Clinical assessment of stand-up and sit-down motion assist by personal standing mobility QoLo in people with spinal cord injury

Abstract

We developed Qolo, a new personal mobility device for those with motor disability in their lower limbs It assists sit-to-stand and stand-to-sit postural transitions, as well as navigation in standing posture with hands-free operation Its mechanism to assist postural transition is implemented with passive gas springs without using electric actuators, making it compact, light-weight and low cost The purpose of this study is to report a clinical assessment of the device with people with spinal cord injury (SCI), and investigate plausibility of the device and discuss further technical improvements. Four participants with SCI (age: 31–52y, 3 males and one female, neurological level: T10-L3, AIS: A-C, MMT Hip Ext: 0-1, Knee Ext: 1–5) were asked to conduct stand-up and sit-down postural transitions using the device ( Fig. 1 ) Feasibility and duration of the assisted motions were evaluated. Two of the participants conducted stand-up motion by themselves using the device (duration: 14 and 16 s) The other two needed external posture support The main factor that differed in relation to the ability of performing stand-up motion using the device was MMT Knee Ext; greater than 2 for the group that was able to perform, and 1 for the other All participants conducted sit-down motion by themselves using the device without external support (10–15 s). Capability of the device to assist posture transition was shown for some SCI people through the experiment At the same time, greater assistance on the knee joint was found to be necessary Because the device utilizes voluntary control of the trunk to induce assisted motion of knee and ankle joints for posture transition, we considered that assistance for trunk motion would be helpful for them For the next step, we plan to introduce a mechanism for lumbar posture stabilization that can support motion of hip in coordination with knee.