Work technique and its consequences for musculoskeletal disorders

Abstract

Work in the manufacturing industry is associated with a high prevalence of cervicobrachial disorders. The outcome in individual cases varies; some go without symptoms for many years, others have to be relocated because of serious disorders after only a few years. Since the gross characteristics of the work tasks do not show a large variation, powerful individual factors must exert their influence, either protecting the individual or increasing vulnerability. A prospective study was conducted to identify such factors. The aim was to relate the outcome in terms of disorders in the neck-shoulder-arm region to such factors as individual variations in working technique, physical capacity, and medical and work history. In order to investigate individual differences in working technique two subgroups of women were studied. The results show that the number of changes in posture, as well as the percentage of work cycle time spent with the upper arm in different angular sectors, varied to a large extent among workers. Thus, some worked in a more relaxed way, seeking support for their arms as much as possible, whereas others strained their shoulder and neck muscles during long-lasting static postures with flexed neck and raised arms. At the one and two-year follow-up it was obvious that some of the work technique variables were important risk factors for deterioration to more severe cervicobrachial disorders. Thus, those who worked with forward flexion of the neck and raised arms ran a high risk, whereas those with a more dynamic pattern of movements ran a low risk of deterioration. Other risk factors were: perceived stress, previous sick-leave, individual productivity, and previous work in physically heavy jobs. Low muscular strength appeared as only a weak factor in some analyses.