Rotator Interval

Abstract

The general dilemma of the shoulder as a ball-and-socket joint is to provide high mobility and, at the same time, maintain sufficient stability. This is reflected in the controversial pathoanatomical role of the rotator interval (RI), both as a dynamic stabilizer and also a structural weak spot, serving as a capsular reserve space and an outlet for the long head of biceps tendon (LHBT). 1,2 In experimental studies, a section of the RI leads to an increased anterior inferior and posterior translation of the humeral head, whereas surgical closure of the rotator interval limits external rotation, elevation, and extension. 3-5 Thus, although not generally agreed, the rotator interval structures are thought to contribute to joint stability, and consequently pathologic changes of these structures might affect glenohumeral stability and mobility. 1 Imaging of the RI is mostly based on MR techniques. Normal anatomy and MR imaging findings in pathologic conditions involving the RI have been addressed by various review-type articles but only relatively few scientific studies. Therefore, in certain aspects, current practice is not fully based on reproducible results but also on personal experience.This article further extends the list of review articles on the RI. With a focus on MR imaging and MR arthrography it discusses anatomical features, technical aspects, as well as pathology of the RI capsule, the LHBT, and the pulley system. AnatomyThe rotator cuff has two tendinous gaps that are exclusively covered by capsular tissue: one anteriorly between the subscapularis (SSC) tendon and the supraspinatus (SSP) tendon, termed the anterior rotator interval, and one posteriorly between the supraspinatus tendon and the infraspinatus tendon, termed the posterior rotator interval. However, the term rotator interval usually refers to the anterior RI, and thus, to make things more simple, this convention is also assumed for this article.The RI is a triangular shaped space bordered by the anterior free edge of the SSP tendon superiorly, the superior free edge of the SSC tendon inferiorly, and the coracoid process medially. The intertubercular sulcus and transverse ligament represent the lateral apex of this triangle, the coracoid process its base (►Fig. 1). The RI contains the intra-articular portion of the LHBT. It is covered by a fibrous capsule that represents an extension of the anterior joint capsule termed the rotator interval capsule. The RI capsule is reinforced by two ligaments: the coracohumeral ligament (CHL) on its bursal side and the superior glenohumeral ligament (SGHL) on its articular side (►Fig. 1). As the RI capsule forms the roof of the RI, its floor is formed by the articular cartilage surface of the humeral head. [6][7][8][9] If viewed on sagittal sections (►Fig. 1c), the RI shows a quadrilateral configuration with the superior border of the SSC tendon inferiorly, the anterior border of the SSP tendon superiorly, the RI capsule anteriorly, and the humeral head posteriorly. 8 On midsagittal sections, the LHBT is l...

Anatomical structure of the coracohumeral ligament and its effect on shoulder joint stability

“…Since Neer [16] first proposed to describe the portion of the rotator cuff between supraspinatus tendon and subscapularis tendon with the term "rotator interval" in 1970, many scholars have conducted a series of dissected anatomical and biomechanical studies on the RI and its composition [12,21,25]. In 1980, Neer and Foster [17] verified the effects of the RI on anterior shoulder stability.…”

Glenohumeral Ligaments and Unstable Shoulder: CT and MR Arthrography

“…On sagittal images, a thickened structure with inhomogeneous signal could be described associated to a synovitis of the rotator interval [4].…”

“…In a midsubstance rupture of MGHL, the medial stump can remain attached to the labrum; the lateral stump is found between subscapularis tendon and humeral head. A torn MGHL may appear as absent with an open and broad rotator interval (between CHL and subscapularis tendon) [4].…”

“…In adhesive capsulitis (frozen shoulder), the IGHL (and axillary capsule) may be infiltrated by scarring and granulation tissue, appear thickened (especially on nonsaturated T2-weighted sequences) and show contrast enhancement. The rotator interval can also be obliterated by abnormal tissue with contrast enhancement in adhesive capsulitis [1,2,3,4,5].…”

How I do it – MRT der Schulter

“…Auch werden Patienten mit ausgeprägten Überkopftätigkeiten (Sportler, beruflich exponierte Personen) und Schulterschmerzen einer direkten MR-Arthrografie unterzogen, da bei ihnen typischerweise mit subtilen Verletzungen von Labrum, Gelenkkapsel und Rotatorenmanschette zu rechnen ist. Bei der Frage nach einer Pulley-Läsion der langen Bizepssehne führen wir ebenfalls primär eine direkte MR-Arthrografie durch [3,5,7,8].…”