Lower limb joint-specific contributions to standing postural sway in persons with unilateral lower limb loss

Courtney M Butowicz; Adam J Yoder; Shawn Farrokhi; Brittney Mazzone; Brad D Hendershot

doi:10.1016/j.gaitpost.2021.06.020

Lower limb joint-specific contributions to standing postural sway in persons with unilateral lower limb loss

Gait Posture. 2021 Sep:89:109-114. doi: 10.1016/j.gaitpost.2021.06.020. Epub 2021 Jul 2.

Authors

Courtney M Butowicz¹, Adam J Yoder², Shawn Farrokhi³, Brittney Mazzone², Brad D Hendershot⁴

Affiliations

¹ Research & Surveillance Division, DoD-VA Extremity Trauma & Amputation Center of Excellence, USA; Walter Reed National Military Medical Center, Bethesda, MD, USA. Electronic address: courtney.m.butowicz.civ@mail.mil.
² Research & Surveillance Division, DoD-VA Extremity Trauma & Amputation Center of Excellence, USA; Naval Medical Center, San Diego, CA, USA.
³ Research & Surveillance Division, DoD-VA Extremity Trauma & Amputation Center of Excellence, USA; Naval Medical Center, San Diego, CA, USA; Department of Rehabilitation Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, USA.
⁴ Research & Surveillance Division, DoD-VA Extremity Trauma & Amputation Center of Excellence, USA; Walter Reed National Military Medical Center, Bethesda, MD, USA; Department of Rehabilitation Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, USA.

PMID: 34271526
DOI: 10.1016/j.gaitpost.2021.06.020

Abstract

Background: Individuals with lower limb loss are at an increased risk for falls, likely due to impaired balance control. Standing balance is typically explained by double- or single-inverted pendulum models of the hip and/or ankle, neglecting the knee joint. However, recent work suggests knee joint motion contributes toward stabilizing center-of-mass kinematics during standing balance.

Research question: To what extent do hip, knee, and ankle joint motions contribute to postural sway in standing among individuals with lower limb loss?

Methods: Forty-two individuals (25 m/17f) with unilateral lower limb loss (30 transtibial, 12 transfemoral) stood quietly with eyes open and eyes closed, for 30 s each, while wearing accelerometers on the pelvis, thigh, shank, and foot. Triaxial inertial measurement units were transformed to inertial anterior-posterior components and sway parameters were computed: ellipse area, root-mean-square, and jerk. A state-space model with a Kalman filter calculated hip, knee, and ankle joint flexion-extension angles and ranges of motion. Multiple linear regression predicted postural sway parameters from intact limb joint ranges of motion, with BMI as a covariate (p < 0.05).

Results: With eyes open, intact limb hip flexion predicted larger sway ellipse area, whereas hip flexion and knee extension predicted larger sway root-mean-square, and hip flexion, knee extension, and ankle plantarflexion predicted larger sway jerk. With eyes closed, intact limb hip flexion remained the predictor of sway ellipse area; no other joint motions influenced sway parameters in this condition.

Significance: Hip, knee, and ankle motions influence postural sway during standing balance among individuals with lower limb loss. Specifically, increasing intact-side hip flexion, knee extension, and ankle plantarflexion motion increased postural sway. With vision removed, a re-weighting of lower limb joint sensory mechanisms may control postural sway, such that increasing sway may be regulated by proximal coordination strategies and vestibular responses, with implications for fall risk.

Keywords: Amputation; Balance; Biomechanics; Coordination; Postural control; Sensors.

Published by Elsevier B.V.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Ankle
Ankle Joint*
Biomechanical Phenomena
Humans
Knee Joint
Lower Extremity
Postural Balance*