The Validation of Musculoskeletal Model During Isokinetic Exercise at Knee Joint: An Experimental and Simulation Study / 대한정형외과연구학회지

PURPOSE: This study validated the musculoskeletal model of the human lower extremity by comparative study between calculated muscle parameters through simulation using modified hill-type model and measured muscle parameters through isokinetic exercise. The relationship between muscle forces and moments participated in motion was quantified from the results of simulation. MATERIALS AND METHODS: For simulation of isokinetic motion, a three-dimensional anatomical knee model was constructed using gait analysis. The EMG-force model was used to determine muscle activation level exciting muscles. The modified Hill-type model was used to calculate individual muscle force and moment in dynamic analysis. This method was validated by comparing analytical data with experimental data. RESULTS: The results showed that there was a significant correlation between calculated torques from simulation and measured torque from isokinetic motion experiments (R=0.97). We also found that muscle forces and moments during knee flexion and extension have nonlinearly proportional or inversely proportional relationship, since lower extremity muscles were simultaneously involved in flexion/extension motion and inner/outer rotation. CONCLUSION: We concluded that the simulation by using musculoskeletal model may be a useful mean to predict and recover musculoskeletal-related diseases, and analyze complicated experiment such as clash condition.

Carpal Tunnel Syndrome among Service and Manufacturing Workers with Repetitive Motion Tasks / 대한산업의학회지

The objectives of this study were to investigate the prevalence and risk factors of occupationally related carpal tunnel syndrome (CTS) among workers employed in services and manufacturing industries analysing the sensitivity and specificity of clinical symptoms and signs. Three surveys were made for this study. The first survey was done for 1,447 workers employed by 25 companies. The jobs of the employees were repetitive works at VDT and assembly lines. Therefore, employees could be divided to two groups, doing repetitive works and non repetitive works. The second survey was made for 189 workers who were randomly selected from 517 workers complained some symptoms at their hands and wrists. We examined their symptoms and carried out neurological examinations for CTS (Tinel's sign, Phalen's sign, pin prick test, carpal compressive test, toniquet compression test). The third survey was made for nerve conduction study (NCS) for 57 workers who had shown positive signs for CTS. The main results of this study were as follows: 1. From the first survey, we have found that there were significant statistical differences in getting uncomfortable neuromuscular symptoms by sex, job type, total working hours during a week, duration of current work, and kinds of work. Odds ratio in male vs female, repetitive vs non repetitive, service vs manufacturing companies, total working hours during a week, and duration of current work were 1.867(95% CI=1.467-2.377), 1.680 (95% CI=1.121-2.279), 1.663(95% CI=1.213-2.279), 1.016(95% CI=1.006-1.027) and 1.283 (95% CI=1.097-1.501) respectively. 2. From the second survey, we have found that 46 peoples (25.0%) were positive for one or more than one signs in neurological examinations of NIOSH criteria. Positive findings from neurological examinations were high among workers of low level of education (p-value=0.008), manufacturing jobs (p-value=0.00), long hours a week (p-value=0.028), and long duration of current work (p-value=0.00). 3. From the third survey, we diagnosed 35 peoples (61.4%) had CTS by NCS. They had abnormally delayed latent period or velocity in median nerve conduction velocity.

Assessment of Autonomic Nervous Function in Young Adults by Power Spectral Analysis of Heart Rate Variability

The powers of the low-frequency(LF) and high-frequency(HF) components characterizing heart rate variability (HRV) appear to reflect, in their reciprocal relationship, changes in the state of the sympatho-vagal balance occurring during orthostatic stress with head-up tilt. We studied 24 healthy volunteers (median age, 23.1 years) who were subjected after a rest period to a series of passive head-up tilt steps chosen from the following angles: 0 degree. 15 degrees, 30degrees, 45degrees, 70degrees, and 90degrees under the condition of frequency controlled respiration(0.25Hz) in order to get data of the Korean young adults. During head-up tilt, heart rate and normalized low frequency power(LF(N : 0.05-0.15 Hz) of HRV showed significant increase(p=0.000), but normalized high frequency power(HFN : 0.2-0.3 Hz) and total power showed progressive decrease(p=0.000, p<0.01 respectively). Male showed significantly higher LF(N and lower HFN than female at tilt table angle 0degree(p<0.01). Power spectral analysis of HRV appears to be capable of providing a noninvasive quantitatibve evaluation of graded changes in the state of the sympatho-vagal balance.

Electroencephalography, brain CT and evoked potentials in cerebral palsy

No abstract available.