• Journal of Biomedical Engineering Research
• /
• v.32 no.2
• /
• pp.105-108
• /
• 2011

The purpose of the present study was to analyze the lower stiffness over the difference between soft and stiff landings during hopping. Five male subjects performed hopping on two legs at 2.5 Hz. During the experiments, 3D motion capture system was used to obtain the kinematic data and two force plates were synchronized to calculate the kinetic data. We determined lower extremity stiffness of the knee and ankle from kinetic and kinematic data. Leg stiffness was approximately 1.2-times significantly higher in stiff landing than in soft landing_ There was no significant difference in knee joint stiffness between soft and stiff landings. Ankle joint stiffness was approximately 1.34-times significantly higher in stiff landing than in soft landing. These results suggest that humans adjust lower extremity stiffness over the comparison of two different landing methods we evaluated.

• Journal of the Korean Arthroscopy Society
• /
• v.2 no.1
• /
• pp.72-76
• /
• 1998

Between March 1992 and December 1995 at St. Paul's, Holy Family, St. Vincent and Eui Jung Bu St. Mary Hospitals Catholic University, two hundred and eighty patients underwent arthroscopic anterior cruciate ligament(ACL) reconstruction using central one-third bone-patellar tendon-bone autograft. Nine of these patients had limitation of motion(LOM) defined as a knee flexion contracture greater than 10o or less than 125o of passive knee flexion. This study analyzes the causes of LOM after ACL reconstruction as well as the results after passive manipulation or arthroscopic adhesiolysis under anesthesia for LOM. The results are as follows: 1. Out of nine patients, initially three had isolated ACL injuries and six had combined injuries. Seven of nine cases were perfomed by ACL reconstruction within four weeks and two were performed after four weeks following injury. 2. Treatment for LOM after ACL reconstruction was done after 5.5 months on average. 3. Arthroscopic adhesiolysis was done in 5 cases. There were fibrous adhesions at suprapatellar pouch and femoral intercondylar notch in all cases, respectively, infrapatellar fat pad in 3 cases and medial para patellar gutter in 2 cases. Two patients had a fibrous nodule, "cyclops" lesion, which formed anterior to the ACL graft. 4. Range of motion and Lysholm knee score were much improved following passive manipulation or arthroscopic adhesiolysis under anesthesia for LOM.

• Journal of Institute of Control, Robotics and Systems
• /
• v.17 no.8
• /
• pp.814-823
• /
• 2011

Nowadays many neurological diseases such as stroke and Parkinson diseases are continually increasing. Orthotic devices as well as exoskeletons have been widely developed for supporting movement assistance and therapy of patients. Robotic knee orthosis can compensate stiff-knee gait of the paralyzed limb and can provide patients consistent assistance at wearable environments. With keeping a robotic orthosis wearable, however, it is not easy to develop a compact and safe actuator with fast rotation and high torque for consistent supports of patients during walking. In this paper, we propose a novel kinematic model for a robotic knee orthosis to drive a knee joint with independent actuation during swing and stance phases, which can allow an actuator with fast rotation to control swing motions and an actuator with high torque to control stance motions, respectively. The suggested kinematic model is composed of a hamstring device with a slide-crank mechanism, a quadriceps device with five-bar/six-bar links, and a patella device for knee covering. The quadriceps device operates in five-bar links with 2-dof motions during swing phase and is changed to six-bar links during stance phase by the contact motion to the patella device. The hamstring device operates in a slider-crank mechanism for entire gait cycle. The kinematics and velocity/force relations are analyzed for the quadriceps and hamstring devices. Finally, the adequate actuators for the suggested kinematic model are designed based on normal gait requirements. The suggested kinematic model will allow a robotic knee orthosis to use compact and light actuators with full support during walking.

• Archives of Reconstructive Microsurgery
• /
• v.21 no.2
• /
• pp.143-148
• /
• 2012

Purpose: This report presents the authors' experience of twelve patients with sural artery flap for soft tissue defects around the knee joint. Materials and Methods: The patients' age ranged from 25 to 80 years; seven of the patients were male and five were female. The cause of soft-tissue defects involved wide excision for malignant soft tissue tumor, tumor prosthesis related infection, infection after total knee arthroplasty and chronic osteomyelitis. Postoperative range of motion was checked. The sensibility of flap was evaluated by Semmes-Weinstein monofilaments and two-point discrimination. Results: All flaps survived and provided satisfactory coverage of the defect. There was no complication except one delayed skin graft incorporation at donor site. Seven knee joints which had been stiff previously gained average 58 degrees of ROM postoperatively. All flaps retained sensibility and showed no significant increase in sensory thresholds comparing with contralateral side. Conclusion: Sural artery flap not only shows high survival rate and broad coverage ability, but also offers improvement in range of motion and preservation of sensation. We speculate that sural artery flap is valuable for the reconstruction of the soft tissue defects around knee joint.

• Korean Journal of Applied Biomechanics
• /
• v.25 no.3
• /
• pp.311-322
• /
• 2015

Objective : The purpose of this study was to investigate the effects of landing height and knee joint muscle fatigue on the movement of the lower extremity during cutting after landing. Method : Subjects included 29 adults (age: $20.83{\pm}1.56years$, height: $172.42{\pm}9.51cm$, weight: $65.07{\pm}10.18kg$). The subjects were asked to stand on their dominant lower limb on jump stands that were 30 and 40 cm in height and jump from each stand to land with the dominant lower limb on a force plate making a side step cutting move at a $45^{\circ}$ angle with the non-dominant lower limb. The fatigue level at 30% of the knee extension peak torque using an isokinetic dynamometer. Results : The results showed that the difference of landing height increased maximum range of motion and angular velocity of hip, knee, and ankle joints in the sagittal plane, and in the angular velocity of motion of the hip joint in the sagittal plane. The maximum range of motion of the knee joint in the sagittal plane and the frontal plane decreased on landing from both heights after the fatigue exercise. The angular velocity of the hip joint in the sagittal plane, and the maximum range of motion of the hip joint in the transverse plane decreased for both landing heights after the fatigue exercise. The angular velocity of the hip joint in the frontal plane decreased for the 30 cm landing height after the fatigue exercise. On the other hand, the angular velocity and maximum range of motion of the ankle joint in the sagittal plane for both landing heights, and the angular velocity and maximum range of motion of the ankle joint in the frontal plane increased on landing from the 40 cm height after the fatigue exercise. Conclusion : Different landing heights of 30 and 40 cm and 30% fatigue of peak torque of knee extensor found a forefoot and stiff landing strategy, when cutting after landing. These results might be due to decline in the shock absorption capability of the knee joint and the movement capability related to cutting while increasing the contribution of the ankle joint, which may cause increased ankle joint injuries.

• Journal of the Korean Arthroscopy Society
• /
• v.13 no.1
• /
• pp.39-45
• /
• 2009

Purpose: To investigate the outcome of arthroscopic treatment for the complications of knee arthroplasty and to evaluate the effectiveness of arthroscopy. Materials and Methods: We analyzed 25 patients who underwent arthroscopy to treat complications of knee arthroplasty between May 1992 and June 2008. Nineteen cases out of 25 had total knee arthroplasty (TKA) and the remaining 6 cases had unicompartmental knee arthroplasty (UKA). Before arthroscopy, physical examinations and radiographic evaluations were carried out to find out the causes of complications. Joint fluid aspiration and hematologic evaluation were added when infection was suspected. Results: Among the diagnosis at the time of arthroscopy, there were 11 cases of infection, 6 cases of stiffness due to adhesion and fibrosis, and 2 cases of soft tissue impingement in the cases of TKA. Among the cases of UKA, one for each case of meniscal tear, subluxation of mobile insert, hemarthrosis, cement loose body, soft tissue impingement, and stiff knee was found. Nine out of 11 patients who had infection were treated successfully with arthroscopy but the remaining 2 cases underwent revision arthroplasty. Seven patients with arthrofibrosis had improved range of motion from $65^{\circ}$ preoperatively to $105^{\circ}$ postoperatively. The others also showed successful results after arthroscopy. Conclusion: Arthroscopy to treat complications after knee arthroplasty was a safe and effective method when appropriate selection of patients was made.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.23 no.3
• /
• pp.238-243
• /
• 2013

This paper analyzes a virtual work of the knee and hip joints of bipedal walking robots. For the purpose, we consider a model of bipedal leg mechanism with a compliant foot and a typical walking pattern. We also check the torque characteristics at the joint space propagated from the space of the foot contacting a flat and stiff surface, and present the works accumulated at the joint space. As a result, it is shown that this analysis is useful for evaluating the fatigue of the leg mechanism by the physical walking contact between the foot and the surface, and it is applicable for improving the compliant characteristics at the foot space by employing a proper footgear.

• Korean Journal of Applied Biomechanics
• /
• v.20 no.1
• /
• pp.13-23
• /
• 2010

The purposes of this study was to investigate the biomechanical influence of the walking shoe with a plate spring in the heel and interchangeable heel cushioning elements. Eighteen subjects walked in three conditions: 1) the walking shoes Type A-1 with a soft heel insert, 2) the Type A-2 shoe with a stiff heel insert, 3) a general walking shoe(Type B). Ground reaction forces, leg movements, leg muscle activity and ankle, knee and hip joint loading were measured and calculated during overground walking. During walking, the ankle is a few degrees more dorsiflexed during landing and the knee is slightly more flexed during takeoff with the Type A shoes. As a result of the changes in the walking movement, the ground reaction forces are applied more quickly and the peak magnitudes are higher. Muscle activity of the quadricep, hamstring and calf muscles decrease during the first 25% of the stance phase when walking in the Type A shoes. The resultant joint moments at the ankle, knee and hip joints decrease from 30-40% with the largest reductions occurring during landing.

• International Journal of Internet, Broadcasting and Communication
• /
• v.13 no.1
• /
• pp.47-53
• /
• 2021

Gait kinematics and kinetics have a similar tendency between men and women, yet it remains unclear how walking while carrying a load affects the gait mechanism. Twenty adults walked with preferred velocity on level ground of 20 m relative to change of a load carriage (no load, 15%, 30% of the body weights) aimed to observe gait mechanism. We measured gait posture using the three-dimensional image analysis and ground reaction force system during stance phase on left foot. In main effect of gender difference, men showed increased displacement of center of gravity (COG) compared to women, and it showed more extended joint angle of hip and knee in sagittal plane. In main effect of a load difference, knee joint showed more flexed postuel relative to increase of load carriage. In main effect of load difference on the kinetic variables, medial-lateral force, anterior-posterior force (1st breaking, 2nd propulsive), vertical force, center of pressure (COP) area, leg stiffness, and whole body stiffness showed more increased values relative to increase of load carriage. Also, men showed more increased COP area compared to women. Interaction showed in the 1st anterior-posterior force, and as a result of one-way variance analysis, it was found that a load main effect had a greater influence on the increase in the magnitude of the braking force than the gender. The data in this study explains that women require little kinematic alteration compared to men, while men in more stiff posture accommodate an added load compared to women during gait. Additionally, it suggests that dynamic stability is maintained by adopting different gait strategies relative to gender and load difference.

• Korean Journal of Applied Biomechanics
• /
• v.17 no.4
• /
• pp.57-64
• /
• 2007

The purpose of this study was to investigate comparative analysis of the vertical ground reaction force variables during landing from vertical jump blocking in volleyball through GRF analysis system. The subjects participated in this study were 6 male university volleyball player and 6 male acted as a control group. The results are as follows: 1. The skilled group was longer than the unskilled group in flight time during vertical jump blocking. 2. The skilled group was faster than the unskilled group in tFz2 during landing from vertical jump blocking. 3. The skilled group was higher than the unskilled group in Fz2 during landing from vertical jump blocking. 4. The skilled group was higher than the unskilled group in Fz2LR during landing from vertical jump blocking. 5. The skilled group was higher than the unskilled group in impulse during landing from vertical jump blocking. Consequently, during landing from vertical jump, the landing strategy of the skilled group was found as a form of a stiff landing. Therefore, this landing strategy will be required to strengthen of hip and knee extensors and ankle plantar flexors for injury prevention.