I. Superior Labrum Anterior-to-Posterior Lesions
A. Epidemiology/overview
1. Superior labrum anterior-to-posterior (SLAP) lesions are injuries to the superior labrum of the glenoid.
2. The labrum is a fibrocartilage ring of tissue that surrounds and attaches to the glenoid; it deepens the glenoid and has a stabilizing function.
B. Pathoanatomy
1. SLAP lesions may result from overuse or trauma.
2. SLAP lesions are most commonly seen in athletes who perform overhead motions such as throwing, and they are often associated with other shoulder injuries.
C. Evaluation
1. History
a. Patients may present with an insidious onset of symptoms (overuse), or a more discrete injury (trauma) may incite symptoms.
b. Symptoms are often brought on by throwing or other overhead physical activities, but this is not always the case.
c. Symptoms may vary from a sharp pain anterosuperiorly to a sensation of a "dead arm" with activity.
2. Physical examination
a. There are several provocative maneuvers; in general, they have high sensitivity but low specificity.
[
Figure 1. The O'Brien active compression test. A, The patient's arm is forward flexed to 90°, adducted 10° to 15°, and maximally internally rotated. The patient is instructed to resist as the examiner applies a uniform downward force. B, The patient maximally supinates the arm, and the maneuver is repeated.]
[
Figure 2. Oblique coronal T2-weighted MR arthrogram of the left shoulder shows tracking of contrast material medial to the labral attachment (arrow), consistent with a SLAP lesion.]
b. A positive Speed test (pain on resisted forward elevation to 60° with the elbow extended and the forearm supinated) may indicate pathology of the biceps tendon or biceps labral complex.
c. The Jobe relocation test (posterior-directed force on an abducted, externally rotated shoulder) is used to assess anterior and superior instability.
d. The O'Brien (active compression) test (Figure 1) is considered the most reliable for SLAP lesions. For this test, the patient's arm is forward flexed to 90°, adducted 10° to 15°, and maximally internally rotated. The patient is instructed to resist as the examiner applies a uniform downward force. Symptoms are then relieved when the test is performed with the patient's shoulder externally rotated.
3. Imaging
a. Plain radiographs are usually normal.
b. MR arthrography (Figure 2) is the best imaging modality for identifying labral pathology.
c. Diagnostic arthroscopy may be necessary if the physical examination is suggestive of a SLAP lesion and the MRI is not diagnostic for such a lesion.
[
Figure 3. Snyder and associates' classification of SLAP lesions. A, Type I lesion has degenerative fraying along its free margin, with an intact biceps root. B, Type II lesion is characterized by disruption of the attachments of the superior labrum and biceps to the glenoid. C, Type III lesion has a bucket-handle tear of the superior labrum, with an intact attachment of the root of the biceps. D, Type IV lesion has a bucket-handle tear of the superior labrum that extends into the biceps tendon.]
D. Classification—Snyder and associates' classification (Figure 3) is based on the involvement of the biceps tendon insertion and anterior inferior labrum.
E. Treatment
1. Nonsurgical
a. Nonsteroidal anti-inflammatory drugs
b. A directed physical therapy program for strengthening the rotator cuff muscles, to aid in stabilizing the shoulder during throwing or overhead motion
2. Surgical
a. Surgery is indicated when symptoms persist despite an adequate trial of physical therapy. The on-season and off-season schedule of the athlete may be a consideration, as the recovery period for SLAP lesion repair is typically 6 to 9 months (depending on the sport).
b. Contraindications—SLAP lesions in older athletes (age 40 to 60 years) with multiple concomitant pathologies should be addressed carefully. Often, the SLAP lesion is not the primary cause of pain in the shoulder.
3. Surgical procedures
a. Type I and III lesions: Debridement
b. Type II and IV lesions: Arthroscopic repair with suture anchors
c. Type IV lesions with extension into the biceps tendon: Consider biceps tenodesis.
F. Complications
1. Injury to the articular cartilage of the glenoid and/or humeral head
2. Failed repair
3. Stiffness
G. Rehabilitation
1. A short period of immobilization is followed by progressive range-of-motion and strengthening exercises.
2. Typically, the patient can return to sports or labor 6 to 9 months after surgery.
II. Internal Impingement
A. Epidemiology/overview
1. Internal impingement is abnormal contact between the posterior rotator cuff and the posterior margin of the glenoid (which results in tearing/fraying of the undersurface of the rotator cuff and/or labrum).
2. The etiology of internal impingement is debated. One theory is that it results from a combination of anterior microinstability and excessive tightness of the posterior capsule (which causes an imbalance in the forces acting on the glenohumeral joint during throwing or other overhead motions).
B. Pathoanatomy—Internal impingement (
Figure 4) can result in a spectrum of pathology.
1. Fraying of the posterior rotator cuff
2. Hypertrophy and scarring of the posterior capsule at the margin of the glenoid (Bennett lesion)
3. Cartilage wear in the posterior glenoid
4. Posterior/superior labral lesions
[Figure 4. Mechanism of internal impingement. The position of abduction and extreme external rotation that occurs during overhead throwing compresses the supraspinatus and infraspinatus muscles and their tendons between the posterosuperior glenoid rim, the posterior humeral head, and the greater tuberosity, causing fraying of the deep layers of the infraspinatus.]
C. Evaluation
1. History—Patients are predominantly overhead athletes who report pain while throwing or performing other overhead motions (cocking phase).
2. Physical examination
a. There is often a decrease in passive internal rotation (in abduction) of the affected side, which indicates excessive tightness of the posterior capsule.
b. A positive Jobe test indicates anterior instability.
c. Rotator cuff weakness may be noted.
d. Pain is typically elicited during abduction and external rotation.
3. Imaging
a. Plain radiographs are usually normal.
b. MRI is the most useful imaging modality for identifying rotator cuff and/or labral pathology.
D. Treatment
1. Nonsurgical
a. Most internal impingement can be treated nonsurgically.
b. Treatment involves a physical therapy program (rotator cuff strengthening and posterior capsule stretching) designed to address the specific pathology.
2. Surgical
a. Indications—Failed nonsurgical treatment
b. Contraindications—Voluntary dislocation
3. Surgical procedures
a. Debridement of the rotator cuff is performed for partial articular-side tendon avulsion (PASTA) lesions that are ≤50% of the thickness of the tendon.
b. A PASTA repair is indicated if a lesion is substantial (>50%). A transtendon repair is performed by repairing the tendon to the insertional footprint without taking down the intact tendon.
c. Debridement or excision is indicated if a Bennett lesion is present. A Bennett lesion is an extra-articular posterior ossification associated with a posterior labral injury and a posterior undersurface rotator cuff injury.
d. Labral repair and/or capsulorrhaphy are indicated if instability is present.
E. Complications—Damage to articular cartilage can occur during arthroscopy.
F. Pearls and pitfalls—Surgical pitfalls include incorrect diagnosis and failure to recognize underlying rotator cuff or bursal pathology.
G. Rehabilitation
1. A short period of immobilization is followed by progressive range-of-motion and strengthening exercises.
2. Typically, the patient can return to sports or labor 4 to 6 months after surgery.
III. Spinoglenoid Notch Cysts
A. Epidemiology/overview—Spinoglenoid notch cysts occur infrequently.
B. Pathoanatomy
1. Spinoglenoid notch cysts are often associated with SLAP lesions. Fluid escapes from the glenohumeral joint through a labral tear (usually a SLAP lesion) and forms the cyst.
2. The cyst compresses the suprascapular nerve and interferes with innervation of the infraspinatus muscle.
3. Rotator cuff weakness in the absence of a cyst indicates nerve compression at another location (eg, the suprascapular notch). An electromyogram (EMG) is helpful in making that diagnosis.
C. Evaluation
1. History
a. Weakness, not pain, is often the major symptom.
b. Symptoms also may include a dull ache in the shoulder during overhead activity.
2. Physical examination
a. Patients will exhibit disproportionate weakness in the infraspinatus muscle compared with the other muscles of the rotator cuff.
b. Visible atrophy of the infraspinatus muscle in the infraspinatus fossa may be noted.
c. If both the supraspinatus and the infraspinatus muscles are weak, compression of the suprascapular nerve may be occurring at the suprascapular notch.
3. Imaging
a. Plain radiographs are usually normal.
b. A spinoglenoid notch cyst will appear as an area of high signal intensity on T2-weighted MRI (
Figure 5); MRI will also show a SLAP lesion.
D. Treatment
1. Nonsurgical
a. Nonsurgical treatment is contraindicated for symptomatic nerve compression.
b. Labral or SLAP lesions associated with cysts must be repaired to prevent recurrence of cysts.
2. Surgical
a. Indications
i. Nerve compression
ii. SLAP lesion
b. Contraindications—Weakness in the absence of a cyst
3. Surgical procedures
a. Cyst decompression
b. SLAP lesion repair
E. Complications
1. Articular cartilage injury
2. Injury to the suprascapular nerve can occur during cyst decompression.
F. Pearls and pitfalls
1. Early diagnosis is helpful in preventing further atrophy of the infraspinatus muscle.
2. Patients with spinoglenoid cysts and suprascapular nerve compression have isolated weakness in the infraspinatus muscle.
3. Weakness out of proportion to pain is highly suggestive of a spinoglenoid notch cyst.
4. SLAP lesion repair without cyst decompression will usually be successful because cysts will likely resorb.
G. Rehabilitation
1. A short period of immobilization is followed by progressive range-of-motion and strengthening exercises.
2. Typically, the patient can return to sports or labor 6 months after surgery.
[Figure 5. Axial (A) and coronal (B) MRI scans of the shoulder showing spinoglenoid notch cysts (arrows).]
Top Testing Facts
SLAP Lesions
1. SLAP lesions are most commonly seen in athletes who perform overhead motions such as throwing.
2. MR arthrography is the best imaging modality for identifying labral pathology.
Internal Impingement
1. Most internal impingement is treated nonsurgically.
2. Surgical procedures for internal impingement include labral repair and/or capsulorrhaphy if instability is present.
3. Debridement of the rotator cuff is performed for PASTA lesions that are ≤50% of the thickness of the tendon. A PASTA repair is indicated if a lesion is substantial (>50%).
4. Surgical pitfalls include incorrect diagnosis and failure to recognize underlying rotator cuff or bursal pathology.
Spinoglenoid Notch Cysts
1. Patients with spinoglenoid notch cysts will exhibit disproportionate weakness in the infraspinatus muscle compared with the other muscles of the rotator cuff.
2. A spinoglenoid notch cyst will appear as an area of high signal intensity on T2-weighted MRI. Cysts are associated with SLAP lesions.
3. Rotator cuff weakness in the absence of a cyst indicates nerve compression at another location (eg, the suprascapular notch). An EMG is helpful in making that diagnosis.
4. Labral or SLAP lesions associated with cysts must be repaired to prevent recurrence of cysts.
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