Effect of alpha-tocopherol and OTR-4131 on muscle degeneration after rotator cuff tear in rats: An experimental protocol

BACKGROUND Massive rotator cuff tears (RCTs) result in impaired shoulder function and quality of life. These tears lead to structural changes in the rotator cuff muscles, which compromise recovery after repair and increase re-tear rates. AIM To investigate the potential inhibitory effects of alpha-tocopherol (vitamin E) and OTR-4131 on muscle atrophy, fatty infiltration, and fibrosis in rotator cuff muscles following a massive RCT using a Wistar rat model, and establish a standardized methodology for evaluating potential therapeutic agents. METHODS This protocol outlines a controlled animal study using 40 male Wistar rats, randomized into five groups. The experimental groups will receive either systemic administration of alpha-tocopherol or local administration of OTR-4131 via intramuscular injection into the supraspinatus and infraspinatus muscles. Two sham groups will receive systemic and local saline injections respectively, while a control group will undergo no intervention. The interventions will be administered after surgical transection of the supraspinatus and infraspinatus tendons. Outcomes will be assessed via wet muscle weight measurements, muscle fiber diameter, fatty infiltration percentage, and fibrosis evaluation using histological methods. RESULTS The study anticipates that alpha-tocopherol and OTR-4131 will reduce muscle atrophy, fatty infiltration, and fibrosis compared to control and sham groups, supporting their potential protective role in rotator cuff muscle degeneration. CONCLUSION The results are expected to improve the understanding on the role of alpha-tocopherol and OTR-4131 in rotator cuff muscle protection after massive RCT and may serve as a foundation for further preclinical and clinical research aimed at improving rotator cuff repair outcomes.