서강대학교

초록/요약

The metatarsophalangeal (MTP) joint plays an important role during walking. However, it is rarely considered in current walking assistive devices. This study aimed to develop a new MTP assistive device and evaluate its effect on the muscle activities of the lower extremities during walking while wearing the device. The new MTP assistive device was designed to support MTP flexion using a cable-driven mechanism. A cable that runs parallel with the plantar fascia transmits the actuation force to the toe plate fixed on the toes. The prototype was manufactured using a 3D printer, and it weighs 0.985 kg without a battery and control unit. Musculoskeletal simulation was conducted to determine the actuation onset timing, that is when the motor starts pulling the cable. An FSR sensor placed under the heel was used to detect heel strike. Eight participants were instructed to walk at a constant speed on a treadmill while wearing the device. The muscle activities of their lower extremities and MTP joint kinematics were obtained during walking under both actuated and non-actuated conditions. Paired t-tests were performed to compare the differences in muscle activities and MTP joint kinematics between the two conditions. The muscle activity of the MTP flexor was significantly reduced during walking under actuated conditions (p = 0.013). In contrast, no differences were found in the muscle activities of other muscles or in the MTP joint angle between actuated and non-actuated conditions (p > 0.05 for all comparisons). In conclusion, the new powered MTP assistive device can properly assist the MTP flexor without interfering with the action of other muscles in the lower extremities. This developed MTP assistive device clearly demonstrated the potential to offer improved walking assistance by reducing the amount of muscle activity needed from the MTP flexor if integrated into existing exoskeleton designs. This study is expected to influence the design of an assistive device for MTP joint using a cable-driven mechanism in the future.