A novel look at the posterior rotator interval of the shoulder

The capsular structures of the posterior rotator interval have not been fully described yet. Moreover, their clinical importance is still being questioned. The purpose of this study was to investigate and in detail report which part of the glenocapsular ligament is located within the posterior rotator interval.

Seventeen fixed cadaveric shoulder specimens from 6 females and 11 males, with a mean age of 72.7 years (±7.2), were included. All specimens were finely dissected to reveal the superficial and deep structures of the posterior rotator interval.

The posterior rotator interval is visible as a distinct space between the supraspinatus and infraspinatus muscles medially, while the tendons and joint capsule fuse laterally. The superficial and deep structures located in the posterior rotator interval are in line with the scapula. The capsular fibres of the glenocapsular ligament are divided into two distinct parts, that is, the posterosuperior and mediosuperior parts. The mediosuperior part varies in shape, and in seven of seventeen cases it was absent, but the posterosuperior part was found to be constant in all specimens. The posterosuperior part of the glenocapsular ligament is located in the posterior rotator interval, attaching medially to the supraglenoid tubercle/scapular neck and laterally to the semicircular humeral ligament (rotator cable) between the middle and inferior facets of the greater tubercle of the humerus.

The posterosuperior part of the glenocapsular ligament was shown to be a constant connective tissue structure of the posterosuperior capsule of the shoulder joint, located in the posterior rotator interval. The glenocapsular ligament may be of potential clinical relevance as an anatomical reference, serving as a posterior landmark for superior capsule restoration and as an anterior landmark for supraspinatus and infraspinatus tendon restoration in large rotator cuff tears.

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