How Long Should We Wait to Create the Goutallier Stage 2 Fatty Infiltrations in the Rabbit Shoulder for Repairable...

Area of Science:

• Orthopedics
• Regenerative Medicine
• Animal Models

Background:

• Rotator cuff tears (RCTs) are common, with many being repairable and showing Goutallier stage 1 or 2 fatty infiltration.
• Animal models with similar fatty infiltration are crucial for researching repairable RCTs.
• This study focuses on establishing a suitable rabbit RCT model.

Purpose of the Study:

• To determine the optimal time frame for developing a rabbit rotator cuff tear (RCT) model.
• To achieve Goutallier stage 1 or 2 fatty infiltration in the rabbit RCT model.
• To facilitate research on repairable RCTs in humans.

Main Methods:

• Created supraspinatus tendon tears in 40 rabbits, with sham operations on the contralateral limb.
• Divided rabbits into five groups (2, 4, 6, 8, and 12 weeks post-injury).
• Harvested muscle specimens for H&E staining, histological, and Goutallier grading evaluation.

Main Results:

• Fatty infiltration (Goutallier stage 2) and mature adipocytes were observed at 4 weeks (2.13 ± 0.35).
• Muscle atrophy was significant at 4 weeks (1.50 ± 0.53) compared to sham (p < 0.05).
• Inflammation peaked at 2 weeks (1.88 ± 0.35), decreased at 4 weeks (0.50 ± 0.53), and showed a biphasic pattern.

Conclusions:

• Rabbit supraspinatus muscles showed Goutallier grade 2 fatty infiltration at 2 and 4 weeks.
• Four weeks is a suitable time point for a repairable RCT animal model.
• This model aids research into human rotator cuff tears, considering early tissue reactions.