Rotator cuff muscle degeneration in a mouse model of glenohumeral osteoarthritis induced by monoiodoacetic acid.

Abstract

Osteoarthritis (OA) is a disease of joint degeneration and impaired function. Muscle atrophy, fatty infiltration (FI), and fibrosis are degenerative features of muscle injury and predict poor outcomes in some degenerative and exercise-related injuries. Patients with glenohumeral joint OA are usually accompanied by rotator cuff muscle degeneration, even though the rotator cuff is intact. However, the mechanism and correlation between OA and degeneration of muscles around joints are still unknown. Forty-five 12-month-old C57BL/6J mice received a single injection of monoiodoacetic acid(MIA)into the right glenohumeral joint. The sham group was injected with saline on the same day in the right glenohumeral joint. 3 and 6 weeks after the operation, gait analysis was conducted to evaluate the function of the forelimb. Then, the shoulder joint and supraspinatus muscle (SS) were collected for histological staining, RT-qPCR, and biomechanics test. Correlations between fat area fraction in muscle, percentage wet muscle weight change or OARSI score and gait analysis,/muscle mechanics tests were assessed using Pearson's correlation coefficient or Spearman's correlation coefficient. Compared with the sham group, the MIA group developed significant glenohumeral joint OA, and the SS developed significant FI and muscle atrophy. Shoulder function correlated with glenohumeral joint OA/rotator cuff muscle severity, weight loss, and FI. In mice, glenohumeral joint OA can lead to rotator cuff degeneration and inferior limb function. The small animal model could be a powerful tool to further study the potential mechanisms between glenohumeral OA and rotator cuff muscle degeneration. Basic Science Study; In-Vivo Animal Model.