Ganganalyse bei Patienten mit Oberschenkelamputation

This examination analyzes kinematic variability in gait of transfemoral amputees compared to healthy controls and the association between kinematic variability and daily activity. Gait variability was greater during walking in transfemoral amputees compared to healthy controls. Additionally there is a correlation between daily activity and gait variability. Kinematic variability could be a potential marker for quality of gait with diagnostic implications.Diese Arbeit untersucht die Variabilität der Kinematik im Gangbild bei Patienten mit Oberschenkelamputation im Vergleich zu Gesunden sowie den Zusammenhang von kinematischer Variabilität zur Alltagsaktivität. Die Gangvariabilität war bei Patienten im Vergleich zu Gesunden erhöht. Zudem zeigte sich eine Korrelation zwischen Alltagsaktivität und Gangvariabilität. Variabilität der Kinematik kann als Marker für Gangqualität zur Verbesserung der Diagnostik beitragen

The Effects of Prosthetic Alignment over Uneven Terrain

The purpose of this study was to analyze kinetic and kinematic data of individuals with unilateral transtibial limb loss and the effect different alignments have on the individual’s gait while they walk over uneven terrain. Individuals with lower limb loss are currently having their prostheses dynamically aligned to ensure a satisfactory walking gait on level ground with smooth surfaces, usually in the clinician\u27s office or hallway. This study was looking to determine whether or not current prosthesis alignment procedures are adequate for determining a satisfactory walking gait on non-level and non-smooth terrains as well level smooth surfaces. An effective and efficient walking pattern is necessary to prevent degenerative conditions within the bones, muscles or other tissues of the body, due to compensations of the gait pattern. Sometimes, individuals are able to mask any compensations if their safety is unaffected by their surroundings and they are able to maintain a gait that appears normal or optimal. However, if terrains used on a daily basis present a sense of insecurity, gait compensations could be more problematic to the individual and they need to be addressed and corrected as best they can. This study determined that while there were some changes in gait on the uneven surface, due to the number of subjects it is unclear whether the changes are significant. The individuals showed a decrease in walking speed and step length and an increase in step width. There were also changes in the peak axial force

Anticipatory Muscle Responses for Transitioning Between Rigid Surface and Surfaces of Different Compliance: Towards Smart Ankle-foot Prostheses

abstract: Locomotion is of prime importance in enabling human beings to effectively respond in space and time to meet different needs. Approximately 2 million Americans live with an amputation with most of those amputations being of the lower limbs. To advance current state-of-the-art lower limb prosthetic devices, it is necessary to adapt performance at a level of intelligence seen in human walking. As such, this thesis focuses on the mechanisms involved during human walking, while transitioning from rigid to compliant surfaces such as from pavement to sand, grass or granular media. Utilizing a unique tool, the Variable Stiffness Treadmill (VST), as the platform for human walking, rigid to compliant surface transitions are simulated. The analysis of muscular activation during the transition from rigid to different compliant surfaces reveals specific anticipatory muscle activation that precedes stepping on a compliant surface. There is also an indication of varying responses for different surface stiffness levels. This response is observed across subjects. Results obtained are novel and useful in establishing a framework for implementing control algorithm parameters to improve powered ankle prosthesis. With this, it is possible for the prosthesis to adapt to a new surface and therefore resulting in a more robust smart powered lower limb prosthesis.Dissertation/ThesisMasters Thesis Biomedical Engineering 201

Effects of Physical Exertion and Alignment Alterations on Trans-Tibial Amputee Gait, and Concurrent Validity of Prosthesis-Integrated Measurement of Gait Kinetics

This study investigated the effects of slight changes in the alignment of the artificial limb of trans-tibial amputees on the walking pattern on the level of forces and moments, particularly when physical exertion levels increase. Two alignment conditions were assessed in ten trans-tibial amputees while walking with low and with strong levels of exertion. Two separate data collection methods were utilized simultaneously: a conventional motion analysis, and continuous recordings from prosthesis-integrated force sensors. While the former was used to compare bilateral leg symmetry across conditions, the latter allowed analyzing unilateral step variability within subjects. This paper presents both analyses in separate chapters. A third chapter addresses the question of concurrent validity of the utilized integrated-sensor-based gait data collection method. Findings indicate that increased physical exertion and prosthesis ankle plantar-flexion angle was related to decreases in step length symmetry, maximal knee flexion angle, knee moment, and dorsi-flexion moment, but had no significant effect on an overall gait symmetry index. It was also shown, that effects were different among participants, with only three of them showing a significant change in parameters measured by the integrated sensor system. Integrated sensor measurements namely of axial force and joint moments were found to be closely correlated to conventional measurements, while pertaining to slightly different biomechanical quantities. The detected effects of alignment perturbations and physical exertion were small in magnitude and inconsistent between participants of our sample population. The concept of a range of acceptable prosthesis alignments, within which no optimization is feasible, is supported. However, amputee gait pattern and responses to alignment perturbations seem to change with the level of exertion. This suggests a consideration of real life conditions for the individual optimization of prosthetic alignment. Provided the systematic limitations of the integrated sensor measurements are carefully considered, it appears possible to use this method for the assessment of individual effects of alignment changes

Biomechanical adaptations involved in ramp descent: Impact of microprocessor-controlled ankle-foot prothesis. Kinetic and kinematic responses to using microprocessor-controlled ankle-foot prosthesis in unilateral trans-tibial amputees during ramp descent

Ramp descent is a demanding task for trans-tibial amputees, due to the difficulty in controlling body weight progression over the prosthetic foot. A deeper understanding of the impact of foot function on ramp descent biomechanics is required to make recommendations for rehabilitation programs and prosthetic developments for lower-limb amputees. The thesis aim was to determine the biomechanical adaptations made by active unilateral trans-tibial amputees (TT) using a microprocessor-controlled ankle-foot prosthesis in active (MC-AF) compared to non-active mode (nonMC-AF) or elastically articulated ankle-foot device. A secondary aim was to determine the biomechanical adaptation made by able-bodied individuals when ankle motion was restricted using a custom made ankle-foot-orthosis and provide further insight into the importance of ankle dynamics when walking on ramps. Kinetic and kinematic data were recorded from nine TT’s and twenty able-bodied individuals. Able-bodied participants, ankle restriction, led to an increase in involved limb loading response knee flexion that is accompanied by the increased knee power generation during the single-limb-support phase that correlates to TTs results. TT’s use of an MC-AF reduced the ‘plantar-flexion’ resistance following foot contact allowing foot-flat to be attained more quickly. Followed by the increased ‘dorsi-flexion’ resistance which reduced the shank/pylon rotation velocity over the support foot, leading to an increase in negative work done by the prosthesis. These findings highlight the importance of having controlled ankle motion in ramp descent. Use of an MC-AF can provide TTs controlled motion for descending ramps and hence provide biomechanical benefits over using more conventional types of ankle-foot devices.Engineering and Physical Science Research Council (EPSRC) via Doctoral Training Account (DTA) (EP/P504821/1) Chas. A. Blatchford and Sons Ltd., Basingstoke, UK provided the prosthetic hardware, prosthetist support, and facilitated the attendance of the TT participants for this stud

Postural Stability in Unilateral Transtibial Amputees Using Two Suspension Systems: SmartpuckTM vs Lock and Pin

The number of individuals with lower limb amputation is growing. Individuals with transtibial amputation (TTA) face an increased risk of falling. Center of pressure (COP) is measured during quiet stance to assess postural stability and fall risk. The purpose of the present study was to examine postural stability of individuals with TTA using two suspension systems: SmartPuck™ (PUCK) and lock and pin (PIN). Four participants with TTA (71.34 ± 41.52 kg, 1.39 ± 0.08 m; 49.2 ± 27.79 years, K3 - K4) performed 30 seconds of quiet standing for four different conditions with each suspension system: (a) rigid surface eyes open (RSEO), (b) rigid surface eyes closed (RSEC), (c) compliant surface eyes open (CSEO), and (d) compliant surface eyes closed (CSEC). Center of pressure and vertical ground reaction forces (GRF) (1000 Hz) were collected using two force plates (AMTI, Watertown, MA). Throughout the four conditions, significant interlimb differences were observed in mean resultant velocity, mean AP velocity, 95% CE area, sway area, and %BWT, demonstrating greater reliance of the intact limb. As conditions increased in difficulty, more interlimb differences in measures of postural stability were present, demonstrating increased reliance of the intact limb when stability is challenged. No significant differences were found in either limb between PUCK and PIN suspensions. However, trends demonstrating increased control of postural stability were observed with PUCK suspension in the RSEO, RSEC, and CSEO conditions. Conversely, trends in measures of postural stability in the CSEC condition suggest increased stability with PIN suspension. As vision was removed and the standing surface was manipulated, participants demonstrated loss of control of postural stability, or instability. Confidence in the significance of the results is low due to the small number of individuals who participated in the study. Considering the direct relationship between instability and increased fall risk, it is important to identify whether different prosthesis designs can aid in postural steadiness. Further research with more participants is needed to understand the differences in postural stability caused by suspension systems

General estimates of the energy cost of walking in people with different levels and causes of lower-limb amputation:a systematic review and meta-analysis

BACKGROUND: Energy cost of walking (ECw) is an important determinant of walking ability in people with a lower-limb amputation. Large variety in estimates of ECw has been reported, likely because of the heterogeneity of this population in terms of level and cause of amputation and walking speed. OBJECTIVES: To assess (1) differences in ECw between people with and without a lower-limb amputation, and between people with different levels and causes of amputation, and (2) the association between ECw and walking speed. STUDY DESIGN: Systematic review and meta-analysis. METHODS: We included studies that compared ECw in people with and without a lower-limb amputation. A meta-analysis was done to compare ECw between both groups, and between different levels and causes of amputation. A second analysis investigated the association between self-selected walking speed and ECw in people with an amputation. RESULTS: Out of 526 identified articles, 25 were included in the meta-analysis and an additional 30 in the walking speed analysis. Overall, people with a lower-limb amputation have significantly higher ECw compared to people without an amputation. People with vascular transfemoral amputations showed the greatest difference (+102%) in ECw. The smallest difference (+12%) was found for people with nonvascular transtibial amputations. Slower self-selected walking speed was associated with substantial increases in ECw. CONCLUSION: This study provides general estimates on the ECw in people with a lower-limb amputation, quantifying the differences as a function of level and cause of amputation, as well as the relationship with walking speed