A unified deformable (UD) segment model for quantifying total power of anatomical and prosthetic below-knee structures during stance in gait

Takahashi, Kota; Kepple, Thomas M.; Stanhope, Steven J.

doi:10.1016/j.jbiomech.2012.08.017

Cited by 111 publications

(103 citation statements)

References 32 publications

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“…Our biomechanical estimates were in good qualitative agreement with prior literature reporting 3DOF joint (Eng and Winter, 1995), 6DOF ankle (Buczek et al, 1994), Foot (Takahashi et al, 2012) and COM power (Donelan et al, 2002a). To our knowledge, 6DOF knee and hip power and Peripheral rate of energy change have not been published for level-ground walking.…”

Section: Comparison With Prior Literaturesupporting

confidence: 89%

“…This estimates 6DOF power due to compression and rotation of the Foot. As this Foot power (sometimes called 'distal foot power' in the literature) calculation has been explained in prior work (Takahashi et al, 2012), we only briefly summarize it here:…”

Section: −1mentioning

confidence: 99%

“…One of the most common biomechanical estimates is rotational joint power, computed from 3DOF inverse dynamics and denoted as 3DOF power in this study. Recently, foot power estimates computed assuming a deformable segment model have also become more widely used and accepted (Prince et al, 1994;Takahashi et al, 2012). In the absence of a true gold standard (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Six degree-of-freedom analysis of hip, knee, ankle and foot provides updated understanding of biomechanical work during human walking

Zelik

Takahashi

Sawicki

2015

Journal of Experimental Biology

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117

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Measuring biomechanical work performed by humans and other animals is critical for understanding muscle-tendon function, jointspecific contributions and energy-saving mechanisms during locomotion. Inverse dynamics is often employed to estimate jointlevel contributions, and deformable body estimates can be used to study work performed by the foot. We recently discovered that these commonly used experimental estimates fail to explain whole-body energy changes observed during human walking. By re-analyzing previously published data, we found that about 25% (8 J) of total positive energy changes of/about the body's center-of-mass and >30% of the energy changes during the Push-off phase of walking were not explained by conventional joint-and segment-level work estimates, exposing a gap in our fundamental understanding of work production during gait. Here, we present a novel Energy-Accounting analysis that integrates various empirical measures of work and energy to elucidate the source of unexplained biomechanical work. We discovered that by extending conventional 3 degree-of-freedom (DOF) inverse dynamics (estimating rotational work about joints) to 6DOF (rotational and translational) analysis of the hip, knee, ankle and foot, we could fully explain the missing positive work. This revealed that Push-off work performed about the hip may be >50% greater than conventionally estimated (9.3 versus 6.0 J, P=0.0002, at 1.4 m s −1). Our findings demonstrate that 6DOF analysis (of hipknee-ankle-foot) better captures energy changes of the body than more conventional 3DOF estimates. These findings refine our fundamental understanding of how work is distributed within the body, which has implications for assistive technology, biomechanical simulations and potentially clinical treatment.

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Section: Comparison With Prior Literaturesupporting

confidence: 89%

Section: −1mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Six degree-of-freedom analysis of hip, knee, ankle and foot provides updated understanding of biomechanical work during human walking

Zelik

Takahashi

Sawicki

2015

Journal of Experimental Biology

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117

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“…In essence the approach adopted determined the energy absorbed and returned by the prosthetic foot that contributed to gait propulsion, and was thus in keeping with the approach we used to determine sagittal plane muscle moments and powers at all physiological lower-limb joints. To undertake an evaluation of absolute power absorbed and returned by a dynamic response foot, a different approach is recommended [41]. Similarly, determining total mechanical work done by a physiological joint (rather than just that associated with muscle work; as was carried out in the present study), also requires a different approach [42].…”

Section: Discussionmentioning

confidence: 99%

Walking speed related joint kinetic alterations in trans-tibial amputees: impact of hydraulic 'ankle’ damping

Asha

Munjal

Kulkarni³

et al. 2013

J NeuroEngineering Rehabil

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BackgroundPassive prosthetic devices are set up to provide optimal function at customary walking speed and thus may function less effectively at other speeds. This partly explains why joint kinetic adaptations become more apparent in lower-limb amputees when walking at speeds other than customary. The present study determined whether a trans-tibial prosthesis incorporating a dynamic-response foot that was attached to the shank via an articulating hydraulic device (hyA-F) lessened speed-related adaptations in joint kinetics compared to when the foot was attached via a rigid, non-articulating attachment (rigF).MethodsEight active unilateral trans-tibial amputees completed walking trials at their customary walking speed, and at speeds they deemed to be slow-comfortable and fast-comfortable whilst using each type of foot attachment. Moments and powers at the distal end of the prosthetic shank and at the intact joints of both limbs were compared between attachment conditions.ResultsThere was no change in the amount of intact-limb ankle work across speed or attachment conditions. As speed level increased there was an increase on both limbs in the amount of hip and knee joint work done, and increases on the prosthetic side were greater when using the hyA-F. However, because all walking speed levels were higher when using the hyA-F, the intact-limb ankle and combined joints work per meter travelled were significantly lower; particularly so at the customary speed level. This was the case despite the hyA-F dissipating more energy during stance. In addition, the amount of eccentric work done per meter travelled became increased at the residual knee when using the hyA-F, with increases again greatest at customary speed.ConclusionsFindings indicate that a trans-tibial prosthesis incorporating a dynamic-response foot reduced speed-related changes in compensatory intact-limb joint kinetics when the foot was attached via an articulating hydraulic device compared to rigid attachment. As differences between attachment conditions were greatest at customary speed, findings indicate a hydraulic ankle-foot device is most effectual at the speed it is set-up for.

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“…5). For better accuracy, we estimated intersegmental power flow into the prosthesis (energy storage) and out of it (energy return) using a deformable-segment model (Prince, Winter, Sjonnesen, & Wheeldon, 1994; Takahashi, Kepple, & Stanhope, 2012; Zelik et al, 2011). This computation estimates the power (P) flowing into and out of the shank segment through the ankle, including both linear and angular contributions (ankle force

\overset{F}{true}

and linear velocity

\overset{v}{true}

ankle moment

\overset{M}{true}

and shank angular velocity

\overset{ω}{true}

), without assuming a rigid structure for the foot segment:

P = \overset{⇀}{M} \cdot \overset{⇀}{ω} + \overset{⇀}{F} \cdot \overset{⇀}{v}

…”

Section: Methodsmentioning

confidence: 99%

Sensitivity of biomechanical outcomes to independent variations of hindfoot and forefoot stiffness in foot prostheses

Adamczyk

Roland

Hahn

2017

Human Movement Science

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Many studies have reported the effects of different foot prostheses on gait, but most results cannot be generalized because the prostheses’ properties are seldom reported. We varied hindfoot and forefoot stiffness in an experimental foot prosthesis, in increments of 15 N/mm, and tested the parametric effects of these variations on treadmill walking in unilateral transtibial amputees, at speeds from 0.7 to 1.5 m/s. We computed outcomes such as prosthesis energy return, center of mass (COM) mechanics, ground reaction forces, and joint mechanics, and computed their sensitivity to component stiffness. A stiffer hindfoot led to reduced prosthesis energy return, increased ground reaction force (GRF) loading rate, and greater stance-phase knee flexion and knee extensor moment. A stiffer forefoot resulted in reduced prosthetic-side ankle push-off and COM push-off work, and increased knee extension and knee flexor moment in late stance. The sensitivity parameters obtained from these tests may be useful in clinical prescription and further research into compensatory mechanisms of joint function.

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A unified deformable (UD) segment model for quantifying total power of anatomical and prosthetic below-knee structures during stance in gait

Cited by 111 publications

References 32 publications

Six degree-of-freedom analysis of hip, knee, ankle and foot provides updated understanding of biomechanical work during human walking

Six degree-of-freedom analysis of hip, knee, ankle and foot provides updated understanding of biomechanical work during human walking

Walking speed related joint kinetic alterations in trans-tibial amputees: impact of hydraulic 'ankle’ damping

Sensitivity of biomechanical outcomes to independent variations of hindfoot and forefoot stiffness in foot prostheses

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