Shoulder Dyslexia: The Alphabet Soup Alison Nguyen 4/13/06

Mystery Cases

Case 1

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Case 3

Case 4

Shoulder Dyslexia: The Alphabet Soup

Shoulder dyslexia: addressing the endless alphabet soup Ant-inf labrum: -Bankart, Perthes, ALPSA, GLAD Inferior capsule: -HAGL, PHAGL, Axillary pouch injuries Posterior labrum: -GARD, GIRD, Kim’s lesion, Bennett lesion

Shoulder dyslexia: Part 1 Ant-Inf Labrum Glenoid labral articular disruption Torn labrum, torn periosteum Torn labrum, stripped but intact periosteum “Medialized” labrum, intact periosteum

GLAD lesion Glenoid Labral Articular Disruption Anterior-inferior labral tear involving the adjacent articular cartilage AXIAL PLANE

GLAD Clue: look for disrupted articular cartilage anterior-inferior labral tear associated with an injury to the glenoid articular cartilage. Stoller DW. MRI, Arthroscopy and Surgical Anatomy of the Joints, CD-ROM. Lippincott-Williams & Wilkins Neviaser71 first described the glenolabral articular disruption (GLAD) lesion as a superficial tear of the anteroinferior labrum with an associated injury of the adjacent glenoid articular cartilage. The lesion reportedly results from a forced adduction injury to the shoulder with the arm in abduction and external rotation. The mechanism of injury therefore is impact of the humeral head against the glenoid fossa without anterior subluxation or dislocation. This differs from the typical Bankart lesion, which results from anterior dislocation or subluxation giving rise to a tear of the anterior labroligamentous complex with resulting instability. The patient with a GLAD lesion typically has persistent anterior shoulder pain but demonstrates no evidence of instability on physical examination. Correct identification of this lesion on MRI can be helpful in planning patient management, as the treatment of choice is arthroscopic debridement of the labrum and adjacent chondral injury.71 Clue: look for disrupted articular cartilage Not associated w/ ant shoulder disloc/subluxation Mechanism: Forced adduction of shoulder in ABER position with impaction of HH against glenoid fossa

Shoulder dyslexia: Part 1 Ant-Inf Labrum Glenoid labral articular disruption Torn labrum, torn periosteum Torn labrum, stripped but intact periosteum “Medialized” labrum, intact periosteum

Normal Axial Plane Bankart Lesion Perthes Lesion ALPSA Lesion

Hill-Sachs and Bankart Lesions Figure 3. T1-weighted MR arthrograms of the right shoulder in an 18-year-old man who sustained an acute dislocation of the shoulder. A, Transverse image (570/14) shows contrast medium interposition between the glenoid rim and the detached capsulolabral complex (arrow). The lesion was correctly categorized as a Bankart lesion. B, Transverse image (570/14) at the level of the coracoid process demonstrates a complete tear of the middle glenohumeral ligament, an avulsion of the anterior labrum (thick arrow), and a Hill-Sachs fracture (thin arrow) with subjacent bone marrow edema in the posterolateral humeral head. C, Oblique sagittal image (666/14) shows extension of the anteroinferior labral injury (arrows). 18 yo w/ acute shoulder dislocation

Classic Bankart lesion (case 2) -Detached ant-inf labrum -Detached periosteum FIG. 7. Classic Bankart lesion. Axial T1-weighted image after intraarticular injection of gadolinium demonstrates the detached anterior labrum (arrow) “floating” in the anterior aspect of the joint. Note the separation of the periosteum at the level of the anterior aspect of the glenoid (arrowhead).

GLOM (glenoid labral ovoid mass) in setting of Bankart lesion Kuva 2. Magneettiartrografia, aksiaalikuva vanha Bankartin leesio, jossa labrum näkyy soikeana massana

Shoulder dyslexia: Part 1 Ant-Inf Labrum Glenoid labral articular disruption Torn labrum, torn periosteum Torn labrum, stripped but intact periosteum “Medialized” labrum, intact periosteum

Perthes Lesion Detached, labro-ligamentous complex Medial stripping of anterior scapular periosteum Figure 5. Transverse T1-weighted (650/14) MR arthrogram of the right shoulder in a 37- year-old man demonstrates detachment and anterior displacement of the labral ligamentous attachment (thick arrow). The medially stripped intact periosteum (thin arrow) is clearly delineated with contrast medium. The lesion was correctly categorized as a Perthes lesion.

Perthes Lesion Sometimes only seen on ABER position May look normal on arthroscopy FIG. 11. Perthes lesion seen only in the abduction and external rotation (ABER) position. A: Axial T1 fat-saturated image after intra-articular injection of gadolinium. Note the irregularity of the anterior labrum (arrow). B: ABER position. Note the separation of the anterior labrum from the glenoid margin (arrow).

Normal vs. Perthes lesion Axillary Figure 8 Perthes lesion. A, axial image with the patient’s arm in neutral position demonstrates a normal-appearing anteroinferior labrum (arrow). B, the same patient imaged with the arm in abduction and external rotation places traction on the anterior band of the inferior glenohumeral ligament (arrowheads) and pulls the anteroinferior labrum (arrow) away from the glenoid, allowing contrast material to extend into a superficial tear. This lesion would not have been identified without the abduction-external rotation view. A superficial labral tear was found at arthroscopy. ABER

Shoulder dyslexia: Part 1 Ant-Inf Labrum Glenoid labral articular disruption Torn labrum, torn periosteum Torn labrum, stripped but intact periosteum “Medialized” labrum, intact periosteum

ALPSA: “medialized Bankart” “Differs from the classic Bankart lesion because the avulsed anterior labroligamentous structure is pulled medially by an intact anterior scapular periosteum and eventually heals in this abnormal position, leading to an incompetent anteroinferior glenohumeral ligament. This lesion has been referred to as the medialized Bankart lesion. The significance of the ALPSA lesion to the arthroscopist is that the labrum and attached ligaments, rather than floating free, heal in an abnormal position and eventually resynovialize, and may be difficult to identify as abnormal at the time of arthroscopy”

Acute ALPSA lesion MGHL Torn labrum FIG. 8. Acute anterior labroligamentous periosteal sleeve avulsion (ALPSA) lesion. Axial T1-weighted image after intra-articular injection of gadolinium. Note the medially displaced and detached anterior labrum (open arrow). The low signal intensity structure anterior to the labrum represents the middle glenohumeral ligament (arrowhead). Medially/inferiorly displaced, detached anterior labrum Intact ant scapular periosteum

Chronic ALPSA lesion Thickening, irregularity of anterior medial aspect of capsule-periosteal junction  synovialized ALPSA lesion FIG. 9. Chronic anterior labroligamentous periosteal sleeve avulsion (ALPSA) lesion. Axial T1-weighted image after intra-articular injection of gadolinium demonstrates thickening and irregularity of the anterior medial aspect of the capsular periosteal junction representing a synovializied ALPSA lesion.

ALPSA Medially & inferiorly displaced labrum Figure 4. T1-weighted MR arthrograms of the left shoulder in a 24-year-old man with chronic shoulder instability. A, Transverse image (570/14) demonstrates medial displacement of the labral ligamentous attachment (arrow) correctly interpreted as an ALPSA lesion. B, Oblique coronal image (595/14) shows inferior displacement of the labroligamentous complex (arrow). Medially & inferiorly displaced labrum

ALPSA Clue: look for “labral mass” medial and inferior to glenoid. “MEDIALIZED BANKART LESION”

ALPSA: “Medialized” Bankart lesion (case 1)

Shoulder Dyslexia, Part II Axillary Sling CLUE: All have MR@ contrast leakage below the inferior capsule. Look for location to differentiate: anterior, axillary pouch, or posterior

HAGL PHAGL Posterior humeral avulsion of PIGHL Humeral avulsion of AIGHL BHAGL (bony avulsion of AIGHL) CLUE: arthrogram contrast extravasation at humeral neck Associated w/ subscapularis tendon tears Posterior humeral avulsion of PIGHL CLUE: arthrogram contrast extravasation at humeral neck

HAGL (case 3)

PHAGL Fig. 1A. —48-year-old female yoga instructor with long-standing shoulder pain and multidirectional instability at physical examination. Radiographic image obtained after arthrography with patient's arm in external rotation shows abnormal distribution of contrast material within axillary pouch, with contrast material (arrowheads) extending distally along humeral shaft. Coronal oblique fat-saturated fast spin-echo T1-weighted MR arthrogram (TR/TE, 900/12) shows discontinuous retracted fibers (straight arrow) of posterior band of inferior glenohumeral ligament and abnormal distribution of contrast material (curved arrow), which extends distally along humeral shaft.

Probable Axillary Pouch Injury

Shoulder Dyslexia, Part II Axillary Sling CLUE: All have MR@ contrast leakage below the inferior capsule. Look for location to differentiate: anterior, axillary pouch, or posterior

Shoulder Dyslexia: Part III Posterior Capsule/Labrum “Cyst” at jxn of cartilage + post labrum Post labrum thickening in throwing shoulder Bone & cartilage disruption at post glenoid rim

Shoulder Dyslexia: Part III Posterior Capsule/Labrum Crescentic bone at post-inf glenoid; EXTRA-articular “Cyst” at jxn of cartilage + post labrum Post labrum thickening in throwing shoulder Bone & cartilage disruption at post glenoid rim

Bennett lesion Mechanism: traction of PIGHL during deceleration phase of pitching A Bennett lesion is an extra-articular posterior capsular avulsive injury associated with a posterior labral injury and posterior undersurface rotator cuff damage. This injury is seen most commonly in baseball pitchers. The diagnosis of this lesion should raise suspicion for associated labral and rotator cuff abnormalities. The mechanism is from traction of the posterior band of the IGHL during decelerating phase of pitching. Clinically, the throwing athlete presents with posterior shoulder pain during pitching with posterior point tenderness. If left untreated, patients progress from functional to anatomic instability. Figure 4. CT detection of bony spur. CT scanning was useful to evaluate the size of the bony spur. In this case an avulsed bone fragment (arrow) was detected. PRINT EMAIL POSTERIOR CAPSULAR AND TERES MINOR DISRUPTION WITH BENNETT LESION Internal rotation Abduction Ax T1 with intraarticular contrast Sag T1 Fat Sat 47 yo patient with shoulder injury A Bennett lesion is an extra-articular posterior capsular avulsive injury associated with a posterior labral injury and posterior undersurface rotator cuff damage. This injury is seen most commonly in baseball pitchers. The diagnosis of this lesion should raise suspicion for associated labral and rotator cuff abnormalities. The mechanism is from traction of the posterior band of the IGHL during decelerating phase of pitching. Clinically, the throwing athlete presents with posterior shoulder pain during pitching with posterior point tenderness. If left untreated, patients progress from functional to anatomic instability. The Bennett lesion, as described in 1941, is a mineralization of the posterior inferior glenoid noted in overhead-throwing athletes. Bennett originally believed that the lesion was secondary to traction of the long head of the triceps muscle. Subsequent authors believe it more likely represents reactive bone formation resulting from capsular traction associated with the repetitive stresses involved with overhead throwing. In support of this is the fact that the lesion is found in the area of the attachment of the posterior band of the inferior glenohumeral ligament complex. In addition, some authors believe that impaction of the humeral head on the posterior glenoid during the abduction external rotation motion necessary for throwing may cause further irritation and growth of the lesion. Posterior shoulder instability in athletes is not common and is difficult to diagnose. Examination of athletes with this condition can show pain, instability, or both. Unless the athlete can demonstrate the instability, the diagnosis can be difficult. The abnormality can include lax glenohumeral ligaments, a torn labrum, or a bony deficiency. The glenohumeral ligaments can tear at the labral or at the humeral insertions. Humeral avulsion of the glenohumeral ligaments has been previously described in the context of anterior instability. This case shows patient with posterior instability due to an disruption of the posterior capsule in its mid portion and disruption of teres minor. The avulsion of the posterior glenohumeral ligament from the humerus is not seen.

Bennett lesion: throwing athletes (case 4) FIG. 2. Case 2. Bennett lesion. Axillary shoulder radiograph (A) and air contrast transverse computed arthrotomographic image (B) at the level of the inferior glenoid demonstrate an area of crescent-shaped mineralization (arrow) on the posteroinferior portion of the glenoid rim. From:   De Maeseneer: J Comput Assist Tomogr, Volume 22(1).January/February 1998.31-34 Case 3. Bennett lesion. A: Axillary view of the shoulder demonstrates an area of mineralization (arrow) at the posterior aspect of the glenoid rim. B: Transverse (SPGR, 60° flip angle, TR/TE 60/10) MR image demonstrates the low signal intensity crescent-shaped lesion along the posteroinferior glenoid (arrow) From:   De Maeseneer: J Comput Assist Tomogr, Volume 22(1).January/February 1998.31-34 “crescentic” bony mineralization at posterior-inferior glenoid rim EXTRA-articular posterior capsule avulsive injury Assoc w/ posterior labral tears and RCTs

Shoulder Dyslexia: Part III Posterior Capsule/Labrum Crescentic bone at post-inf glenoid; EXTRA-articular “Cyst” at jxn of cartilage + post labrum Post labrum thickening in throwing shoulder Bone & cartilage disruption at post glenoid rim

Kim’s Lesion Mechanism: force applied in posterior direction. Force exerted on PIGHL  post labral tear, propagating in medial to lateral direction Preserved chondro-labral junction. Figure 7. The MR arthrogram findings, which suggested Kim’s lesion. (A) Incomplete avulsion or cystic lesion and intact junction between the glenoid articular cartilage and posterior labrum. (B) Loss of labral height and contour. Figure 8. We hypothesize that this lesion can be generated by submaximal force in the posterior direction. (A) Posterior-directed force initially exerts on the medial part of the labral attachment where the posterior band of the inferior glenohumeral ligament attaches (arrow). This force begins the tearing of the posterior labrum at the medial portion and propagates to the lateral portion of the labrum. (B) When the magnitude of the posterior-directed force is small, detachment of the labrum is limited to the inner portion without involving the chondrolabral junction. Loss of posterior labral height & contour

Shoulder Dyslexia: Part III Posterior Capsule/Labrum Crescentic bone at post-inf glenoid; EXTRA-articular “Cyst” at jxn of cartilage + post labrum Post labrum thickening in throwing shoulder Bone & cartilage disruption at post glenoid rim

GIRD Glenoid internal rotation deficit Tight posterior capsule in the throwing shoulder (ie pitchers) MRI finding: thickening of the posterior capsule and labrum

GIRD Major League Baseball Pitcher ( San Diego Padres) Images courtesy of Arash Tehranzadeh

Shoulder Dyslexia: Part III Posterior Capsule/Labrum Crescentic bone at post-inf glenoid; EXTRA-articular “Cyst” at jxn of cartilage + post labrum Post labrum thickening in throwing shoulder Bone & cartilage disruption of post glenoid rim

GARD: glenoid articular rim divot 22 yo M w/ shoulder impaction injury while weightlifting, w/ posterior labral tear Osseous defect at posterior glenoid rim Figure 11 Posterior labral tear. A, axial T1-weighted image with fat saturation in a 27-year-old man who injured his shoulder while weightlifting demonstrates contrast material extending into a tear of the posterior labrum (white arrow). An area of cortical irregularity is also noted along the anterior humeral head, representing a reverse Hill-Sachs lesion (black arrow). B, GARD lesion: axial gradient-echo image in a 22-year-old man after an impact injury to his shoulder demonstrates a displaced posterior labral tear (large arrow) in conjunction with an osseous defect in the posterior aspect of the glenoid rim (small arrow). Arrowheads denote a small associated labral cyst. Labral cyst Displaced posterior labral tear

GARD vs GLAD Both are similar lesions in different locations!

Shoulder dyslexia: The alphabet soup Ant-inf labrum: -Bankart, Perthes, ALPSA, GLAD Inferior capsule: -HAGL, PHAGL, Axillary pouch injuries Posterior capsule/labrum: -GARD, GIRD, Kim’s lesion, Bennett lesion

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References Chung et al. AJR 2004; 183:355-359 Resnick D. Bone and Joint Imaging. John Hunter's MSK Teaching File Beltran et al. Shoulder: Labrum and Bicipital Tendon. Topics in Magnetic Resonance Imaging. 14(1): 35–50 Waldt et al. Anterior Shoulder Instability. Radiology 2005; 237:578–583 Parmar H et al: MR Arthrography in Recurrent Anterior Shoulder Instability. J Postgrad Med 2002;48:270-274 De Maeseneer: J Comput Assist Tomogr, Volume 22(1).January/February 1998.31-34 Sanders et al. The American Journal of Sports Medicine 28:414-434 (2000) Kim et al. Arthroscopic Capsulolabroplasty for Posteroinferior Multidirectional Instability of the Shoulder. The American Journal of Sports Medicine 32:594-607 (2004) Kim et al. Kim’s lesion: An incomplete and concealed avulsion of the posteroinferior labrum in posterior or multidirectional posteroinferior instability of the shoulder. Arthroscopy: The Journal of Arthroscopic & Related Surgery Volume 20, Issue 7 , September 2004, Pages 712-720 Nagakawa et al. Posterior shoulder pain. Journal of Shoulder and Elbow Surgery Volume 15, Issue 1 , January-February 2006, Pages 72-77