Poster 163: Evaluating the Role of Subacromial Impingement in Rotator Cuff Tendinopathy: Development and Analysis of a Novel Rat Model

Objectives: Subacromial impingement of the rotator cuff caused by variations in acromial anatomy is an extrinsic factor that leads to inflammation and degeneration of the rotator cuff, ultimately contributing to the development of tendinopathy. However, microscopic and molecular changes in the impin...

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Bibliographic Details
Published in:Orthopaedic journal of sports medicine 2022-07, Vol.10 (7_suppl5)
Main Authors: Deng, Xianghua, Rodeo, Scott, Liu, Yulei
Format: Article
Language:English
Subjects:
Biomechanics
Gene expression
Orthopedics
Rodents
Rotator cuff
Sports medicine
Variance analysis
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Summary:Objectives: Subacromial impingement of the rotator cuff caused by variations in acromial anatomy is an extrinsic factor that leads to inflammation and degeneration of the rotator cuff, ultimately contributing to the development of tendinopathy. However, microscopic and molecular changes in the impinged tendon remain poorly understood, and a robust rat model for studying rotator cuff tendinopathy is still lacking. Methods: Our study was approved by the Institutional Animal Care and Use Committee. A total of 44 adult male Sprague-Dawley rats were included in the study. Animals were randomly allocated to one of four study groups: intact control group (Group 1, n=11); bilateral subacromial surgical clip placement to induce supraspinatus impingement for 2 weeks (Group 2, n=11), 4 weeks (Group 3, n=11) and 8 weeks (Group 4, n=11). At time of sacrifice, bilateral shoulder specimens were harvested for biomechanical testing, histological and quantitative real-time polymerase chain reaction (qRT-PCR) analysis. One-way analysis of variance (ANOVA) with the post-hoc Tukey test was used to analyze differences among groups. Results: Radiography confirmed that all microvascular clips remained in stable position in the subacromial space. Gross inspection of supraspinatus tendon specimens in the impingement groups revealed frayed and hazy tendon discoloration at the enthesis and mid-substance. Biomechanical evaluation demonstrated decreased supraspinatus tendon failure force and tissue stiffness at all time points compared to control group. Histologic specimens demonstrated significant, persistent tendinopathic changes over 8 weeks, with the mean modified Bonar scores significantly increased in the clip impingement groups compared to the control group (control: 1.56±0.86; 2 weeks group: 9.17±0.76; 4 weeks group: 9.11±0.65; and 8 weeks group: 6.56±0.50. P
ISSN:2325-9671
2325-9671
DOI:10.1177/2325967121S00724