Cette étude examine les relations quantitatives exposition-réponse entre les plaintes et diagnostics de TMS et des expositions physiques, des caractéristiques individuelles et des conditions de travail psychosociales. Des associations ont été trouvées entre la vitesse de la tête, l’activité du trapèze, la vitesse du haut du bras, l’activité de l’extenseur de l’avant-bras et la posture et la vitesse du poignet, ainsi que la plupart des plaintes et diagnostics cou / épaule et coude / main. L’ajustement en fonction de l’âge, d’autres caractéristiques individuelles et des conditions de travail psychosociales n’a eu qu’un effet limité sur ces associations. Sur la base des résultats, les auteurs proposent des valeurs limites limites pour la vitesse du bras et du poignet.
We have previously reported quantitative exposure-response relationships between physical exposures recorded by technical methods, and complaints and diagnoses in the neck/shoulders, and the elbows/hands, based on group data. In the present study the number of workers was doubled, and information on individual factors, and psychosocial working conditions was used. Relationships between various kinds of exposure and response have been analysed in this larger and more detailed sample.
The prevalence of complaints (Nordic Questionnaire) and diagnoses (clinical examination) were recorded in a number of occupational groups within which the participants had similar work tasks, 34 groups of female employees (N = 4733 women) and 17 groups of male employees (N = 1107 men). Age and other individual characteristics were recorded, as well as psychosocial work environment factors (job-content questionnaire) for most participants. Postures and velocities (inclinometry) of the head (N = 505) and right upper arm (N = 510), right wrist postures and velocities (electrogoniometry; N = 685), and muscular activity (electromyography; EMG) in the right trapezius muscle (N = 647) and forearm extensors (N = 396) were recorded in representative sub-groups. Exposure-response relationships between physical exposure and musculoskeletal disorders, adjusted for individual factors with Poisson regression were then calculated. The effect of introducing psychosocial conditions into the models was also assessed.
Associations were found between head velocity, trapezius activity, upper arm velocity, forearm extensor activity and wrist posture and velocity, and most neck/shoulder and elbow/hand complaints and diagnoses. Adjustment for age, other individual characteristics and psychosocial work conditions had only a limited effect on these associations. For example, the attributable fraction for tension neck syndrome among female workers with the highest quintile of trapezius activity was 58%, for carpal tunnel syndrome versus wrist velocity it was 92% in men in the highest exposure quintile.
Based on the findings, we propose threshold limit values for upper arm and wrist velocity.