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Updated: Apr 27, 2026
Development of a Rabbit Chronic-Like Rotator Cuff Injury Model for Study of Fibrosis and Muscular Fatty Degeneration
Published on: March 31, 2023
Chronic massive rotator cuff tear in rats: in vivo evaluation of muscle force and three-dimensional histologic
Konstantinos Ditsios1, Achilleas Boutsiadis1, Dorothea Kapoukranidou2
1First Orthopaedic Department, Aristotle University of Thessaloniki, G. Papanikolaou General Hospital, Exohi, Thessaloniki, Greece.
Background:
Massive rotator cuff tear repair is frequently complicated by unsatisfactory clinical results due to possible tendon retraction, muscle atrophy, and fatty degeneration. The objective of this study was the development of a chronic massive tear in a rat model and the evaluation of the muscle force in vivo and of the histologic changes in a 3- dimensional manner.
Methods:
To simulate massive rotator cuff tears, both the supraspinatus (SS) and the infraspinatus (IS) tendons were surgically detached from the right humerus of 15 male adult Sprague-Dawley rats. Twelve weeks postoperatively, all animals underwent isometric tension recordings of both the SS and IS muscles. Histologic analysis and image deconvolution processing were performed to estimate the presence and the distribution of atrophy in 3 dimensions.
Results:
An overall 30% and 35% reduction in muscle force of the SS and IS muscles, respectively, was observed compared with the left uninjured shoulder (P < .005). Histologic analysis revealed that the degeneration and the fatty infiltration were more evident near the tendon and at the dorsal side in both muscle groups.
Conclusions:
These results show that functional impairment of SS and IS muscles after chronic massive tendon tears could be attributed to the decrease in muscle force production during their repair on the greater tuberosity and, second, to the comparatively greater degeneration of their dorsal part.
