Impaired Limb Shortening following Stroke: What’s in a Name?

Little, Virginia L.; McGuirk, Theresa E.; Patten, Carolynn

doi:10.1371/journal.pone.0110140

Cited by 45 publications

(36 citation statements)

References 39 publications

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“…However, the causal relations between these compensations and reduced foot clearance have never been established. Stroke patients exhibit similar or higher foot clearance values compared to healthy individuals (Little, McGuirk, & Patten, 2014; Matsuda et al, 2017) suggesting one or more of these aforementioned compensations could be redundant. It is a commonly held belief that hip abduction, the main frontal plane component of hip circumduction, compensates for lack of knee flexion (Perry & Burnfield, 1992).…”

Section: Introductionmentioning

confidence: 99%

Hip circumduction is not a compensation for reduced knee flexion angle during gait

Akbaş

Prajapati

Ziemnicki

et al. 2019

Preprint

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It has long been held that hip abduction compensates for reduced swing-phase knee flexion angle, especially in those after stroke. However, there are other compensatory motions such as pelvic obliquity (hip hiking) that could also be used to facilitate foot clearance with greater energy efficiency. Our previous work suggested that hip abduction may not be compensation for reduced knee flexion after stroke. Previous study applied robotic knee flexion assistance in people with post-stroke Stiff-Knee Gait (SKG) during pre-swing, finding increased abduction despite improved knee flexion and toe clearance. Thus, our hypothesis was that hip abduction is not a compensation for reduced knee flexion. We simulated the kinematics of post-stroke SKG on unimpaired individuals with three factors: a knee orthosis to reduce knee flexion, an ankle-foot orthosis commonly worn by those post-stroke, and matching gait speeds. We compared spatiotemporal measures and kinematics between experimental factors within healthy controls and with a previously recorded cohort of people with post-stroke SKG. We focused on frontal plane motions of hip and pelvis as possible compensatory mechanisms. We observed that regardless of gait speed, knee flexion restriction significantly increased pelvic obliquity (2.79 deg, p<0.01) compared to unrestricted walking (1.5 deg, p<0.01), but similar to post-stroke SKG (3.4 deg). However, those with post-stroke SKG had significantly greater hip abduction (8.2 deg) compared to unimpaired individuals with restricted knee flexion (4.2 deg, p<0.05). These results show that pelvic obliquity, not hip abduction, compensates for reduced knee flexion angle. Thus, other factors, possibly neural, facilitate exaggerated hip abduction observed in post-stroke SKG.

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Section: Introductionmentioning

confidence: 99%

Hip circumduction is not a compensation for reduced knee flexion angle during gait

Akbaş

Prajapati

Ziemnicki

et al. 2019

Preprint

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“…(Leiper and Craik 1991) Influence values, as used here, represent more than the magnitude of joint excursion. Influence represents the relational contribution of the joint excursion to the functional tasks of limb clearance and limb shortening (Little, McGuirk, and Patten 2014), that is the concurrent coordination between joints to achieve a task goal. Furthermore, influence quantifies the respective joint contributions that are temporally linked to their task goal throughout the gait cycle.…”

Section: Is Slow Walking a Different Behavior?mentioning

confidence: 99%

“…Gait researchers commonly speed-match, using healthy individuals walking at very slow speeds, for a direct comparison with pathologic gait. (Lehmann et al 1987;Chen et al 2005;Little, McGuirk, and Patten 2014) However, it has been suggested that very slow walking (<0.4-0.5 m/sec) may be a unique motor behavior utilizing a different control strategy than walking at comfortable walking speeds. (Leiper and Craik 1991;Smith and Lemaire 2018) If this were the case, speed-matching for biomechanical studies may not always be appropriate.…”

Section: Introductionmentioning

confidence: 99%

Inter-joint and temporal coordination change in very slow walking

Little

McGuirk

Patten

2019

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Purpose: Very slow walking has been suggested to be a distinctively different motor behavior than walking at comfortable gait speeds. While kinematic and spatiotemporal gait parameters are known to scale with gait speed, inter-joint coordination during swing remains consistent, at least across comfortable speeds. The purpose of this study was to determine whether coordination patterns serving limb clearance and shortening differ with very slow walking, providing additional support for the premise that very slow walking represents a unique motor behavior. Methods:We assessed nine healthy adults walking overground at their self-selected speed and two-tothree progressively slower speeds. We collected lower extremity kinematics with 3D motion analysis and quantified joint motion contributions to limb clearance and shortening. We investigated changes in coordination using linear mixed models to determine magnitude and timing differences of joint influence across walking speeds.Results: Hip and knee influences serving limb clearance reduced considerably with slower walking speeds. Similarly, knee influence on limb shortening reduced with very slow walking. Importantly, ankle influence remained unchanged across gait speeds for limb shortening and reduced subtly for limb clearance. Temporally, joint influences on limb clearance varied across walking speeds. Specifically, the temporal order of peak hip and knee influences reversed between comfortable and very slow walking. For limb shortening the timing of ankle influence remained unchanged while the timing of knee influence occurred later in the gait cycle for slower walking speeds. Conclusions:Our results demonstrate temporal coordination and the relative joint contributions serving limb clearance and shortening differ with very slow walking providing additional evidence that slow walking may be a behavior distinct from walking at comfortable speeds.

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“…A2 is typically diminished following stroke; the extent to which A2 is decreased is strongly associated with walking speed, capacity for gait speed modulation, and severity of walking dysfunction (Winter 1983; Olney et al 1991; Jonkers et al 2009; Kitatani et al 2016). Propulsive power generated by the plantarflexors also drives knee flexion during swing, one of the major contributors to limb clearance (Nadeau et al 1999; Little et al 2014). For all that is known about the biomechanical deficits following stroke, much less is known about the specific neural mechanisms underlying these impairments.…”

Section: Introductionmentioning

confidence: 99%

Lower Extremity Long-Latency Reflexes Differentiate Walking Function After Stroke

Banks

Little

Walker

et al. 2019

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The neural mechanisms of walking impairment after stroke are not well characterized. There is a need for a neurophysiologic marker that can unambiguously differentiate functional status and potential for walking recovery. The long-latency reflex (LLR) is a supraspinally-mediated response that integrates sensorimotor information during movement. It is hypothesized that lower extremity LLRs contribute to regulation of motor output during walking in healthy individuals. The goal of the present study was to assess the relationship between lower extremity LLRs, measures of supraspinal drive, and walking function. Thirteen individuals with chronic post-stroke hemiparesis and thirteen healthy controls performed both isometric and dynamic plantarflexion. Transcranial magnetic stimulation (TMS) assessed supraspinal drive to the tibialis anterior. LLR activity was assessed during dynamic voluntary plantarflexion and individuals post-stroke were classified as either LLR present (LLR+) or absent (LLR-). All healthy controls and nine individuals post-stroke exhibited LLRs, while four did not. LLR+ individuals revealed higher clinical scores, walking speeds, and greater ankle plantarflexor power during walking compared to LLR- individuals. LLR- individuals exhibited exaggerated responses to TMS during dynamic plantarflexion relative to healthy controls. This LLR- subset revealed dysfunctional modulation of stretch responses and antagonist supraspinal drive relative to healthy controls and the higher functioning LLR+ individuals post-stroke. These abnormal responses allow for unambiguous differentiation between individuals post-stroke and are associated with multiple measures of motor function. These findings provide an opportunity to distinguish among the heterogeneity of lower extremity motor impairments present following stroke by associating them with responses at the nervous system level.

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Impaired Limb Shortening following Stroke: What’s in a Name?

Cited by 45 publications

References 39 publications

Hip circumduction is not a compensation for reduced knee flexion angle during gait

Hip circumduction is not a compensation for reduced knee flexion angle during gait

Inter-joint and temporal coordination change in very slow walking

Lower Extremity Long-Latency Reflexes Differentiate Walking Function After Stroke

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