Superior Labrum Lesions

Etiology

SLAP tears are typically defined as superior labrum fraying/tearing from the glenoid. If one were to liken the glenoid to a clock face, these occur in the 10 o’clock to 2 o’clock position. There are several different patterns of SLAP tears with varying degrees of instability and magnitude of labral damage.  In the acute setting, traumatic injury can occur in traction/torsion and compressive/subluxation mechanisms.[2][3] Repetitive overhead motions, such as those with baseball pitchers, other overhead athletes, and manual laborers, place these individuals at an increased risk for SLAP tears as well. Finally, SLAP tears can occur in a degenerative setting for the aging population.

Epidemiology

The incidence of SLAP tears is a controversial topic in the current literature. A 2012 study evaluating trends in SLAP repair found SLAP tears were more common in men (greater than 3:1) compared to women. The highest incidences of SLAP repairs were found in the 20 to 29 and 40 to 49 decades at 29.1 and 27.8 per 10,000 patients, respectively.[4] Other studies have shown rates between 6% and 26% at the time of arthroscopy.[5][6] Specific populations, however, can present with increased rates of SLAP tears, with one study demonstrating upwards of an 83% prevalence in overhead athletes.[1]

The variation in SLAP tear reporting may be attributed to some SLAP tears being considered an incidental finding on advanced imaging or at the time of arthroscopy. SLAP tears are a common coexisting injury in patients with other shoulder pathologies, and they do not always account for the primary cause of symptoms.

Pathophysiology

There are several proposed mechanisms for the cause of SLAP tears. In the acute traumatic setting, a fall onto an extended and abducted arm leads to a compressive and superior directed force from the humeral head into the superior labrum.[2] This position has also been implicated in a sport-specific traumatic force (hyperabduction or traction) as well as during the cocking phase of throwing. In this mechanism, a “peel-back” avulsion of the superior labrum by a torsional force via the biceps anchor.[3] The biceps has also been implicated in the follow-through phase of throwing as an eccentric contraction of the biceps transmits an extensive pull on the superior labrum.[1]

In various patient populations, internal impingement is also a culprit of SLAP tears. The cocking phase of throwing can place direct posterosuperior impingement on the superior labrum. Repetitive overhead motion may also lead to the attenuation of static stabilizers, resulting in altered biomechanics of the dynamic stabilizers. This can lead to instability and, ultimately, impingement of the superior labrum with degenerative tearing.[7] Internal impingement can also result from rotator cuff tears via chronic posterosuperior or anterosuperior migration/subluxation of the humeral head.[8]

History and Physical

Specific physical examination of SLAP tears is difficult as they typically present with other pathology in the shoulder. A standard detailed history is required, as with all patients presenting to the clinic. Determining the onset of symptoms and mechanism (trauma, dislocation, or exacerbating maneuvers with overhead activity) can clue an examiner into labral pathology. Some SLAP tears present in the degenerative setting with no definitive onset of symptoms or discrete mechanisms. In these situations, evaluating the patient’s history of repetitive overhead activity or general functional history will help isolate suspicion towards the superior labrum.

It is important to discuss the patients’ activities such as athletics, profession, and baseline activity level. Ascertaining patients’ goals is also paramount as post-intervention physical demands and expectations of a high-level athlete are likely different than the aging population. Patients often complain of vague, deep shoulder pain and mechanical clicking with exacerbating activities. They may complain of night pain, which is a common complaint with several shoulder pathologies. SLAP tear patients typically admit to resolution or reduction of symptoms at rest.

Initial physical examination includes visual inspection for gross asymmetry and muscle atrophy. The skin should also be evaluated for prior surgical incisions or injuries attributed to an acute mechanism. A detailed neurovascular examination is performed and documented, complete with muscle strength testing. Active and passive motion needs to be assessed and compared to the contralateral side. Specific attention should be paid to scapulothoracic motion, as altered mechanics of the global shoulder complex can be the result of or a contributing factor to SLAP tears. As several types of SLAP tears can also be associated with instability, the general stability of the shoulder should be evaluated. The possibility of generalized hyperlaxity of tissues in all patients with instability should also be considered, and a Beighton score can easily be obtained.

There is no gold standard physical exam test that specifically identifies SLAP tears. Multiple exam maneuvers point to either labral involvement via impingement or compression mechanisms. Some tests isolate the tension placed on the superior labrum by the biceps via provocative maneuvers in active and passive forms. Additionally, specific biceps testing can be used; however, they are not reliable for SLAP tears as they can be positive with other pathologies. Below is a list of tests used to evaluate the labrum and the biceps.[9][10][11][12] While the O’Brien test (active compression) originally reported 100% sensitive and 99% specific results, several studies have stated lower rates.[10][13][14] Multiple tests of the shoulder should be used to gain information collectively towards suspicion for labral pathology.

Biceps Tests

• Speed’s
• Uppercut
• Yergason’s
• Bicipital groove tenderness

Labral Tests

• Anterior slide
• Biceps load I and II
• Crank
• Forced shoulder abduction and elbow flexion
• Jobes relocation
• Labral tension
• Mimori pain provocation
• Dynamic labral shear (O’Driscoll’s)
• O’Brien (active compression)
• Pronated load
• Resisted supination external rotation

Evaluation

Initial evaluation of the shoulder typically starts with x-rays to rule out osseous pathology. In the chronic setting, degenerative changes within the shoulder may be present, and while testing of the superior labrum may be positive, it may not be the main cause of their symptoms. Typically, an MR arthrogram (MRA) is performed to evaluate the shoulder labrum. SLAP tear type is determined by the anatomical location of the tear as well as the severity of its extension. A paralabral cyst found on MRI is a diagnostic clue for a SLAP tear. Suprascapular nerve compression from a paralabral cyst may occur. Depending on location, it can lead to combined supraspinatus and infraspinatus weakness (suprascapular notch) or isolated infraspinatus atrophy (spinoglenoid notch).[15][16] 

While MRA has a sensitivity and specificity of 82% to 100% and 71% to 98%, respectively, there are normal anatomic variants that can be confused with a SLAP tear. A sublabral recess or foramen can be misread as a labral tear. These are identified by smooth rather than rough edges, specific anatomic locations, and orientation medially rather than into the lateral substance of the labrum.[17] Anatomical variations such as a Buford complex, a thickened middle glenohumeral ligament (MGHL), and absent anterosuperior labrum may be confused with a SLAP tear as well. A sulcus between the supraglenoid tubercle and the labrum may also give a false-positive result and is deemed a pseudo SLAP tear.

Snyder et al. first described the classification of SLAP tears in 1990. Additional subtypes for type II tears, as well as additional tear patterns, were described in subsequent years.[2][9][6][12]

• Type I – Fraying of the superior labrum with intact biceps anchor
• Type II – Fraying of the superior labrum with detached biceps anchor
  • A) anterior
  • B) posterior
  • C) combined anterior and posterior
• Type III – Bucket handle tear of the superior labrum with intact biceps anchor
• Type IV – Bucket handle tear of the superior labrum with detached biceps anchor (remains attached to the torn labrum)
• Type V – Type II + Bankart lesion
• Type VI – Type II + unstable flap either anteriorly or posteriorly
• Type VII – Type II + anterior extension inferior to the MGHL
• Type VIII – Type II + posterior labrum extension
• Type IX – Circumferential labrum tear
• Type X – Type II + reverse Bankart lesion

Treatment / Management

Non-operative management focuses on the initial restriction of provoking maneuvers. Typically, an anti-inflammatory and/or corticosteroid injection are utilized as initial treatment as well. Gentle ROM activities are recommended. Glenohumeral internal rotation deficit (GIRD) is a common associated finding in throwing athletes. Focus on stretching the posterior capsule is also a focus of rehabilitation. As symptoms diminish, a structured rehabilitation protocol focusing on rotator cuff and pericapsular strengthening exercises are utilized.[18](B2)

Operative management varies widely depending on patient activity level and treatment goals. Additionally, classification and severity of the SLAP tear, in combination with concomitant pathology, affects the type of operative management selected. Trends in the early 2000s showed an increase in SLAP repairs.[19][20][4] Subsequently, as the understanding of the injury continued to unfold, rates of repair have steadily declined.[19][21] The recent overlying trend appears to favor tenodesis rather than repair; however, the decision for the type of intervention remains patient-specific.[19](B2)

Types I and III SLAP tears may be selected to undergo simple debridement as the integrity of the biceps anchor is not completely compromised. Unstable SLAP lesions are typically repaired with anchor fixation, and the extent of the injury typically determines the pattern of repair. The ultimate goal of fixation for all repair techniques is to provide a robust and stable fixation, promoting the stability of the glenohumeral joint and allowing for adequate rehabilitation without failure of repair.[9]

Alternatively, the biceps anchor may be sacrificed, and a biceps tenotomy or tenodesis performed. Tenodesis can be performed by subpectoral, all-arthroscopic, and mini-open techniques. While elite athletes and young patients typically undergo repair, these techniques provide satisfactory results for a wide variety of patients.[22] Tenotomy can lead to a cosmetic deformity with retraction of the biceps muscle. The resulting tear of the labrum can then be debrided or fixed depending upon the severity of the tear.

Management of paralabral cysts is dependent upon location and concomitant symptomatic nerve compression. In the absence of compressive symptoms, a range of non-operative treatments can be considered, including observation, anti-inflammatories, or percutaneous aspiration.[16] For those with atrophy, weakness, or continued pain, surgical decompression is indicated. Care must be taken to avoid iatrogenic nerve injury during decompression.[15][16]

Differential Diagnosis

• Biceps tendonitis
• Internal impingement
•  Glenohumeral internal rotation deficit
• Other labral pathology and/or instability
• Rotator cuff tears
• Scapular dyskinesis

Prognosis

Nonoperative management has efficacy for many symptomatic SLAP tears and should be considered for initial treatment. Previous studies have demonstrated non-operative management successful for 22 to 85% of patients.[18][23]

Operative intervention in adults has been reported to be successful between 80 and 97% of patients in several populations.[24][25] Several of these studies, however, are heterogeneous and successful treatment is a matter of definition. Alleviation of pain and return of range of motion may result in treatment success for some; however, in overhead athletes, many patients are unable to return to their prior level of sport or performance. Results are widely varied in these athletes, demonstrating the return to the prior level of sport between 7% and 84%.[23][26][27][28][29][30] Non-overhead athletes return to sport at a consistently higher rate, although some patients inevitably are unable to return to participation. Additionally, adolescents also demonstrated successful outcomes with operative repair in regards to pain and function; however, there remain similar considerations regarding return to sport.[24] As patients age, typically beyond 40 years of age, repair becomes consistently inferior to tenodesis or tenotomy. Several authors recommend against repair in these populations.[23][31]

Ultimately, nonoperative and operative management yields successful results for many patients; however, treatment success is highly dependent upon the patient's functional level and treatment goals. An honest dialogue of outcomes with each patient is vital before selecting the appropriate intervention.

Complications

Treatment failure and complications are dependent upon intervention, patient adherence to rehabilitation protocols, and patient-specific factors. Increasing age, activity level, obesity, female sex, smoking, and concomitant shoulder pathology are risk factors for failure.[23][27] The most common complications after surgical fixation are residual pain and stiffness.[25][32] Additionally, infection, failure of repair, residual pain, neurovascular injury, and recurrent instability may occur.