Sequential Changes in Range of Motion and Capsular Fibrosis Following Remobilization in a Rat Adhesive Capsulitis Model Using Cast Immobilization
- Author:
Du-Han KIM
1
;
Ji-An KIM
;
Jong Pil YOON
;
Chul-Hyun CHO
Author Information
- Publication Type:Original Article
- From:Clinics in Orthopedic Surgery 2026;18(1):107-115
- CountryRepublic of Korea
- Language:English
-
Abstract:
Background:The objective of this study was to investigate sequential changes in range of motion (ROM) and histopathology of the joint capsule after remobilization in a rat adhesive capsulitis (AC) model using cast immobilization.
Methods:Thirty-five 6-week-old Sprague-Dawley rats were immobilized with casting of the left shoulder. After 4 weeks, the rats were randomly divided into 7 groups (n = 5 per group) according to the duration of remobilization following cast removal: 0 (D0), 1 (W1), 2 (W2), 3 (W3), 4 (W4), 5 (W5), and 6 (W6) weeks. At each time point, 5 rats were euthanized for measurement of the glenohumeral abduction angle and evaluation of capsular thickness in the axillary recess.
Results:Abduction angle was sequentially increased at each time point after remobilization with cast removal. Significant differences between immobilized and non-immobilized shoulders were observed at D0 (130.4° vs 161.3°), W1 (144.7° vs 160.7°), and W2 (142.3° vs 161.3°). Significant differences in capsular thickness of the axillary recess were observed between immobilized and non-immobilized shoulders at all time periods including D0 (98.0 μm vs. 12.9 μm), W1 (117.7 μm vs. 12.2 μm), W2 (115.7 μm vs.13.1 μm), W3 (54.1 μm vs. 14.9 μm), W4 (54.5 μm vs. 13.4 μm), W5 (23.8 μm vs. 13.5 μm), and W6 (19.8 μm vs. 12.4 μm). Significant differences in capsular fibrosis scores were observed between immobilized and non-immobilized shoulders at W1 (2.2 vs. 0.2) and W2 (2.2 vs. 0.0).
Conclusions:Our study showed that ROM increased sequentially after remobilization in a rat AC model using cast immobilization, and it was normalized at 6 weeks after cast removal. Capsular thickening decreased sequentially, but remained at 6 weeks after cast removal. These findings may provide useful information for further research into verifying potential therapeutic targets using a rat AC model with cast immobilization.
