Yonsei Fraunhofer IZFP Medical Device Lab YFMED

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Effectiveness of micro-current electrical stimulation for treating rheumatoid arthritis

2016 , Kim, S.H. , Lee, H. , Hwang, D.H. , Seo, D.H. , Kim, H.S. , Cho, S.

Induction of micro-current in subject is known to be effective on the treatment of inflammatory disease. Thus, this study evaluated that the micro-current electrical treatment (MET) can reduce rheumatoid arthritis (RA), which is one of inflammatory disease, and tried to find optimized level of current for treatment. 55 male 11-week-old C57BL/6 mice were used and randomly allocated into five groups; normal group (N; n=11), the group of induced RA (C; n=11) and three groups of induced RA with MET (M) using different levels of current by 22 mA, 50 mA, and 400 mA (22M, 50M and 400M; n=11, respectively). MET was carried out for 1 hour each day. Both 3rd metatarsal (3rd MT) and tarsal (T) were scanned by in-vivo micro computed tomography (micro-CT) at 0week and after 3weeks in order to obtain structural parameters including BMD (Bone mineral density), BV (Bone volume) and Obj.N (Mean number of objects per slice). In M groups, all the measured parameters after 3 weeks were significantly higher than those of C group regardless of the current levels. However, there is no significant difference among the different levels of electrical current at 3week. These results indicated that the MET may be effective on the treatment of RA. However, we cannot assure the optimized level of current to treat RA tremendously.

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Special issue on biomechanics

2015 , Kim, H.S. , Cho, S.

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Effect of stool height on slumped posture during push-and-pull weeding motion

2015 , Cho, Y.K. , Myeong, S.-S. , Cho, S. , Kim, H.S.

Purpose: The excessive accumulation of work burden is one of the main factors underlying musculoskeletal disorders in the farming population. The present study was carried out to determine the joint torques and muscle contractions of the lower body in relation to slumped postures with or without a stool during push-and-pull weeding motions. Methods: Using data from a 3D motion analysis system, a 3D virtual human body model was created consisting of 19 segments and 59 muscles. Among these, the lower body joints (ankle, knee, hip, and lumbar) and muscles (tibialis anterior, gastrocnemius, biceps femoris, and erector spinae) were analyzed for four cases of slumped postures: without a stool and with stools of various heights (10, 15, and 20 cm). Results: The flexion of the lumbar joint was presented during push-and-pull weeding motions without a stool. However, the extension of the lumbar joint was presented during pushand-pull weeding motions with a stool. The ranges of th e joint torques did not change in a meaningful way between the results for the cases without a stool and with a stool. In addition, the results according to the stool height did not present meaningful outcomes associated with the angle change in the joints. Conclusions: Irrespective of the height, a stool may provide support for slumped postures involving the lumbar joint and erector spinae.

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Enhancement of bone quality and longitudinal growth due to free-fall motion in growing rats

2015 , Cho, S. , Eom, S. , Seo, D.-H. , Park, J. , Ko, C.-Y. , Kim, H.S.

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. Howe ver, 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.

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