Elsevier

Gait & Posture

Volume 40, Issue 4, September 2014, Pages 616-621
Gait & Posture

Can external lateral stabilization reduce the energy cost of walking in persons with a lower limb amputation?

https://doi.org/10.1016/j.gaitpost.2014.07.013Get rights and content

Highlights

  • We aimed to evaluate the energy cost for balance control in amputees and controls.

  • External lateral stabilization was used to determine the energy cost for balance control.

  • Stabilization was beneficial in transtibial but detrimental in transfemoral amputees.

  • The stabilization device possibly impedes necessary gait adaptations in amputees.

  • The energy cost for balance control in amputees remains to be determined.

Abstract

The aim of this study was to examine whether impaired balance control is partly responsible for the increased energy cost of walking in persons with a lower limb amputation (LLA). Previous studies used external lateral stabilization to evaluate the energy cost for balance control; this caused a decrease in energy cost, with concomitant decreases in mean and variability of step width. Using a similar set-up, we expected larger decreases for LLA than able-bodied controls.

Fifteen transtibial amputees (TT), 12 transfemoral amputees (TF), and 15 able-bodied controls (CO) walked with and without external lateral stabilization provided via spring like cords attached to the waist. Effects of this manipulation on energy cost, step parameters, and pelvic motion were evaluated between groups.

TT (−5%) and CO (−3%) showed on average a small reduction in energy cost when walking with stabilization, whereas TF exhibited an increase in energy cost (+6.5%) The difference in the effect of stabilization was only significant between TT and TF. Step width, step width variability, and medio-lateral pelvic displacement decreased significantly with stabilization in all groups, especially in TT.

Contrary to expectations, external lateral stabilization did not result in a larger decrease in the energy cost of walking for LLA compared to able-bodied controls, suggesting that balance control is not a major factor in the increased cost of walking in LLA. Alternatively, the increased energy cost with stabilization for TF suggests that restraining (medio-lateral) pelvic motion impeded necessary movement adaptations in LLA, and thus negated the postulated beneficial effects of stabilization on the energy cost of walking.

Introduction

Regaining walking ability is an important rehabilitation goal for lower limb amputees (LLA). Achieving this goal may be hampered by a significantly elevated energy cost of walking with a lower limb prosthesis, with reported increases between 9and 33% for transtibial, and 66 and 100% for transfemoral amputees [1], [2], [3]. While this increased cost of walking is well documented, its underlying causes are still poorly understood.

Previous research has associated the elevated cost of walking in LLA with compensatory strategies related to forward progression of the body. LLA compensate for the lack of ankle push-off power with increased mechanical work produced at the hip, which increases step-to-step transition costs [4]. Furthermore, particularly transfemoral amputees show vaulting, hip hiking and circumduction of the prosthetic leg to ensure foot clearance during swing in the absence of active ankle dorsiflexion and knee flexion, which supposedly comes with an extra metabolic cost [5]. However, correlations between these adaptations and the elevated energy cost of walking are moderate at best [4], [6], [7], suggesting a role for other factors, possibly not directly related to forward progression. One such factor could be the impaired balance control in LLA [8], [9]. While the energy demand of the motor responses associated with balance control is relatively low in healthy subjects, this cost might rise considerably as a result of compensatory strategies associated with the neuromuscular impairments in LLA, and thus contribute to the elevated energy cost of walking in LLA [1].

Especially in the frontal plane, the most unstable direction during walking, active feedback control appears necessary to ensure stability [10], [11]. Primary strategies for medio-lateral balance control are a stepping strategy, a lateral ankle strategy, and a hip strategy [12]. The stepping strategy provides gross balance control through adequate foot placement, while fine-tuning is accomplished by ankle inversion/eversion and hip abduction/adduction torques during stance. In LLA, the use of these strategies is hampered by reduced neuromuscular control to correctly place the foot, and a lack of control over the prosthetic ankle joint. Moreover, particularly in transfemoral amputees, the hip strategy is also often impaired due to atrophy and loss of control over the remaining muscles around the hip joint [13].

These impairments can be dealt with by taking wider steps to ensure a sufficient margin of stability [14]. Indeed, an increase in step width has been observed in LLA compared to controls, with larger increases for transfemoral amputees [12], [15], [16], [17]. Moreover, increased step width variability has been observed in LLA, indicating an increased reliance on the stepping strategy to compensate for the reduced ability to use an ankle and/or hip strategy [18], [19]. While these compensations may help ensure stability, previous work has demonstrated that increasing step width and step width variability adversely affects the energy cost of walking [20], [21] due to increased mechanical work to redirect the center of mass from side-to-side [20], [21], [22], or increased muscle activity to ensure adequate foot placement [23].

To estimate the contribution of medio-lateral balance control to the total energy cost of walking, the need for active balance control can be reduced artificially. To this end, Donelan et al. [24] constructed a set-up to externally stabilize subjects in the medio-lateral direction via stiff spring-like cords attached to the waist. In healthy subjects this resulted in significant reductions in step width and step width variability, with a concomitant reduction in energy cost of 3–7.5% [24], [25], [26], [27]. Since LLA, and especially transfemoral amputees, naturally take wider and more variable steps, it can be hypothesized that they will benefit more from external lateral stabilization than able-bodied controls, resulting in a substantially larger reduction in energy cost due to stabilization for LLA, particularly for transfemoral amputees.

The aim of the current study was thus to examine whether the increased energy cost of walking in LLA compared to able-bodied people is related to an increased effort for balance control. More specifically, we sought to examine whether external lateral stabilization leads to larger reductions in the energy cost of walking in transfemoral and transtibial amputees compared to able-bodied controls, and expected the largest reductions to occur in transfemoral amputees. Furthermore, we expected concomitant decreases in step width and step width variability.

Section snippets

Study population

Thirteen unilateral transfemoral amputees (TF), sixteen unilateral transtibial amputees (TT) and seventeen age-matched able-bodied controls (CO) agreed to participate. All amputees were experienced walkers who had completed their rehabilitation period and were able to walk 5 min on a treadmill. Subjects were excluded in case of contraindications for moderate exercise, or co-morbidities or medication use that could interfere with energy expenditure or balance control. Additional exclusion

Results

In each group one subject was unable to complete the protocol, for different reasons: soreness in the stump (TF), difficulty walking on a treadmill (TT) and dizziness (CO). Oxygen data for one subject (CO) were aberrant, therefore this subject was excluded, leaving a total of 12 TF, 15 TT and 15 CO subjects that were included in the analysis.

Discussion

The goal of this study was to investigate whether the increased energy cost of walking in LLA could partly be explained by impaired balance control, by evaluating the effect of external lateral stabilization in LLA and able-bodied subjects. Our hypothesis that external lateral stabilization would result in larger reductions in energy cost for LLA, especially for TF, was not corroborated by the results. The effect of stabilization on energy cost was small in light of previous studies with

Conflict of interest statement

We wish to confirm that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome.

Acknowledgements

This research was supported by a non commercial grant from OIM Foundation, Assen, The Netherlands (reference number 1104b).

References (32)

Cited by (25)

  • The impact of added mass placement on metabolic and temporal-spatial characteristics of transfemoral prosthetic gait

    2022, Gait and Posture
    Citation Excerpt :

    Energy expenditure during gait is a major obstacle for individuals with amputation at the transfemoral (TF) level, despite numerous advancements in lower limb prosthetic technologies. Metabolic costs during walking for this population are known to be greater than those of their counterparts without amputation [1–9] and even young, active individuals with TF amputation have reported metabolic costs of 20 % [1] to 47 % [2] greater than their peers without amputation. High metabolic costs of walking may limit mobility and discourage prosthesis users from being more active, although this relationship is not well understood.

  • Variability in trunk and pelvic movement of transfemoral amputees using a C-leg system compared to healthy controls

    2019, Human Movement Science
    Citation Excerpt :

    Therefore, our study clearly demonstrates kinematic variability in transfemoral amputees walking on different types of surface compared to healthy controls. A further strength of our study is the very homogeneous group of amputees compared to previous literature, which examined more heterogeneous amputee groups (IJmker et al., 2014; Lamoth et al., 2010; Lin et al., 2014; Parker et al., 2013; Sagawa Jr. et al., 2011; Tanimoto, Anan, Sawada, Takahashi, & Shinkoda, 2016; Vanicek et al., 2009). Tanimoto et al. (2016) acknowledged in their study that kinematic data variability could be a useful marker to assess gait pattern in healthy persons.

  • Energy expenditure in people with transtibial amputation walking with crossover and energy storing prosthetic feet: A randomized within-subject study

    2018, Gait and Posture
    Citation Excerpt :

    Energy expenditure, the primary outcome of this study, was measured while participants with unilateral transtibial amputation walked at self-selected speeds on a treadmill. The range of comfortable walking speeds selected by participants varied (0.6–1.2 m/s), but were similar to speeds (0.68–1.07 m/s [4,21,24,25]) exhibited by people who use transtibial prostheses walking on a treadmill. Speeds were, however, generally lower than those adopted by individuals with transtibial amputation and healthy adults walking over-ground (1.1–1.2 m/s [2,3,19,24,26,27] and 1.0–1.7 m/s [2], respectively).

View all citing articles on Scopus
View full text