The Influence of Four-Bar Linkage Knees on Prosthetic Swing-Phase Floor Clearance

Gard, Steven A.; Childress, Dudley S.; Uellendahl, Jack E.

doi:10.1097/00008526-199603000-00006

Cited by 13 publications

(25 citation statements)

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“…These sensitivity analyses may aid in the design and evaluation of lower-limb prostheses and orthoses by indicating which joints have the greatest influence on toe clearance and effective leg length during swing phase [24][25][26][27][28][29]. Artificial limbs should be designed to produce adequate toe clearance during swing.…”

Section: Discussionmentioning

confidence: 99%

Methodology for determining the sensitivity of swing leg toe clearance and leg length to swing leg joint angles during gait

Moosabhoy

Gard

2006

Gait & Posture

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Section: Discussionmentioning

confidence: 99%

Methodology for determining the sensitivity of swing leg toe clearance and leg length to swing leg joint angles during gait

Moosabhoy

Gard

2006

Gait & Posture

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“…Polycentric knee units exist that are designed to offer improved cosmesis by enabling the instant center of rotation to be placed near to the knee joint's anatomical position, a feature that is especially beneficial for individuals with relatively long residual limbs that do not permit a knee unit to be physically placed at the level of the knee's anatomical axis of rotation (54). Polycentric knee units have also been shown to offer increased foot clearance during swing phase compared with a single-axis knee (54,55), which may decrease the likelihood of the user stubbing their toes and tripping during prosthetic swing. Four-bar linkage knees may also allow for a closer leglength equality in unilateral transfemoral amputees (55).…”

Section: Prosthetic Knee Unitsmentioning

confidence: 99%

“…Polycentric knee units have also been shown to offer increased foot clearance during swing phase compared with a single-axis knee (54,55), which may decrease the likelihood of the user stubbing their toes and tripping during prosthetic swing. Four-bar linkage knees may also allow for a closer leglength equality in unilateral transfemoral amputees (55). The length of the transfemoral prosthesis is often fabricated to be slightly shorter than the length of the sound leg to aid clearance during swing phase, but because of the greater floor clearance afforded by four-bar knees, the prosthetic length can be made closer to the full length.…”

Section: Prosthetic Knee Unitsmentioning

confidence: 99%

“…Transducers in the knee units, such as strain gauges and goniometers, monitor loading and the state of the knee, and the microprocessor adjusts the knee's performance accordingly during gait through feedback to operate mechanical and hydraulic systems. Some microprocessor knee units are able to compensate and adapt to the demands of walking on stairs, slopes, and irregular terrain (55)(56)(57)(58)(59). Walking speeds have been shown to increase with some microprocessor-controlled knees (60), and energy consumption may be reduced (57,58).…”

Section: Prosthetic Knee Unitsmentioning

confidence: 99%

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Prosthetic Devices and Methods

Gard

2006

Wiley Encyclopedia of Biomedical Engineering

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Limb prostheses are designed to replace missing or absent anatomical limbs for the purpose of providing increased function or cosmesis. The goal of the prosthetist is to fit the patient with a prosthesis that best suits their needs and is able to maximize their rehabilitation potential while minimizing disability. Some of the issues that the prosthetist must consider when fabricating a prosthesis include the patient's level of amputation, the condition of their residual anatomy, and the potential impact other health problems may have on their prosthetic usage. Furthermore, the patient's age, gender, activity level, rehabilitation goals, vocational needs, and avocational desires must also be taken into account. The goal in the fitting of lower‐limb prostheses is generally to restore a person's ability to stand and ambulate, and the components are selected by the prosthetist according to the potential walking ability of the patient. Upper‐limb prostheses are used for reaching, grasping, holding, and positioning objects. Issues concerning the control and interfacing of the upper‐limb prosthesis with the body are of primary consideration. The latest technological advances in prosthetic limb components have been aimed at improving function and simplifying operation, with the goal of enabling users to move naturally and to effectively interact with the environment.

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“…9,10 Polycentric knee joints also showed more ground clearance during swing phase when compared to monocentric knee joints. 1,11 Due to their technical design, prosthetic knee components can be divided into two main categories: monocentric and polycentric knee joints. Monocentric knee joints have a single center of rotation (CR) that is independent of the knee flexion angle.…”

Section: Introductionmentioning

confidence: 99%

Polycentric Exoprosthetic Knee Joints – Extent of Shortening During Swing Phase

Köhler

Bellmann

Blumentritt

2020

Can. Prosthet. Orthot. J.

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BACKGROUND: An often assumed advantage of polycentric knee joints compared to monocentric ones is the improved ground clearance during swing phase due to the geometric shortening of the lower leg segment (LLS). OBJECTIVE: To investigate whether polycentric knee joints considerably improve ground clearance and to evaluate the influence of prosthetic alignment on the extent of ground clearance. METHODOLOGY: 11 polycentric and 2 monocentric knee joints were attached to a rigid, stationary testing device. Shortening of the LLS and the resulting ground clearance during knee flexion were measured. Prosthetic components were mounted at the same height and the anterior-posterior position was in accordance with the manufacturer's alignment recommendations. FINDINGS: Shortening of up to 14.7 (SD=0.0) mm at the instance of minimal ground clearance during swing phase was measured. One knee joint elongated by 4.4 (SD=0.0) mm. Measurements of the ground clearance demonstrated differences up to 25.4 (SD=0.0) mm. One monocentric knee joint provided more ground clearance when compared to 8 of the polycentric knee joints investigated. CONCLUSION: Only some polycentric knee joints shorten appreciably during swing phase. With an optimized prosthetic alignment and a well-designed swing phase control, a monocentric knee joint may generate greater ground clearance compared to a polycentric knee joint. LAYMAN’S ABSTRACT Tripping is a safety risk for amputees and it is mainly affected by ground clearance during swing phase. An often assumed advantage of polycentric knee joints compared to monocentric ones is the improved ground clearance during swing phase due to the geometric shortening of the lower leg segment (LLS). Based on this statement safety benefits for above knee-amputees due to reduced danger of stumbling are discussed commonly for the entire group of polycentric knee joints. We believe that this statement is not true for all polycentric knee joint designs. Therefore, we analyzed 11 polycentric and two monocentric knee joints in a rigid, stationary testing device with their individual prosthetic alignments according to the manufacturer’s alignment recommendations. Shortening of the LLS and the resulting ground clearance during knee flexion were measured. The results showed shortening effects of up to 15 mm. One knee joint elongated by 4 mm. One monocentric knee joint provided more ground clearance when compared to 8 of the polycentric knee joints investigated. We conclude, that only some polycentric knee joints shorten appreciably during swing phase. With an optimized prosthetic alignment a monocentric knee joint may generate greater ground clearance compared to a polycentric knee joint. Article PDF Link: https://jps.library.utoronto.ca/index.php/cpoj/article/view/33768/26547 How To Cite: Köhler T.M, Bellmann M, Blumentritt S. Polycentric Exoprosthetic Knee Joints – Extent of Shortening during Swing Phase. Canadian Prosthetics & Orthotics Journal. 2020;Volume3, Issue1, No.5. https://doi.org/10.33137/cpoj.v3i1.33768 Corresponding Author: Thomas Maximilian Köhler, MScOttobock: Hermann-Rein-Straße 2a, 37075, Göttingen.E-mail: thomasmaximilian.koehler@ottobock.deORCID: https://orcid.org/0000-0002-5063-121X

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The Influence of Four-Bar Linkage Knees on Prosthetic Swing-Phase Floor Clearance

Cited by 13 publications

References 0 publications

Methodology for determining the sensitivity of swing leg toe clearance and leg length to swing leg joint angles during gait

Methodology for determining the sensitivity of swing leg toe clearance and leg length to swing leg joint angles during gait

Prosthetic Devices and Methods

Polycentric Exoprosthetic Knee Joints – Extent of Shortening During Swing Phase

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