A rat model of massive rotator cuff tears

Area of Science:

• Orthopedics
• Musculoskeletal Research
• Animal Models

Background:

• Rotator cuff tears (RCTs) are common orthopedic injuries, with massive tears often leading to poor outcomes due to muscle atrophy and fatty infiltration.
• The underlying pathophysiology of rotator cuff muscle degeneration following massive tears remains poorly understood.
• Existing small animal models have not adequately replicated the histological and molecular changes observed in human massive RCTs.

Purpose of the Study:

• To establish and characterize a novel rat model that accurately reproduces the muscle atrophy and fatty infiltration associated with massive rotator cuff tears.
• To provide a reliable preclinical tool for investigating the mechanisms behind rotator cuff muscle degeneration and for testing potential therapeutic interventions.

Main Methods:

• A novel surgical technique involving rotator cuff tendon transection and denervation was performed on rats to induce a massive rotator cuff tear model.
• Muscle atrophy was quantified by measuring the wet weight of the supraspinatus and infraspinatus muscles at 2 and 6 weeks post-surgery.
• Histological assessment was used to evaluate the extent of fatty infiltration in the rotator cuff muscles.

Main Results:

• The rat model demonstrated significant and consistent muscle atrophy in the supraspinatus and infraspinatus muscles.
• Supraspinatus muscle lost 25.4% and infraspinatus lost 28.9% of wet weight by 2 weeks post-transection.
• Significant fatty infiltration was observed in the infraspinatus muscle 6 weeks after tendon transection.

Conclusions:

• The developed rat model successfully replicates key pathological features of massive rotator cuff tears, including muscle atrophy and fatty infiltration.
• This model serves as a valuable tool for future research into the pathophysiology of rotator cuff degeneration and the development of new treatments.