Orange DE, Blachere NE, DiCarlo EF, et al. - Since morning stiffness is a hallmark symptom of rheumatoid arthritis (RA), however, its etiology is poorly understood, researchers ascertained if any synovium histological features were correlated with this symptom. From 176 patients with RA undergoing arthroplasty, patient reports of morning stiffness duration, stiffness severity and disease activity scores (DAS28) have been obtained. DAS28 was significantly associated with severity of stiffness and duration of morning stiffness. The patient-reported severity of stiffness was not correlated with any of the synovial characteristics studied. In RA, prolonged morning stiffness can be associated with impaired fibrinolysis of neutrophil enmeshed fibrin deposits along the synovial membrane. In addition, the results suggest that the severity and duration of morning stiffness can reflect distinct pathophysiological phenomena.