Anterior Labroligamentous Complex Injuries



Anterior Labroligamentous Complex Injuries


Julia Crim, MD



TERMINOLOGY


Abbreviations and Synonyms



  • Anterior labroperiosteal sleeve avulsion (ALPSA)


  • Coracohumeral ligament (CHL)


  • Glenolabral articular disruption (GLAD)


  • Humeral avulsion of inferior glenohumeral ligament (HAGL)



    • By convention, term refers to anterior band of inferior glenohumeral ligament


  • Inferior glenohumeral ligament (IGHL)


  • Middle glenohumeral ligament (MGHL)


  • Reverse HAGL (RHAGL), avulsion of posterior band of inferior glenohumeral ligament


  • Superior glenohumeral ligament (SGHL)


  • Superior labrum tear from anterior to posterior (SLAP)



    • By definition involves biceps anchor


    • May propagate to involve anterior &/or posterior labrum


Definitions



  • Injury to anterior labrum &/or anterior glenohumeral ligaments


  • Multiple different patterns of injury are distinguished


IMAGING FINDINGS


General Features



  • Location



    • Labrum, capsule, juxtalabral cartilage, and anterior glenohumeral ligaments are all vulnerable to injury



      • Specific injuries are distinguished as described below


      • May have similar signs & symptoms and conventional MR appearance


      • Can usually be distinguished from each other by MR arthrography


    • Most commonly involve anteroinferior quadrant



      • Exception: SLAP tears often extend into anterosuperior quadrant and may spare anteroinferior labrum


Imaging Recommendations



  • Best imaging tool: MR arthrography


  • Protocol advice



    • Injection should be performed from posterior approach



      • Anterior approach can result in contrast in ligaments, mimicking tear


    • FOV 15-16 cm


    • Axial T1WI FS


    • Axial T2WI FS


    • Coronal oblique T1WI FS


    • Sagittal oblique PD WI FS


    • Some radiologists add abduction external rotation (ABER) positioning


MR Findings



  • Labral tear



    • Anterior labrum is uncommonly torn without other injuries also being present



      • Most commonly associated with injury of anterior ligaments or SLAP tear


    • Key MR arthrography features



      • Linear high signal intensity extends to free edge of labrum


      • Must see on at least 2 images to diagnose tear


      • Complex signal in nondisplaced labrum usually degenerative in origin


  • Bankart lesion



    • Avulsion of anterior labrum plus



      • Tear of glenoid attachment of inferior glenohumeral ligament (anterior band) at glenoid attachment plus


      • Tear of anterior glenoid periosteum


      • Labrum and IGHL are displaced from glenoid, distinguishing this from ALPSA


    • Key MR arthrography features



      • Anterior ± inferior displacement of labrum and IGHL


      • Contrast extends between glenoid and labrum and IGHL


      • In chronic injuries, contrast may not extend into tear


  • Bony Bankart lesion



    • Fracture of anteroinferior glenoid plus



      • Tear of glenoid attachment of inferior glenohumeral ligament (anterior band) at glenoid attachment


    • Large bony Bankart fragment may alter glenoid shape from oval to “inverted pear”



      • High risk of recurrent dislocation


    • Key MR arthrography features



      • Bankart fracture extends obliquely through anterior margin of glenoid, perpendicular to joint surface


      • Small bony fracture can be difficult to distinguish from labral avulsion since both are low signal on MR


      • Evaluate contour of glenoid in axial plane, look for disruption of normal triangular anterior margin


  • Perthes lesion



    • Avulsion of labrum plus



      • Stripping of anterior periosteum adjacent to labral avulsion


      • Periosteum remains continuous medially


    • IGHL intact


    • Key MR arthrography features



      • Labrum displaced anteriorly


      • On axial images, see periosteum as thin diagonal line adjacent to anterior margin glenoid neck


      • Extends from displaced labrum medially to attach to glenoid neck


  • ALPSA



    • Avulsion of labrum plus



      • Tear of glenoid attachment of inferior glenohumeral ligament (anterior band) at glenoid attachment


    • Periosteum remains intact



      • Distinguishes this lesion from Bankart and Perthes lesions


    • Key MR arthrography features




      • Labrum displaced medially and inferiorly onto anterior margin of glenoid neck (normally sits on articular surface of glenoid)


      • Labrum may have normal triangular contour


      • Contrast does not extend between labrum and glenoid


      • Labrum may appear absent on axial images because of inferior displacement


      • Inferior glenohumeral ligament attachment to labrum normal


  • HAGL



    • Tear of IGHL away from glenoid origin



      • Term used for midsubstance tears as well as tears at humeral insertion


    • May occur in conjunction with MGHL tear


    • Key MR arthrography features



      • Contrast extends through IGHL either in midsubstance or humeral attachment


      • IGHL fibers are wavy and discontinuous


      • Usually best seen on coronal oblique images


    • Pitfall: Contour of axillary pouch changes with rotation and degree of distention


    • Pitfall: May see IGHL as separate structure posterior to anterior joint capsule in distended joint


  • GLAD



    • Labrum avulsed together with juxtalabral cartilage


    • Not associated with shoulder instability


    • Key MR arthrography features



      • Labrum displaced from glenoid


      • Hyaline cartilage fragment attached to labrum


      • Hyaline cartilage defect seen in juxtalabral articular surface


  • MGHL tear



    • Usually torn in combination with IGHL tear


    • Key MR arthrography features



      • Look on axial, sagittal oblique images for discontinuity of fibers


      • Tear may occur at origin or midsubstance


DIFFERENTIAL DIAGNOSIS


Labral Degeneration



  • Very common after age 40


  • Seen at a younger age in athletes, related to swimming or overhead throwing


  • Key MR arthrography features



    • Complex or amorphous high signal intensity in labrum


    • Decreased size of labrum



      • Normally anterior labrum is larger than posterior


Capsular Laxity



  • Causes multidirectional instability


  • Clinical diagnosis


  • Overdistention of joint with contrast may mimic capsular laxity on MR arthrography


  • Key MR arthrography features



    • Capacious joint recesses


    • MGHL sometimes absent


    • No accepted criteria on MR arthrography for diagnosis


  • Secondary features: Labral degeneration and premature osteoarthritis


Sublabral Window



  • Normal variant


  • Present in anterosuperior quadrant of labrum


  • Key MR arthrography features



    • Does not extend below coracoid


    • Does not extend posterior to biceps anchor


    • Smoothly marginated


Buford Complex



  • Normal variant


  • Associated with increased risk of SLAP tears


  • Key MR arthrography features



    • Cord-like middle glenohumeral ligament


    • Absent or diminutive anterosuperior labrum


PATHOLOGY


General Features



  • Etiology



    • Stability of shoulder highly dependent on glenohumeral ligaments


    • Degree of contribution by labrum to stability is debated


    • Injuries can occur with shoulder dislocation or other mechanisms


    • Anterior shoulder dislocation



      • Variety of injury patterns occurs in anterior labroligamentous complex


      • Usually causes injury to labrum plus ligaments: Bankart, Perthes, ALPSA


      • May cause isolated ligamentous injury: HAGL, MGHL tear


      • Most dislocations are anteroinferior


      • Pure anterior dislocation may cause MGHL tear without IGHL tear


    • Inferior shoulder dislocation



      • Uncommon pattern of injury


      • Causes tear of IGHL, inferior labrum


      • Hill-Sachs lesion absent


    • Forced adduction



      • When shoulder is abducted, externally rotated


      • Causes GLAD lesion


    • Forced hyperextension



      • When shoulder is in neutral rotation


      • Causes isolated MGHL tear


    • Repeated overhead activity



      • Causes isolated MGHL tear or anterior labral tear


      • Also causes rotator interval injury (discussed in chapter on shoulder capsule injuries)


      • Also causes SLAP tear


  • Associated abnormalities



    • Clinical shoulder instability



      • Usually seen with Bankart, Perthes, ALPSA, HAGL, MGHL tear


    • Recurrent shoulder dislocation



      • Risk increases with large Hill-Sachs &/or bony Bankart lesions


    • Hill-Sachs lesion




      • Wedge-shaped osteochondral depression fracture of posterior superior humeral head


      • Located posterior, superior, lateral aspect of humeral head


      • Seen with Bankart, Perthes, ALPSA, HAGL lesions


      • Indicates prior anterior dislocation


    • Cartilage injury



      • Cartilage sheared from posterior superior humeral head OR


      • Glenoid articular surface


    • Intraarticular loose bodies



      • Shear injury may dislodge cartilage fragments


      • Often migrate to subscapularis or axillary recess


    • SLAP tear



      • Tear of superior labrum involving biceps anchor


      • Often propagates into anterior labrum


    • Rotator cuff tear



      • Occurs with shoulder dislocation in older individuals (usually > age 40)


      • May involve subscapularis, supraspinatus or infraspinatus tendons


    • Rotator interval tear



      • Often seen with inferior dislocation


    • Axillary nerve stretch injury



      • Occurs with anterior dislocation


CLINICAL ISSUES


Presentation



  • Most common signs/symptoms



    • Anterior shoulder pain


    • Subjective instability


    • Recurrent dislocations


  • Other signs/symptoms: Clicking, catching, and locking in joint


Demographics



  • Age: Young adults


  • Gender: More common in men


Natural History & Prognosis



  • Bankart, Perthes, ALPSA and HAGL lesions cause anterior instability



    • Remember key features with mnemonic TUBS



      • Traumatic


      • Unilateral


      • Bankart lesion


      • Surgery indicated


  • Bony Bankart if large may need bony augmentation to restore glenoid contour



    • Often use bone graft from coracoid process


  • Capsular laxity causes multidirectional instability



    • Remember key features with mnemonic AMBRI



      • Atraumatic


      • Multidirectional


      • Bilateral


      • Rehabilitation is primary method of treatment


      • Inferior capsular shift can be used for surgical treatment


Treatment



  • Anterior instability treated with repair of labroligamentous complex



    • Usually performed arthroscopically


  • GLAD lesions not associated with shoulder instability but can be debrided


  • Multidirectional instability treated with capsular plication


  • Thermal capsulorrhaphy has been used for capsular shrinkage



    • Causes capsular atrophy and chondrolysis


DIAGNOSTIC CHECKLIST


Image Interpretation Pearls



  • Good joint distention is key to identifying avulsion of labrum &/or ligaments


  • ALPSA, HAGL sometimes identifiable only on coronal images


  • Axial images are mainstay for other injuries listed above



    • Coronal and sagittal images used for confirmation


  • Hill-Sachs lesions often missed when small



    • On axial images, look at and above coracoid process


    • When present, have high suspicion for anterior labroligamentous complex injuries


  • Evaluate contour of glenoid on sagittal images to distinguish between bony and non-bony Bankart lesions



SELECTED REFERENCES

1. Waldt S et al: Anterior shoulder instability: accuracy of MR arthrography in the classification of anteroinferior labroligamentous injuries. Radiology. 237(2):578-83, 2005

2. Bui-Mansfield LT et al: Humeral avulsions of the glenohumeral ligament: imaging features and a review of the literature. AJR Am J Roentgenol. 179(3):649-55, 2002

3. Burkart AC et al: Anatomy and function of the glenohumeral ligaments in anterior shoulder instability. Clin Orthop Relat Res. (400):32-9, 2002

4. Wischer TK et al: Perthes lesion (a variant of the Bankart lesion): MR imaging and MR arthrographic findings with surgical correlation. AJR Am J Roentgenol. 178(1):233-7, 2002

5. Savoie FH 3rd et al: Straight anterior instability: Lesions of the middle glenohumeral ligament. Arthroscopy. 17(3):229-235, 2001


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Sep 18, 2016 | Posted by in GENERAL RADIOLOGY | Comments Off on Anterior Labroligamentous Complex Injuries

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