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Glenoid Labrum Injury MRI

Practice Essentials

The shoulder has the greatest range of motion of any joint in the body, making it tremendously versatile. This versatility makes the joint unstable and liable to injuries. In the United States, the incidence of shoulder dislocations is 23.0 per 100,000 person-years, with the highest rates in adults in their 20s.
 

Anatomically, the articulation of the large humeral head with the small glenoid cavity confers relatively little joint stability. The glenoid labrum provides attachments for the shoulder capsule and various tendons and ligaments, which contributes to shoulder stability by increasing the glenoid surface.

Normally, a delicate balance exists between the static and dynamic constraints in the shoulder. Any injury that disturbs this balance can lead to instability, progressive shoulder dysfunction, and pain. The labrum may be torn with shoulder dislocations. Activities involving overhead arm movements, especially throwing and bowling, can stress the shoulder excessively and also cause labral injury.

The subject of glenohumeral instability is complex. The methods of classification are based on the degree and direction of instability, its chronology, and its pathogenesis. The glenoid labrum plays an important role in maintaining shoulder function, and although labral injuries are relatively infrequent, when they do occur, they can incapacitate athletes. Traumatic detachment of the glenoid labrum is seen in 85% of patients after a traumatic anterior dislocation. The inferior glenohumeral ligament attached to the inferior half of the anterior glenoid labrum is the most important ligament that stabilizes the shoulder. With traumatic dislocation, the humeral head is displaced.

Imaging plays an important role in the assessment of labral injuries and includes conventional radiography and computed tomography (CT) or magnetic resonance (MR) arthrography.
Labral injuries associated with fractures and dislocations need urgent surgical attention.
Other labral injuries are initially treated in an expectant manner, with 2-4 weeks of rest and physiotherapy.

The following are some images of normal shoulder anatomy.

(Click Image to enlarge.) Line axial plane diagram

(Click Image to enlarge.) Line axial plane diagram depicts the normal insertion of the inferior glenohumeral labroligamentous complex (IGHLC) at the apex of the glenoid labrum.

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(Click Image to enlarge.) Anatomy: The diagram sho

(Click Image to enlarge.) Anatomy: The diagram shows how the trough line is formed after a posterior dislocation. AP = anteroposterior.

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Magnetic resonance arthrogram: The normal inferior

Magnetic resonance arthrogram: The normal inferior glenohumeral ligament, anterior band (arrow).

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MR arthrogram: Normal inferior glenohumeral ligame

MR arthrogram: Normal inferior glenohumeral ligament.

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Rotator Cuff Tendons

The rotator cuff tendons blend in with the capsule posteriorly, superiorly, and anteriorly. Distally, the capsule inserts into the anatomic neck of the humerus, and proximally, the capsule is attached to the scapula. The posterior proximal capsule attaches either to the labrum or to the junction of the labrum and glenoid. The anterior proximal capsule may also attach to the labrum or to the neck of the scapula or occasionally more medially to the base of the scapular neck.

The glenoid inclination refers to the relationship of the glenoid articular surface and the transverse axis of the scapula. Normally, slight retroversion of approximately 5° is present but with a range of up to 25° in retroversion and 8° in anteversion. The average retroversion of the glenoid in habitual anterior dislocations is 0.3°, and it is 10-12° in posterior dislocations. On CT scans, the glenoid inclination angle can easily be measured through the midpoint of the glenoid. However, normal and abnormal angles significantly overlap, and therefore, the measurement is clinically useful only in extreme cases.

Associated and Other Injuries

The spectrum of glenohumeral joint instability is wide, ranging from joint dislocation, which is easily recognizable on clinical examination, to transient glenohumeral joint subluxation, which may be difficult to recognize, as the joint may spontaneously relocate. This event may sometimes go unrecognized, even by the patient.

The direction in which the humeral head is subluxed is also variable and may take any direction, or it may be multidirectional. Many bony, ligamentous, tendinous, and muscle elements contribute to joint stability, although the individual contribution of these structures has long been debated. However, authorities generally agree on the important contribution of glenohumeral ligaments to joint stability despite inconsistencies in their size.

With the advent of shoulder joint arthroscopy, an increasing number of abnormalities of the various components of the glenohumeral joint have been recognized, and no longer are the depiction of a Bankart lesion and a Hill-Sachs lesion regarded as sufficient diagnostic criteria for glenohumeral instability. However, these 2 lesions remain important, as they allow for the documentation of a previous anterior glenohumeral dislocation. Hurley and Anderson found anteroinferior labral tears in 92% of shoulders with recurrent subluxation or dislocations.

Bankart lesion

Arthur Sydney Blundell described the Bankart lesion as a traumatic detachment of the glenoid labrum. This lesion is seen in more than 85% of all cases after a traumatic anterior dislocation. At the time of the original injury, the humeral head is forced against the joint capsule and inferior glenohumeral ligament, which it stretches. Then, as a result of traction, the fibrous labrum is pulled off from the inferior half of the anterior rim of the glenoid. (See the following images.)

Line diagram depicting an avulsed inferior glenohu

Line diagram depicting an avulsed inferior glenohumeral labroligamentous complex (IGHLC) associated with avulsion of the scapular periosteum in a Bankart lesion.

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Several procedures have been described in the mana

Several procedures have been described in the management of glenohumeral instability. In 1938, Bankart described an open procedure in which the deltopectoral interval is used to access the joint, incise the capsule, and then reattach the capsulolabral complex to the bony glenoid rim. This technique has been modified; bony drill holes are made in the glenoid, through which sutures are threaded to secure the labrum. A recent modification of the drill method involves modern suture anchors composed of ferromagnetic, nonferromagnetic, plastic, and bioabsorbable materials. Here, ferromagnetic sutures are seen securing the labrum to the glenoid.

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Bankart described this lesion as an unusual condition affecting individuals with epilepsy and athletes, above all football players, reporting only 27 cases in 1923-1938. How the term Bankart lesion became embedded in the radiology literature is unclear, as Bankart emphatically denied the presence of a glenoid rim fracture in any of his cases. He stated that he had never seen a recurrent dislocation associated with a glenoid fracture and went on to say that if such an association existed, it must be rare.

Hill-Sachs lesion

Harold Arthur Hill and Maurice D. Sachs were 20th-century American radiologists who described the association between an anterior dislocation of the glenohumeral joint and a compression fracture of the posterolateral aspect of the humeral head. This type of injury is caused by impaction of the humerus against the anterior rim of the glenoid cavity. (See the images below.)

Radiography: Value of the axial view; anterior dis

Radiography: Value of the axial view; anterior dislocation causing the Hill-Sachs deformity.

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Radiography: Grashey view; Hill-Sachs deformity.

Radiography: Grashey view; Hill-Sachs deformity.

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The most common method of determining the Hill-Sachs lesion is the Calandra classification, which uses arthroscopy to measure the depth of the lesion as follows
:

Grade I: Defect in articular surface that does not affect subchondral bone

Grade II: Defect includes subchondral bone

Grade III: Large defect in the subchondral bone

Superior labral, anterior and posterior lesion

A superior labral, anterior and posterior (SLAP) lesion is often seen in athletes involved with sports with repetitive overhead arm activities. The lesion affects the superior portion of the glenoid labrum and occasionally the biceps anchor. (See the following images.)

Labral tear. Sagittal view showing a superior labr

Labral tear. Sagittal view showing a superior labral, anterior and posterior (SLAP) tear.

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Superior labral, anterior and posterior (SLAP) tea

Superior labral, anterior and posterior (SLAP) tear (axial plane) in a badminton player: The lower image shows the tear in the axial plane (arrow). The tear extends to the posterior labrum,

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Labral abnormalities with posterior shoulder joint instability

Labral abnormalities are frequently seen in association with anterior instability of the shoulder joint. By contrast, relatively few labral abnormalities are seen with posterior instability. Hurley et al found no posteroinferior labral tears among 3 shoulders with posterior instability and 4 patients with multidirectional instability. Patients with posterior shoulder instability had increased glenoid retroversion when compared with an uninjured population.

Singson et al performed double-contrast CT arthrography in 54 shoulders in 53 patients with recurrent dislocation or subluxation and observed no difference in the degree or number of labral lesions between subluxations and dislocations.
However, more severe capsular lesions, subscapularis tendon tears, and widened subscapularis bursae were consistently found in patients with dislocations. Lesions of the anterior labrum in 52 (96%) of 54 cases and of the capsuloligamentous complex in 42 (78%) of 54 cases were the 2 most common abnormalities.

Rafii et al examined 60 professional and recreational athletes with CT arthrography of the shoulder and determined CT arthrography is a minimally invasive and highly accurate technique for evaluated suspected glenohumeral derangement.
The investigators noted that the extent of pathologic changes associated with instability can be determined and differentiated from other intra-articular causes of incapacity, such as labral tears caused by throwing, or degenerative changes.

Bennett lesion

The Bennett lesion represents an enthesophyte arising from the posterior portion of the glenoid rim, which is commonly seen in baseball pitchers. The posterior labrocapsular periosteal sleeve avulsion (POLPSA) lesion is an abnormality that can be associated with posterior instability. It differs from a reverse Bankart lesion in that the periosteum, although detached, remains intact with the posterior capsule and detached posterior labrum. This lesion may represent an acute form of a Bennett lesion.

POLPSA lesion

Yu et al used MRI to examine 6 male athletes aged 19-43 years with POLPSA lesions and found that the size of the periosteal sleeve and redundant joint recess was variable.
Fibrous proliferation was noted arthroscopically beneath the sleeve in 4 shoulders. Although the posterior labrum was detached in all studies, only 1 labrum had a tear, whereas 2 showed marked degeneration.

Perilabral ganglion cyst

A perilabral ganglion cyst is often associated with a labral tear.

Anterior labroligamentous periosteal sleeve avulsion

The anterior labroligamentous periosteal sleeve avulsion (ALPSA) lesion is seen in association with recurrent anterior glenohumeral dislocation usually due to an incompetent anterior portion of the inferior glenohumeral ligament complex. (See the image below.)

(Click Image to enlarge.) Line diagram depicting a

(Click Image to enlarge.) Line diagram depicting an anterior labral ligamentous periosteal sleeve avulsion (ALPSA).

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Anterior labroligamentous periosteal sleeve avulsi

Anterior labroligamentous periosteal sleeve avulsion (ALPSA).

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Humeral avulsion of the glenohumeral ligament

The humeral avulsion of the glenohumeral ligament (HAGL) lesion is also associated with recurrent anterior glenohumeral instability, but it is generally seen in older individuals. A HAGL lesion becomes a bony HAGL (BHAGL) lesion when, in addition, a bone fragment is avulsed from the humeral insertion of the inferior glenohumeral complex.

Glenolabral articular disruption

A glenolabral articular disruption (GLAD) occurs with a tear of the anteroinferior portion of the labrum and avulsion of articular cartilage of the glenoid fossa and has no association with glenohumeral joint instability (see the images below).

Line diagram depicting a glenolabral articular dis

Line diagram depicting a glenolabral articular disruption (GLAD) lesion.

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GLAD (glenoid labral articular disruption), associ

GLAD (glenoid labral articular disruption), associated with anterior labral tear.

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Arthroscopy has depicted many normal variants within the glenohumeral joint leading to the introduction of many terms and acronyms. A sublabral foramen is being increasingly recognized as a normal anatomic variant. This foramen is placed between the anterosuperior parts of the glenoid labrum and the articular cartilage of the glenoid cavity. In up to 18% of patients, normal clefts (eg, sublabral holes) can be seen, and in less than 6%, other rare variations (eg, Buford complex) are seen. A Buford complex is a cordlike middle glenohumeral ligament associated with absence of the anterosuperior portion of the glenoid labrum.

Preferred Examination

Controversy exists among orthopedic surgeons regarding the role of imaging in glenohumeral instability in all patients. Some argue that arthroscopy improves the diagnostic yield and also serves as a therapeutic tool. However, arthroscopy is invasive, and many orthopedic surgeons concede that an accurate diagnosis of virtually any symptomatic problem involving the shoulder joint is needed before therapeutic intervention is undertaken.

Because most shoulder instabilities can be diagnosed on the basis of the patient’s history, physical findings, and conventional radiographs, the use of MRI solely to diagnose instability appears unwarranted. Although glenohumeral instability and rotator cuff disorders were once thought to be mutually exclusive, this is no longer considered to be true. Many authors have shown that patients who have disease of the rotator cuff or symptoms of impingement have associated shoulder joint instability. MRI is the imaging study of choice for assessing rotator cuff problems.

Two categories of patients have been described: (1) patients in whom the clinical diagnosis is certain and who can be referred for arthroscopy without any form of imaging and (2) patients in whom the clinical diagnosis is uncertain and who should be referred for imaging of the shoulder joint.

Radiographic studies may be undertaken first and should include special views to delineate specific lesions, such as the Bankart lesion and the Hill-Sachs defect. MRI offers several advantages, including its ability to depict other abnormalities that may mimic shoulder instability on clinical examination. This information is of importance to the orthopedic surgeon, as he or she may alter the treatment (eg, arthroscopic vs open surgery) accordingly. The deficiencies of standard MRI in depicting lesions associated with glenohumeral instability have led to the increasing use of arthrographic techniques. (See the images below.)

Radiography: Value of the axial view; anterior dis

Radiography: Value of the axial view; anterior dislocation causing the Hill-Sachs deformity.

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Radiography: Grashey view; Hill-Sachs deformity.

Radiography: Grashey view; Hill-Sachs deformity.

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Shoulder computed tomography scan: Posterior dislo

Shoulder computed tomography scan: Posterior dislocation; Reverse Hill-Sachs deformity.

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Arthrography may be carried out in conjunction with CT scanning or MRI. Both of these techniques improve delineation of the capsular attachments, the labrum and glenohumeral ligaments, as compared with standard CT scanning or MRI. Because soft-tissue contrast is better with MRI than with CT scanning, MRI is the preferred arthrographic technique. (See the following MR arthrograms.)

Magnetic resonance arthrogram: The normal inferior

Magnetic resonance arthrogram: The normal inferior glenohumeral ligament, anterior band (arrow).

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MR arthrogram: Normal inferior glenohumeral ligame

MR arthrogram: Normal inferior glenohumeral ligament.

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Magnetic resonance arthrogram: Anteroinferior labr

Magnetic resonance arthrogram: Anteroinferior labral tear following recurrent anterior dislocation.

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Two techniques are used in MR arthrography: (1) the direct method in which a gadolinium-based contrast agent, an iodinated contrast agent, or saline is injected into the joint space, and (2) the indirect method in which an intravenous injection of gadolinium-based contrast agent is given and in which delayed images are obtained at 20 minutes with or without shoulder exercise. Direct MR arthrography improves definition, but it is invasive and labor intensive for the radiologist, although it is safe.

Limitations of Techniques

MRI is expensive and has limitations associated with metallic implants, certain cardiac pacemakers, ferromagnetic foreign bodies, and claustrophobia. Although standard MRI and CT and MR arthrography allow for an assessment of the labrum, the process is complicated by the considerable variation in the size and morphology of the labrum in asymptomatic individuals. Variations in the signal intensity of the labrum and surrounding structures, such as the glenohumeral ligaments and the long biceps tendon, are also seen in asymptomatic individuals; these variations are further sources of false-positive diagnoses.

Most of the anatomic variants and lesions can be depicted at arthroscopy, but whether MRI can depict all of these is unclear. The presence of fluid in the glenohumeral joint helps in identifying these variants and pathologic lesions. Therefore, standard MRI performed in patients with a history of glenohumeral instability with no associated joint effusion is not a reliable test for these variations and pathologies.

Stetson and Templin compared the results of the crank test, the O’Brien test, and routine MRI in the diagnosis of labral tears and found that MRI had a positive predictive value of 63%, specificity of 92%, sensitivity of 42%, and negative predictive value of 83%.
However, the O’Brien and crank tests did not provide sensitive clinical indicators for detecting glenoid labral tears and other tears of the anterior and posterior labrum. Results were often falsely positive for patients with other shoulder conditions, including impingement and rotator cuff tears.

Special Concerns

Imaging techniques have both false-positive and false-negative rates; moreover, there are normal variants that can be confused with pathology. The radiologist needs to be aware of the potential pitfalls. Familiarity with the limitations of techniques and normal anatomic variants is therefore important. Potential problems associated with arthrography include discomfort to patients, risk of septic arthritis, and the need for contrast administration.

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