The Impact of a Lightweight Pneumatic Robotic Knee Wearable on Gait

Exoskeletons may provide quadriceps augmentation to patients with a torn or permanently weak extensor mechanism. Pneumatic exoskeletons utilize pressurized gas to improve gait, but their use and biomechanical impact have not been well described.

A lightweight pneumatic robotic wearable device was piloted in a clinical gait case report study using four different conditions-no devices, walking stick, inactive brace, and active brace. Walking speed, step length, step time, step width, and hip and knee flexion/extension angles were assessed while walking on a flat, declined, and inclined surface.

Walking speed on a flat surface with the active brace (0.41 ± 0.03 m/s) was 45% faster than walking with no devices (0.28 ± 0.04 m/s). Knee flexion at initial contact (19.0^° ± 0.2^°) and peak knee flexion during stance (19.0^° ± 0.2^°) were greater with the active brace than with no device (-2.3^° ± 1.7^° and -1.3^° ± 0.7^°, respectively). The active brace (0.89 ± 0.07 s) was associated with a 17% shorter step time during incline walking compared to no devices (1.06 ± 0.09 s). It was also associated with a 62% longer step length during decline walking compared to no devices (0.27 ± 0.04 vs. 0.17 ± 0.03 m).

In this case report, a pneumatic robotic knee wearable device improved quadriceps function and increased walking speed while freeing one arm to perform other tasks. A training program that optimizes function and comfort may improve device adoption as patients may need time to become acquainted with external torque delivery to the limb.