Yoav Morag, MDJon A. Jacobson, MDGregory Shields, MDRajiv Rajani, BSDavid A. Jamadar, MB, BSBruce Miller, MDCurtis W. Hayes, MD

Published online before print10.1148/radiol.2351031455

Radiology 2005; 235:21–30

1 From the Departments of Radiology(Y.M., J.A.J., G.S., R.R., D.A.J., C.W.H.)and Orthopaedic Surgery (B.M.), Uni-versity of Michigan Medical Center,1500 E Medical Center Dr, TC 2307,Ann Arbor, MI 48109-0001. ReceivedSeptember 8, 2003; revision re-quested November 19; revision re-ceived February 16, 2004; acceptedApril 20. Address correspondence toY.M. (e-mail: yoavm@umich.edu).

Authors stated no financial relation-ship to disclose.© RSNA, 2005

MR Arthrography of RotatorInterval, Long Head of theBiceps Brachii, and BicepsPulley of the Shoulder1

The rotator interval and the long head of the biceps brachii tendon are anatomicallyclosely associated structures believed to confer stability to the shoulder joint. Ab-normalities of the rotator interval may be acquired or congenital and are associatedwith instability of the long head of the biceps brachii tendon. Clinical and arthro-scopic diagnoses of rotator interval abnormalities and subtle instability patterns ofthe long head of the biceps brachii tendon are difficult. Magnetic resonancearthrography, owing to its superior depiction of ligaments with distention of thejoint capsule, may be the procedure of choice, barring open surgery, for help indiagnosis of these conditions.© RSNA, 2005

Growing emphasis has been put on previously neglected structures in the anterosuperioraspect of the shoulder: the rotator interval. Orthopedic surgeons and radiologists alike arefocusing on this area because of a prevalent view in the orthopedic and anatomic literaturethat links passive shoulder stability with the structural integrity of the rotator interval andthe long head of the biceps brachii tendon, which are both intimately associated anatom-ically and functionally (1–3).

There is a spectrum of abnormalities that involve the rotator interval complex, whichencompass various rotator interval tears and associated instability patterns of the longhead of the biceps brachii tendon. In this article, we will review the anatomy andbiomechanics of the structures that compose the rotator interval, and we will presentexamples of pathologic conditions.

ANATOMY

The shoulder comprises four layers that overlie and support the glenohumeral joint. Themost superficial layer consists of the deltoid and pectoralis muscles and the overlyingfascia. The second layer is formed by the clavipectoral fascia, the conjoined tendon of theshort head of the biceps and coracobrachialis originating from the coracoid apex, thecoracoacromial ligament, and the scapular fascia. The third layer includes the rotator cuff.The deepest layer is the glenohumeral joint capsule (4).

The glenohumeral joint capsule is a continuous cylinder between the humerus and theglenoid and is composed of three layers: a synovial lining on the articular surface, asubsynovial layer with loosely packed collagen, and a relatively thicker bursal surface layerconsisting of dense collagen (5,6). The thin capsular tissue is reinforced by bandlikecollagenous thickening, termed ligaments—specifically, the superior glenohumeral, themiddle glenohumeral, the inferior glenohumeral, and the coracohumeral ligaments,which form a distinct z-shaped pattern (7,8). The inferior glenohumeral ligament complexis a hammocklike structure with anchor points on the anterior and posterior glenoid andattachment to the humeral head. The middle glenohumeral ligament originates at thesupraglenoid tubercle and anterosuperior region of the labrum and blends distally with thesubscapularis tendon. Both the superior glenohumeral and the coracohumeral ligamentstraverse the rotator interval (9).

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The rotator interval is a triangular an-atomic area defined superiorly by the an-terior edge of the supraspinatus tendonand inferiorly by the superior edge of thesubscapularis tendon (Figs 1, 2). The baseof this triangle is at the base of the cora-coid process, and its apex is at the trans-verse ligament over the bicipital groove.The rotator interval is bridged by the gle-nohumeral joint capsule, the superiorglenohumeral ligament, the coracohu-meral ligament, and crisscrossing fibersfrom the supraspinatus and subscapularistendons (1,10,11).

The coracohumeral and superior gleno-humeral ligaments, two distinct structureswith separate origins and insertions, areconsidered part of the rotator interval (Fig3). In the majority of shoulders, the cora-cohumeral ligament is a well-developedstructure (1,12). Neer et al (12) identified

the coracohumeral ligament as a clear,well-developed structure in 59 of 63 shoul-der dissections. The remaining four shoul-ders had either a vestigial or a missing cor-acohumeral ligament.

The coracohumeral ligament originatesat the lateral aspect of the base of the cor-acoid. Distally, the ligament forms two ma-jor bands. The larger lateral band inserts onthe greater tuberosity and on the anteriorborder of the supraspinatus tendon, whilethe smaller medial band crosses over theintraarticular biceps tendon to insert onthe lesser tuberosity, the superior fibers ofthe subscapularis, and the transverse liga-ment (Fig 4) (1,13). The smaller of the twoligaments—the superior glenohumeral lig-ament—originates at the supraglenoid tu-bercle; it blends distally with the coracohu-meral ligament and inserts on the lessertuberosity (Fig 5) (1,9). The subscapularistendon and supraspinatus tendon inser-tion fibers blend with the coracohumeralligament at its insertion and are thus inti-mately associated (1,2).

The long head of the biceps brachiitendon arises from the supraglenoid tu-berosity and the superior labrum. Themain labral attachment varies, arisingfrom the posterior, the anterior, or bothaspects of the superior labrum (14). Thelong head of the biceps brachii tendontraverses the rotator interval on its coursefrom the bicipital-labral anchor to thebicipital groove. The intraarticular por-tion of the biceps tendon has an intimateassociation both anatomically and func-tionally with the rotator interval (Fig 6).The coracohumeral ligament and supe-rior glenohumeral ligament form a sling-like band surrounding the biceps brachiitendon proximal to the bicipital groove(1,15) (Fig 7). The medial portion of thecoracohumeral ligament, the superiorglenohumeral ligament inserting on thelesser tuberosity, and the superior fibersfrom the subscapularis tendon are be-lieved to act as a pulley, which is criticalin keeping the biceps tendon from sub-luxating or dislocating (Figs 5, 8). Injuriesto this structure have been termed pulleylesions (1,16).

GLENOHUMERAL JOINTSTABILITY AND THE ROTATORINTERVAL

The precise role that structures in the ro-tator interval play in static and dynamicstabilization of the glenohumeral joint isdebated. In a cadaveric study, Harrymanet al (13) demonstrated instability or dis-location of the glenohumeral joint infe-

riorly and posteriorly after section of therotator interval capsule. Alternatively,imbrication of this part of the capsuleincreased resistance to inferior and pos-terior translation. Some cases of capsularredundancy that led to instability wereassociated with redundancy in the bicip-ital sheath or coracohumeral ligament. Itwas shown that although the coracohu-meral ligament adds to joint stabilitythrough its structural presence, the rota-tor interval capsule maintains negativepressure in the joint, thereby contribut-ing its part to the stability (1,2,17).

The presumed role in stabilization of thejoint has led some orthopedic surgeons tosurgically treat isolated rotator interval de-fects in the unstable shoulder. During opensurgery, the rotator interval defects arefreshened by removing granulation andscar tissue. The edges are then approxi-mated or closed in an overlapping manner.In some cases, redundant rotator intervaltissue is fashioned into a functional cora-cohumeral ligament. Overlapping of laxsuperior glenohumeral ligaments may alsobe performed (18).

In a similar fashion, some authors haveprofessed a role for the long head of thebiceps tendon in anterior stability of theshoulder, thereby explaining observa-tions of a tendency for anterior shouldersubluxation in patients with a rupturedbiceps tendon (19). Itoi et al (20) replacedthe long head and the short head of thebiceps brachii tendon with spring devicesin 13 cadaveric shoulders. The shoulderswere put into different angles of abduc-tion with different loads on the longhead and the short head of the bicepsbrachii tendons while a 1.5-kg anteriorforce was applied with the capsule eitherintact, vented, or damaged by a Bankartlesion. The conclusions were that boththe long head and the short head of thebiceps brachii tendon have a role as an-terior stabilizers to the glenohumeraljoint with the arm in abduction and ex-ternal rotation.

This role increases as shoulder stabilitydecreases. Data from a study by Rodoskyet al (21), who used a dynamic cadavericshoulder model, suggest that the longhead of the biceps brachii tendon con-tributes to anterior stability of the gleno-humeral joint by increasing the shoul-der’s resistance to torsional forces in theabducted and externally rotated position.In addition, the long head of the bicepsbrachii tendon helps diminish stress onthe inferior glenohumeral ligament. Arole in superior stabilization of the hu-meral head has also been attributed tothe tendon of the long head of the biceps

ESSENTIALS● MR arthrography appears to be a

promising imaging modality for evalua-tion of the rotator interval through thedistention of the capsule and depictionof the associated ligaments.

● Diagnosis of injury to the rotator inter-val capsule, the coracohumeral liga-ment, and the long head of the bicepsbrachii tendon is important given theirpresumed role in glenohumeral jointstabilization.

● The intraarticular portion of the longhead of the biceps brachii tendon isintimately associated with the coraco-humeral and the superior glenohu-meral ligaments, which, together withsuperior fibers from the subscapularistendon, act as a pulley that keeps thelong head of the biceps brachii tendonfrom subluxating or dislocating.

● Instability patterns of the long head ofthe biceps brachii tendon vary accord-ing to the injured supporting structure.

● Structures within the rotator intervalare an anatomic and functional unit,and injury to one of the componentsmay have associated findings in otherportions of the rotator interval, includ-ing the long head of the biceps brachiitendon.

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brachii tendon (22,23), although electro-myographic studies have yielded con-flicting evidence (24,25).

EVALUATION OF THEROTATOR INTERVAL

The clinical manifestation of injury tothe rotator interval or biceps brachii ten-

don may be nonspecific chronic shoulderpain and instability (1–3,26). The insta-bility may be in an anterior direction,manifesting with recurrent anterior sub-luxations associated with rotator intervaldefects, rotator interval widening, andinjury (27–29). A clinical manifestationof posterior and multidirectional gleno-humeral joint instability has been associ-ated with rotator interval injury (30,31).

Superior glenohumeral joint instabilitymay occur with rupture of the long headof the biceps brachii tendon (23), whileinferior instability in certain shoulder po-sitions may occur as part of specific liga-mentous injury involving the superiorglenohumeral ligament or coracohu-meral ligament (9,17,32).

The nonspecific clinical manifestationunderlines the importance of diagnosticimaging. Rotator interval abnormalitieshave been called “hidden” lesions—aphrase first used by Walch et al (16). Thisterm indicates the difficulty with arthro-scopic identification. The usual lax ap-

Figure 1. Illustration of rotator interval anat-omy. Frontal view depicts anatomic boundariesof rotator interval. B � long head of bicepsbrachii tendon, C � coracohumeral ligament,SSC � subscapularis tendon, SST � supraspinatustendon, T � transverse humeral ligament.

Figure 2. Normal anatomy as depicted on coronal oblique T1-weighted magnetic resonance(MR) arthrographic images (repetition time msec/echo time msec � 700/10) obtained with fatsaturation after intraarticular administration of dilute gadolinium compound. (a) Rotator inter-val is anatomically defined by superior border of subscapularis tendon (�) and anterior border ofsupraspinatus tendon. Also shown is distal portion of normal coracohumeral–superior glenohu-meral ligamentous anchor (arrow) at site of insertion on the lesser tuberosity medial to andintimately associated with the long head of the biceps brachii tendon (arrowhead in a and b).Long head of the biceps brachii tendon slips over the coracohumeral–superior glenohumeralligamentous anchor to insert on the superior labrum, as shown on (b) subsequent image. The“pulley” effect of this ligamentous anchor can be inferred from a.

Figure 3. Normal anatomy as depicted ontransverse T1-weighted MR arthrographic image(700/10) obtained with fat saturation after intra-articular administration of dilute gadoliniumcompound. Proximal portions of coracohumeralligament (arrows), superior glenohumeral liga-ment (large arrowhead), and nearby long head ofbiceps brachii tendon (small arrowhead) areshown. Coracohumeral ligament is well definedbecause of adjacent contrast agent. Note normalrelationship between the smaller superior gleno-humeral ligament as it joins the relatively morerobust coracohumeral ligament.

Figure 4. Coracohumeral ligament on nonar-thrographic coronal T1-weighted MR image(700/10). A portion of coracohumeral ligament(arrow) can be seen arising from the coracoidprocess (arrowhead) to insert, in a broad fash-ion, on lesser tuberosity (star) and on distalportion of subscapularis tendon (�).

Figure 5. Illustrationshows distal portionof coracohumeral liga-ment (C) and superiorglenohumeral ligament(SGHL) near their inser-tions. Sagittal obliqueview depicts distal por-tion of the coracohu-meral and superior gle-nohumeral ligamentssuperior to lesser tuber-osity (LT) and just me-dial to long head of bi-ceps brachii tendon (B)entering the bicipitalgroove. H � humeralhead, SSC � subscapu-laris tendon, SST � su-praspinatus tendon.

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pearance of the anterior capsule and gle-nohumeral ligaments (18) and possibleobscuration of anatomy during anteriorportal arthroscopy (15) are possible ex-planations for this difficulty. In a studyby Field et al (18), 15 patients with surgi-cally proved rotator interval defects wereretrospectively evaluated. Twelve rotatorinterval defects measured 1–5 cm in me-dial-to-lateral width and 1–4 cm in supe-rior-to-inferior height, while the remain-ing three cases were described as “large/very large.” Preoperative MR imaging wasperformed in four cases, but the reportsfailed to comment on capsular irregular-ity. Three arthroscopic procedures per-formed in two patients before definitive

Figure 6. Illustration in coronal plane depictsassociation between long head of biceps brachiitendon (B), coracohumeral ligament (C), and su-perior glenohumeral ligament (S) medially.CPSL � glenohumeral capsule, IST � infraspina-tus, SSC � subscapularis, SST � supraspinatus.

Figure 7. Normal anatomy depicted on sag-ittal T1-weighted MR arthrographic image(700/10) obtained with fat saturation after in-traarticular administration of dilute gadolin-ium compound. Long head of biceps brachiitendon (arrow) enveloped by contrast agent–distended “sling” (arrowhead) formed by cor-acohumeral and superior glenohumeral liga-ments.

Figure 8. Normal anatomy as depicted onsagittal T1-weighted MR arthrographic image(700/10) obtained with fat saturation after in-traarticular administration of dilute gadolin-ium compound. Blended coracohumeral andsuperior glenohumeral ligaments (arrow) traceinferiorly and medially to long head of thebiceps brachii tendon (arrowhead) before in-serting on lesser tuberosity.

Figure 9. Arthroscopically confirmed partialtear of bicipital sling. (a–c) Transverse and(d) oblique coronal T1-weighted MR arthro-graphic images (700/10) obtained with fat sat-uration after intraarticular administration ofdilute gadolinium compound. (a–c) Contrastagent is seen leaking (black arrow) in an irreg-ular fashion through long focal cleft extendingsuperiorly from lateral portion of rotator inter-val inferiorly and laterally through lateral por-tion of bicipital sling. Arrowhead � superiorglenohumeral ligament, white arrow � coraco-humeral ligament. (d) Thickened irregular tis-sue (arrow) is seen at area of bicipital slingabove superior aspect of the lesser tuberosity(�), just medial to long head of biceps brachiitendon (arrowhead).

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surgery had also failed to help identifyrotator interval capsular defects. In anadditional series by Le Huec et al (33),preoperative MR imaging with no intra-articular contrast agent failed to demon-strate surgically proved rotator intervalcapsular tears. Missed rotator interval le-sions can be one of the reasons for failedarthroscopic glenohumeral instability re-pair (29). Rotator interval lesions and bi-cipital instability with associated bicepstendon injury not addressed during thearthroscopic rotator cuff repair may be acause for persistent pain (18,34–36).

Evaluation of shoulder instability rou-tinely entails an MR arthrogram, which isindicated mainly for assessment of thelabrum. In a cadaveric study by Chung etal (37), the normal rotator interval anat-omy was well demonstrated with MR ar-thrography, which was found to be supe-rior to nonarthrographic MR imaging indepicting normal rotator interval struc-tures. The dimensions of the rotator in-terval could be depicted on sagittal im-ages obtained after MR arthrography,while the coracohumeral ligament wasseen inconsistently and the superior gle-nohumeral ligament was not clearlyidentified on nonarthrographic MR im-ages. Ho (38) presented nonarthro-graphic MR images of rotator interval in-juries but did not compare this modalitywith MR arthrography. Small rotator in-terval defects or tears not identified atroutine MR imaging may be seen at MRarthrography, with a distended joint andpossible extraarticular contrast agent leakthat fills an anatomic space such as thesubcoracoid space (33,39). Subtle irregu-

Figure 10. Arthroscopically proved rotator interval defect after acute injury to shoulder.(a, b) Sagittal, (c) coronal oblique, and (d) transverse T1-weighted MR arthrographic images(700/10) obtained with fat saturation after intraarticular administration of dilute gadoliniumcompound show contrast agent extravasating (arrow) through large defect in the rotator intervalanterior to supraspinatus musculotendinous junction (�).

Figure 11. Anterior extension of supraspinatus tendon tear (arrow) to involve the subscapularis tendon (�). (a, b) Sagittal (a, more medial; b, morelateral) and (c) transverse T1-weighted MR arthrographic images (700/10) obtained with fat saturation after intraarticular administration of dilutegadolinium compound. In this setting, rotator interval injury should be suspected.

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larities and fraying may be better demon-strated by observing contrast agent sur-rounding the coracohumeral ligament,superior glenohumeral ligament, and bi-ceps brachii tendon. Contrast agent thatextends over the superior aspect of thehumeral tuberosities, which are normallycovered by the attaching pulley liga-ments, may be the only sign of a subtlepulley tear (16)—an “uncovered” hu-meral tuberosity. Subluxation of the bi-ceps brachii tendon may also be intermit-tent, and associated injury to thesupporting structures is often the onlyclue to possible biceps subluxation onstatic images (38,40).

ROTATOR INTERVALABNORMALITIES

Rotator interval abnormalities encom-pass a spectrum of disease that may beacquired or congenital in nature. Rotatorinterval injury can occur as a result of achronic derangement such as anterior in-stability with repetitive dislocations,acute trauma, or as part of a more diffusedegenerative process with accompanyingrotator cuff tears (41,42). Injury to therotator interval and biceps tendon canoccur in an isolated fashion in the over-head-throwing athlete or in occupationalinjury associated with overhead labor,which repetitively stress these structures(2,38,43,44).

In the acute setting, the rotator inter-val capsule may be thickened, irregular,or disrupted (Fig 9) (38). As many as 50%

of surgically treated cases of glenohu-meral instability may have defects in therotator interval capsule (28) (Fig 10),which are isolated findings in some cases(18). A rotator interval tear after acutetrauma may extend to involve the sub-scapularis tendon (33). Alternatively, arotator interval injury may occur as anextension of injury from the adjacent ro-tator cuff (26) (Fig 11). An arthroscopicevaluation by Bennet (2) revealed that

47% of subscapularis tendon tears in-volved the superior glenohumeral andmedial coracohumeral ligaments. Theproximal portion of the coracohumeralligament and the distal portion of thesuperior glenohumeral ligament werefound to be prone to injury (45). Onemust also be aware that rotator intervaldefects may be congenital, with similar-ity between fetuses and adults in terms ofcapsular defects (46). Patients with a ro-

Figure 12. Arthroscopically proved rotator interval defect with thickened, scarred, and redundant rotator interval tissue. The subscapularis tendonwas partially torn, with long head of the biceps brachii tendon encased by bone. (a–c) Transverse T1-weighted MR arthrographic images (700/10)obtained with fat saturation after intraarticular administration of dilute gadolinium compound show thickened tissue of rotator interval (blackarrowhead). High-signal-intensity cleft in a is consistent with contrast agent extension (white arrowhead). Long head of biceps brachii tendon(arrow) is almost completely encased by bone.

Figure 13. Arthroscopically confirmed injurywith fraying of superior glenohumeral liga-ment. Transverse T1-weighted MR arthro-graphic image (700/10) obtained with fat sat-uration after intraarticular administration ofdilute gadolinium compound. Superior gleno-humeral ligament (black arrow) is thickenedand slightly irregular. A normal superior gle-nohumeral ligament is usually smaller thanthe coracohumeral ligament (white arrow).

Figure 14. Arthroscopically proved bicipitalsling injury with intact subscapularis tendon.Sagittal T1-weighted MR arthrographic image(700/10) obtained with fat saturation after in-traarticular administration of dilute gadolin-ium compound. Bicipital sling (arrow) is thick-ened and inhomogeneous, with high signalintensity. Arrowhead � long head of bicepsbrachii tendon, � � subscapularis tendon.Compare with Figure 4.

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tator interval defect may be predisposedto additional injury due to humeral headinstability (18).

In chronic settings, the rotator intervalcapsule and ligaments may be thickenedand scarred (Figs 12–14) with associatedsynovial hypertrophy and debris (38) orattenuated (Fig 15). Nobuhara and Ikeda(10) described two types of rotator inter-val lesions in unstable shoulders withoutprior trauma; their report was based onsurgical observation, arthrographic find-ings, and motion analysis. They de-scribed type 1, a contracted state associ-ated with inflammatory changes insuperficial bursal area, and type 2, an un-

stable condition with inflammation inthe rotator interval deep to the superfi-cial bursae extending to the capsule andcoracohumeral and superior glenohu-meral ligaments. Hypertrophy of the sy-novium; hypertrophy, elongation, or tearof the middle glenohumeral ligament;and granulation tissue over the long headof the biceps brachii tendon and adjacentsubscapularis may be seen. An associa-tion has been found between adhesivecapsulitis and contractures of the coraco-humeral ligament and rotator interval.Ozaki et al (47) described 17 patientswith recalcitrant chronic adhesive capsu-litis. At surgery, the major cause of re-

stricted glenohumeral movement wasfound to be contracture of the coracohu-meral ligament and the rotator interval.With an average 6.8 years of follow-up,pain relief and restoration of motionwere shown in all patients after the con-tracted tissues were released. The rotatorinterval may also enlarge in a shoulderwith multidirectional instability withoutan apparent full-thickness tear (42).

BICEPS BRACHII TENDONINSTABILITY

Instability of the long head of the bicepsbrachii tendon is a possible complicationof pulley lesions. Walch et al (35) retro-spectively evaluated surgical reports in445 patients who had previously beentreated for rotator cuff injury. Subluxa-tions and dislocations of the long head ofthe biceps brachii tendon were found in16% of the patients during surgery. Dis-location, defined as nonreducible andcomplete loss of contact between thelong head of the biceps brachii tendonand the bicipital groove, was identified in46 cases. Subluxation, which was surgi-cally identified in cases where the longhead of the biceps brachii tendon liesacross the superior portion of the lessertuberosity, with possible associated bi-ceps tendonitis, was seen in 25 cases. Allbiceps tendon dislocations medial to thelesser tuberosity were accompanied bytears of the ligamentous pulley, whileonly some of the subluxations at thelesser tuberosity were accompanied byan attenuated ligamentous pulley. Thetransverse ligament overlying the bicipi-

Figure 15. Arthroscopically confirmed injury to superior glenohumeral ligament on T1-weighted MR arthrographic images (700/10) obtained withintraarticular administration of dilute gadolinium compound. (a, b) Transverse images and (c) sagittal image obtained with fat saturation showattenuated and slightly irregular superior glenohumeral ligament (arrow). Compare with normal anatomy in Figure 2.

Figure 16. Intraarticular dislocation of long head of biceps brachii tendon (black arrow).(a) Transverse and (b) coronal oblique T1-weighted MR arthrographic images (700/10) obtainedwith fat saturation after intraarticular administration of dilute gadolinium compound showmedial displacement of tendon of long head of the biceps brachii. Also shown is torn andretracted subscapularis tendon (white arrow).

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tal groove is not considered a crucial sta-bilizing structure unless the medial cora-cohumeral ligament is torn (3,48). In ashallow bicipital groove, the possibilityof subluxation of a tendon is potentiallygreater (43,48).

There are different patterns of bicepssubluxation, which are dependent on thesupporting structures injured: the coraco-humeral–superior glenohumeral sling,the coracohumeral ligament, the sub-scapularis tendon, or injuries to a combi-nation of structures (19,48). Biceps brachiiinstability patterns have been arthro-scopically classified into four basic typesaccording to the direction of the bicepstendon subluxation or dislocation (2): in-traarticular, between the coracohumeralligament and subscapularis tendon, ex-ternal to the coracohumeral ligament,and within the biceps tendon sheath. In-traarticular dislocations (Fig 16) with thebiceps tendon entering the medial jointspace can occur only if both the insertionof the subscapularis tendon and the su-perior glenohumeral–medial coracohu-meral ligaments are torn. Lesions of thesuperior glenohumeral–medial coracohu-meral complex with an intact lateral cora-cohumeral ligament may allow the bicepsto subluxate between the subscapularistendon and the coracohumeral ligament(Fig 17). A supraspinatus tear that ex-tends to involve the lateral coracohu-meral ligament may allow the biceps ten-don to subluxate medially superficial tothe coracohumeral ligament and sub-scapularis tendon in an extracapsular lo-cation (Fig 18). Isolated subscapularistendon tear (Fig 19) will not result insubluxation of the tendon (2,49), butthere may be increased biceps tendonmotion secondary to plastic deformationof the medial portion of the ligamentoussling (2). There may also be variations inlesions of the rotator interval (2) (Fig 20).

Tears of the far lateral portion of theanterior edge of the supraspinatus ten-don may be associated with injury to thebiceps tendon and rotator interval (48).Isolated tears of this portion of the su-praspinatus tendon in the presence of anintact rotator interval may also cause bi-ceps instability due to loss of tension ofthe rotator interval and pulley mecha-nism (16,26,38).

SUMMARY

The active pursuit of rotator interval ab-normalities by orthopedic surgeons withintention to treat as part of shoulder in-stability surgery or rotator cuff repair or

as a solitary finding necessitates a greaterawareness by radiologists of this rela-tively neglected region. MR arthrographyappears to be a promising modality forthe evaluation of the rotator intervalthrough the distention of the capsuleand the depiction of associated liga-ments. The importance of MR arthrogra-phy in depiction of these lesions is com-pounded when considering the difficultyin evaluating these structures both clini-cally and arthroscopically. Sagittal or

transverse T2-weighted MR sequencesmay assist in identifying injury in caseswithout a definite contrast agent leak.When evaluating the rotator interval, itmust be recognized that the differentstructures composing or traversing thisarea are a functional and anatomic unit.Injury to one of the components may beassociated with findings in other parts ofthe rotator interval or in the long head ofthe biceps brachii tendon. Understand-ing of function through the anatomy is

Figure 17. Arthroscopically confirmed subluxated and partially torn long head of biceps brachiitendon (arrow) and partially torn subscapularis tendon. (a, b) Transverse T1-weighted MRarthrographic images (700/10) obtained with fat saturation after intraarticular administration ofdilute gadolinium compound show long head of biceps brachii tendon is surrounded by contrastagent anterior to the superficial subscapularis tendon fibers (�), deep to the coracohumeralligament (white arrowheads). Black arrowhead � bicipital groove.

Figure 18. Anterior supraspinatus tendon tear with associated medial subluxation of long headof biceps brachii tendon. (a) Sagittal and (b) transverse intermediate-weighted MR images(2500/28) obtained with fat saturation. (a) Distal anterior supraspinatus tendon tear (arrow) isvisible. (b) Long head of biceps brachii tendon (black arrow) shows medial subluxation superficialto the subscapularis tendon (white arrow). Intermediate-signal-intensity linear structure (arrow-heads) superficial to subscapularis tendon and deep to biceps tendon is compatible with coraco-humeral ligament. Empty bicipital groove is fluid filled.

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key in making diagnoses of subtle find-ings that may otherwise be missed andleft untreated.

References1. Jost B, Koch PP, Gerber C. Anatomy and

functional aspects of the rotator interval.J Shoulder Elbow Surg 2000; 9:336–341.

2. Bennett WF. Subscapularis, medial andlateral coracohumeral ligament insertionanatomy: arthroscopic appearance andincidence of “hidden” rotator interval le-sions. Arthroscopy 2001; 17:173–180.

3. Slatis P, Aalto K. Medial dislocation of thetendon of the long head of the biceps

brachii. Acta Orthop Scand 1979; 50:73–77.

4. Cooper DE, O’Brien SJ, Warren RF. Sup-porting layers of the glenohumeral joint:an anatomic study. Clin Orthop 1993;289:144–155.

5. Clark J, Sidles JA, Matsen FA. The relation-ship of the glenohumeral joint capsule tothe rotator cuff. Clin Orthop 1990; 254:29–34.

6. McFarland EG, Kim TK, Banchasuek P,McCarthy EF. Histologic evaluation of theshoulder capsule in normal shoulders,unstable shoulders, and after failed ther-mal capsulorraphy. Am J Sports Med2002; 30:636–642.

7. O’Brien S, Neeves MC, Arnoczky SP, et al.The anatomy and histology of the infe-rior glenohumeral ligament complex ofthe shoulder. Am J Sports Med 1990; 18:449–456.

8. Ferrari DA. Capsular ligaments of theshoulder: anatomical and functionalstudy of the anterior superior capsule.Am J Sports Med 1990; 18:20–24.

9. Burkart AC, Debski RE. Anatomy andfunction of the glenohumeral ligamentsin anterior shoulder instability. Clin Or-thop 2002; 400:32–39.

10. Nobuhara K, Ikeda H. Rotator interval le-sion. Clin Orthop 1987; 223:44–50.

11. Edelson JG, Taitz C, Grishkan A. The cor-acohumeral ligament: anatomy of a sub-stantial but neglected structure. J BoneJoint Surg Br 1991; 73:150–153.

12. Neer CS 2nd, Satterlee CC, Dalsey RM,Flatow EL. The anatomy and potentialeffects of contracture of the coracohu-meral ligament. Clin Orthop 1992; 280:182–185.

13. Harryman DT, Sidles JA, Harris SL, Mat-sen FA. The role of rotator interval cap-sule in passive motion and stability of theshoulder. J Bone Joint Surg Am 1992; 74:53–66.

14. Vangsness CT Jr, Jorgenson SS, Watson T,Johnson DL. The origin of the long headof the biceps from the scapula and gle-noid labrum: an anatomical study of 100shoulders. J Bone Joint Surg Br 1994; 76:951–954.

15. Bennett WF. Visualization of the anat-omy of the rotator interval and bicipitalsheath. Arthroscopy 2001; 17:107–111.

16. Walch G, Nove-Josserand L, Levigne C,Renaud E. Tears of the supraspinatus ten-don with “hidden” lesions of the rotatorinterval. J Shoulder Elbow Surg 1994;3:353–360.

17. Itoi E, Berglund LJ, Grabowski JJ, NaggarL, Morrey BF, An KN. Superior-inferiorstability of the shoulder: role of the cor-acohumeral Ligament and the rotator in-

Figure 19. Extensive subscapularis tendon tear with nondislocated tendon of long head of the biceps brachii. (a, c) Transverse and (b) coronalintermediate-weighted MR images (2500/28) obtained with fat saturation. (a, b) Acute shoulder injury with “natural” arthrogram effect due tointraarticular fluid. Complete tear of subscapularis tendon (�) is visible, but long head of biceps brachii tendon (arrow) is still held in the grooveby thickened pulley ligaments (arrowhead). (c) Section cranial to a shows superior portion of lesser tuberosity covered by thickened irregular tissue(arrowhead), consistent with injured but not completely disrupted medial pulley ligament complex, with partial volume averaging of long head ofbiceps brachii tendon proximal to entrance to the groove. Lateral portion of sling appears to be injured (arrow).

Figure 20. Arthroscopically proved delamination-type tear of subscapularis tendon with ex-tremely degenerative and frayed long head of biceps brachii tendon subluxated into y-shapedsplit. (a) Transverse and (b) coronal T1-weighted MR arthrographic images (700/10) obtainedwith fat saturation after intraarticular administration of dilute gadolinium compound show splitsubscapularis tendon (�) with subluxated long head of biceps brachii tendon (black arrow). Whitearrow � bicipital groove.

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terval capsule. Mayo Clin Proc 1998; 73:508–515.

18. Field LD, Warren RF, O’Brien SJ, AltchekDW, Wickiewicz TL. Isolated closure ofrotator interval defects for shoulder insta-bility. Am J Sports Med 1995; 23:557–563.

19. Nidecker A, Guckel G, Von Hochstetter A.Imaging the long head of the biceps ten-don: a pictorial essay emphasizing mag-netic resonance. Eur J Radiol 1997; 25:177–187.

20. Itoi E, Kuechle DK, Newman SR, MorreyBF, An KN. Stabilising function of thebiceps in stable and unstable shoulders.J Bone Joint Surg Br 1993; 75:546–550.

21. Rodosky MW, Harner CD, Fu FH. The roleof the long head of the biceps muscle andsuperior glenoid labrum in anterior sta-bility of the shoulder. Am J Sports Med1994; 22:121–130.

22. Neer CS 2nd. Anterior acromioplasty forthe chronic impingement syndrome inthe shoulder: a preliminary report. J BoneJoint Surg Am 1972; 54:41–50.

23. Warner JJ, McMahon PJ. The role of thelong head of the biceps brachii tendon insuperior stability of the glenohumeraljoint. J Bone Joint Surg Am 1995; 77:366–372.

24. Ting A, Jobe FW, Barto P, et al. An EMGanalysis of the lateral biceps in shoulderswith rotator cuff tears. Presented at theThird Open Meeting of the Society ofAmerican Shoulder and Elbow Surgeons,San Francisco, Calif, January 21–22, 1987.

25. Yamaguchi K, Riew KD, Galatz LM, SymeJA. Biceps activity during shoulder mo-tion: an electromyographic analysis. ClinOrthop 1997; 336:122–129.

26. Weishaupt D, Zanetti M, Tanner A, Ger-ber C, Hodler J. Lesions of the reflectionpulley of the long biceps tendon. InvestRadiol 1999; 34:463–469.

27. Rowe CR. Recurrent transient anteriorsubluxation of the shoulder: the “deadarm” syndrome. Clin Orthop 1987; 223:11–19.

28. Rowe CR, Zarins B. Recurrent transientsubluxation of the shoulder. J Bone JointSurg Am 1981; 63:863–872.

29. Gartsman GM, Roddey TS, HammermanSM. Arthroscopic treatment of anterior-inferior glenohumeral instability: two tofive-year follow-up. J Bone Joint Surg Am2000; 82-A:991–1003.

30. Schenk TJ, Brems JJ. Multidirectional in-stability of the shoulder: pathophysiol-ogy, diagnosis, and management. J AmAcad Orthop Surg 1998; 6:65–72.

31. Selecky MT, Tibone JE, Yang BY, McMa-hon PJ, Lee TQ. Glenohumeral jointtranslation after arthroscopic thermalcapsuloplasty of the rotator interval. JShoulder Elbow Surg 2003; 12:139–143.

32. Warner JJ, Deng XH, Warren RF, TorzilliPA. Static capsuloligamentous restraintsto superior inferior translation of the gle-nohumeral joint. Am J Sports Med 1992;20:675–685.

33. Le Huec JC, Schaeverbeke T, Moinard M,et al. Traumatic tear of the rotator inter-val. J Shoulder Elbow Surg 1996; 5:41–46.

34. Sethi N, Wright R, Yamaguchi K. Disor-ders of the long head of the biceps ten-don. J Shoulder Elbow Surg 1999; 8:644–654.

35. Walch G, Nove-Josserand L, Boileau P,Levige C. Subluxations and dislocationsof the tendon of the long head of thebiceps. J Shoulder Elbow Surg 1998;7:100–108.

36. Berlemann U, Bayley I. Tenodesis of thelong head of the biceps brachii in thepainful shoulder: results in the long term.J Shoulder Elbow Surg 1995; 4:429–435.

37. Chung CB, Dwek JR, Cho GJ, Lektrakul N,Trudell D, Resnick D. Rotator cuff inter-val: evaluation with MR imaging and MRarthrography of the shoulder in 32 cadav-ers. J Comput Assist Tomogr 2000; 24:738–743.

38. Ho CP. MR. Imaging of rotator interval,long biceps and associated injuries in theoverhead-throwing athlete. Magn ResonImaging Clin N Am 1999; 7:23–37.

39. Grainger AJ, Tirman PF, Elliot JM, King-zett-Taylor A, Steinbach LS, Genant HK.MR anatomy of the subcoracoid bursaand the association of subcoracoid effu-sion with tears of the anterior rotator cuff

and the rotator interval. AJR Am J Roent-genol 2000; 174:1377–1380.

40. Farin PU, Jaroma H, Harju A, SoimakallioS. Medial displacement of the bicepsbrachii tendon: evaluation with dynamicsonography during maximal externalshoulder rotation. Radiology 1995; 195:845–848.

41. Rokito AS, Bilgen OF, Zuckerman JD,Cuomo F. Medial dislocation of the longhead of the biceps tendon: magnetic res-onance imaging evaluation. Am J Orthop1996; 25:314, 318–323.

42. Seeger LL, Lubowitz J, Thomas BJ. Casereport 815: tear of the rotator interval.Skeletal Radiol 1993; 22:615–617.

43. O’Donoghue DH. Subluxing biceps ten-don in the athlete. Clin Orthop 1982;164:26–29.

44. Zarins B, McMahon MS, Rowe CR. Diag-nosis and treatment of traumatic anteriorinstabilty of the shoulder. Clin Orthop1993; 291:75–84.

45. Boardman ND, Debski RE, Warner JJ, etal. Tensile properties of the superior gle-nohumeral ligament and coracohumeralligaments. J Shoulder Elbow Surg 1996;5:249–254.

46. Cole BJ, Rodeo SA, O’Brien SJ, et al. Theanatomy and histology of the rotator in-terval capsule of the shoulder. Clin Or-thop 2001; 390:129–137.

47. Ozaki J, Nakagawa Y, Sakurai G, Tamai S.Recalcitrant chronic adhesive capsulitisof the shoulder: role of contracture of thecoracohumeral ligament and rotator in-terval in pathogenesis and treatment.J Bone Joint Surg Am 1989; 71:1511–1515.

48. Petersson CJ. Spontaneous medial dislo-cation of the tendon of the long bicepsbrachii: an anatomic study of the preva-lence and pathomechanics. Clin Orthop1986; 211:224–227.

49. Werner A, Mueller T, Boehm D, Gohlke F.The stabilizing sling for the long head ofthe biceps tendon in the rotator cuff in-terval: a histoanatomic study. Am J SportsMed 2000; 28:28–31.

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