Relationship between rotator cuff posterior delamination and subscapularis tear: a large cross-sectional analysis

BACKGROUND: Rotator cuff posterior delamination and subscapularis tear are commonly observed in rotator cuff injuries. However, there are very few studies on the relationship between posterior delamination and subscapularis tendon tear. This study aimed to investigate the relationship between posterior delamination and subscapularis tendon tear. METHODS: The study was conducted from March 2018 to June 2021 with 553 patients who underwent rotator cuff repairs at two institutions. The age and gender, size of rotator cuff tear, duration of symptoms, range of motion of shoulder joint, visual analog scale score, Korean Shoulder Scale score, gap and width of rotator cuff tear, and fatty degeneration of the supraspinatus and infraspinatus muscles were compared to confirm the differences between a delaminated and nondelaminated rotator cuff tear. Moreover, the proportions of the subscapular tendon rupture and subscapularis tendon rupture according to the size of the rotator cuff tear were analyzed in both the delaminated and nondelaminated rotator cuff tear groups. RESULTS: Compared to the nondelaminated rotator cuff tear group, the age of the delaminated rotator cuff tear group was significantly higher, and as the size of the rotator cuff tear increased, the proportion of delaminated tear increased (P < .001). Furthermore, the duration of symptoms was longer, visual analog scale score was higher, Korean Shoulder Scale score was lower, gap and width of rotator cuff as well as fatty degeneration of the supraspinatus and infraspinatus were more severe in the group with posterior delamination than that without. In the nondelaminated rotator cuff tear group, 212 subjects (84.46%) had no subscapularis tear, and 39 subjects (15.54%) had subscapularis tear. In the delaminated rotator cuff tear group, 103 subjects (34.11%) had no subscapular tendon tear while 199 subjects (65.89%) had a subscapular tendon tear (P < .001). Furthermore, as the size of the rotator cuff tear increased, the rate of subscapular tendon tear increased in both the delaminated and nondelaminated rotator cuff tear groups. CONCLUSIONS: The results suggest that there is a high probability of concomitant rupture of the subscapularis tendon in the patient group with posterior delamination tear. Therefore, it should be noted that if a posterior delamination is confirmed during surgery, it is necessary to carefully check for rupture of the scapular tendon.