Occupational and individual factors in acute shoulder-neck disorders among industrial workers.

Abstract

Twenty workers, consecutively attending the industrial health care centre for the first time with acute shoulder-neck pains, were subject to extensive rheumatological and ergonomic examinations. In seven patients congenital malformations or diseases causing musculoskeletal symptoms, or both, were probable aetiological factors. In the remaining 13 patients a significantly higher load was found on both shoulders (assessed by biomechanical film analysis) than in matched controls. The aim of the present investigation was to evaluate the influence of disease and to study the significance of measured individual and occupational factors in acute non-traumatic shoulder-neck pain among industrial workers. Material and methodsThe methods used for this investigation were approved by the ethical committee of the medical faculty, Umea University. PATIENTSThe first 20 workers (17 men, 3 women) at a manufacturing plant who attended the industrial health care centre with acute non-traumatic, shoulderneck pain were included in the study. The mean age of the patients was 35 years (SD 13-2). CONTROLSThe case-control method was used in this study to evaluate the role of ergonomic factors in acute non-traumatic shoulder-neck disorders. To eliminate confounding factors the controls were selected bypaired sampling and individual matching.6 Two controls were selected for each patient in whom causative disease or malformation was not found. The controls (n = 26) were obtained by paired sampling from employment records. The paired sampling was done with the additional requirements that the workers selected must match the corresponding case in the following criteria: age, sex, and place of work (the controls had to work in the factory halls). Furthermore, the workers selected as controls were not to have consulted the industrial health care centre for shoulder-neck disorders; this was verified by checking the patient records of the workers. From an age-class employment listing, the two workers who satisfied the above defined criteria closest to each patient were selected.

Alterations in Shoulder Kinematics and Associated Muscle Activity in People With Symptoms of Shoulder Impingement

“…This population was of particular interest because of their increased risk for developing shoulder problems. 3,8,9 In addition, we believe that people who do not engage in overhead activities, even though they might not have symptoms of shoulder impingement, may demonstrate abnormal kinematic patterns that could contribute to the development of shoulder impingement if they routinely used their arms in elevated positions. We believed that equal occupational exposure between the 2 groups would improve the potential to detect kinematic or muscle activity differences.…”

“…Frequent or sustained shoulder elevation at or above 60 degrees in any plane during occupational tasks has been identified as a risk factor for the development of shoulder tendinitis or nonspecific shoulder pain. 3,8,9 Evidence relating occupational exposure of frequent or sustained shoulder elevation to shoulder musculoskeletal symptoms is strongest for combined exposure to multiple physical factors, such as holding a tool while working overhead. 9 Multiple theories exist as to the primary etiology of shoulder impingement, including anatomic abnormalities of the coracoacromial arch or humeral head 10,11 ; "tension overload," ischemia, or degeneration of the rotator cuff tendons [12][13][14] ; and shoulder kinematic abnormalities.…”

Industrial seating and spinal loading

“…Also other symptoms seem to be more common among workers in repetitive jobs. A particularly high risk of neck and shoulder pain also seems to be present in repetitive work (LuopajErvi et al 1979, Bjelle et al 1981, Kvarnstr6m 1983. It must be observed that continuous and repetitive arm movements give rise to static muscle load in the shoulder muscles.…”

Erratum to “Pathophysiology of upper extremity muscle disorders” [Journal of Electromyography and Kinesiology 16 (2006) 1–16]

“…Using electromyographic fatigue indicators several authors have shown more rapid development of fatigue in the descending part of the trapezius muscle in patients with UEMDs compared to healthy subjects [40,45,129]. Bjelle et al [9,10] compared cases with acute, non-traumatic shoulder-neck pain to age-and sex-matched, paired controls. An increased blood concentration of creatine kinase (CK), a marker of muscle damage, was found in a substantial part of the cases.…”