Principles of obstacle avoidance with a transfemoral prosthetic limb

Keeken, Helco van; Vrieling, Aline H.; Hof, At L.; Postema, Klaas; Otten, Bert

doi:10.1016/j.medengphy.2011.11.017

Cited by 9 publications

(8 citation statements)

References 30 publications

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“…For example, in response to this strategy, swing-phase knee flexion may be reduced such that toe clearance is compromised. Previous studies of transfemoral amputee gait have shown that subjects compensate for insufficient knee flexion during swing phase by circumducting their affected-side hip and plantarflexing their intact ankle [24,48]. Therefore, we might expect one or both of these compensatory strategies to manifest during swing phase with POST.…”

Section: Late-stance Response To Alignment Perturbationmentioning

confidence: 97%

“…Specifically, it is assumed that during early stance phase, persons with transfemoral amputation exert a hip extension moment to shift the ground reaction force (GRF) vector anterior to the knee joint center, thereby promoting knee extension for stable weight bearing. Conversely, it is assumed that during late stance phase, persons with transfemoral amputation exert a hip flexion moment to reorient the GRF vector so that it is posterior to the knee joint center, thereby triggering knee flexion in preparation for limb advancement [24]. Additionally, persons with transfemoral amputation may influence the GRF vector acting at their knee joint by altering the angle at which they place their foot on the ground [25,26] or by varying their body center of mass position through postural adjustments of their trunk [27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

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The biomechanical response of persons with transfemoral amputation to variations in prosthetic knee alignment during level walking

2016

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Prosthetic alignment is an important factor in the overall fit and performance of a lower-limb prosthesis. However, the association between prosthetic alignment and control strategies used by persons with transfemoral amputation to coordinate the movement of a passive prosthetic knee is poorly understood. This study investigated the biomechanical response of persons with transfemoral amputation to systematic perturbations in knee joint alignment during a level walking task. Quantitative gait data were collected for three alignment conditions: bench alignment, 2 cm anterior knee translation (ANT), and 2 cm posterior knee translation (POST). In response to a Participation Follow-Up: The authors do not plan to inform participants of the publication of this study. However, participants have been encouraged to check the Northwestern University Prosthetics-Orthotics Center Web site for updated publications related to the program's activities, which include the present study. Disclaimer:The views expressed in this article are those of the authors and do not necessarily reflect the position or policy of the VA or the U.S. Government. U.S. Department of Veterans AffairsPublic Access Author manuscript J Rehabil Res Dev. Author manuscript; available in PMC 2017 August 17. VA Author ManuscriptVA Author Manuscript VA Author Manuscript destabilizing alignment perturbation (ANT), subjects significantly increased their early-stance hip extension moment, confirming that persons with transfemoral amputation rely on a hip extensor strategy to maintain knee joint stability. However, subjects also decreased the rate at which they loaded their prosthesis, decreased their step length, increased their trunk flexion, and maintained their limb in a more vertical posture at the time of opposite toe off. Collectively, these results suggest that persons with transfemoral amputation rely on a combination of strategies to coordinate stance-phase knee flexion. Further, no significant changes were observed in response to the POST condition, suggesting that a bias toward posterior alignment may have fewer implications in terms of stance-phase, knee-joint control.

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Section: Late-stance Response To Alignment Perturbationmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

The biomechanical response of persons with transfemoral amputation to variations in prosthetic knee alignment during level walking

2016

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“…A TFP user might adopt a compensatory strategy such as circumduction, hip hiking, vaulting, and/or hip flexion-extension strategy for foot clearance when the prosthetic knee cannot provide sufficient foot clearance. [43][44][45][46][47] Such compensatory strategies can cause larger deviations from normal gait, increased hip effort, influence metabolic energy consumption, and secondary health disorders with the long-term use of prosthesis. [48][49][50][51] Hence, the prosthetic knee and its recommended alignment should be designed to extend completely before heel contact without compromising foot clearance and thereby reduce compensatory strategies as much as possible.…”

Section: Discussionmentioning

confidence: 99%

The Effects of Polycentric Knee Design and Alignment on Swing Phase Gait Parameters: A Simulation Approach

2021

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IntroductionTypically, polycentric prosthetic knees have been designed with a focus on improved performance during stance. This study analyzes the influence of geometric aspects such as linkage dimensions of the polycentric knees and anterior-posterior (A/P) alignment on the swing phase of walking. Such a study would enable the development of polycentric knees with improved performance during both stance and swing phases.MethodsA simulation-based approach was used to analyze the influence of geometric aspects on swing dynamics. A newly developed four-bar knee called IITM polycentric knee (IPK) was used as a baseline prosthesis. First, the swing was simulated with the baseline prosthesis. The IPK in the lower limb was then replaced with the linkage dimensions of four other commercial polycentric knees (Ottobock's 3R36, 3R55, and 3R70 and Ohio Willow Wood's Pendulum knee) for the simulation of swing phase. Effect of A/P alignment was analyzed by translating the socket adapter of the IPK along the A/P axis in the baseline prosthesis, which has the effect of moving the knee and foot in the opposite direction. A maximum of 20 mm translation of the socket adapter was applied on either side of its base location in the lower-limb model. The gait parameters from the simulations and the centrode of different polycentric knees were then analyzed to understand how linkage dimensions and A/P translations of the knee and foot affect the swing dynamics.ResultsAll four-bar knees without extension assists extended to less than 6° before heel contact, which is significantly lower than the 24° obtained for a single-axis knee in a previous study. The swing performances of the different four-bar knees studied here were found to depend on their centrode. The instant centers (ICs) of the 3R55 and IPK, which were comparatively located more superior to the anatomical knee center during swing, enabled better knee extension and foot clearance than other knees. A/P translation of the knee and foot significantly affected the foot clearance. A 20 mm anterior translation increased toe and heel clearance by 1.6 cm and 1.4 cm, respectively, when compared with a 20 mm posterior translation.ConclusionsThis study shows that polycentric knees, which generally perform better than single-axis knees with improved stance stability and ease of push-off, can also perform well during swing in terms of knee extension before heel contact and foot clearance throughout swing. The extended moment arm for the weight of the shank and foot due to the superior location of the IC in polycentric knees is the reason for the improved swing performance of polycentric knees. Appropriate placement of the socket adapter, which affects A/P alignment, is crucial so that foot clearance during swing is not compromised. The insights obtained from the study would be useful in developing simpler polycentric knees, which can extend completely without any extension assist if proper alignment is used as recommended.Clinical RelevanceThe study provides better understanding of ...

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“…Components between the prosthetic knee and the ankle-foot prosthesis are changed to keep the height of the prosthesis the same throughout the experiment. Similar prosthetic simulators have been used to study the gait of an individual with a transfemoral amputation 27–30 because simulators exhibit similar kinematic and kinetic joint mechanics during gait 31 . Our rationale for using a prosthetic simulator as opposed to individuals with an amputation includes ease of recruitment and experimentation, the ability of each participant to serve as his or her own able-bodied control, and the provision of a method to evaluate the CAPA in the early stages of development without putting individuals with an amputation through undue stress.…”

Section: Methodsmentioning

confidence: 99%