The influence of a user-adaptive prosthetic knee across varying walking speeds: A randomized cross-over trial
TL;DR: Comparison of walking with the Rheo Knee II to walking with a NMPK across different walking speeds showed limited differences in gait parameters.
About: This article is published in Gait & Posture.The article was published on 2017-01-01. It has received 20 citations till now. The article focuses on the topics: Preferred walking speed.
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TL;DR: The main challenges in the field of powered, active MPKs (A-MPKs) to boost commercial viability are first to demonstrate the benefit of A-MPks compared to passive MPks or mechanical non-microprocessor knees using biomechanical, performance-based and patient-reported metrics.
Abstract: Goal: To provide an overview of control strategies in commercial and research microprocessor-controlled prosthetic knees (MPKs). Methods: Five commercially available MPKs described in patents, and five research MPKs reported in scientific literature were compared. Their working principles, intent recognition, and walking controller were analyzed. Speed and slope adaptability of the walking controller was considered as well. Results: Whereas commercial MPKs are mostly passive, i.e., do not inject energy in the system, and employ heuristic rule-based intent classifiers, research MPKs are all powered and often utilize machine learning algorithms for intention detection. Both commercial and research MPKs rely on finite state machine impedance controllers for walking. Yet while commercial MPKs require a prosthetist to adjust impedance settings, scientific research is focused on reducing the tunable parameter space and developing unified controllers, independent of subject anthropometrics, walking speed, and ground slope. Conclusion: The main challenges in the field of powered, active MPKs (A-MPKs) to boost commercial viability are first to demonstrate the benefit of A-MPKs compared to passive MPKs or mechanical non-microprocessor knees using biomechanical, performance-based and patient-reported metrics. Second, to evaluate control strategies and intent recognition in an uncontrolled environment, preferably outside the laboratory setting. And third, even though research MPKs favor sophisticated algorithms, to maintain the possibility of practical and comprehensible tuning of control parameters, considering optimal control cannot be known a priori. Significance: This review identifies main challenges in the development of A-MPKs, which have thus far hindered their broad availability on the market.
52 citations
TL;DR: Compared to the SACH foot, the ESAR foot allowed an improvement of step length symmetry while preserving the backward margin of stability at community ambulation speed, which may possibly contribute to the subjective preference for ESAR feet in people with a lower limb amputation.
Abstract: Energy storing and return (ESAR) feet are generally preferred over solid ankle cushioned heel (SACH) feet by people with a lower limb amputation While ESAR feet have been shown to have only limited effect on gait economy, other functional benefits should account for this preference A simple biomechanical model suggests that enhanced gait stability and gait symmetry could prove to explain part of the difference in the subjective preference between both feet To investigate whether increased push-off power with ESAR feet increases center of mass velocity at push off and enhance intact step length and step length symmetry while preserving the margin of stability during walking in people with a transtibial prosthesis Fifteen people with a unilateral transtibial amputation walked with their prescribed ESAR foot and a SACH foot at a fixed walking speed (12 m/s) over a level walkway while kinematic and kinetic data were collected Push-off work generated by the foot, center of mass velocity, step length, step length symmetry and backward margin of stability were assessed and compared between feet Push-off work was significantly higher when using the ESAR foot compared to the SACH foot Simultaneously, center of mass velocity at toe-off was higher with ESAR compared to SACH, and intact step length and step length symmetry increased without reducing the backward margin of stability Compared to the SACH foot, the ESAR foot allowed an improvement of step length symmetry while preserving the backward margin of stability at community ambulation speed These benefits may possibly contribute to the subjective preference for ESAR feet in people with a lower limb amputation
27 citations
28 Oct 2019
TL;DR: The main recommendation is to include daily activities in a case-report and in a later stage in a randomized controlled study design, which led to guidelines and recommendations for the evaluation of a LLPD.
Abstract: Introduction Evaluating the efficacy of a lower-limb prosthetic device (LLPD) is a crucial step in the iterative process of redesigning and product development of new generation prostheses. To date, no standardized experimental methodology for the evaluation of LLPDs is available which complicates the comparison of results. Objective This systematic review provides an overview of study designs, tests and outcome measures to evaluate a LLPD. Ultimately, guidelines and recommendations are formulated. Methods Two databases were screened on studies evaluating a LLPD, published between 2009 and 2019. Results 109 articles were eventually included. We identified 43 outcome measures in four main categories: 53% were biomechanical, 26% physiological, 14% physical performance and 7% psychological. Mainly walking tests were included (78%), of which 31% were performed on a slope, followed by stair climbing (15%) and other functional tasks (15%). Conclusion An overview of currently used study designs and experimental protocols is presented, which led to guidelines and recommendations for the evaluation of a LLPD. The main recommendation is to include daily activities in a case-report and in a later stage in a randomized controlled study design. Biomechanical, physiological, physical performance and psychological outcome measures are key for the evaluation of a LLPD.
17 citations
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...Treadmill (37%, n=40) [32], [34], [37], [38], [40], [41], [46], [47], [52], [53], [56], [57], [60], [64], [71], [73], [89],...
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...measures were investigated in 28% of the included articles (n=30) [35], [36], [38], [42], [46]–[48], [50], [56], [57], [60], [62], [65], [66], [71], [83], [87], [88], [90], [96], [101], [103], [104], [109], [116], [117], [122], [130], [132], [134], i....
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TL;DR: The results of this study indicated that the new microprocessor-controlled prosthetic knee was suitable for transfemoral amputees and was more adaptive to speed changes.
Abstract: Background The microprocessor-controlled prosthetic knees have been introduced to transfemoral amputees due to advances in biomedical engineering. A body of scientific literature has shown that the microprocessor-controlled prosthetic knees improve the gait and functional abilities of persons with transfemoral amputation. Objective The aim of this study was to propose a new microprocessor-controlled prosthetic knee (MPK) and compare it with non-microprocessor-controlled prosthetic knees (NMPKs) under different walking speeds. Methods The microprocessor-controlled prosthetic knee (i-KNEE) with hydraulic damper was developed. The comfortable self-selected walking speeds of 12 subjects with i-KNEE and NMPK were obtained. The maximum swing flexion knee angle and gait symmetry were compared in i-KNEE and NMPK condition. Results The comfortable self-selected walking speeds of some subjects were higher with i-KNEE while some were not. There was no significant difference in comfortable self-selected walking speed between the i-KNEE and the NMPK condition (P= 0.138). The peak prosthetic knee flexion during swing in the i-KNEE condition was between sixty and seventy degree under any walking speed. In the NMPK condition, the maximum swing flexion knee angle changed significantly. And it increased with walking speed. There is no significant difference in knee kinematic symmetry when the subjects wear the i-KNEE or NMPK. Conclusions The results of this study indicated that the new microprocessor-controlled prosthetic knee was suitable for transfemoral amputees. The maximum swing flexion knee angle under different walking speeds showed different properties in the NMPK and i-KNEE condition. The i-KNEE was more adaptive to speed changes. There was little difference of comfortable self-selected walking speed between i-KNEE and NMPK condition.
13 citations
05 Nov 2020
TL;DR: Comparing outcomes from four common knee models indicated relative parity among the 4 microprocessor knees with regard to functional mobility and satisfaction, in contrast to mobility, neither satisfaction nor quality of life values reflected declines with aging.
Abstract: IntroductionMicroprocessor knee analyses to date have been primarily limited to microprocessor knees as a category rather than comparisons across different models. The purpose of the current analys...
13 citations
References
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TL;DR: A magnetorheological knee prosthesis is presented that automatically adapts knee damping to the gait of the amputee using only local sensing of knee force, torque, and position, indicating that a user‐adaptive control scheme and local mechanical sensing are all that is required for amputees to walk with an increased level of biological realism.
Abstract: A magnetorheological knee prosthesis is presented that automatically adapts knee damping to the gait of the amputee using only local sensing of knee force, torque, and position. To assess the clinical effects of the user‐adaptive knee prosthesis, kinematic gait data were collected on four unilateral trans‐femoral amputees. Using the user‐adaptive knee and a conventional, non‐adaptive knee, gait kinematics were evaluated on both affected and unaffected sides. Results were compared to the kinematics of 12 age, weight and height matched normals. We find that the user‐adaptive knee successfully controls early stance damping, enabling amputee to undergo biologically‐realistic, early stance knee flexion. These results indicate that a user‐adaptive control scheme and local mechanical sensing are all that is required for amputees to walk with an increased level of biological realism compared to mechanically passive prosthetic systems.
335 citations
TL;DR: The results of this study indicate that variable-damping knee prostheses offer advantages over mechanically passive designs for unilateral transfemoral amputees walking at self-selected ambulatory speeds, and the results further suggest that a magnetorheological-based system may have advantages over hydraulic-based designs.
Abstract: Johansson JL, Sherrill DM, Riley PO, Bonato P, Herr H: A clinical comparison of variable-damping and mechanically passive prosthetic knee devices. Am J Phys Med Rehabil 2005;84:563–575.Objective:Although variable-damping knee prostheses offer some improvements over mechanically passive prost
328 citations
"The influence of a user-adaptive pr..." refers background or result in this paper
...Differences in preferred walking speed between user-adaptive prosthetic knees and NMPKs have both been found to be significant (increased in user-adaptive knees) [5– 7,13] and non-significant [4,14]....
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...If we look at knee yielding for instance, both trials reporting no differences in knee yielding [4,7,13] as an increase in knee yielding [1,15] are available (respectively 8 and 1 )....
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TL;DR: The C-Leg (Otto Bock, Duderstadt, Germany) is a microprocessor-controlled prosthetic knee that may enhance amputee gait that is compared with a common noncomputerized prosthesis, the Mauch SNS (Ossur, Reykjavik, Iceland).
Abstract: INTRODUCTION Lower-limb amputees must relearn basic ambulatory skills to successfully function within the community. The two primary concerns for lower-limb amputees are comfort and mobility [1]. Despite continuous advances in prosthetic technology, 55 percent of amputees report they are unable to use their prosthesis to the extent they desire [2]. Most transfemoral (TF) amputees wear a noncomputerized prosthetic knee that incorporates friction, pneumatic, or hydraulic swing phase control. These devices are thought to be limited because the resistance setting that controls the rate of knee extension during swing remains constant and is therefore only optimal at specific walking speeds, which results in nonoptimal kinematics at a complete range of speeds. In addition, these non-adaptive, mechanically passive devices do not incorporate adaptive stance phase control, which requires the amputee Abbreviations: %BW = percent body weight, CWS = controlled walking speed, OHS = opposite heel strike, SD = standard deviation, SSWS = self-selected walking speed, TF = transfemoral, VGRF = vertical ground reaction force. to lock the knee mechanism in full extension during stance to avoid buckling. These limitations result in gait asymmetries [3-4], such as increased prosthetic swing phase knee flexion and decreased prosthetic stance phase knee flexion, which may contribute to such problems as increased metabolic cost [5] and secondary disability [6-8]. Therefore, further developments in prosthetic technology are needed to normalize amputee ambulation and minimize gait asymmetries. Past research has suggested that many challenges associated with TF-amputee ambulation are caused by gait asymmetries associated with stance phase kinetics [3-4,6]. For example, previous research demonstrated that amputee subjects had decreased loading on the prosthetic limb with increased loading on the intact limb compared with control subjects [9]. The higher forces on the intact limb may result from the lack of damping of the prosthetic knee during stance because of a decrease in prosthetic knee flexion, which causes excessive rise of the center of mass over the prosthetic limb [4-5]. The high forces shown to occur at the intact limb are thought to lead to pain and joint degeneration, which explains why TF amputees have a higher incidence of degenerative arthritis in their intact limbs compared with non-disabled subjects [6-8]. Specifically, coronal knee moments have been shown to be a major determinant of the load distribution during walking, with a significant correlation between external knee-adduction moment and bone distribution between the proximal-medial and proximallateral plateaus [10]. Sagittal-plane moments have also been shown to play a role in determining the overall compressive load on the knee joint. Therefore, both coronal and sagittal-plane knee moments are relevant measures when the relationship between loading and knee osteoarthritis is studied [10]. In a recent study of transtibial amputees, researchers measured coronal knee moments and found an increase in abduction moment of 56 percent compared with the prosthetic limb and 10 percent compared with the control group [11]. Despite the high occurrence of osteoarthritis in the intact limb of TF amputees, few studies have examined coronal knee moments [12]. In addition to the inability to use normal stance phase knee flexion to maintain stability and avoid inadvertent knee buckling [3], TF amputees have another common asymmetry: increased hip extensor activity for assisting stabilization of the knee. The increased hip power output may help compensate for the lack of ankle power generated by the prosthetic foot [13]. Mechanical power measurements, defined as the product of the joint moment of force and the angular velocity, are important measures of muscle function during concentric and eccentric phases of gait [14]. Therefore, increased power measurements may result in increased fatigue and secondary disability. …
267 citations
"The influence of a user-adaptive pr..." refers result in this paper
...If we look at knee yielding for instance, both trials reporting no differences in knee yielding [4,7,13] as an increase in knee yielding [1,15] are available (respectively 8 and 1 )....
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TL;DR: Use of the C-Leg improves performance and quality of life and can increase MFCL and community ambulation level and was preferred over the NMKM by 14 subjects.
Abstract: This study compared subjects' performance with a nonmicroprocessor knee mechanism (NMKM) versus a C-Leg on nine clinically repeatable evaluative measures. We recorded data on subjects' performance while they used an accommodated NMKM and, following a 90-day accommodation period, the C-Leg in a convenience sample of 19 transfemoral (TF) amputees (mean age 51 +/- 19) from an outpatient prosthetic clinic. We found that use of the C-Leg improved function in all outcomes: (1) Prosthesis Evaluation Questionnaire scores increased 20% (p = 0.007), (2) stumbles decreased 59% (p = 0.006), (3) falls decreased 64% (p = 0.03), (4) 75 m self-selected walking speed on even terrain improved 15% (p = 0.03), (5) 75 m fastest possible walking speed (FPWS) on even terrain improved 12% (p = 0.005), (6) 38 m FPWS on uneven terrain improved 21% (p < 0.001), (7) 6 m FPWS on even terrain improved 17% (p = 0.001), (8) Montreal Rehabilitation Performance Profile Performance Composite Scores for stair descent increased for 12 subjects, and (9) the C-Leg was preferred over the NMKM by 14 subjects. Four limited community ambulators (Medicare Functional Classification Level [MFCL] K2) increased their ambulatory functional level to unlimited community ambulation (MFCL K3). Objective evaluative clinical measures are vital for justifying the medical necessity of knee mechanisms for TF amputees. Use of the C-Leg improves performance and quality of life and can increase MFCL and community ambulation level.
188 citations
TL;DR: Transfemoral amputees using a microprocessor-controlled knee have significant improvements in gait and balance.
177 citations
"The influence of a user-adaptive pr..." refers result in this paper
...If we look at knee yielding for instance, both trials reporting no differences in knee yielding [4,7,13] as an increase in knee yielding [1,15] are available (respectively 8 and 1 )....
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