Background: The objective of this study was to evaluate the efficacy of subacromial injections of collagenase and corticosteroid in rats with experimentally induced adhesive capsulitis. Method: Thirty adult Wistar albino male rats were distributed into 3 groups of 10 rats each after stabilization of their shoulders for 3 weeks: the first group received a single dose of 0.002 mg (0.25 mL) subacromial collagenase; the second group received a single dose of 1.60 mg (0.25 mL) subacromial steroid, and the third group received a single dose of 0.25 mL subacromial saline solution. One week later, we investigated shoulder range of motions, collagen content of the shoulder, and joint cartilage structure. Results: There was no statistically significant difference in the cartilage damage between the groups (p > 0.05). Fibrosis measurements were significantly lower in the collagenase group than in the steroid and saline groups. There was no significant difference in fibrosis between the steroid and saline groups (p > 0.05). Abduction measurements were significantly higher in the collagenase group than in the steroid and saline groups (p 0.05). Conclusion: We observed that subacromial injections of collagenase Clostridium histolyticum effectively treated adhesive capsulitis. The results suggest that this treatment could be considered for use in patients with an intact rotator cuff
