have on the accuracy of the model’s output. Results demonstrated sensitivity to the muscle insertion points, suggesting that the use of MRI scans could increase the accuracy of the model. The third study was a case study focused on evaluating the assumption of a constant within the skeletal muscle force model remaining constant over time. Results indicated that the collection of maximum EMG recordings for these studies may not have been controlled to a desirable level and that the inclusion of specialized equipment for maximum EMG recordings would likely validate this assumption. The final study analyzed the</p> <p>knee joint of ten subjects in a similar fashion to that of the ankle joint. The goal was to observe the model’s performance on a more anatomically complex joint. The average percent error across all subjects was 20.6%, approximately two times higher than the ankle joint.</p> <p>However, the majority of the error associated with this study came from the deviation in calculated moments about an axis of much smaller importance and magnitude than the primary flexion/extension axis. When errors were excluded from this axis, the average percent error for all subjects was 8.8%, almost identical to that of the ankle joint application. These findings as a whole indicate that the model has predictive ability and is capable of providing reasonable estimates of both muscle forces and surrounding musculoskeletal tissue loading. Therefore, the model could be used in various biomechanical advancements and applications in injury prevention, performance optimization, tissue engineering, prosthetic design, and more.</p>

Over one million amputees are living in the United States with major lower limb loss (Ziegler-Graham et al. 2008). Lower limb amputation leads to the functional loss of the ankle plantar flexor muscles, which are important contributors to body support, forward propulsion, and leg swing initiation during walking (Neptune et al. 2001; Liu et al. 2006). Effective prosthetic component design is essential for successful rehabilitation of amputees to return to an active lifestyle by partially replacing the functional role of the ankle muscles. The series of experimental and computer simulation studies presented in this research showed that design characteristics of energy storage and return prosthetic ankles, specifically the elastic stiffness, significantly influence residual and intact leg ground reaction forces, knee joint moments, and muscle activity, thus affecting muscle output. These findings highlight the importance of proper prosthetic foot stiffness prescription for amputees to assure effective rehabilitation outcomes. The research also showed that the ankle muscles serve to stabilize the body during turning the center of mass. When amputees turn while supported by their prosthetic components, they rely more on gravity to redirect the center of mass than active muscle generation. This mechanism increases the risks of falling and identifies a need for prosthetic components and rehabilitation focused on increasing amputee stability during turning. A proper understanding of the effects of prosthetic components on amputee walking mechanics is critical to decreasing complications and risks that are prevalent among lower-limb amputees. The presented research is an important step towards reaching this goal. / text