Refixation of the supraspinatus tendon in a rat model--influence of continuous growth factor application on tendon structure.

The purpose was to evaluate histological changes of the supraspinatus tendon (SSP) after refixation under continuous growth factor application over 20 days in comparison to the native healing process. In a chronic rat tendon tear model (15 rats/group), a transosseous SSP refixation was performed and growth factors (control, G-CSF, b-FGF, combination) were continuously released into the subacromial space by an osmotic pump. Tendon healing was evaluated histologically by a modified MOVIN-Score, and Collagen I/III content was determined by immunohistology at 6 weeks.

Rotator cuff changes in a full thickness tear rat model: verification of the optimal time interval until reconstruction for comparison to the healing process of chronic lesions in humans.

Background: The aim of the study was to develop a standardized rat model for chronic rotator cuff tears. Therefore, a time point of degenerative changes that shows comparable histological changes to the chronic tendon tears in humans had to be determined. The rat shoulder has already been described as a standardized model for investigation of the healing behavior in acute supraspinatus lesions.