Journal Of Shoulder And Elbow Surgery, vol.20, pp.1-6, 2020 (Peer-Reviewed Journal)
Background: Numerous reports have shown that retracted rotator cuff tears may cause suprascapular nerve injury, and nerve injury
causes atrophy and fat accumulation in the rotator cuff muscles. However, the effect of suprascapular nerve injury on rotator cuff enthesis
has not been directly defined. This study aimed to investigate the effect of suprascapular nerve injury on rotator cuff enthesis.
Methods: Twenty-four Wistar albino rats underwent bilateral transection of the suprascapular nerve. Additional 6 rats were used as the
sham group. Bilateral supraspinatus and infraspinatus entheses were examined after 1, 4, 8, and 12 weeks of nerve transection. Histomorphometric
analyses were performed for each zone of enthesis.
Results: Compared with normal enthesis, significant and consistent decrease in cellularity were observed in the tendon and bone at all
time points (P <.001). Collagen bundle diameter in the tendon also decreased in a similar manner (P <.001). Apart from the tendon and
bone zones, fibrocartilage and calcified fibrocartilage zones showed similar response, and significant decrease in cellularity was
observed 8 weeks after nerve transection (P < .001).
Conclusion: This study identifies suprascapular nerve injury as an underlying mechanism leading to compromise of the rotator cuff
enthesis structure. Suprascapular nerve injury may be considered as an etiologic factor for the impaired healing after repair of a massive