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Shoulder, Glenoid Labrum Injury (MRI)
Updated: Jan 30, 2009
Introduction
Background
The shoulder is the most unstable joint in the animal kingdom. In 1986, Calvin proposed a theory for why humans developed this evolutionary liability. He postulated that the ability to throw objects was a major contribution to the evolution of Homo sapiens. Our ancestors used the act of throwing rocks while hunting animals. Calvin explains that during the rapid development of the human brain, it acquired a large number of neurons to cope with a large range of shoulder movement to achieve accurate throwing. It is this range of motion that makes the joint unstable.
(Click Image to enlarge.) Line axial plane diagram depicts the normal insertion of the inferior glenohumeral labraligamentous complex (IGHLC) at the apex of the glenoid labrum.
Anatomically, the articulation of the large humeral head with the small glenoid cavity confers relatively little joint stability. Shoulder joint instability was known to Hippocrates, and he proposed a surgical treatment for it. The glenoid labrum provides attachments for the shoulder capsule and various tendons and ligaments, which contributed to shoulder stability by increasing the glenoid surface. 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.
In 1923, Bankart described the "essential lesion" — that is, a single abnormality that causes recurrent instability of the shoulder joint. Initially, he stated that the essential feature is the detachment of the capsule from the labrum. In 1938, he modified his thinking, suggesting that the labrum shears off from its bony attachment at the glenoid rim. He proposed that these lesions be treated by reattaching the labrum to the bone.
Labrum injuries are common in association with glenohumeral joint instability. 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. Labral injuries may cause poorly localized pain, which is made worse by overhead and behind-the-back motions and by popping, catching, or grinding motions.
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.1 Other labral injuries are initially treated in an expectant manner, with 2-4 weeks of rest and physiotherapy. However, if symptoms remain unresolved, further investigations are generally carried out.
Pathophysiology
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. 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. This balance is particularly important in athletes who engage in throwing and other overhead arm motions and who require a strong, stable shoulder to compete.2
The glenoid labrum plays an important role in maintaining shoulder function, and though 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.
Mechanisms of injury
The most common mechanism of injury to the glenoid labrum is acute and chronic excessive traction and compression. Excessive inferior traction may occur as a result of activities such as carrying, dropping, or catching a heavy object, and excessive superior traction may be caused by activities such as weight lifting. Injuries related to traction are common in overhead athletes as a result of the chronic repetitive overload to the shoulder. Pitchers, swimmers, and tennis players are particularly at risk for labral injuries, as compared with other athletes. Compression injuries may be caused by a fall on an outstretched arm with the shoulder forward flexed and externally rotated.
Chronic overuse and age-related degenerative changes are included in the spectrum of labral injuries. When the pathogenesis of labral injuries is studied, in athletes it is worthwhile to look at the mechanism of throwing motion. The act of throwing involves the abduction of the arm about 100° in association with 175° external rotation. Scapulothoracic motion and trunk extension actively contribute to the act of throwing. In the follow-through phase of throwing, the arm internally rotates up to 105°. In addition, the speed of arm rotation has been calculated at an astonishing 7000°/second. These forces impose tremendous torque on the shoulder, and the forces are modulated and controlled by the surrounding muscles. Any weakness of the surrounding tissues or unusual abrupt forces may result in labral injuries.
Associated and other injuries
Labral injuries are common in association with glenohumeral joint instability. The methods of classification are based on the degree and direction of instability and its pathogenesis. 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, though 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.3,4
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. 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.
Radiography: Value of the axial view; anterior dislocation causing the Hill-Sachs deformity.
Radiography: Grashey view; Hill-Sachs deformity.
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.
Labral tear- Sagittal view showing a SLAP tear.
Slap tear (axial plane): SLAP tear in a badminton player. The lower image shows the tear in the axial plane(arrow). The tear extends to the posterior labrum,
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 (P <.05).3
Altchek et al retrospectively examined 40 patients who underwent arthroscopic labral debridement of the shoulder. All patients were active participants in sports involving use of the shoulder. All patients presented with shoulder pain. Only 40% had distinct glenohumeral instability on examination. Ten patients had anterosuperior labral tears, 20 had anteroinferior labral tears or detachments, and 10 had posteroinferior labral tears or detachments.5
Singson et al performed double-contrast CT arthrography in 54 shoulders in 53 patients with recurrent dislocation or subluxation to detect responsible underlying bony or soft tissue abnormalities. 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. They 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.6
Rafii et al examined 60 professional and recreational athletes (46 men, 14 women; age range, 15-60 y; mean age, 32 y) with CT arthrography of the shoulder to evaluate suspected shoulder joint derangement. All had persistent pain that interfered with their sports activity and that was resistant to conservative treatment. Seventeen patients had shoulder instability based on clinical manifestations and CT arthrographic findings. An additional 5 patients were considered to have an unobtrusive degree of anterior joint laxity on the basis of clinical manifestations and CT arthrographic findings.7
Twenty patients with anterior instability had an anteroinferior tear or detachment of the glenoid labrum, as well as some violation of the insertion of the joint capsule onto the scapula. Those with posterior instability (2 patients) had a combination of labral and capsular tears. Two other major patterns of labral tears, both unaffiliated with shoulder instability, were identified. These included total or partial detachment of superior segments of the labrum and anterior labral tears at the midglenoid level. Moreover, various degrees of labral attenuation (or, less often, enlargement), osteophyte formation, and alterations in articular cartilage were observed.
Bennett lesion
The Bennett lesion represents an entheseophyte 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, though 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 examined 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, while 2 showed marked degeneration.8
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.
Anterior labroligamentous periosteal sleeve avulsion (ALPSA).
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 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.
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.
Frequency
United States
Shoulder instability is an increasingly recognized trauma in young athletes, though its exact incidence is difficult to determine. Shoulder injuries reportedly account for 4-8% of all injuries in an active population. Figures from the American Academy of Orthopaedic Surgeons show that more than 4 million people in the United States seek medical care each year for shoulder sprain, strain, or dislocation. Each year, shoulder problems account for about 1.5 million visits to orthopedic surgeons.
Hill-Sachs lesions occur in more than 50% of patients with primary dislocation.
The incidence of recurrent dislocations decreases with advancing age. Associated rotator cuff tears are seen in 50% of patients aged 40 years or younger and in 80% of those older than 60 years. Associated vascular injuries also increase in frequency with advancing age. Neurologic injury related to axillary neuropathy occurs in 20% of patients at 10 years after dislocation.
International
There are no data to suggest that the frequency of glenoid labrum injury internationally is at variance with that in the US.
Mortality/Morbidity
Although there is no mortality from labral tears, shoulder instability has a significant impact in young patients, especially in professional athletes. Evidence suggests that primary repair at the time of injury prevents recurrence.
Race
There is no racial glenoid labrum injury predilection.
Age
Glenoid labrum injury is an adult affliction and appears to be common in young adults in the athletic age group, although older people may also be affected. The injury is rare in children.
Anatomy
Shoulder joint arthroscopy and MRI have a made an outstanding contribution to our understanding of the clinical anatomy of the shoulder joint.
Glenoid labrum
The glenoid labrum is composed of circularly arranged collagenous fibers attached to the osseous margin of the glenoid by a fibrocartilaginous transitional zone. The cranial part of the labrum is more compact than the caudal one. It is also connected to the joint capsule and the integrated ligaments. It is triangular on section; the base is fixed to the circumference of the bony glenoid cavity, while the free edge is thin and sharp.
(Click Image to enlarge.) Anatomy: The diagram shows how the trough line is formed after a posterior dislocation.
(Click Image to enlarge.) Line axial plane diagram depicts the normal insertion of the inferior glenohumeral labraligamentous complex (IGHLC) at the apex of the glenoid labrum.
The labrum varies in size and shape and has a wedge-shaped appearance on cross-section, similar to the appearance of the meniscus. The labrum has a rich vascular supply to all but its superior aspect. It deepens the articular cavity and protects the edges of the bone. The form of the labral attachment to the edge of the glenoid varies.
The attachment may be meniscoid with a free labrum edge that extends over the rim of the glenoid onto the articular surface. This anatomic variant may mimic a labral tear on arthroscopy. More often, the labral attachment is continuous with the edge of the glenoid and blends directly into the articular surface.
The labrum increases the superoinferior diameter of the glenoid by 75% and the anteroposterior (AP) diameter by 50%. It is continuous above with the tendon of the long head of the biceps brachii muscle, which blends with the fibrous tissue of the labrum. Besides increasing the area and depth of the glenoid, the labrum serves as the primary attachment site for the shoulder capsule and glenohumeral ligaments.
The primary function of these ligaments is to stabilize the shoulder, especially at the extremes of motion. The superior rim of the glenoid labrum also serves as the attachment site for the tendon of the long head of the biceps muscle. This site may be more vulnerable to injury and age-related degenerative changes than the rest of the labrum because of a relatively poor blood supply. A large redundant capsule surrounds the shoulder joint.
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 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.
Presentation
Presentation
Labral injuries often occur in association with other shoulder pathology, making the diagnosis challenging. Careful history taking and thorough physical examination are essential to diagnose labral injuries on clinical grounds. A labrum injury should always be suspected in patients with a history of shoulder instability, either dislocation or subluxation, or a traction or compression injury to the shoulder.
Often, symptoms related to shoulder instability and labral injuries are vague and include poorly localized shoulder pain, which is often exacerbated by overhead and behind-the-back arm motions. Patients may also describe mechanical symptoms, such as popping, catching, or grinding. Physical findings are also subtle and nonspecific, adding to the difficulty of diagnosis. The patient may describe pain in the shoulder with resisted biceps contraction. Tenderness directly over the anterosuperior glenohumeral joint is not uncommon.
Clinical tests
Several clinical tests have been devised with varying degrees of sensitivity and specificity in the diagnosis of labral injuries. One test is not necessarily more reliable than the others, and the findings of all aid the clinical diagnosis. These tests include the following: anterior slide test; O'Brien active compression test; apprehension test; Jobe relocation test, or Fowler test; anterior release test; SLAP test; crank test; and pain provocation test.9,10,11
In a meta-analysis study by Meserve et al comparing accuracies of active compression, anterior slide, crank, and Speed tests for superior labral anterior-posterior lesions, the results showed that the anterior slide test was significantly inferior to that of the other tests. The authors suggested that when a labral lesion is suspected, the active compression test should be used first, followed in order by the crank and Speed tests.9
Anterior slide test
Kibler published the first report of a diagnostic clinical test, the anterior slide test, which has a sensitivity of 78% and specificity of 91.5%. Patients can be examined either standing or sitting, with their hands on their hips with the thumbs pointing posteriorly. One of the examiner's hands is placed on the top of the patient's shoulder from behind, with the tip of his or her index finger extending over the anterior aspect of the acromion at the glenohumeral joint. The examiner's other hand is placed behind the patient's elbow, and a forward and slightly superiorly directed force is applied to the elbow and upper arm. The patient is asked to push back against this force.12
Pain localized to the front of the shoulder under the examiner's hand, along with a click in the same area, is considered to be a positive result. The result is also considered positive if the maneuver reproduces the symptoms that occur during overhead activity. The test is a useful addition to clinical tests as an aid to diagnosis, but it is not completely reliable when used alone.
O'Brien active compression test
O'Brien et al described a test to distinguish superior labral and acromioclavicular abnormalities. The test is carried out with the examining clinician standing behind the patient. The patient is asked to flex the symptomatic arm to 90° with the elbow in full extension. The patient is asked to medially adduct the arm 10-15°. The arm is internally rotated so that the thumb points downward. The clinician then applies a downward force to the arm. With the arm held in the same position, the palm is fully supinated, and the procedure is repeated.13
The result is positive if pain is elicited with the first maneuver and reduced with the second maneuver. Pain localized to the acromioclavicular joint is diagnostic of acromioclavicular joint abnormality. Pain or painful clicking described as being within the glenohumeral joint itself is indicative of a labral abnormality. The test has a sensitivity of 100% and a specificity of 99% for labral abnormalities. For the acromioclavicular joint, a sensitivity of 100% and a specificity of 97% have been reported.
Apprehension test
The apprehension test is performed to evaluate chronic anterior shoulder dislocations. The shoulder is externally rotated with the elbow flexed to 90° in an abducted position.
The result is positive when the patient feels extreme discomfort and expresses apprehension as the head of the humerus rocks to the edge of the glenoid. This test can be performed for anterior apprehension (with the arm in an abducted, externally rotated position) and for posterior apprehension (with the elbow flexed to 90°, the shoulder flexed to 90°, and pressure applied to the elbow, forcing the humeral head posteriorly so that it is against the posterior edge of the glenoid labrum.)
Jobe relocation test, or Fowler test
The Jobe relocation test, or Fowler test, can be carried out in conjunction with the apprehension test. With the patient's shoulder abducted and externally rotated, the head of the humerus is pushed from anterior to posterior. The test is deemed positive if this relocates or relieves the patient's discomfort. The test is best when performed with the patient in the supine position.
Anterior release test
Gross and Distefano described the anterior release test to identify occult instability. The test is performed with the patient in the supine position. The symptomatic shoulder is placed over the edge of the examining couch. The arm is abducted 90° while the clinician applies a posteriorly directed force on the patient's humeral head with his or her hand. While the posterior force is maintained, the arm is brought into the extreme of external rotation. The humeral head is then released.
The result is deemed positive if the patient experiences a sudden pain or a distinct increase in pain or if the patient states that his or her symptoms have been reproduced. Sensitivity and specificity have been reported as 92% and 89%, respectively.
SLAP tests
Snyder et al first classified the SLAP lesions in light of the first tests for clinical diagnosis. Since then, a number of alternative tests have been described to determine this lesion. The Snyder biceps tension and the compression-rotation tests are useful additional diagnostic tests. The compression-rotation test is performed with the patient supine, the shoulder abducted at 90°, and the elbow flexed at 90°. A compression force is applied to the humerus, which is then rotated, in an attempt to trap the torn labrum. Labral tears may be felt to catch and snap during the test, akin to the analogous finding on the MacMurray test for meniscal tears in the knee joint. The sensitivity and specificity of these tests are unknown.14
Crank test
Liu described the crank test. This test is performed with the patient in the upright position with the arm elevated at 160° in the scapular plane. Joint load is applied along the axis of the humerus with 1 hand, while the other hand performs humeral rotation.
The result is deemed positive when pain is elicited during the maneuver, with or without a click or reproduction of the symptoms. The patient usually feels pain or a catching sensation during athletic or work activities. This test should be repeated with the patient in the supine position, in which the patient is more relaxed. Frequently, if the crank test result is positive in the upright position, it is also positive in the supine position. The sensitivity is 91%, and the specificity is 93%.
Pain provocation test
Mimori et al described another SLAP pain provocative test in 1999. The test is performed with the patient in the sitting position. During the procedure, the abduction angle of the upper arm is maintained at 90-100°, and the shoulder is rotated externally by the clinician. This test is similar to the anterior apprehension test. This pain provocation test is performed with the forearm in 2 positions: maximum pronation and maximum supination.
The result is considered positive for a superior labral tear if pain is provoked only when the forearm is in the pronated position or if pain is more severe in this position than with the forearm supinated.
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.
Radiography: Value of the axial view; anterior dislocation causing the Hill-Sachs deformity.
Radiography: Grashey view; Hill-Sachs deformity.
Shoulder CT scan: Posterior dislocation; Reverse Hill-Sachs deformity.
Arthrography may be carried out in conjunction with CT or MRI. Both of these techniques improve delineation of the capsular attachments, the labrum and glenohumeral ligaments, as compared with standard CT or MRI. Because soft tissue contrast is better with MRI than with CT, MRI is the preferred arthrographic technique.
MR arthrogram: Normal inferior glenohumeral ligament.
MR arthrogram: Anteroinferior labral tear following recurrent anterior dislocation.
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, though 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. They concluded that 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.15
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Further Reading
Guidelines:
The diagnosis and management of soft tissue shoulder injuries and related disorders. New Zealand Guidelines Group - Private Nonprofit Organization. 2004. 66 pages. NGC:003865
ACR Appropriateness Criteria® shoulder trauma. American College of Radiology - Medical Specialty Society. 1995 (revised 2005). 6 pages. NGC:004632
Clinical studies:
Arthroscopic Versus Open Stabilization for Traumatic Shoulder Instability
Shoulder Rotational Flexibility and Throwing Arm Injuries of Baseball Pitchers
SLAP Lesions; a Comparison of Conservative and Operative Treatment. A Prospective, Randomized Study
Keywords
glenoid labrum, glenoid labrum injury, glenoid labrum injury of shoulder, labral injury, shoulder joint injury, chronic shoulder injury, overuse shoulder injury, throwing injury, Bankart's lesion, Bankart lesion, Hill-Sachs' lesion, Hill-Sachs lesion, anterior slide test, O'Brien's active compression test, O'Brien active compression test, apprehension test, Jobe's relocation test, Jobe relocation test, Fowler's test, Fowler test, anterior release test, SLAP test, crank test, pain provocation test, Bennett's lesion, posterior labrocapsular periosteal sleeve avulsion, POLPSA lesion, Snyder's biceps tension test, compression-rotation test, glenolabral articular disruption, GLAD lesion, anterior labroligamentous periosteal sleeve avulsion, ALPSA lesion, humeral avulsion of the glenohumeral ligament, HAGL lesion, BHAGL lesion
