scholarly journals Development and Evaluation of a Powered Artificial Gastrocnemius for Transtibial Amputee Gait

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Michael F. Eilenberg ◽  
Jiun-Yih Kuan ◽  
Hugh Herr
Keyword(s):  
Ankle Joint ◽  
Knee Flexion ◽  
Gastrocnemius Muscle ◽  
Preliminary Results ◽  
Transtibial Amputee ◽  
Affected Side ◽  
Flexion Moment ◽  
Metabolic Data ◽  
Knee Orthosis ◽  
Positive Work

Existing robotic transtibial prostheses provide only ankle joint actuation and do not restore biarticular function of the gastrocnemius muscle. This paper presents the first powered biarticular transtibial prosthesis, which is a combination of a commercial powered ankle-foot prosthesis and a motorized robotic knee orthosis. The orthosis is controlled to emulate the human gastrocnemius based on neuromuscular models of matched nonamputees. Together with the ankle-foot prosthesis, the devices provide biarticular actuation. We evaluate differences between this biarticular condition and a monoarticular condition with the orthosis behaving as a free-joint. Six participants with transtibial amputation walk with the prosthesis on a treadmill while motion, force, and metabolic data are collected and analyzed for differences between conditions. The biarticular prosthesis reduces affected-side biological knee flexion moment impulse and hip positive work during late-stance knee flexion, compared to the monoarticular condition. The data do not support our hypothesis that metabolism decreases for all participants, but some participants demonstrate large metabolic reductions with the biarticular condition. These preliminary results suggest that a powered artificial gastrocnemius may be capable of providing large metabolic reductions compared to a monoarticular prosthesis, but further study is warranted to determine an appropriate controller for achieving more consistent metabolic benefits.

scholarly journals Biomechanic and Energetic Effects of a Quasi-Passive Artificial Gastrocnemius on Transtibial Amputee Gait

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Michael F. Eilenberg ◽  
Ken Endo ◽  
Hugh Herr
Keyword(s):  
Ankle Joint ◽  
Knee Flexion ◽  
Gastrocnemius Muscle ◽  
State Of The Art ◽  
Metabolic Cost ◽  
Mechanical Work ◽  
Preliminary Results ◽  
Ankle Joints ◽  
Metabolic Data ◽  
Knee Orthosis

State-of-the-art transtibial prostheses provide only ankle joint actuation and thus do not provide the biarticular function of the amputated gastrocnemius muscle. We develop a prosthesis that actuates both knee and ankle joints and then evaluate the incremental effects of this prosthesis as compared to ankle actuation alone. The prosthesis employs a quasi-passive clutched-spring knee orthosis, approximating the largely isometric behavior of the biological gastrocnemius, and utilizes a commercial powered ankle-foot prosthesis for ankle joint functionality. Two participants with unilateral transtibial amputation walk with this prosthesis on an instrumented treadmill, while motion, force, and metabolic data are collected. Data are analyzed to determine differences between the biarticular condition with the activation of the knee orthosis and the monoarticular condition with the orthosis behaving as a free-joint. As hypothesized, the biarticular system is shown to reduce both affected-side knee and hip moment impulse and positive mechanical work in both participants during the late stance knee flexion phase of walking, compared to the monoarticular condition. The metabolic cost of walking is also reduced for both participants. These very preliminary results suggest that biarticular functionality may provide benefits beyond even those of the most advanced monoarticular prostheses.

scholarly journals Individuals With an Anterior Cruciate Ligament–Reconstructed Knee Display Atypical Whole Body Movement Strategies but Normal Knee Robustness During Side-Hop Landings: A Finite Helical Axis Analysis

2020 ◽  
Vol 48 (5) ◽  
pp. 1117-1126 ◽  
Author(s):  
Jonas L. Markström ◽  
Helena Grip ◽  
Lina Schelin ◽  
Charlotte K. Häger
Keyword(s):  
Knee Flexion ◽  
Cruciate Ligament ◽  
Body Movement ◽  
Whole Body ◽  
Helical Axis ◽  
Initial Contact ◽  
Movement Strategies ◽  
Flexion Moment ◽  
Anterior Cruciate ◽  
Whole Body Movement

Background: Atypical knee joint biomechanics after anterior cruciate ligament reconstruction (ACLR) are common. It is, however, unclear whether knee robustness (ability to tolerate perturbation and maintain joint configuration) and whole body movement strategies are compromised after ACLR. Purpose: To investigate landing control after ACLR with regard to dynamic knee robustness and whole body movement strategies during sports-mimicking side hops, and to evaluate functional performance of hop tests and knee strength. Study Design: Controlled laboratory study. Methods: An 8-camera motion capture system and 2 synchronized force plates were used to calculate joint angles and moments during standardized rebound side-hop landings performed by 32 individuals with an ACL-reconstructed knee (ACLR group; median, 16.0 months after reconstruction with hamstring tendon graft [interquartile range, 35.2 months]) and 32 matched asymptomatic controls (CTRL). Dynamic knee robustness was quantified using a finite helical axis approach, providing discrete values quantifying divergence of knee joint movements from flexion-extension (higher relative frontal and/or transverse plane motion equaled lower robustness) during momentary helical rotation intervals of 10°. Multivariate analyses of movement strategies included trunk, hip, and knee angles at initial contact and during landing and hip and knee peak moments during landing, comparing ACLR and CTRL, as well as legs within groups. Results: Knee robustness was lower for the first 10° motion interval after initial contact and then successively stabilized for both groups and legs. When landing with the injured leg, the ACLR group, as compared with the contralateral leg and/or CTRL, demonstrated significantly greater flexion of the trunk, hip, and knee; greater hip flexion moment; less knee flexion moment; and smaller angle but greater moment of knee internal rotation. The ACLR group also had lower but acceptable hop and strength performances (ratios to noninjured leg >90%) except for knee flexion strength (12% deficit). Conclusion: Knee robustness was not affected by ACLR during side-hop landings, but alterations in movement strategies were seen for the trunk, hip, and knee, as well as long-term deficits in knee flexion strength. Clinical Relevance: Knee robustness is lowest immediately after landing for both the ACLR group and the CTRL and should be targeted in training to reduce knee injury risk. Assessment of movement strategies during side-hop landings after ACLR should consider a whole body approach.

Tension Bands Placed on the Thigh and Shank Produce Changes in the Knee Flexion Moment and Gait Asymmetry

2009 ◽  
Author(s):  
Ariel V. Dowling ◽  
Nathan Fenner ◽  
Thomas P. Andriacchi
Keyword(s):  
Quality Of Life ◽  
Knee Flexion ◽  
Daily Living ◽  
Risk Of Falling ◽  
Substantial Impact ◽  
Gait Asymmetry ◽  
Flexion Moment ◽  
Risk Of Falls ◽  
Tension Bands

Decreased symmetry in walking mechanics is common to many conditions associated with falling, such as muscle weakness, poor balance or flexibility, dizziness or vertigo, confusion, and vision problems [1]. Falls and the risk of falls have a substantial impact on the quality of life with aging. More than one in three adults over 65 years experience falls each year, and in half of these cases the falls are recurrent [2,3]. As patients with asymmetric gait are at a greater risk of falling during activities of daily living such as walking [1], conducting experiments on methods to correct gait asymmetries on this cohort can be potentially dangerous. However, experiments conducted with healthy patients that have an induced gait asymmetry during walking would minimize the risk to the unhealthy population while still allowing the researcher to test a subject with a gait asymmetry.

Validity of inertial measurement unit–based knee flexion strength-power test

2019 ◽  
Vol 233 (3) ◽  
pp. 443-449
Author(s):  
Ryu Nagahara ◽  
Mai Kameda ◽  
Jonathon Neville
Keyword(s):  
Knee Flexion ◽  
Inertial Measurement Unit ◽  
Correlation Coefficients ◽  
Measurement Unit ◽  
Mean Power ◽  
Inertial Measurement ◽  
Power Test ◽  
Angular Impulse ◽  
Flexion Strength ◽  
Positive Work

This study aimed to examine the concurrent validity of inertial measurement unit–based knee flexion strength-power test variables. Ten physically active males performed a knee flexion strength-power test, consisting of serial right knee flexion-extension motions. Two trials were performed, each at 50%, 75% and 100% effort. Lower-extremity motion during the trial was recorded using a motion capture system and an inertial measurement unit. For inertial measurement unit data, the measured length of each lower-extremity segment was used to estimate segment endpoint coordinates. Knee flexion kinetic variables were then computed using inverse dynamics analysis for both systems. The inertial measurement unit provided comparable values with the motion capture system for angular impulse, mean moment, positive work and mean power (−0.8%, 1.0%, −0.9%, and 1.5%, respectively). Moreover, intraclass correlation coefficients and correlation coefficients for angular impulse, mean moment, positive work and mean power of knee flexion were acceptably high (ICC or r = 0.903–0.970). For positive mean power, however, a Bland–Altman plot showed heteroscedasticity. For knee flexion negative work and mean power, the inertial measurement unit clearly showed an overestimation of the values (32.5% and 23.5%, respectively). Moreover, the intraclass correlation coefficients and correlation coefficients were not acceptably high for knee flexion negative work and mean power (ICC or r = 0.541–0.899). These results indicate that the angular impulse, mean moment and positive work can be measured accurately and validly using an inertial measurement unit for knee flexion strength-power test variables. Given its simplicity, the suggested inertial measurement unit–based knee flexion strength-power test would improve on-the-field physical fitness evaluation.

Sign in / Sign up

Export Citation Format

Share Document