The aetiological significance of work-load in the development of osteoarthritis of the distal interphalangeal joint.

The incidence of Heberden's nodes was determined in three groups of Japanese women with different occupations to investigate the role of work-load in their pathogenesis. School cooks (n = 260), each of whom prepared 150 to 450 lunches daily, pre-school cooks (n = 222), each of whom prepared 30 to 80 lunches daily, and municipal employees (n = 298) underwent physical examination and X-ray of the hand if pathology was present. The incidence of Heberden's nodes and X-ray incidence of osteoarthritis was 19.2% and 13.5%, 8.6% and 5.4%, 5.9% and 2.0% among school cooks, pre-school cooks and municipal workers, respectively. The incidence of Heberden's nodes and osteoarthritis was significantly higher among school cooks. These findings support the concept that work-load is an aetiological factor in the pathogenesis of Heberden's nodes and also support Radin's hypothesis that women's daily work pattern explains the increased incidence of DIP joint osteoarthritis in women.