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Updated: May 25 2023

Pectoralis Major Rupture

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  • SUMMARY
    • A rare acute injury caused by avulsion of the pectoralis major tendon and usually seen in weightlifters.
    • Diagnosis is generally made clinically and is confirmed with MRI studies.
    • Treatment is usually surgical repair when presenting acutely.
  • Epidemiology
    • Incidence
      • rare injury (< 1 per 100,000 per year) that is increasing in incidence
        • 75% of all reported cases have occurred since 1990
    • Demographics
      • almost exclusively seen in males (20-40 years of age)
      • often occurs in weightlifters
        • commonly during bench-pressing
    • Location
      • most commonly occurs as a tendinous avulsion
      • sternocostal head insertion of the pectoralis major tendon is the most common site of rupture
    • Risk factors
      • anabolic steroid use
  • Etiology
    • Pathophysiology
      • mechanism
        • excessive tension on a maximally eccentrically contracted muscle
          • occurs during the downward portion of a bench press, with the arm in the final 30 degrees of humeral extension while pushing against heavy resistance
        • tendon fails in a predictable sequence
          • inferior fibers of sternocostal head fail first
          • then superior fibers of the sternocostal head 
          • finally the clavicular head
  • Anatomy
    • Pectoralis major
      • innervation
        • lateral pectoral nerve (C5-C7) 
          •  supplies clavicular head and upper portion of sternocostal head
        • medial pectoral nerve (C8-T1) 
          •  supplies the lower portion of the sternocostal head
      • origin (two heads)
        • clavicular head
          • from medial clavicle and proximal sternum
        • sternocostal head
          • from distal sternum, costal cartilage ribs 1-6, external oblique aponeurosis
          • sternocostal portion is larger (>80% of muscle volume)
      • insertion
        • humeral shaft just lateral to the bicipital groove
      • action
        • shoulder adduction and internal rotation, to a lesser extent forward flexion (chiefly the clavicular head)
      • other
        • one of four muscles connecting the upper limb to the thoracic wall
          • other muscles include
            • pectoralis minor
            • subclavius
            • serratus anterior
    • Biomechanics
      • inferior fibers of sternal head at maximal stretch during final 30 degrees of humeral extension
        • position at which pectoralis major is most vulnerable to rupture (as with bench pressing)
  • Classification
      • Modified Tietjen (Anatomic) Classification
      • Type
      • Description
      • I
      • Muscle contusion or sprain
      • II
      • Partial tear
      • III
      • Complete tear (further subclassified by location)
      • Location
      • III-A
      • Muscle origin
      • III-B
      • Muscle belly
      • III-C
      • Musculotendinous junction
      • III-D
      • Intra-tendinous rupture
      • III-E
      • Tendon avulsion off humerus (no bone)
      • III-F
      • Bony tendon avulsion off humerus 
  • Presentation
    • History
      • patient may report a sudden pop or tearing sensation with resisted adduction and internal rotation
    • Symptoms
      • pain and weakness of shoulder
    • Physical exam
      • inspection & palpation
        • swelling and ecchymosis of anterolateral chest wall and/or proximal medial brachium
          • if localized to the anterior brachium, then humeral attachment rupture is more likely than a musculotendinous junction rupture
        • "dropped nipple" sign
          • ipsilateral nipple will appear lower than the unaffected side due to medial retraction of muscle belly
        • palpable defect and loss of anterior axillary contour
          • accentuated by resisted adduction
      • motion & strength
        • weakness most pronounced in adduction and internal rotation
          • to a lesser extent forward flexion
  • Imaging
    • Radiographs
      • indications
        • limited utility
      • recommended views
        • standard shoulder trauma series (true AP, scapular Y, and axillary lateral)
      • findings
        • most often normal
        • may show loss of pectoralis major shadow or bony avulsion
    • MRI
      • indications
        • investigation of choice
          • can differentiate between complete and partial tears
      • views
        • requires dedicated sequence (standard shoulder MRI will not capture adequately)
        • T2 sequence better for acute injuries
        • T1 for evaluating chronic injuries
      • findings
        • useful in identifying the location and extent of the rupture (partial versus complete)
          • may show avulsion of the pectoralis major tendon from the humerus
          • integrity of clavicular head may mask partial rupture of sternocostal head
  • Treatment
    • Nonoperative
      • initial sling immobilization, rest, ice, NSAIDs, physical therapy
        • indications
          • low-demand, sedentary, and elderly patients
          • muscle belly tears, low-grade partial ruptures
        • outcomes
          • inferior to operative management for young, active individuals
          • cosmetic disfigurement, significant deficit in strength (most pronounced with isokinetic adduction) and peak torque, delayed recovery, poor patient satisfaction, lower return to competitive sports
    • Operative
      • open primary repair
        • indications
          • gold standard for acute tears in high level athletes, and most young, active patients
          • tendon avulsion, myotendinous junction tears
        • outcomes
          • reliable strength recovery, return to sport, and patient satisfaction
          • may show improvement regardless of location of tear
          • excellent success with all methods
      • reconstruction
        • indications
          • chronic tears that cannot be adequately mobilized for primary repair
            • primary repair may still be possible years after the injury
          • persistent strength deficit in chronic tears
        • outcomes
          • reliable strength recovery and patient satisfaction, albeit generally inferior to primary repair
          • still significantly better than nonoperative management in young, active patients
  • Techniques
    • Initial sling immobilization, rest, ice, NSAIDs, physical therapy
      • technique
        • sling in adduction and internal rotation, begin passive range of motion immediately as tolerated
        • active assisted and active motion over the first 6 weeks
        • transition to strengthening and unrestricted activity at 2-3 months
    • Open primary repair
      • approach
        • standard deltopectoral approach
      • repair technique
        • all repair techniques have been shown to have comparably excellent success
          • transosseous suture repair with cortical trough
          • cortical button fixation
          • suture anchor repair
            • both PEAK screw and all suture available
              • some evidence suggests that cortical button fixation and transosseous suture repair with cortical trough are superior to suture anchor repair
              • direct repair may be indicated for tears at the muscle belly or myotendinous junction
    • Reconstruction
      • approach
        • standard deltopectoral approach
      • mobilization
        • need to release adhesions superficial and deep to pectoralis major
          • careful to avoid injury to the medial and lateral pectoral nerves during deep release
        • supplemental fascial release may be necessary to mobilize the muscle belly in chronic situations
      • graft options
        • Achilles allograft (most common)
          • advantages
            • avoids donor site morbidity, excellent load characteristics, favorable dimensions, and good surgical outcomes reported
        • Gracillis weave (allograft versus autograft)
  • Complications
    • Re-rupture (5-7%)
      • failure most often occurs at suture-tendon interface
    • Persistent pain 
      • incidence
        • most common complication
    • Residual weakness
    • Cosmetic deformity
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