What is morning stiffness? How is morning stiffness useful in sorting out the causes of polyarticular symptoms?
Morning stiffness refers to the amount of time it takes for patients with polyarthritis to “limber up” after arising in the morning. It is useful in differentiating inflammatory from noninflammatory arthritis. In inflammatory arthritis, morning stiffness lasts for >1 hour. In untreated RA, it averages 3.5 hours and tends to parallel the degree of joint inflammation. In contrast, noninflammatory processes, such as OA, may produce transient morning stiffness that lasts for <15 minutes.