Latissimus dorsi injury

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Latissimus dorsi muscle injuries have gained increasing awareness as a sports injury.

Epidemiology

The injury is fairly uncommon and mainly seen in overhead athletes, e.g. professional baseball pitchers .

Risk factors
  • overhead athletes e.g. baseball pitcher, tennis
  • rock climbing
  • water skiing, wakeboarding
  • martial arts e.g. wrestling, judo
  • gymnasts, cross-fit athletes

Clinical presentation

Patients usually report pain, burning or tearing sensation and might show an asymmetry or bruise of the posterior axillary fold or lump at the latissimus dorsi muscle belly. Pain increases with internal rotation and resisted shoulder extension . Baseball pitchers might complain of accuracy and a loss of pitching velocity.

Pathology

The latissimus dorsi plays an important role in internal rotation power during the late cocking and acceleration phase of the throwing movement . A tear of the latissimus dorsi muscle is a discontinuity of muscle or tendon fibers usually at the site of insertion or myotendinous junction.

Mechanism

The following mechanism can lead to latissimus dorsi tear

  • forceful abduction and external rotation during resisted contraction
  • pulling the body upward and forward while arms are overhead (in a fixed hand positioning)
Classification

Tears can be graded in regard to their severity (strain, partial-thickness, full-thickness) and if full-thickness according to the extent of tendon retraction and in relation to the site of the injury (tendon insertion or myotendinous junction) .

Location

Typical locations of a latissimus dorsi tear include the insertion site at the floor of the intertubercular groove of the proximal humerus distal to the quadrilateral space or less often at its myotendinous junction.

Associations

Radiographic features

MRI

Typical features of muscle injuries on MRI include fluid signal intensity tracking and surrounding the muscle fibers of the latissimus dorsi muscle and/or discontinuity at the insertion site on the floor of bicipital groove, just lateral and inferior to the teres major muscle, and medial to the pectoralis muscle at the anteromedial aspect of the proximal humerus .

A magnetic resonance imaging classification has been proposed for tears of the latissimus dorsi and teres major :

  • grade 1: fluid along the teres major, latissimus dorsi muscles
  • grade 2: partial-thickness tear
  • grade 3: full-thickness tear with <2 cm tendon retraction
  • grade 4: full-thickness tear with >2 cm tendon retraction

Treatment and prognosis

Latissimus dorsi injuries can be managed conservatively or surgically. Higher grade tears benefit from surgical repair .

Conservative management includes activity modification, cryotherapy, nonsteroidal anti-inflammatory drugs, physical therapy and active rehabilitation including scapular stabilization exercise as well as other modalities .

Full-thickness tears benefit from surgical management, which includes retrieving and mobilization of the tendon stump and refixation to the humeral footprint from a combined anterior and posterior approach or single posterior approach. Due to the proximity to the radial, axillary and posterior brachial cutaneous nerves and the posterior circumflex humeral artery special care needs to be taken in respect of those structures  .

There is still no accepted general treatment algorithm for which patients should be treated conservatively and which should undergo surgery.

Practical points

The latissimus dorsi attachment site is usually not fully seen on standard shoulder MRI scans, which potentially will lead to a missed diagnosis. Radiographer or radiology technicians need to be informed, so that the field of view is extended or moved together with the coil more distally .

See also