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Ko C.-Y.,Korea Orthopedics & Rehabilitation Engineering Center | Jung Y.J.,Yonsei University | Seo D.H.,Yonsei University | Lee S.D.,IM Healthcare CO. | Kim H.S.,Yonsei University
International Journal of Precision Engineering and Manufacturing | Year: 2014

Sciatic nerve injury (SNI) can lead to significant bone loss in the lower extremities. However, the effects of SNI on the lumbar vertebrae are controversial. The present study aimed to evaluate the longitudinal effects of SNI on the lumbar vertebrae. Twenty-four 12-week-old male C57BL/6 mice (24.55±0.17 g) were randomly assigned to 3 groups (8 mice each) and underwent unilateral sciatic neurectomy (USN group), bilateral sciatic neurectomy (BSN group), or no surgery (CON group). The third (L3) and fourth (L4) lumbar vertebrae were scanned by in-vivo micro-computed tomography (ìCT) preoperatively and at 14 and 28 days postoperatively. Using μCT images, structural parameters and bone mineralization density distribution of the trabecular bone were analyzed among the 3 groups. In the BSN group, structural and material properties of L3 and L4 worsened after 14 days. Deterioration in the structural properties of L3 was observed at 28 days in the USN group, whereas no changes were observed in L4. These results implied that SNI can cause considerable deterioration in the microarchitecture of trabecular bone in the lumbar vertebrae. However, differences in the magnitude and rate of the deterioration and its onset period are observed between cases of unilateral and bilateral SNI. © 2014, Korean Society for Precision Engineering and Springer-Verlag Berlin Heidelberg. Source


Heo Y.,Korea Orthopedics & Rehabilitation Engineering Center | Hong E.-P.,Korea Orthopedics & Rehabilitation Engineering Center | Mun M.-S.,Korea Orthopedics & Rehabilitation Engineering Center | Choi T.-H.,Kyungpook National University
International Journal of Precision Engineering and Manufacturing | Year: 2015

In this study, a new torque balancing technique is proposed to improve the driving performance of power assisted wheelchairs (PAWs). For a PAW to maintain a straight driving direction, the same force must be delivered to both the right and the left push-rims. However, humans typically have different strength in the right and left arms, and therefore, they cannot control the force uniformly at all times. As a result, the driving direction may need frequent corrections during PAW operation. Toward this end, appropriate assist torques need to be generated to compensate for unbalanced human torque inputs by detecting the driving intention in order to maintain a uniform direction in straight sections or to quickly change direction in curved sections. We propose an assist torque balancing control scheme that estimates the human driving intention by considering the temporal similarity between the right and the left torque signals as well as the proportion of both torques. Simulation results show that the proposed balancing control scheme has better performance than the existing method for straight and circular driving conditions. © 2015, Korean Society for Precision Engineering and Springer-Verlag Berlin Heidelberg. Source


Cho S.,Yonsei University | Cho S.,Yonsei Fraunhofer Medical Device Laboratory | Eom S.,Yonsei University | Seo D.-H.,Yonsei University | And 6 more authors.
Biomedical Engineering Letters | Year: 2015

Objectives: This study is to investigate the synchronous phenomena between bone quality and longitudinal length in a same subject affected by landing exercise. Physical exercise on the ground induces external loading to human body due to resistance from ground which can activate bone generation or remodeling. Especially, when the impact stimulation is applied to bone, it may improve bone quality and lengthening. Methods: 6-week-old male Wistar rats were randomly allocated to one of two conditions: free fall from 40 cm-height (I40; n = 7), and control (IC; n = 7). The impact stimulations were administered to the free fall groups, 10 times/day, and 5 days/week for 8 weeks. Structural parameters and longitudinal length of tibia were measured to quantitatively evaluate the variation in morphological characteristics and bone length with maturing. Results: The landing impact seems to be commonly effective on the enhancement of bone quality as well as longitudinal growth. However, the extent of enhancement may be more dominant in bone quality than longitudinal growth. On the other hand, the ratio of longitudinal growth seems to be dependent on the duration of stimuli whereas the enhancement of bone quality does not. Conclusions: This study verified that free-falls exercise can be effective on the enhancement of bone qualities and promotion of vertical growth in long bones. We expect that it might be possible for the moderate impact stimulation to be proposed as an aid for prevention of bone loss and promotion of bone lengthening. © 2015, Korean Society of Medical and Biological Engineering and Springer. Source


Ko C.-Y.,Korea Orthopedics & Rehabilitation Engineering Center | Kim S.-B.,Korea Orthopedics & Rehabilitation Engineering Center | Kim J.K.,Korea Orthopedics & Rehabilitation Engineering Center | Chang Y.,Korea Orthopedics & Rehabilitation Engineering Center | And 3 more authors.
International Journal of Precision Engineering and Manufacturing | Year: 2014

This study aimed to investigate kinetics and kinematics of the ankle joint during level ground, ramp, and stair ambulations using different types of adaptive ankle feet (AAFs), Proprio-FootTM (Össur, IcEland), élan foot (Endolite, USA), and Echelon foot (Endolite, USA). A transtibial amputee was asked to walk on a level ground, a ramp with a 7° slope, and a stair of height 15 cm. The ankle angle and symmetry index (SI) based on the symmetry of the external work performed were measured for AAFs and ambulation. The single support time and stance phase during ambulation were higher for AAFs than the fixed ankle foot. During level ambulation, dorsiflexion increased for all AAFs. During slope ascent ambulation, dorsiflexion increased for the élan foot and Proprio-Foot™, as well as during the swing phase of the Echelon foot. During slope descent ambulation, the maximum dorsiflexion decreased for the Proprio-Foot™. During stair ascent, the élanElan foot and Proprio-Foot™ feet improved the dorsiflexion. During stair descent, all AAFs improved the dorsiflextion. Furthermore, SI increased for most of the adaptive ankle feet for all terrain conditions. These results indicate that AAFs can be used to improve the kinetics and kinematics of the ankle on the involved side. © 2014, Korean Society for Precision Engineering and Springer-Verlag Berlin Heidelberg. Source

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