Development and Feasibility Assessment of a Rotational Orthosis for Walking with Arm Swing

 Useless for us, tested on healthy subjects.

14 years post stroke and my arm swing takes 30-60 minutes to occur and even then spasticity keeps my arm bent.

Development and Feasibility Assessment of a Rotational Orthosis for Walking with Arm Swing

 

Juan Fang^1,2, Qing Xie³, Guo-Yuan Yang² and Le Xie^2,4*

• ¹Jiangsu Key Laboratory of Advanced Food Manufacturing, Equipment and Technology, Jiangnan University, Wuxi City, China
• ²The Joint Lab of the Institute of Rehabilitation Centre and Chejing Robotics Technology (Shanghai) Co., Ltd., Med-X Research Institute, Shanghai Jiao Tong University, Shanghai, China
• ³Department of Rehabilitation Medicine of Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
• ⁴School of Material Science and Engineering, Shanghai Jiao Tong University, Shanghai, China

Interlimb neural coupling might underlie human bipedal locomotion, which is reflected in the fact that people swing their arms synchronously with leg movement in normal gait. Therefore, arm swing should be included in gait training to provide coordinated interlimb performance. The present study aimed to develop a Rotational Orthosis for Walking with Arm Swing (ROWAS), and evaluate its feasibility from the perspectives of implementation, acceptability and responsiveness. We developed the mechanical structures of the ROWAS system in SolidWorks, and implemented the concept in a prototype. Normal gait data were used as the reference performance of the shoulder, hip, knee and ankle joints of the prototype. The ROWAS prototype was tested for function assessment and further evaluated using five able-bodied subjects for user feedback. The ROWAS prototype produced coordinated performance in the upper and lower limbs, with joint profiles similar to those occurring in normal gait. The subjects reported a stronger feeling of walking with arm swing than without. The ROWAS system was deemed feasible according to the formal assessment criteria.

Introduction

People swing their arms synchronously with leg movement during walking due to interlimb neural linkage, in addition to mechanical factors. Although the arms have no direct function for propulsion (Barbeau et al., 1987), people normally swing their arms so as to improve gait stability (Behrman and Harkema, 2000; Bovonsunthonchai et al., 2012) and energy efficiency (Dietz, 2002; Collins et al., 2009). Apart from such behavioral relevance, many phenomena imply that arm swing during walking is a neural-coordinated motor output. Rhythmic muscle activity was observed in the constrained arms during walking overground (Eke-Okoro et al., 1997), which implies the existence of neural coupling between the upper and lower limbs. Furthermore, adding mass to one ankle induced adaptive changes in both arms, in addition to changes in EMG from the leg muscles (Donker et al., 2002). This resulted in a coordinated movement pattern similar to that seen in unloaded normal gait. Studies of walking on a split-belt treadmill with different speed ratios between the legs resulted in coordinated locomotion in the legs and arms (Dietz et al., 2001). Short accelerations or decelerations randomly applied to the right leg during treadmill walking produced EMG response in the bilateral arm muscles, in addition to that in the right leg (Dietz et al., 2001). Interlimb neural interaction thus appears to be an underlying neural mechanism of human bipedal locomotion.

The theory of interlimb neural coupling brings new requirements for gait rehabilitation robotics. Interlimb modulation is active during walking, but not in standing or sitting (Dietz et al., 2001; Zehr et al., 2012). The neural interaction between the upper and lower limbs is maintained in patients with injury to central nervous system (Visintin and Barbeau, 1994; Stephenson et al., 2010). The task-specific practice strategy suggests gait restoration robotic systems should provide locomotion–like movements to improve gait control and functional ability (Harkema, 2001). Judging from the implication of interlimb neural coupling and the fact of arm swing during walking, it was suggested that gait training after neurological injury should incorporate simultaneous upper limb and lower limb rhythmic exercise to take advantage of neural coupling (Ferris et al., 2006).

In spite of the existence of many types of rehabilitation robots, there is no system which activates both the upper and lower limbs in the same way as during walking. Over the last few decades many types of rehabilitation systems have emerged, including systems for gait restoration (Díaz et al., 2011) or for upper limb rehabilitation (Lum et al., 2005). Several lower-limb exoskeletons are commercially available to assist walking restoration, such as the Lokomat (Hidler et al., 2008) and the G-EO (Hesse et al., 2010) systems. They induce upright walking movement at variable speeds in the lower limbs. The arms often hold horizontal fixed bars to support the body. There are also several systems, such as the Armeo (Nef et al., 2006) and GENTLE/s (Loureiro et al., 2003), for those who have functional impairments in the upper limbs. The users often practice various arm movements in a sitting position. To the best of the authors' knowledge, there is no gait orthosis which incorporates arm swing.

Based on these limitations, a new rehabilitation system was to be developed in the present work. As the early initiation of gait rehabilitation is generally deemed important (Fang et al., 2011), the requirements of the proposed system included:

(1) to allow the users to practice walking at the early post-injury stage;

(2) to mimic the ground reaction forces on the foot which occur during walking;

(3) to activate the upper limbs synchronously with the lower limb movement.

The aim of this work was to develop and evaluate the feasibility of a Rotational Orthosis for Walking with Arm Swing (ROWAS). The formal criteria for feasibility assessment were (Bowen et al., 2009): (i) implementation—was the system technically implementable? (ii) acceptability—was the system acceptable to the users? and (iii) responsiveness—was there a measurable movement that was close to the target joint trajectories?