Disorders of the Labrum and Proximal Biceps

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Introduction

Glenoid Labrum Tear : A tear in a specialized piece of cartilage tissue which sits as a rim between the two bones of the ball and socket shoulder joint

Anatomy

  • The shoulder joint is a very mobile joint, at the expense of stability
  • The labrum is a rim of fibro-cartilage attached to the glenoid which sits within the shoulder joint and is distinct from the articular cartilage
  • It normally acts as a "bumper" which
    • Deepens the socket by about 50%
    • Increases potential ROM
    • Helps to stabilize the joint by keeping the ball of the socket in place

Pathogenesis

  • There are a couple of theories which try to explain this increasingly prevalent tear
    • The first theory suggests that it originates when the shoulder joint tries to "dislocate"
      • The biceps tendon contracts to prevent the dislocation
      • Contraction puts a significant amount of stretch/distension on the superior glenoid labrum
      • As the head of the humerus slides back into the joint, it may clip the distended labrum and induce a tear
    • A second theory places more emphasis on the stress of repeated motion
      • As one throws a ball repeatedly, the superior labrum is put under high amounts of stress by the biceps tendon
      • Stress is particularly evident during the deceleration phase; once the ball is released
      • Over time this may result in microtrauma and a tear to the labrum
    • I tend to believe that the second theory is probably more likely to explain SLAP tears
    • Perhaps the first theory may be true in select cases, depending on an individual person's anatomy. However, I would think that if the humerus was hitting the labrum repeatedly, an athlete would feel PAIN and possibly ease up before definitive damage would occur
  • When the labrum is torn due to an injury, instability and loss of ROM can ensue
    • The ball has the potential to slide partially out of the socket (subluxate) or may even dislocate completely
    • Flaps of tissue within the joint space may hinder movement of the humerus and cause clicking and pain
  • The second function of the labrum is to serve as an attachment for other structures or tissues around the joint, such as the ligaments and the biceps tendon
  • Damage to these structures in conjunction with the labrum can intensify any shoulder instability and make dislocations more likely; e.g. Bankart lesion

Aetiology

  • Labrum tears tend to occur in two primary settings:
    • Acute trauma
      • Falling on an outstretched arm
      • Direct blow to the shoulder
      • Sudden jerky movement when trying to lift a heavy object
      • Violent overhead reach, such as when trying to stop a fall or slide
    • Repetitive stressful shoulder motion
      • Athletes are particularly prone
        • Pitchers
        • Quarterbacks
        • Weightlifters
      • The SLAP tear is particularly common in these cases

Risk factors

  • Athletes who engage in repetitive overhead motion, contracting their biceps against the labrum :
    • Baseball
    • Weightlifting
    • Golf
    • Tennis
    • Swimming
  • Increasing age
    • More sensitive tissue
    • More prone to falls
    • It is harder to break falls with muscles

Prevention

  • Strengthening the muscles of the shoulder girdle and upper back is the best defence against shoulder injuries
  • Adequate warm-up before activity; e.g. soft-throwing in pitchers
  • Adequate rest intervals between episodes of intense activity; e.g. rest between pitching outings
  • Avoidance of high-impact sports; e.g. football

Natural History

  • I could not find any data as to whether untreated tears are more likely to develop arthritis of the affected joint downstream
  • Athletes who engage in repetitive overhead activities that load the shoulder are at greater risk for glenoid labral tears, especially the SLAP variant
    • Baseball pitching
    • Tennis serving
    • Swimming
  • In one of the largest series reported, SLAP lesions were found in 6% of 2375 patients who underwent shoulder arthroscopy
  • Kampa and Clasper (2005) evaluated the presentation and incidence of SLAP lesions in military and civilian populations
    • Of 178 patients who underwent arthroscopy for complaints of either pain, instability or both pain and instability, 39 (22%) SLAP lesions were found
    • The authors found that patients with a history of trauma or symptoms of instability were more likely to have a SLAP lesion than patients presenting with non-traumatic aetiologies

Clinical Presentation

  • The symptoms of labrum tear tend to include
    • Non-specific deep shoulder pain
    • Catching / locking / popping of the shoulder joint; due to a flap of loose cartilage
    • A sense of instability in the shoulder
    • Decreased range of motion
    • Loss of strength
  • Symptoms aggravate with reaching overhead or across one's body
  • No single physical sign or test has been shown to have both great sensitivity and specificity
    • The Obrien's active compression test may be considered to have good specificity
      • The patient stands upright with the affected arm flexed 90° and adducted 15° medial to the sagittal plane of the body
      • With the arm internally rotated, the examiner pushes the arm downward
      • The test is then repeated with the forearm in maximal supination
      • A positive test result is recorded when pain elicited by the first maneuver is decreased by the second maneuver
    • Deep pain or click is correlated with labral abnormalities in 94% of the patients studied

Psychosocial Impact of the Disease

  • Athletes with labral tears would likely be sidelined for a prolonged amount of time, which would include post-op recovery and rehabilitation
  • Careers could theoretically be jeopardized depending on the severity of injury and healing potential
  • Non-athletes with labor intensive jobs may have a hard time performing their normal duties, as a result of shoulder instability and pain with overhead movements. They may also have a hard time working out at the gym or doing other strenuous activities which stress the shoulder

Differential Diagnosis

  • Rotator cuff Injury : Many of the same mechanisms which cause rotator cuff injury (tendinitis and tears) can also produce tears of the labrum
  • Bicipital Tendonitis
  • Shoulder subluxation / dislocations plus labrum tears : the cartilage may become completely sheared off the bone while the head is pushed out of the socket

Imaging and Diagnostic Studies

  • Numerous studies have confirmed the utility of gadolinium-enhanced MR arthrography in the detection of labral tears
    • The sensitivity is 82-96%
    • The specificity is 91-98%
  • CT arthography is another option, which has similar accuracy
  • Findings that suggest damage to the labrum or the biceps tendon include:
    • High signal intensity at the labrum/anchor interface
    • Increased signal at the superior glenoid fossa
    • Displacement of the superior labrum away from the glenoid surface
    • The presence of a glenoid-labral cyst

Classification

  • Complete tear
    • The labrum is sheared completely off the bone
    • It will be observed hanging off of its normal attachment to the glenoid as a flap of tissue
  • Intar-substance
    • Within the substance of the labrum
    • Usually appearing as fraying and loss of smoothness within the fibro-cartilage
  • SLAP (Superior Labrum Anterior and Posterior) tear
    • A specific kind of tear involving the biceps tendon
    • Sits at the superior portion of the labrum
  • There are multiple subtypes, ranging from fraying of the superior labrum to complete detachment of an intact or torn (bucket handle) labrum/biceps tendon complex

Treatment

  • The relationship between labrum tears and symptoms has not been totally figured out, so it is not clearly known which ones should be repaired and which ones can be left alone
  • There are probably a large number of untreated labral tears that heal spontaneously since the labrum has a rich blood supply that helps the healing process (except in the anterior and superior locations)
  • Most clinicians agree that very few patients with SLAP lesion injuries return to full capability without surgical intervention
  • If symptoms persist with conservative management, surgery is usually required

No Treatment

  • An incidental finding of a labral tear on imaging that is not symptomatic does not require any treatment

Non-operative Treatment

  • The idea here is that some labral tears may heal with time
  • Anti-inflammatory medications
    • Provide symptomatic pain relief
    • May reduce swelling and facilitate healing
  • Physical therapy
    • May help overcome subtle functional limitations/ shoulder instability
    • Might promote strengthening of the rotator cuff muscles which could compensate for any potential deficit
    • Usually does not work in most young active patients

Arthroscopic repair

  • The type of repair is dependent on the subtype of injury
    • Injury is confined to the rim, without involving the biceps tendon :
      • Small flap : remove the torn flap
      • Large flap : reattach the torn flap
    • Injury extends into the biceps tendon : repair and reattach the tendon using absorbable tacks, wires or sutures
    • Tendon is detached : reattach the tendon using absorbable tacks, wires or sutures
  • The vast majority of patients have full function of the shoulder after labrum repair
  • Most patients can return to their previous level of sports with no or few restrictions

Outcome

  • In a review of 34 patients with isolated SLAP lesions that underwent arthroscopic, Kim et al. (2002) found that
    • 94% had a satisfactory result
    • 91% returned to their pre-injury level of shoulder function
    • Inferior results were noted in overhead throwing athletes
  • A different retrospective study by Ide et al. (2005) demonstrated "good" to "excellent" subjective results in 90% of overhead throwing athletes treated for type II SLAP tears
  • In 39 patients with circumferential labrum tears undergoing arthroscopic repair, Tokish et al. (2009) found
    • Significant improvement in pain, degree of instability, and other objective and subjective parameters
    • All patients returned to their pre-injury activity level

Complications

  • Injury to nerves around the shoulder
    • The most common complication of surgery
    • Occurs in less than 1% of patients
    • Known as post-traumatic neuropathy
    • Usually resolves in within 6 weeks
    • Permanent injury that results in diminished function is quite rare
  • Infection
    • 1% of patients
    • May require antibiotics or surgical debridement
  • Joint stiffness or arthritis
    • May occur at some point following surgery
    • Either due to the initial injury or surgery
  • Failure to achieve the desired result in terms of re-gaining shoulder function and relieving pain

Pearls and Pitfalls

Tips and problems to avoid

Controversy

Include current controversies in diagnosis or treatment

Related Topics

Researchers at the University of Washington have been experimenting with in vitro models to assess potential mechanisms for enhancing the stabilizing function of the glenoid labrum. Specifically, they tested the hypothesis that this could be augmented by inflating it with blood. In one study, they demonstrated a mean increase in stability (measured by a change in angle in response to a force) for 6 glenoid specimens ranging from 19% to 30%

References


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