Analysis of disability in knee osteoarthritis. Relationship with age and psychological variables but not with radiographic score.

Sixty-one women with symptomatic knee osteoarthritis were given the Italian version of Arthritis Impact Measurement Scale which showed a good construct through the factorial analysis. The disability index was then related to the body mass index, the anatomical/radiographic damage, to the severity of pain assessed either through the McGill Pain Questionnaire or a visual analog scale, and finally to the degree of anxiety and depression as obtained from the Zung depression and anxiety inventory scores. A statistically significant relationship was found between radiographic damage and body weight, while disability correlated with the degree of psychological involvement and with the age of the patients. Through the stepwise multiple regression analysis we demonstrated that the pain experience and disability scores are strongly influenced by psychological impact. Our data may have important therapeutic implications.