Musculoskeletal disorders of the neck and shoulders in female sewing machine operators: prevalence, incidence, and prognosis

OBJECTIVES To assess the occurrence and persistence of two restrictively defined neck-shoulder disorders among sewing machine operators. To assess factors associated with the development of neck-shoulder disorder and prognostic factors for remaining a case, when disorders were already present. METHODS In an initial group of 243 sewing machine operators, 178 were followed up for 2 years. At baseline and at 1 and 2 years follow up the participants underwent a clinical examination of the neck and arms and filled in a questionnaire about current musculoskeletal complaints. Clinical criteria for two main neck-shoulder disorders were defined: rotator cuff tendinitis and myofascial pain syndrome. A baseline control group consisted of 357 women with varied non-repetitive work. RESULTS At baseline the overall prevalence of myofascial pain syndrome and rotator cuff tendinitis was 15.2% and 5.8% among sewing machine operators compared with 9.0% and 2.2%, respectively, among controls. The presence of the disorders was strongly associated with a self perception of poor general health. Although myofascial pain syndrome showed a U shaped association with years as a sewing machine operator, rotator cuff tendinitis was absent among the newest recruits and present among 15% of the women with more than 20 years as a sewing machine operator. Besides years as a sewing machine operator, the risk of having a neck-shoulder disorder at baseline was significantly associated with high stress (prevalence ratio (PR)=2.54; 95% confidence interval (95% CI) 1.28 to 5.05) when adjusted for age, body mass index, smoking, living alone with children, job strain, and social support from colleagues and supervisors. Only one of 13 participants with rotator cuff tendinitis at baseline recovered during follow up. Myofascial pain syndrome showed a much more fluctuating tendency. Low social support (RR 3.72; 95% CI 1.22 to 11.30) and smoking (RR 3.93; 95% CI 1.33 to 11.58) were associated with the development of neck-shoulder disorders, which was also associated with neck-shoulder pain score and living alone with children. CONCLUSION Rotator cuff tendinitis showed a higher degree of persistence than myofascial pain syndrome. Both disorders highly influenced the perception of general health. Women who lived alone with children, were smokers, or experienced low support from colleagues and supervisors had a higher risk of contracting a neck-shoulder disorder.