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Yes / Most clinically available prosthetic feet have a rigid attachment or incorporate an “ankle” device allowing elastic articulation during stance, with the foot returning to a “neutral” position at toe-off. We investigated whether using a foot with a hydraulically controlled articulating ankle that allows the foot to be relatively dorsiflexed at toe-off and throughout swing would increase minimum toe clearance (MTC). Twenty-one people with unilateral transtibial amputation completed overground walking trials using their habitual prosthetic foot with rigid or elastic articulating attachment and a foot with a hydraulic ankle attachment (hyA-F). MTC and other kinematic variables were assessed across multiple trials. When using the hyA-F, mean MTC increased on both limbs (p= 0.03). On the prosthetic limb this was partly due to the device being in its fully dorsiflexed position at toe-off, which reduced the “toes down” foot angle throughout swing (p = 0.01). Walking speed also increased when using the hyA-F (p = 0.001) and was associated with greater swing-limb hip flexion on the prosthetic side (p = 0.04), which may have contributed to the increase in mean MTC. Variability in MTC increased on the prosthetic side when using the hyA-F (p = 0.03), but this did not increase risk of tripping.

Millions of individuals around the globe are impacted by osteoarthritis, which is the prevailing type of arthritis. This condition arises as a result of gradual deterioration of the protective cartilage that safeguards the ends of the bones. This is especially true of transtibial amputees, who have a significantly higher incidence of osteoarthritis of the knee in their intact limb than non-amputees. Engaging in regular physical activity, managing weight effectively, and undergoing specific treatments can potentially slow down the advancement of the disease and enhance pain relief and joint function. Nevertheless, the relationship between the type of exercise and its impact on cartilage stress remains uncertain. In order to address this question, tibiofemoral finite element analysis (FEA) models were developed. The models incorporated more realistic material properties for cartilage, hexahedral elements, and non-linear springs for ligaments. To ensure their accuracy, the models were validated against experimental data obtained from cadaveric studies. The contact loads and flexion angles of two individuals with amputations and one individual without amputation, which were obtained in a previous study conducted at Cal Poly, were implemented in the FEA models for gait, cycling, and elliptical exercises. The FEA models were used to extract the maximum stress values experienced in the tibial contact areas, specifically in the medial and lateral compartments of the knee. In cycling, the normalized contact pressure on the tibial articular cartilage, relative to body weight, was generally higher for the two participants with amputations compared to the control participant, except for the medial compartment. Furthermore, when comparing different exercises, cycling resulted in the lowest contact pressure values, with elliptical and walking exercises producing similar maximum values. The findings indicated that individuals with amputations are at a greater risk of developing OA, regardless of the type of exercise performed. However, among the different exercises studied, cycling was found to exert the lowest levels of compression stress on the tibial cartilage.

Several studies have been devoted to the metabolic costs of amputees walking on prostheses with different masses added to their components. However, limited study has been directed at quantifying the mass differences of the actual materials available to amputees and the metabolic and mechanical work required to walk on these materials. The energetics of two materials currently used in the design of lower extremity prosthetics were examined in an attempt to determine if mass differences had an effect on amputee walking. A total of fifteen, unilateral amputees (8 transfemoral and 7 transtibial) performed treadmill walking on prostheses assembled from titanium and stainless steel components. Standardized components (knees, pylons, adapters, feet) made from each material were added below the level of the socket. Submaximal oxygen consumption {W/kg} and mechanical power allowing transfers within and between segments {W/kg} were calculated as subjects walked at self-selected velocities until steady state was achieved. Results show that despite significant mechanical differences [F(1,12)= 4.85, p<.048], the decreased mass associated with the use of titanium materials does not have an effect on the metabolic costs [F(1,14)=1.45, p<.249] of the subjects in this study. In addition, stride rate and stride length showed little differences when walking with both materials. Further division of subjects by age and experience walking on a prosthesis do suggest that older amputees and established walkers do benefit most from the use of titanium, both metabolically and mechanically. The choice of materials for use in every day walking will display differences in the mechanical work of amputees however, these differences are not great enough to realize metabolic consequences. / Thesis / Master of Science (MS)

Motor control of any movement task involves the integration of neural, muscular and skeletal systems. This integration must occur throughout the sensorimotor system and focus its efforts on controlling the system endpoint, e.g. the foot during locomotion. A person with a uni-lateral trans-tibial amputation has lost the foot, ankle joint, and muscles crossing those joints, hence the residuum becomes the new terminus of the motor system. The amputee must now adjust to the additional challenges of utilizing a compromised motor system as well as the challenges of controlling an external device, i.e. prosthesis, through the mechanical interface between the residuum and prosthetic socket. The obvious physical and physiologic asymmetries between the sound and amputated limbs are also involved in strategies for locomotion involving kinematic and kinetic asymmetries (Winter&Sienko, 1988). There are many questions as to why these asymmetric locomotor strategies are selected and what factors may be influencing that strategy. Factors influencing a change in locomotor strategy could be related to 1) the central nervous system accounting for the loss of sensorimotor feedback, 2) the altered mechanics of this new human/prosthetic system, or some combination of these factors. Understanding how the human motor system adjusts to the amputation and to the addition of an external mechanical device can provide useful insight into how robust the human control system may be and to adaptations in human motor control. This research uses a group of individuals with a uni-lateral trans-tibial amputation and a group of intact individuals using an Ankle Foot Orthosis (AFO) performing a cycling task to understand the "motor adjustments" necessary to utilize an external device for locomotion. Results of these experiments suggest 1) the motor system does account for the activation-contraction dynamics when coordinating muscle activity post amputation, 2) the motor system also changes joint kinetics and muscle activity, 3) these changes are related to control of the interface between the limb and the external device, and 4) the motor system does not alter kinetic asymmetries when kinematic asymmetries are minimized, contrary to a common practice in rehabilitation (Kapp, 2004). Results suggest that control of the external device, i.e. prosthesis or AFO, via the interface between the limb and the device reflect "motor adjustments" made by the nervous system and may be viewed in the context of tool use. Clinical goals in rehabilitation currently focus on minimizing gait deviations whereas the clinical application of these results suggest these deviations from normal locomotion are motor adjustments necessary to control a tool, i.e. prosthesis, by the motor system. Examining amputee locomotion in the context of tool use changes the clinical paradigm from one designed to minimize deviations to one intended to understand this behavior as related to interface control of the device thereby shifting the focus to improving function of the limb/prosthesis system. Kapp SL. (2004) Atlas amp limb def: surg pros rehab princ. 3rd ed: 385 - 394. Winter&Sienko. (1988) J Biomech, 21: 361 - 367.

Subject of this diploma thesis is a design of a prosthetic foot for an additive manufacturing. It is a dynamic foot made of plastic, designed for an 80 kg patient with a second level of a movement aktivity. From a few concepts is chosen one, which is then optimalized and printed with a MJF method. Functional sample is then undergoing static and cyclic tests according to ISO 10328.

This master thesis deals with lower-limb prosthesis. The aim of the first part of this work is stress-strain analysis of trans-tibial prosthesis, which is understand without prosthetic socket and the foam prosthetic feet. Analysis is made using finite element method in ANSYS Workbench 12.0 software. For the purpose of setting up the computational model it is necessary to make few partial models. Model of geometry of the prosthesis is made in SolidWorks 2009. Based on the outputs of stress-strain analysis and the results evaluation, the critical component is chosen and this one is evaluated according to limite state for fatigue. The algorithm of evaluation of named component in the state of high cycle fatigue is discussed in the second part of this thesis.

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

This work is aiming to the area of biomechanics and deals with the experimental finding of appropriate kinematic ratios of crank mechanism on racing bicycle and transtibial prosthesis of racing cyclists with an assessment of kinematic ratios depending on the overall athletic performance. The primary aim of the work is investigation of the impact of inappropriate existing kinematic ratios of leg prosthesis and crank mechanism on the kinematics and dynamics of top athlete. The work presents experiments that proposes find out appropriate kinematic ratio of the length of kinematic members and possibility to improve overall athletic performance. The measurement is supplemented about cycling analysis of racer realized via cameras tracking system and measuring muscle activity by EMG. The work also includes a description of impact of various factors on cycling.

The master thesis deals with the engineering design and realization of a transtibial prosthesis for recreational in-line skating. The first part of thesis summarize background information about skating. The next part analyzes the kinematics of ankle joint based on gained information and own measurement by Motion capture method in Kinovea software. The thesis continues with realization of more versions of prosthesis followed by testing with patient. Finally, the thesis discus measured data.