Seunghyeon Kim

Functional Electrical Stimulation to Ankle Dorsiflexor and Plantarflexor Using Single Foot Switch in Patients With Hemiplegia From Hemorrhagic Stroke

Objective To evaluate the effects of functional electrical stimulation (FES) to ankle dorsiflexor (DF) and ankle plantarflexor (PF) on kinematic and kinetic parameters of hemiplegic gait. Methods Fourteen post-stroke hemiplegic patients were considered in this study. Electrical stimulation was delivered to ankle DF during the swing phase and ankle PF during the stance phase via single foot switch. Kinematic and kinetic data were collected using a computerized motion analysis system with force plate. Data of no stimulation (NS), DF stimulation only (DS), DF and PF stimulation (DPS) group were compared among each other. Results Peak ankle dorsiflexion angle during swing phase is significantly greater in DS group (-1.55°±9.10°) and DPS group (-2.23°±9.64°), compared with NS group (-6.71°±11.73°) (p<0.05), although there was no statistically significant difference between DS and DPS groups. Ankle plantarflexion angle at toe-off did not show significant differences among NS, DS, and DPS groups. Peak knee flexion in DPS group (34.12°±13.77°) during swing phase was significantly greater than that of NS group (30.78°±13.64°), or DS group (32.83°±13.07°) (p<0.05). Conclusion In addition to the usual FES application stimulating ankle DF during the swing phase, stimulation of ankle PF during stance phase can help to increase peak knee flexion during the swing phase. This study shows the advantages of stimulating the ankle DF and PF using single foot switch for post-stroke gait.

Torque and power outputs on skilled and unskilled users during manual wheelchair propulsion

Manual wheelchair users are at a high risk of pain and injuries to the upper extremities due to mechanical inefficiency of wheelchair propulsion motion. The kinetic analysis of the upper extremities during manual wheelchair propulsion in various conditions needed to be investigated. We developed and calibrated a wheelchair dynamometer for measuring kinetic parameters during propulsion. We utilized the dynamometer to investigate and compare the propulsion torque and power values of skilled and unskilled users under four different conditions. Skilled manual wheelchair users generated lower torques with more power than unskilled users and reacted alertly and sensitively to changing conditions. We expect that these basic methods and results may help to quantitatively evaluate the mechanical efficiency of manual wheelchair propulsion.

Kinetic analysis of the metatarsophalangeal joint in normal subjects and hallux valgus patients during walking using a four-segment foot model

The foot plays an important role in human walking [1]. The foot has many essential functions such as shock absorption, weight bearing stability and push-off. The metatarsophalangeal (MP) joint, positioned between the metatarsal bones of the foot and the proximal phalanges of the toes, provides a broad area of support across the forefoot. The major role of the MP joint is the energy absorption during the terminal stance of the gait cycle [2]. Hallux valgus (HV), the most common great toe disorder, is a deformity of the first MP joint [3]. In HV patients, the mechanical role of the MP joint might change to compensate for the worsening of the loading condition, decreased weight-bearing function of the medial toe, and weight transfer to the lateral metatarsals [4-7]. Some researchers have investigated kinematics of the MP joint [8,9]. However, there was rare investigation of the MP joint kinetics. In this study, kinetics of the MP joint was determined during the entire stance period of the gait cycle using a four-segment foot model. The three-dimensional motion analysis was used with foot pressure measurement. Twelve normal subjects and ten HV patients were selected for this study. Results showed that a significant difference in stance time was found between the normal (60.86 ± 1.21 %) and HV groups (63.75 ± 0.91 %) (p 0.05). This study had some limitation such as assumption that the MP3−5 joints act as a single joint and small number of the HV patients. In spite of those limitations, our study would be helpful in understanding the mechanical role of the MP joint in patients with foot disease. Figure 1 The MP1, MP2 and MP3−5 joint moments and powers; Normal vs. HV

Metatarsophalangeal Joint Kinetics in Normal Walking

Foot provides body weight supports with dynam- ic stabilities during human walking by storing and releasing energy. Many researchers have been performed to understand the mechanism of foot during walking, assuming that the foot is a single segment; however, the human foot consists of many bones and joints. Especially, metatarsophalangeal (MP) joint, which is one of the largest joints in the foot, plays a crucial role during gait. To analyze the MP joint during normal walking ground reaction forces and foot pressure were measured sim- ultaneously. The measured data were applied to our two- segment foot model for understanding the role of the MP joint. The maximum MP joint moment was 0.13 ± 0.04 Nm/kg at pre-swing. Compared to the previous studies, results of this study showed smooth joint moments from foot-flat the toe-off. A considerable energy absorption of approximately 6.56%GC·J/kg was found at the MP joint during 30 ~ 60% of the gait cycle. In the future study, this method will be applied for patients who have foot disease such as hallux valgus and plantar fasciitis for demonstrating mechanism of these diseases.

단일 3축 가속도센서를 사용한 보행 시 대사에너지 예측

The purpose of this study was to compare metabolic energy expenditure with the computed kinetic energy for different speeds of walking and running over the treadmill and to find the relevance for individual and group equation by performing a statistical analysis, Bland-Altman plot. Seven male subjects participated, and they were required to walk and run on the treadmill with the gas analyzer and triaxial accelerometer. Walking speeds were 3.0, 4.0, 5.0 and 6.0 km/h and running speeds were 7.0, 8.0 and 9.0 km/h respectively. Kinetic energy was calculated by the integration of acceleration data and compared with the metabolic energy measured by a gas analyzer. Correlation coefficients showed relatively good between the measured metabolic energy and the calculated kinetic energy. In addition, a dramatic increase in kinetic energy was also observed at the transition speed of walking and running, and two standard deviations in Bland-Altman plot, derived from the difference between measured and predicted values, were 1.14, 2.53, 2.93, 1.80, 2.80, 0.60 and 2.48 respectively. It was showed that there is no difference for methods of how to predict the kinetic energy expenditure for individual and group even though people had each different physical characteristic.

Quantitative evaluation of rabbit's hepatic function by HEF, DISADA-K, and ICG R/sub max/ methods

The hepatic extraction fraction (HEF), DISIDA-K, and ICG R/sub max/ were obtained to evaluate hepatic function for two normal and four abnormal rabbits with rapidly damaged livers. The correlation coefficients among these three methods were found. The correlation coefficient between the HEF and ICG R/sub max/ which is a standard technique in evaluating hepatic function was found to be 0.93. Therefore the HEF is assumed to be a valuable diagnostic method since it is not only accurate and simple, but possible to estimate remaining hepatic function after surgical removal of cancerous hepatic tissues.