The experimental study of the healing process in the injured rotator cuff / 中华骨科杂志

ABSTRACT

Objective To observe the reparative response and expression of basic fibroblast growth factor (bFGF) protein in the rotator cuff subjected to subacromial impingement. Methods Subacromial impingement of the infraspinatus tendon was experimentally created in 50 male SD rats by thickening the undersurface of the acromion with one platelike bony transplantation of the ipsilateral scapular spine. The contralateral shoulders that had undergone a sham operation were used as controls. The rats were sacrificed at 3, 7, 14, 28, and 56 th day, the whole shoulder joint was removed for detecting bFGF protein and the reparative response in the impinged infraspinatus tendon. Computer image analysis system were used to monitor the expression intensity and numbers of positive cells of bFGF protein. The OD scores and the size of area represent the expression intensity and numbers of positive cells respectively. Results All rats with experimental subacromial impingement showed an infraspinatus tear on the bursal side of the tendon. The shoulders in the control group were found intact without any alteration. There was proliferating cells in the fragmented tendons and vascularised connective tissue covering the area of ruptured area, whose source was the subacromial bursa. Few tenocytes and bursal cells expressed bFGF protein in unwounded tendons. In contrast, tendons subjected to impingement exhibited an increased signal for bFGF protein in both resident tenocytes concentrated along the epitenon and infiltrating fibroblasts and inflammatory cells from the subacromial bursa. Conclusion The bFGF protein is upregulated during tendon healing and the subacromial bursa is the main source of both bFGF secreting and rotator cuff repair; one should preserve as much as possible the subacromial bursa.