Abstract

This study was carried out for evaluating the usefullness of pressure pain threshold as an objective test on shoulder muscles in VDT workers. Subjective symptoms, frequency and intensity of pain complaint were investigated by questionnaire method and objective tests, trigger point and pressure pain threshold of 14 shoulder muscles of dominant and nondominant side each, were performed by physical examination and using pressure algometer on 44 VDT workers (more than 2hrs a day) and 20 controls. And work status including work duration, daily work hours and continuous work hours per one time was also surveyed by questionnaire method. The relations among these items were analysed. Results were as follows; 1. The prevalences of shoulder pain in VDT workers and controls were 72.7% and 50.0%. The mean of pain frequency category scale was not significantly different between 2 groups, while the mean of pain intensity category! scale in VDT workers was higher than that in controls. The trigger point in VDT workers showed the highest frequency in the upper trapezius muscle which followed by the levator scapular muscle. And pressure pain thresholds of VDT workers were significantly lower than those of controls in all 14 shoulder muscles. 2. In VDT workers, the category scales of pain frequency and intensity during last one week in shoulder pain complaint group at the time of investigation were significantly higher than those in non complaint group. And the pressure pain thresholds of nondominant levator scapular, bilateral lower trapezius, nondominant posterior deltoid and nondominant pectoralis major muscles were significantly lower in complaint group. 3. The pressure pain thresholds of bilateral upper trapezius, levator scapular and lower trapezius muscles in VDT workers with trigger point at shoulder muscles were significantly lower than those in VDT workers without trigger point. 4. In terms of work duration, the pain frequency category scale during last one week of '5 years and more' group was significantly higher than that of 'less than 5 years' group, while pain intensity category scale. and pressure pain threshold were showed no significant difference. 5. In terms of daily work hour, pressure pain thresholds of bilateral upper trapezius, nondoininant levator scapular, dominant anterior deltoid, dominant posterior deltoid, dominant supraspinatus, and nondominant pectoralis major of 4 hours and more' group were significantly lower than those of 'less than 4 hours group, while category scales of pain frequency and intensity during last one week were showed no significant difference. 6. In terms of continuous work hour, the frequency and intensity category scale was significantly higher and pressure pain thresholds of dominant upper trapezius, bilateral levator scapular and dominant lower trapezius muscles were significantly lower in 2 hours and more' group than 'less than 2 hours' group. In conclusion, in order to evaluate more objectively the musGuloskeletal. impairment by VDT work it is recommended that objective tests such as trigger point and pressure pain threshold are performed in addition to survey of subjective symptoms. And also more consideration on daily work hour and continuous work hour than total work duration is required.