Evaluation of a Chair-Mounted Passive Trunk Orthosis: A Pilot Study on Able-Bodied Subjects

Ahmad Zahid Rao,Muhammad Abul Hasan

doi:10.3390/s21248366

Ahmad Zahid Rao, Muhammad Abul Hasan

Open Access

https://doi.org/10.3390/s21248366

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Abstract

Trunk stability is important for adequate arm function due to their kinematic linkage. People with Duchenne muscular dystrophy (DMD) can benefit from trunk-assistive devices for seated daily activities, but existing devices limit trunk movement to forward bending. We developed a new trunk orthosis that has spring and pulley design. This study evaluated orthosis performance with 40 able-bodied subjects under with and without orthosis condition in 20 seated tasks for trunk rotation, forward bending, and side bending movements. Subjects adopted static posture in specific trunk orientation while their muscle activity was recorded. They also rated the subjective scales of perceived exertion and usability. A percent change in muscle activity for each task, due to orthosis use, is reported. Significant muscle activity reductions up to 31% and 65% were observed in lumbar and thoracic erector spinae muscles, respectively. Using three-way ANOVA, we found these reductions to be specific to the task direction and the choice of upper limb that is used to perform the asymmetric tasks. A total of 70% participants reported acceptable usability and ~1-point increase in exertion was found for maximum voluntary reaching with the orthosis. The outcomes of this study are promising, though tested on able-bodied subjects. Hence, orthosis mounted on wheelchairs should be further evaluated on DMD patients.

Highlights

The ability to regulate trunk movement and maintain an upright upper body is crucial when seated
A partial or total loss of trunk control can happen due to neuromuscular conditions such as Duchenne muscular dystrophy (DMD) [3,4]
Factors Contributing toward Varied Muscle Activity in extending arm towards target (Extend) and reaching for the target (Reach) Stages

Summary

Introduction

The ability to regulate trunk movement and maintain an upright upper body is crucial when seated. This is because the human trunk is part of the kinematic chain that allow our hands to move in the functional workspace [1,2]. A seated person can only maximally use their upper limb when there is proper trunk flexibility. DMD is a progressive muscle-wasting disease that affects the upper limb and trunk muscles, making it challenging to keep the body upright and stable. It becomes difficult to catch oneself to prevent potential falls resulting from trunk movement in daily activities. An adequate trunk control is, critical for DMD patients in performing daily activities [5]

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