Sequential Changes in Range of Motion and Capsular Fibrosis Following Remobilization in a Rat Adhesive Capsulitis...

Area of Science:

• Orthopedics
• Regenerative Medicine
• Biomechanical Engineering

Background:

• Adhesive capsulitis (AC) is characterized by joint stiffness and limited range of motion (ROM).
• Cast immobilization is a common method to induce an AC model in animal studies.
• Understanding the timeline of recovery after remobilization is crucial for developing effective treatments.

Purpose of the Study:

• To investigate the sequential changes in shoulder joint ROM and joint capsule histopathology following remobilization in a rat model of adhesive capsulitis.
• To evaluate the efficacy of remobilization in restoring shoulder function and reducing capsular changes.

Main Methods:

• A rat model of adhesive capsulitis was created using cast immobilization of the shoulder for four weeks.
• Following cast removal, rats were divided into seven groups based on remobilization duration (0-6 weeks).
• Measurements included glenohumeral abduction angle (ROM) and capsular thickness and fibrosis in the axillary recess.

Main Results:

• Shoulder abduction angle (ROM) progressively increased after remobilization, nearing normalization by six weeks.
• Capsular thickness in the axillary recess significantly decreased over the six-week remobilization period but remained elevated compared to non-immobilized shoulders.
• Capsular fibrosis scores were significantly higher in immobilized shoulders at one and two weeks post-remobilization.

Conclusions:

• Remobilization following cast immobilization leads to sequential improvements in ROM in a rat AC model.
• While capsular thickening diminishes, it persists six weeks after cast removal, suggesting ongoing pathological changes.
• These findings highlight the potential for targeting persistent capsular changes to further enhance recovery in adhesive capsulitis.