Osteoarthritis (OA) is a highly prevalent, disabling condition
afflicting 16 million older adults in the United States
[1]. Nearly 70% of the elderly population show radiographic
evidence of OA [2], and the prevalence of OA increases
with age [3]. Chronic pain and suffering from OA
account for $15.5 billion annually (in 1994 dollars) in
health care expenditures [4]; and among all the potentially
painful disorders in older persons, OA accounts for the
greatest proportion of pain complaints [5]. Pain is an important predictor of functional limitation in persons with
OA of the knee [6].