Instructional course 106

The anatomy, pathology, and definitive treatment of rotator interval lesions: current concepts

Anatomy

The triangular borders and its contents define the RI.5 The base of the triangle is the coracoid process. The apex is the intertubercular groove. The inferior border is the superior aspect of the subscapularis tendon, and the superior border is the anterior aspect of the supraspinatus tendon. This triangular space contains the biceps tendon, superior glenohumeral ligament (SGHL), the glenohumeral capsule, and the coracohumeral ligament (CHL) (Fig 1). The quality of the capsular tissue in the

Pathology and treatment

Injuries to the rotator interval (RI) include lesions to (1) the anterior aspect of the supraspinatus tendon; (2) superior aspect of the subscapularis tendon; (3) long head of the biceps tendon; (4) coracohumeral ligament (CHL); (5) superior glenohumeral ligament; and (6) RI capsule. In a discussion of pathology of the RI, it is important to realize that any one of these structures or a combination of structures may be affected. In 1987, Nobuhara and Ikeda2 were the first to attempt to classify

Rotator interval contractures

The normal RI contains elastic, membranous tissue. In pathologic situations, the RI can become thickened, fibrotic, and contracted. RI contractures vary in severity. Mild cases may aggravate or cause impingement of the rotator cuff. Severe contractures occur in cases of adhesive capsulitis. The etiology and pathogenesis of adhesive capsulitis is not clearly understood but is frequently associated with varying degrees of trauma and a period of immobilization. Patients commonly complain of pain

Rotator interval laxity

Harryman et al.13 in a cadaveric study, showed the importance of the RI in maintaining glenohumeral stability. They made a transverse incision through the capsule, CHL, and SGHL. Sectioning produced increased translation in all planes. In particular, after sectioning of the RI capsule posterior and inferior instability with the arm at 60° of abduction and 60 degrees of external rotation, with dislocation in half of specimens.

Imbrication of the RI caused a decrease in inferior translation of the

Coracoid impingement

Several authors have reported coracoid impingement as an etiology of RI injury.19, 20 Diagnosing coracoid impingement can be challenging. Traumatic etiology is often a sudden forced internal rotation of the humerus. Predisposition to coracoid impingement is seen in patients with a narrowed distance from the coracoid to the lesser tuberosity (Fig 6). Gerber et al.21 measured the distance from the coracoid to the lesser tuberosity with the shoulder in internal rotation using computed tomography

Biceps instability and subscapularis tears

Biceps instability and subscapularis tears frequently occur together. The proximal long head of the biceps tendon passes through the RI from its origin on the supraglenoid tubercle. The long head of the biceps courses into the intertubercular groove (Fig 8). As the tendon exits the glenohumeral space and enters the intertubercular groove, the tendon is held in place by a pulley system that is formed from the coalescence of the insertion of the subscapularis tendon and the coracohumeral

Conclusions

Rotator interval lesions are a source of significant shoulder pathology resulting in patient discomfort and dysfunction. Rotator interval tightness is associated with impingement, contracture with adhesive capsulitis, and widening with anteroinferior, posterior, or multidirectional instability. Coracoid impingement can cause damage to the structures of the rotator interval. Injuries of the interval are associated with subscapularis tears as well as biceps tendonitis, fraying, subluxation, and