A general model for estimating lower extremity inertial properties of individuals with transtibial amputation

Ferris, Abbie E.; Smith, Jeremy D.; Heise, Gary D.; Hinrichs, Richard N.; Martin, Philip E.

doi:10.1016/j.jbiomech.2017.01.034

Cited by 16 publications

(8 citation statements)

References 22 publications

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“…The calculation of the inertial parameters of the lower limb of the affected side might be more influential. In the absence of geometrical information and precise center of mass values for the residual limb and prosthesis we chose to modify the inertial properties of the shank segment according to the generic correction presented by Ferris et al [28]. A brief examination into the effect of computationally manipulating inertial values revealed that considerable differences in the range of L could be attributed simply to a difference in the mass and center of mass position values of the lower leg input into the model.…”

Section: Discussionmentioning

confidence: 99%

“…The center of mass of the body was approximated from segment positions and estimated segment masses of the feet, lower legs, thighs, pelvis and trunk using inertial values from Hanavan et al [27]. Based on the general model of Ferris et al [28], the segment mass of the prosthetic shank was reduced from 4.65 to 3.3% body mass, the center of mass position to 21% of the segment length and the moment of inertia about an axis through the origin parallel to the flexion-extension axis of the limb to 17% of the segment length. Although an approximation, this generalization has been shown to give good approximations of more stringently measured, individualized, inertial parameters [28].…”

Section: Methodsmentioning

confidence: 99%

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Uneven terrain exacerbates the deficits of a passive prosthesis in the regulation of whole body angular momentum in individuals with a unilateral transtibial amputation

Kent

Takahashi

Stergiou

2019

J NeuroEngineering Rehabil

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BackgroundUneven ground is a frequently encountered, yet little-studied challenge for individuals with amputation. The absence of control at the prosthetic ankle to facilitate correction for surface inconsistencies, and diminished sensory input from the extremity, add unpredictability to an already complex control problem, and leave limited means to produce appropriate corrective responses in a timely manner. Whole body angular momentum, L, and its variability across several strides may provide insight into the extent to which an individual can regulate their movement in such a context. The aim of this study was to explore L in individuals with a transtibial amputation, when challenged by an uneven surface. We hypothesized that, similar to previous studies, sagittal plane L would be asymmetrical on uneven terrain, and further, that uneven terrain would evoke a greater variability in L from stride to stride in individuals with amputation in comparison to unimpaired individuals, due to a limited ability to discern and correct for changing contours beneath the prosthetic foot.MethodsWe examined sagittal plane L in ten individuals with a unilateral transtibial amputation and age- and gender- matched control participants walking on flat (FT) and uneven (UT) treadmills. The average range of L in the first 50% of the gait cycle (LR), the average L at foot contact (LC) and their standard deviations (vLR, vLC) were computed over 60 strides on each treadmill.ResultsOn both surfaces we observed a higher LR on the prosthetic side and a reduced LC on the sound side (p < 0.001) in the amputee cohort, consistent with previous findings. UT invoked an increase in LC (p = 0.006), but not LR (p = 0.491). vLR, and vLC were higher in individuals with amputation (p < 0.001, p = 0.002), and increased in both groups on UT (p < 0.001).ConclusionsThese findings support previous assertions that individuals with amputation regulate L less effectively, and suggest that the deficits of the prosthesis are exacerbated on uneven terrain, potentially to the detriment of balance. Further, the results indicate that a greater demand may be placed on the unaffected side to control movement.Electronic supplementary materialThe online version of this article (10.1186/s12984-019-0497-9) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Uneven terrain exacerbates the deficits of a passive prosthesis in the regulation of whole body angular momentum in individuals with a unilateral transtibial amputation

Kent

Takahashi

Stergiou

2019

J NeuroEngineering Rehabil

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“…Visual3D was used to model the body segments and calculate joint angles for the ankles, knees, and hips. The model of the prosthesis shank segment was modified following [24], [25]. We imported the synchronized joint data, EMG, and recordings from the Utah Bionic Leg into MATLAB (Mathworks, Natick, MA).…”

Section: Data Processingmentioning

confidence: 99%

Effect of Increasing Assistance From a Powered Prosthesis on Weight-Bearing Symmetry, Effort, and Speed During Stand-Up in Individuals With Above-Knee Amputation

Hunt

Hood

Gabert

et al. 2023

IEEE Trans. Neural Syst. Rehabil. Eng.

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After above-knee amputation, the missing biological knee and ankle are commonly replaced with a passive prosthesis, which cannot provide net-positive energy to assist the user. During activities such as sit-to-stand, above-knee amputees must compensate for this lack of power using their upper body, intact limb, and residual limb, resulting in slower, less symmetric, and higher effort movements. Previous studies have shown that powered prostheses can improve symmetry and speed by providing positive assistive power. However, we still lack a systematic investigation of the effect of powered prosthesis assistance. Without this knowledge, researchers and clinicians have no framework for tuning powered prostheses to optimally assist users. Here we show that varying the assistive knee torque significantly affected weight-bearing symmetry, effort, and speed during the stand-up movement in eight above-knee amputees. Specifically, we observed improvements in the index of asymmetry of the vertical ground reaction force at the point approximating maximum vertical center of mass acceleration, the integral of the intact vastus medialis activation measured using electromyography, and the stand-up duration compared to the passive prosthesis. We saw significant improvements in all three metrics when subjects used the powered prosthesis compared to the passive prosthesis. We saw improvements in all three metrics with increasing assistive torque levels commanded by the powered prosthesis. We also observed increased weight-bearing asymmetry at the end of movement, and increased kinematic asymmetry with increasing assistance from the powered prosthesis. These results show that powered prostheses can improve functional mobility, potentially increasing quality of life for millions of people living with above-knee amputations.

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“…Notably, a prosthesis cannot be accurately modeled using the assumptions made for an able-bodied individual 33 . Thus, the kinetics and kinematics were calculated using the assumptions that prosthesis side shank weight is 1/3 of the assumed able-bodied shank weight, and the center of mass is 25% below the top of the shank after previous studies 34,35 . Although the prostheses center of mass and inertial properties can be measured experimentally, this approach requires dedicated, custom equipment 36 and was found not statistically different from assumptions we have used 34,35 .…”

Section: Methodsmentioning

confidence: 99%

“…Thus, the kinetics and kinematics were calculated using the assumptions that prosthesis side shank weight is 1/3 of the assumed able-bodied shank weight, and the center of mass is 25% below the top of the shank after previous studies 34,35 . Although the prostheses center of mass and inertial properties can be measured experimentally, this approach requires dedicated, custom equipment 36 and was found not statistically different from assumptions we have used 34,35 . Starting from the specific prostheses components reported in Table 1, researchers may be able find experimental approximations of the center of mass and inertial properties and apply them to the provided marker trajectory data.…”

Section: Methodsmentioning

confidence: 99%

A kinematic and kinetic dataset of 18 above-knee amputees walking at various speeds

et al. 2020

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Motion capture is necessary to quantify gait deviations in individuals with lower-limb amputations. However, access to the patient population and the necessary equipment is limited. Here we present the first open biomechanics dataset for 18 individuals with unilateral above-knee amputations walking at different speeds. Based on their ability to comfortably walk at 0.8 m/s, subjects were divided into two groups, namely K2 and K3. The K2 group walked at [0.4, 0.5, 0.6, 0.7, 0.8] m/s; the K3 group walked at [0.6, 0.8, 1.0, 1.2, 1.4] m/s. Full-body biomechanics was collected using a 10-camera motion capture system and a fully instrumented treadmill. The presented open dataset will enable (i) clinicians to understand the biomechanical demand required to walk with a knee and ankle prosthesis at various speeds, (ii) researchers in biomechanics to gain new insights into the gait deviations of individuals with above-knee amputations, and (iii) engineers to improve prosthesis design and function.

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A general model for estimating lower extremity inertial properties of individuals with transtibial amputation

Cited by 16 publications

References 22 publications

Uneven terrain exacerbates the deficits of a passive prosthesis in the regulation of whole body angular momentum in individuals with a unilateral transtibial amputation

Uneven terrain exacerbates the deficits of a passive prosthesis in the regulation of whole body angular momentum in individuals with a unilateral transtibial amputation

Effect of Increasing Assistance From a Powered Prosthesis on Weight-Bearing Symmetry, Effort, and Speed During Stand-Up in Individuals With Above-Knee Amputation

A kinematic and kinetic dataset of 18 above-knee amputees walking at various speeds

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