The purpose of this study was to estimate mean pressure thresholds over several skeletal muscles, grip and pinch strengths in female telephone operators.

Pressure thresholds on muscles of neck and shoulder were measured with a pressure algometer, and grip and pinch strength were measured with a Jamar dynamometer and a Jamar pinch gauge in 904 female telephone operators.

The pressure threshold was highest in the supraspinatus and lowest in the cervical paraspinals. There was no statistically significant difference between right and left corresponding muscles. The mean grip strength was 22.29 kg in the right hand, 21.97 kg in the left hand. The mean tip pinch strength was 0.56 kg in the right, 0.51 kg in the left. The mean lateral pinch strength was 2.21 kg in the right, 2.12 kg in the left. The mean palmar pinch strength was 1.82 kg in the right, 1.66 kg in the left.

There was no significant correlation between grip, pinch strength and age(p＞0.05). There were positive correlations between height, weight and grip strength. There were positive correlations between exposure duration to visual display terminal and pinch strength.

Objective: To study the reaction of tissues in the carpal tunnel after repeated flexion of wrist in order to verify the pathophysiology and pathomechanism of the carpal tunnel syndrome as a cumulative trauma disorder.

Method: Six groups of adult rabbits (5 rabbits were allocated to each groups) were exposed to repeated contractions of the wrist flexors by the median nerve stimulation at the elbow level for different durations; 2 days, 1 week, 2 weeks, 3 weeks, 4 weeks, and 5 weeks. Histological evaluation, morphometric analysis, and electrophysiological studies were carried out after the stimulation.

Results: There were no typical nor consistent findings in the tissues in the carpal tunnel except the median nerve. Inflammatory cell infiltration and edematous changes were noted in the epineurial tissue of median nerve. Decrease of large myelinated fibers and changes of fiber shape were observed in the median nerve. On the morphometric analysis, fiber diameter was smaller in groups of longer exposure duration. Changes were most prominent in 5 weeks group and in the periphery of the nerve fascicle in all the groups. Significant reduction of amplitude and increase of duration of compound muscle action potential were noted on electrophysiological study of the median nerve.

Conclusion: The authors concluded that repeated experimental wrist flexion could give rise to an injury of the median nerve in the carpal tunnel. Accumulation of microtrauma of median nerve by epineurial edema and direct mechanical compression seems to be the pathomechanism of the carpal tunnel syndrome as a cumulative trauma disorder.

Objective: To survey the prevalence of cumulative trauma disorders (CTDs) and to analyze the ergonomic factors in the paper reviewing workers.

Method: Five hundreds and twenty subjects of paper reviewers were collected from 'National Medical Insurance Association' who had been exposed to risky working environment regarding CTDs. The subjects were first screened by occupational medicine specialists and confirmed by physiatrist. The subjects were also examined by serologic test, radiologic imaging, and electrodiagnostic study. Ergonomists analyzed the job element to identify the risk factors by baseline checklist of CTDs.

Results: Among the workers, 51 (9.8%) of 520 were confirmed to CTDs, the prevalance of myofascial pain syndrome was 22 (43.1%), that of medial epicondylitis was 13 (25.5)%, lateral epicondylitis 8 (15.7%) and others. Pain scale of National Industrial Occupational Safety Health Institute symtoms criteria was highest in the shoulder girdle and the next was in the neck, in the wirst and fingers. The ergonomic risk score was highest 2.56 in the 'verifying' job, and the next 2.20 in 'the 2nd examination' job and 'the 1st examination' job, 1.72 in 'correcting' job.

Conclusion: The result would be helpful for the prevention and management of CTDs in the paper reviewing workers.