AUTHOR=Eken Gökay , Kantarci Adnan , Atici Teoman , Akkoc Ahmet , Akesen Selcan 
  
TITLE=Oral colchicine improves shoulder motion and reduces capsular fibrosis in a rat frozen shoulder model
  
JOURNAL=Experimental Biology and Medicine
  
VOLUME=Volume 251 - 2026
  
YEAR=2026
  
URL=https://www.ebm-journal.org/journals/experimental-biology-and-medicine/articles/10.3389/ebm.2026.11233
  
DOI=10.3389/ebm.2026.11233
  
ISSN=1535-3699
  
ABSTRACT=Primary frozen shoulder is driven by capsular inflammation followed by progressive fibrosis. Current conservative treatments target inflammation alone and do not address the fibrosis that sustains the loss of motion. Since colchicine has both anti-inflammatory and antifibrotic activity, we tested whether oral colchicine limits inflammation, fibrosis, and the loss of shoulder motion in a rat immobilization model of frozen shoulder. Sixty female Wistar albino rats aged 8 months were randomly assigned to five groups of 12: a healthy sham group, a 3-week untreated control, a 3-week treatment group, a 6-week untreated control, and a 6-week treatment group. Frozen shoulder was induced by plaster immobilization in all groups except the sham group. The treated animals received 0.6 mg of oral colchicine daily by gavage, which is approximately equivalent to 2.2 mg/kg/day. Abduction and external rotation were measured radiographically on harvested specimens, and the joint capsule was graded histopathologically for synovial hyperplasia, inflammatory changes, pannus formation, capillary vessel formation, and connective tissue formation. At 6 weeks, the mean abduction angle was greater in the treatment group than in the matched control (109.6° versus 88.1°), as was the mean external rotation angle (26.8° versus 18.9°), whereas the 3-week groups did not differ significantly in abduction angles. Connective tissue formation was lower in both treatment groups than in their respective controls, and inflammatory changes were reduced at both time points. Immunohistochemistry showed that collagen III was lower in the 3-week treatment group than in its control (2.17 versus 3.50) and collagen I was lower in the 6-week treatment group than in its control (2.50 versus 3.50), a phase-dependent pattern. Differences in synovial hyperplasia, pannus formation, and capillary vessel formation did not reach significance. In this model, colchicine improved shoulder abduction and external rotation and reduced capsular fibrosis and inflammation. Colchicine, already used widely for rheumatologic disease, may have anti-inflammatory and antifibrotic potential in frozen shoulder, although further preclinical and clinical studies are needed before any clinical use. These findings concern the development and progression of capsular fibrosis during continued immobilization; whether colchicine can reverse established contracture was not tested.