Prosthetic foot stiffness, which is typically invariable for commercially available prosthetic feet, needs to be considered when prescribing a prosthetic foot. While a biological foot adapts its function according to the movement task, an individual with lower limb amputation may be limited during more functionally demanding gait tasks by their conventional energy storing and return prosthetic foot.
How do changes in prosthetic foot stiffness during incline walking affect biomechanical measures as well as perception of participants.
Kinetic and kinematic data were collected during incline walking, for five participants with trans-tibial amputation. A mixed model analysis of variance was used to analyse the effects of changing the stiffness during incline walking, using a novel variable-stiffness unit built on a commercially available prosthetic foot. Biomechanical results were also analysed on an individual level alongside the participant feedback, for a better understanding of the various strategies and perceptions exhibited during incline walking.
Statistically significant effects were only observed on the biomechanical parameters directly related to prosthetic ankle kinematics and kinetics (i.e., peak prosthetic ankle dorsiflexion, peak prosthetic ankle power, dynamic joint stiffness during controlled dorsiflexion). Participant perception during walking was affected by changes in stiffness. Individual analyses revealed varied perceptions and varied biomechanical responses among participants.
While changes in prosthesis mechanical properties influenced the amputee\'s experience, minimal immediate effects were found with the overall gait pattern. The reported inter-participant variability may be due to the person\'s physical characteristics or habitual gait pattern, which may influence prosthesis function. The ability to vary prosthetic foot stiffness during the assessment phase of setting up a prosthesis could provide useful information to guide selection of the appropriate prosthetic device for acceptable performance across a range of activities.

暂无摘要。

Lower extremity amputations and diabetic foot-related complications in the Caribbean population have been previously reported. However, there is a lack of evidence that assess the quality of life experienced in such amputees. This study aimed to determine the health-related quality of life (HRQoL) in patients after a major lower limb amputation. Data collection was performed for all major lower limb amputations undertaken at a tertiary care institution in Trinidad and Tobago, between January 2012 to December 2016. The quality of life for patients who were accessible, alive, and willing to participate was assessed using the EuroQol 5D-5L tool. Statistical analysis was performed using the Mann-Whitney U and Kruskal-Wallis tests comparing medians across various subgroups. A total of 134 individuals were still alive and willing to participate in the study. The average EQ-5D-5L index value for the cohort was (0.598), which was significantly lower compared to EQ-5D-5L population norms for Trinidad and Tobago p < 0.05. Statistically significant differences were also seen in median EQ-5D-5L index value for patients who ambulated with a prosthesis (0.787) compared to those who used another device for mobilization (0.656), p < 0.05, and to those patients who did not ambulate (0.195), p < 0.05. A comparable Quality of life was seen between the level of amputation (transtibial versus transfemoral) and gender (males versus females), p-values were 0.21 and 1.0, respectively. Overall quality of life after major amputation, as well as independent mobilization with a prosthesis, continues to be problematic in the Caribbean population. Factors adversely related to the quality of life post major amputation include increasing age, problems related to mobility, and non-ambulatory patients.

BACKGROUND: Adaptation of lower limb function to different gait tasks is inherently not as effective among individuals with lower limb amputation as compared to able-bodied individuals. Varying stiffness of a prosthetic foot may be a way of facilitating gait tasks that require larger ankle joint range of motion.
METHODS: Three stiffness settings of a novel prosthetic foot design were tested for level walking at three speeds as well as for 7,5° incline and decline walking. Outcome measures, describing ankle range of motion and ankle dynamic joint stiffness were contrasted across the three stiffness settings. Standardized mechanical tests were done for the hindfoot and forefoot.
RESULTS: Dorsiflexion angle was incrementally increased with a softer foot and a faster walking speed / higher degree of slope. The concurrent dynamic joint stiffness exhibited a less systematic change, especially during INCLINE and DECLINE walking. The small difference seen between the stiffness settings for hindfoot loading limits analysis for the effects of stiffness during weight acceptance, however, a stiffer foot significantly restricted plantarflexion during DECLINE.
CONCLUSIONS: Varying stiffness settings within a prosthetic foot does have an effect on prosthetic foot dynamics, and differences are task dependent, specifically in parameters involving kinetic attributes. When considering the need for increased ankle range of motion while performing more demanding gait tasks, a foot that allows the users themselves to adjust stiffness according to the task at hand may be of benefit for active individuals, possibly enhancing the user\'s satisfaction and comfort during various daily activities.

Most previous studies reported biomechanical deficits in individuals with a trans-tibial amputation (TTA) during gait using zero-dimensional analyses. However, these analyses do not allow to precisely determine during which part of the gait cycle these deficits occur. There is a need to use more appropriate methods to map the differences, such as one-dimensional statistical parametric mapping.
What are the most relevant phases of the gait cycle during which the biomechanical deficits in TTA occur?
Eight TTA and 15 healthy counterparts (CON) underwent one biomechanical gait analysis. Pelvis, hip, knee and ankle kinematics, total support moment (TSM) and gastrocnemius lateralis, vastus lateralis and tibialis anterior muscle activity were compared between the amputated (AmLL), the intact (InLL) and the control (CnLL) lower limbs using one-dimensional statistical parametric mapping.
More ankle dorsiflexion and knee flexion were observed for the AmLL compared to the InLL and CnLL (ankle only) from the end of the stance phase to the beginning of the swing phase. Less knee flexion was also found for the AmLL during early stance phase. More pelvis posterior tilt and rotation toward the contralateral limb was observed during most of the gait cycle for the AmLL compared to the InLL. TSM was smaller for the AmLL compared to the CnLL during early stance phase.
Using a one-dimensional statistical parametric mapping approach for TTA gait analysis, this study provides novel insights on their biomechanical gait deficits compared to CON. Greater reliance on the InLL was observed in TTA as suggested by the asymmetric kinematic and kinetic profiles.

Powered ankle-foot prostheses assist users through plantarflexion during stance and dorsiflexion during swing. Provision of motor power permits faster preferred walking speeds than passive devices, but use of active motor power raises the issue of control. While several commercially available algorithms provide torque control for many intended activities and variations of terrain, control approaches typically exhibit no inherent adaptation. In contrast, muscles adapt instantaneously to changes in load without sensory feedback due to the intrinsic property that their stiffness changes with length and velocity. We previously developed a \"winding filament\" hypothesis (WFH) for muscle contraction that accounts for intrinsic muscle properties by incorporating the giant titin protein. The goals of this study were to develop a WFH-based control algorithm for a powered prosthesis and to test its robustness during level walking and stair ascent in a case study of two subjects with 4-5 years of experience using a powered prosthesis. In the WFH algorithm, ankle moments produced by virtual muscles are calculated based on muscle length and activation. Net ankle moment determines the current applied to the motor. Using this algorithm implemented in a BiOM T2 prosthesis, we tested subjects during level walking and stair ascent. During level walking at variable speeds, the WFH algorithm produced plantarflexion angles (range = -8 to -19°) and ankle moments (range = 1 to 1.5 Nm/kg) similar to those produced by the BiOM T2 stock controller and to people with no amputation. During stair ascent, the WFH algorithm produced plantarflexion angles (range -15 to -19°) that were similar to persons with no amputation and were ~5 times larger on average at 80 steps/min than those produced by the stock controller. This case study provides proof-of-concept that, by emulating muscle properties, the WFH algorithm provides robust, adaptive control of level walking at variable speed and stair ascent with minimal sensing and no change in parameters.

BACKGROUND: Clinicians currently rely on observational clinical data pertaining to the biomechanics of the diabetic foot. However, advances in technology can objectively describe this. A thorough understanding of the functional and mechanical consequences following trans-tibial amputations is lacking.
OBJECTIVE: Does a trans-tibial prostheses significantly increase peak plantar pressures and pressure time integrals in the intact foot of patients with type-2 diabetes and neuropathy?
METHODS: A prospective quantitative matched-subject design was employed. Twenty participants living with diabetes and peripheral sensory neuropathy were recruited. Ten participants presented with a trans-tibial amputation and 10 had intact feet. Participants were matched for gender, age, foot type and BMI. Peak plantar pressure and pressure time integral data were recorded using the Tekscan HR™ pressure mat system, using the two-step gait protocol. The Shapiro-Wilk test was used to determine normality of data. The Independent Samples t-test and the Mann Whitney U test were carried out to reject the null hypothesis.
RESULTS: Although no significant differences (p < 0.05) in mean peak plantar pressures were observed in all the foot masks analysed between the amputee and the control group, a significant difference (p = 0.002) in mean pressure time integrals was recorded with highest pressure time integral (PTI) values under the 2nd-4th metatarsophalangeal joint (MTP joint) for the trans-tibial amputee group.
CONCLUSIONS: Cumulative exposure of both pressure and time can lead to tissue damage. PTI could be considered as an important contributory factor in determining ulcer formation. Elevated PTI under the 2nd-4th MTP joints sustained in the intact contralateral limb in patients using below knee prosthesis could possibly be due to gait alterations in this population. The preservation of the contralateral limb is of great concern and importance as this might impact patient\'s mobility and quality of life.

Many amputees who wear a leg prosthesis develop significant skin wounds on their residual limb. The exact cause of these wounds is unclear as little work has studied the interface between the prosthetic device and user. Our research objective was to develop a quantitative method for assessing displacement patterns of the gel liner during walking for patients with transtibial amputation. Using a reflective marker system and a custom clear socket, evaluations were conducted with a clear transparent test socket mounted over a plaster limb model and a deformable limb model. Distances between markers placed on the limb were measured with a digital caliper and then compared with data from the motion capture system. Additionally, the rigid plaster set-up was moved in the capture volume to simulate walking and evaluate if inter-marker distances changed in comparison to static data. Dynamic displacement trials were then collected to measure changes in inter-marker distance due to vertical elongation of the gel liner. Static and dynamic inter-marker distances within day and across days confirmed the ability to accurately capture displacements using this new approach. These results encourage this novel method to be applied to a sample of amputee patients during walking to assess displacements and the distribution of the liner deformation within the socket. The ability to capture changes in deformation of the gel liner will provide new data that will enable clinicians and researchers to improve design and fit of the prosthesis so the incidence of pressure ulcers can be reduced.

暂无摘要。

BACKGROUND: The majority of lower limb amputations are undertaken in people with peripheral arterial occlusive disease, and approximately 50% have diabetes. Quality of life is an important outcome in lower limb amputations; little is known about what influences it, and therefore how to improve it.
OBJECTIVE: The aim of this systematic review was to identify the factors that influence quality of life after lower limb amputation for peripheral arterial occlusive disease.
METHODS: MEDLINE, EMBASE, CINAHL, PsycINFO, Web of Science and Cochrane databases were searched to identify articles that quantitatively measured quality of life in those with a lower limb amputation for peripheral arterial occlusive disease. Articles were quality assessed by two assessors, evidence tables summarised each article and a narrative synthesis was performed.
METHODS: Systematic review.
RESULTS: Twelve articles were included. Study designs and outcome measures used varied. Quality assessment scores ranged from 36% to 92%. The ability to walk successfully with a prosthesis had the greatest positive impact on quality of life. A trans-femoral amputation was negatively associated with quality of life due to increased difficulty in walking with a prosthesis. Other factors such as older age, being male, longer time since amputation, level of social support and presence of diabetes also negatively affected quality of life.
CONCLUSIONS: Being able to walk with a prosthesis is of primary importance to improve quality of life for people with lower limb amputation due to peripheral arterial occlusive disease. To further understand and improve the quality of life of this population, there is a need for more prospective longitudinal studies, with a standardised outcome measure. Clinical relevance This is of clinical relevance to those who are involved in the rehabilitation of persons with lower limb amputations. Improved quality of life is associated with successful prosthetic use and focus should be directed toward achieving this.