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Morning Stiffness in RA Associated With Synovial Fibrin & Neutrophils

Morning stiffness in patients with rheumatoid arthritis (RA) may be related to impaired fibrinolysis of neutrophil enmeshed fibrin deposits along the synovial membrane, a new study found. Patient reports of morning stiffness duration, stiffness severity and disease activity scores (DAS28) were collected from 176 patients with RA undergoing arthroplasty. Researchers found:

  • Stiffness severity and morning stiffness duration were both significantly associated with DAS28.
  • None of the synovial features examined were associated with patient-reported stiffness severity.
  • 73% of patients with both synovial fibrin and neutrophils reported >1 hours of morning stiffness.


Orange DE, et al. Rheumatoid arthritis morning stiffness is associated with synovial fibrin and neutrophils. [Published online ahead of print October 15, 2019]. Arthritis Rheum. doi: 10.1002/art.41141.


Morning stiffness is a very common symptom in patients with RA. This study looked at the synovial histopathology of RA patients undergoing joint replacement to correlate with symptoms of morning stiffness including duration and severity. Synovial pathology (including the presence of lymphocytes, plasma cells, and hyperplasia) was not found to be associated with severity of stiffness, but neutrophils and fibrin, which were both found along the synovial lining, were associated with >1 hr morning stiffness. In vitro studies looking at combined neutrophil and fibrin clots were more resistant to fibrinolysis than clots not meshed with neutrophils, which the authors suggest may be a mechanism of morning stiffness. Of note, however, while morning stiffness correlated with disease activity scores, these arthroplasties were performed on large joints rather than small joints such as those of the hands, a common location for RA involvement and stiffness. Because of this, and the possible contribution of secondary osteoarthritis to the histopathological findings, it is not clear that the findings are applicable to all areas of RA-associated morning stiffness. Arundathi Jayatilleke, MD