Hyunjun Shin

Gait event detection is essential for controlling an orthosis and assessing the patient’s gait. In this study, patients wearing an electromechanical (EM) knee–ankle–foot orthosis (KAFO) with a single IMU embedded in the thigh were subjected to gait event detection. The algorithm detected four essential gait events (initial contact (IC), toe off (TO), opposite initial contact (OIC), and opposite toe off (OTO)) and determined important temporal gait parameters such as stance/swing time, symmetry, and single/double limb support. These gait events were evaluated through gait experiments using four force plates on healthy adults and a hemiplegic patient who wore a one-way clutch KAFO and a pneumatic cylinder KAFO. Results showed that the smallest error in gait event detection was found at IC, and the largest error rate was observed at opposite toe off (OTO) with an error rate of −2.8 ± 1.5% in the patient group. Errors in OTO detection resulted in the largest error in determining the single limb support of the patient with an error of 5.0 ± 1.5%. The present study would be beneficial for the real-time continuous monitoring of gait events and temporal gait parameters for persons with an EM KAFO.

Lower limb amputees (LLAs) have a high incidence of low back pain (LBP), and identifying the potential risk factors in this group is key for LBP prevention. This study analyzed the intramuscular properties of the resting lumbar muscle in thirteen unilateral LLAs and age-matched controls to predict the onset of LBP. To measure the lumbar intramuscular properties, resting erector spinae muscles located in the upper and lower lumbar regions were examined using a handheld myotonometer. The dynamic stiffness, oscillation frequency, and logarithmic decrement were measured. In our results, the stiffness and frequency of the upper lumbar region were greater in the amputee group than in the control, whereas the decrement did not differ between the two groups. Additionally, the measured values in the lower lumbar region showed no significant difference. Within each group, all three factors increased at the upper lumbar region. In the LLAs, the frequency and stiffness values of the upper lumbar on the non-amputated side were significantly higher than those on the amputated side. These results indicate that the upper lumbar muscles of the amputees were less flexible than that of the control. This study can help in providing therapeutic strategies treating LBP in amputees.