Korea Orthopedics and Rehabilitation Engineering Center

Bupyeong gu, South Korea

Korea Orthopedics and Rehabilitation Engineering Center

Bupyeong gu, South Korea

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Ko C.-Y.,Korea Orthopedics and Rehabilitation Engineering Center | Ko J.W.,Sejong University | Kim H.J.,Hyundai Motor Group | Lim D.,Sejong University
International Journal of Precision Engineering and Manufacturing | Year: 2016

Gait and mobility in patients with gait impairment are important in maintaining and improving their physical and psychological health and to return to society. Thus, the aims of the current study were to develop and evaluate a new wearable exoskeleton for gait rehabilitation assistance integrated with a mobility system (RehabWheel) for patients with gait impairment. A wearable exoskeleton was controlled by artificial pneumatic muscles to mimic joint movement; appropriate gait training was then undertaken. In total, 13 healthy males participated in evaluating RehabWheel by comparing joint angle kinematics and muscle activation patterns during walking over ground with RehabWheel and normal gaits. The joint angle kinematics of the hip and knee joints with RehabWheel were similar to those of normal gait despite differences in their magnitude. Additionally, muscle activations in the hip and knee joints were less during RehabWheel gait than normal gait and were associated with joint kinematics. These findings indicate that RehabWheel may have potential for incorporation into gait rehabilitative training assistance combined with a wheelchair platform for movement. This study is valuable for the initial identification of the practical feasibility of this new mobility system with both mobility and gait rehabilitation functions. © 2016, Korean Society for Precision Engineering and Springer-Verlag Berlin Heidelberg.


Lee B.,Sejong University | Ko C.,Korea Orthopedics and Rehabilitation Engineering Center | Ko J.,Sejong University | Kim J.S.,Konyang University | Lim D.,Sejong University
Biomedical Engineering Letters | Year: 2015

Purpose: A problem related to musculoskeletal function degeneration may be occurred in patients who experience gait disorders if they use wheelchair-based mobility assistive system only with no gait exercise for long periods of time. Therefore, in current study, we aimed to suggest a new concept of a mobility system that integrates a wheelchair platform, used for the implementation of mobility, and a wearable exoskeleton structure, used for the implementation of gait assistance, and to validate its structural stability and gait control confidence. Methods: A new system was designed and manufactured and its structural stability and gait control confidence were validated. The basic structure of the system was designed based on the platform of a wheelchair for the implementation of mobility, and incorporated a wearable exoskeleton structure formed with six one-degree-of-freedom (DoF) rotational joints for implementing the function of gait assistance. In the case of the wearable exoskeleton part, 12 pneumatic artificial muscles were attached for the 1-DoF flexion-extension operation of the hip, knee, and ankle joints. Results: The results showed that the structural stability of the system was sufficient and the control operation of the system accurately simulated the joint angle change patterns that occur during general normal gait, within an error range of 2.6 ± 10.8%. Conclusions: Our new system suggested may potentially be applicable for gait assistive function incorporated with a wheelchair platform for movement. This study may be valuable because it initially suggest a new concept of the wheelchairtype mobility assistive system with gait assistive function. © 2015, Korean Society of Medical and Biological Engineering and Springer.


Ahn J.H.,Sungkyunkwan University | Bae T.S.,Korea Orthopedics and Rehabilitation Engineering Center | Kang K.-S.,Chung - Ang University | Kang S.Y.,Chung - Ang University | Lee S.H.,Kyung Hee University
American Journal of Sports Medicine | Year: 2011

Background: Longitudinal tears of the medial meniscus posterior horn (MMPH) are commonly associated with a chronic anterior cruciate ligament (ACL) deficiency. Many studies have demonstrated the importance of the medial meniscus in terms of limiting the amount of anterior-posterior tibial translation in response to anterior tibial loads in ACL-deficient knees.Hypothesis: An MMPH tear in an ACL-deficient knee increases the anterior-posterior tibial translation and rotatory instability. In addition, MMPH repair will restore the tibial translation to the level before the tear.Study Design: Controlled laboratory study.Methods: Ten human cadaveric knees were tested sequentially using a custom testing system under 5 conditions: intact, ACL deficient, ACL deficient with an MMPH peripheral longitudinal tear, ACL deficient with an MMPH repair, and ACL deficient with a total medial meniscectomy. The knee kinematics were measured at 0°, 15°, 30°, 60°, and 90° of flexion in response to a 134-N anterior and 200-N axial compressive tibial load. The rotatory kinematics were also measured at 15° and 30° of flexion in a combined rotatory load of 5 N•m of internal tibial torque and 10 N•m of valgus torque.Results: Medial meniscus posterior horn longitudinal tears in ACL-deficient knees resulted in a significant increase in anterior-posterior tibial translation at all flexion angles except 90° (P <.05). An MMPH repair in an ACL-deficient knee showed a significant decrease in anterior-posterior tibial translation at all flexion angles except 60° compared with the ACL-deficient/MMPH tear state (P <.05). The total anterior-posterior translation of the ACL-deficient/MMPH repaired knee was not significantly increased compared with the ACL (only)-deficient knee but was increased compared with the ACL-intact knee (P >.05). A total medial meniscectomy in an ACL-deficient knee did not increase the anterior-posterior tibial translation significantly compared with MMPH tears in ACL-deficient knees at all flexion angles (P >.05). In a combined rotatory load, tibial rotation after MMPH tears or a total medial meniscectomy in an ACL-deficient knee were not affected significantly at all flexion angles.Conclusion: This study shows that an MMPH longitudinal tear in an ACL-deficient knee alters the knee kinematics, particularly the anterior-posterior tibial translation. MMPH repair significantly improved anterior-posterior tibial translation in ACL-deficient knees.Clinical Relevance: These findings may help improve the treatment of patients with ACL and MMPH longitudinal tear by suggesting that the medial meniscal repairs should be performed for greater longevity when combined with an ACL reconstruction. © 2011 American Orthopaedic Society for Sports Medicine.


Jung S.,Korea Orthopedics and Rehabilitation Engineering Center | Bae J.,Dong - Eui University | Moon I.,Dong - Eui University
International Conference on Control, Automation and Systems | Year: 2011

This paper proposes a lightweight prosthetic hand with five fingers that are driven by contraction force of shape memory alloy (SMA). Each finger is composed of SMA-wire mechanism similar to the muscle-tendon structure of human. Finger flexion is performed by contraction force of SMA, but its extension is carried out by a restoring force of a spring mounted on the backside of finger. The developed hand has five fingers, but its total DOF is six due to an under-actuated mechanism. Each finger posture is achieved by control of the SMA length using the electric resistance characteristics of SMA. Therefore the developed hand is possible to perform dexterous hand motions such as tip grasp, precision grasp and lateral hip. Based on a statics analysis of finger mechanism, we estimate the hand grip force. In experiments, we measured the grip force and then compared it to the simulation results. As a result, the maximum grip force was 4.52N by the constant input force, 13N, when the MCP joint angle was 90 degrees. © 2011 ICROS.


Jung S.,Korea Orthopedics and Rehabilitation Engineering Center | Moon I.,Dong - Eui University
Journal of Institute of Control, Robotics and Systems | Year: 2012

This paper proposes a biomimetic finger module to be used in a lightweight hand prosthesis. The finger module consists of finger skeleton and an actuator module driven by SMA (Shape Memory Alloy). The prototype finger module can perform flexion and extension motions; finger flexion is driven by a contraction force of SMA, but it is extended by an elastic force of an extension spring inserted into the finger skeleton. The finger motions are controlled by feedback of electric resistance of SMA because the finger module has no sensors to measure length and angle. Total weight of a prototype finger module is 30g. In experiments the finger motions and finger grip force are tested and compared with simulation results when a constant contraction force of SMA is given. The experimental results show that the proposed SMA-driven finger module is feasible to the lightweight hand prosthesis. © ICROS 2012.


Kim S.-B.,Korea Orthopedics and Rehabilitation Engineering Center | Kim S.-B.,Yonsei University | You J.H.,Yonsei University | Kwon O.-Y.,Yonsei University | Yi C.-H.,Yonsei University
American Journal of Sports Medicine | Year: 2015

Background: While the biomechanical characteristics of the golf swing are well established, the lumbopelvic kinematic characteristics of professional golfers with limited hip internal rotation warrant further investigation. Purpose: The specific aim was to ascertain mechanical differences in lumbopelvic-hip movement of asymptomatic professional golfers with and without limited hip internal rotation during the golf swing. Study Design: Controlled laboratory study. Methods: Thirty professional male golfers (aged 25-35 years and 0 handicap matched) were classified into either the limited hip internal motion (LHIM) group (range of motion<20°) or the normal hip internal motion (NHIM) group (range of motion ≥30°). All participants underwent clinical tests (muscle strength, muscle length, and range of motion) and a biomechanical assessment using 8 infrared optic cameras in a motion analysis system. Independent t tests were performed to determine potential mean differences in muscle strength, length, and range of motion and lumbopelvic kinematics at P<.05. Results: Kinematic analysis revealed that the LHIM group showed significantly greater lumbar flexion (P<.001), right and left axial rotation (P<.025), and right-side lateral bending (P = .003) than the NHIM group. A greater pelvic posterior tilt was observed in the LHIM group when compared with the NHIM group (P = .021). Clinical tests showed reduced internal rotator muscle strength and shorter muscle length in the iliopsoas (P = .017) and hamstring (P<.001) among those in the LHIM group when compared with the NHIM group. Clinical Relevance: The study data suggest that constraints to hip joint internal rotation, along with muscle strength imbalances between the agonist and antagonist muscles and muscle tightness, are associated with substantially greater lumbopelvic movement during the golf swing. © 2014 The Author(s).


Chang Y.H.,Korea Orthopedics and Rehabilitation Engineering Center | Bae T.S.,Jungwon University | Kim S.K.,Korea Orthopedics and Rehabilitation Engineering Center | Kim S.B.,Korea Orthopedics and Rehabilitation Engineering Center | And 2 more authors.
International Journal of Precision Engineering and Manufacturing | Year: 2012

The intact knee adduction moment of unilateral transfemoral amputees was in general higher than that of able-bodied subjects and it can be related to prevalence of knee osteoarthritis. Although high knee adduction moment was affected by ankle inversion in amputee gait, biomechanical study for that was rare. This study aimed to analyze the correlation between ankle inversion in gait parameters and the intact knee adduction moment in transfemoral amputees by gait analysis. For 13 transfemoral amputees and 14 healthy persons, kinematical and kinetic data including spatio-temporal parameters, joint angles, and moments on the coronal plane were calculated by 3D motion analysis during level walking. Bilateral hip abduction, the intact ankle inversion and knee abduction angles in transfemoral amputees were larger than that in normal subjects. Knee adduction moment in the terminal stance phase was 26% higher than that in the normal group. As ankle inversion angle and ankle power in the intact side of transfemoral amputees were increased, hip and knee adduction moments were also increased. Increased ankle inversion angle was related to slow walking speed, wider step width and longer stance time of the intact limb. Gait abnormalities by increased ankle inversion affected the intact hip and knee adduction moment of transfemoral amputees. Appropriate rehabilitation intervention like lateral wedge insole should be required to correct these abnormal gait patterns. © KSPE and Springer 2012.


Chang Y.H.,Korea Orthopedics and Rehabilitation Engineering Center | Chang Y.H.,Sahmyook University | Bae T.S.,Korea Orthopedics and Rehabilitation Engineering Center | Kim S.K.,Korea Orthopedics and Rehabilitation Engineering Center | And 2 more authors.
International Journal of Precision Engineering and Manufacturing | Year: 2011

The incidence of osteoarthritis for lower limb amputees, especially unilateral transfemoral amputees, was higher than that of transtibial amputees. Considering level of amputation and bilateral load asymmetry, we could assumed that joint moments in the coronal plane during gait were highly related to the risk of osteoarthritis. Therefore, this study aimed to examine the hip and knee adduction moments in the coronal plane in persons with unilateral transfemoral amputation during walking through gait analysis. The subjects were 12 unilateral transfemoral amputees and 21 healthy persons. Three-dimensional motion analysis was measured bilaterally from 33 persons during walking to calculate temporal-spatial parameters and joint moments. The analysis compared the prosthetic side and the intact side of the amputee group and then analyzed the moment between both the intact sides of the transfemoral amputee group and the healthy persons. The results showed that the intact knee adduction moment of amputees increased by 32% compared to the prosthetic side and more than twice compared to the control group at terminal stance. But the bilateral hip adduction moment was decreased compared to the control group (p<0.05). Therefore it is expected that the higher knee adduction moment on the intact side may cause secondary complication to unilateral transfemoral amputees, but it is difficult to make connection with hip osteoarthritis. © KSPE and Springer 2011.


Bae T.S.,Korea Orthopedics and Rehabilitation Engineering Center | Mun M.,Korea Orthopedics and Rehabilitation Engineering Center
Clinical Biomechanics | Year: 2010

Background: It is important to consider lumbar lordotic angle for setup of training program in field of sports and rehabilitation to prevent unexpected posture deviation and back pain. The purpose of this study was to to analyze the biomechanical impact of the level of lumbar lordosis angle during isokinetic exercise through dynamic analysis using a 3-dimensional musculoskeletal model. Methods: Gait analysis and isokinetic exercise for the healthy adults (n = 10) were performed to design a 3-dimensional musculoskeletal model and then we made each model for normal lordosis, excessive lordosis, lumbar kyphosis, and hypo-lordosis according to lordotic angle and inputted experimental data as initial values to perform inverse dynamic analysis to quantify muscle joint torque, joint forces of each joint, system energy, and estimated muscle forces at lumbosacral joint. Findings: Comparing the joint torques, the largest torque of excessive lordosis was 16.6% larger than that of normal lordosis, and lumbar kyphosis was 11.7% less than normal lordosis. There existed no significant difference in the compressive intervertebral forces of each lumbar joint (P > 0.05), but statistically significant difference in the anterioposterior shear force (lumbar kyphosis > hypo-lordosis > excessive lordosis > normal lordosis, P < 0.05). Lastly, lumbar kyphosis required the least and most energy during flexion and extension respectively. Interpretation: During the rehabilitation process, more efficient training will be possible by taking into consideration not simply weight and height but biomechanical effects on the skeletal muscle system according to lumbar lordortic angles. © 2010 Elsevier Ltd. All rights reserved.


Bae T.S.,Korea Orthopedics and Rehabilitation Engineering Center
Journal of biomechanical engineering | Year: 2010

When car crash experiments are performed using cadavers or dummies, the active muscles' reaction on crash situations cannot be observed. The aim of this study is to estimate muscles' response of the major muscle groups using three-dimensional musculoskeletal model by dynamic simulations of low-speed sled-impact. The three-dimensional musculoskeletal models of eight subjects were developed, including 241 degrees of freedom and 86 muscles. The muscle parameters considering limb lengths and the force-generating properties of the muscles were redefined by optimization to fit for each subject. Kinematic data and external forces measured by motion tracking system and dynamometer were then input as boundary conditions. Through a least-squares optimization algorithm, active muscles' responses were calculated during inverse dynamic analysis tracking the motion of each subject. Electromyography for major muscles at elbow, knee, and ankle joints was measured to validate each model. For low-speed sled-impact crash, experiment and simulation with optimized and unoptimized muscle parameters were performed at 9.4 m/h and 10 m/h and muscle activities were compared among them. The muscle activities with optimized parameters were closer to experimental measurements than the results without optimization. In addition, the extensor muscle activities at knee, ankle, and elbow joint were found considerably at impact time, unlike previous studies using cadaver or dummies. This study demonstrated the need to optimize the muscle parameters to predict impact situation correctly in computational studies using musculoskeletal models. And to improve accuracy of analysis for car crash injury using humanlike dummies, muscle reflex function, major extensor muscles' response at elbow, knee, and ankle joints, should be considered.

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