Back pain in osteoarthritis of the knee.

Abstract

To compare patients with knee osteoarthritis (OA) who have and do not have back pain, and evaluate the prevalence, characteristics, and consequences of back pain among knee OA patients. During a 3-year period, consecutive patients attending an outpatient rheumatology clinic were evaluated for the presence of back pain, and 368 were found to have OA of the knee. Clinical status was evaluated by the Clinical Health Assessment Questionnaire, radiographs, and joint examinations. Back pain was present in 54.6% of patients with OA of the knee. Almost every clinical status measure was worse among those reporting back pain, including Health Assessment Questionnaire (HAQ) disability, pain, global severity, fatigue, and psychological status. Back pain was more common in women and the obese, but was not associated with age, marital status, formal education, smoking history, or knee radiographic scores. In multivariate analyses the strongest correlates of back pain in knee OA patients were anxiety, night pain, HAQ disability, and global severity. Back pain is prevalent among OA clinic patients, more common than in rheumatoid arthritis or population studies, is linked to body mass index, and is associated with clinically significant increases in pain and other measures of clinical distress.