Work related upper limb disorder: the relationship between pain, cumulative load, disability, and psychological factors.

Repetitive strain injury, or work related upper limb disorder, provides an interesting paradigm for the study of the relative contribution of physical and psychological factors to the resulting pain and disability. Sixty three subjects were studied, comprising the work-force of a subsection of a large local industrial company, in whom pain in the arm related to work was known to be common. Ergonomic data were obtained by estimating the cumulative daily load on the wrist joint for each of four identified tasks. Data on the occurrence of pain, treatment sought, and disability were obtained by a structured self administered questionnaire. Psychological data were obtained by administering the Hospital Anxiety and Depression (HAD) scale, a self reported measure of anxiety and depression, and the Bradford Somatic Inventory (BSI), an inventory of somatic symptoms associated with anxiety and depression. The employment specific period prevalence of work related upper limb disorder was 81%, with 30% of the subjects having pain at the time of the study. Domestic disability was minimal in all but two subjects, though the use of devices such as jar openers at home was common (12 of 51 subjects). Medical advice was seldom sought. Twenty per cent of subjects had received anti-inflammatory drugs, 10% had received physiotherapy, and 47% had wrist splints. Pain was related to the tasks with the highest estimated daily loads, but a history of pain and current pain were associated with higher scores on the HAD and BSI scales, suggesting an interaction between physical and psychological factors.