Pectoralis Major Rupture - Shoulder & Elbow

Introduction

Overview
- a rare injury caused by avulsion of the pectoralis major tendon, and usually seen in weightlifters
  - usually treated with repair when presenting acutely
Epidemiology
- incidence
  - increasing in incidence
- demographics
  - almost exclusively seen in males (20-40 years of age)
  - often occurs in weightliftersweightlifters
- location
  - most commonly occurs as a tendinous avulsion
  - sternocostal head of the pectoralis major tendon is the most common site of rupture
Pathophysiology
- mechanism
  - excessive tension on a maximally eccentrically contracted muscle
  - tendon fails in a predictable sequence
    - inferior fibers of sternocostal head fail first, then superior fibers of the sternocostal head, and finally the clavicular head

Anatomy

Pectoralis major
- innervation
  - lateral (C5-C7) and medial (C8-T1) pectoral nerves
  - medial pectoral nerve supplies lower muscle belly, lateral pectoral nerve supplies upper portion
- origin (two heads)
  - clavicular head: medial clavicle and proximal sternum
  - sternocostal head: 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)
- 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
A	Muscle origin
B	Muscle belly
C	Myotendinous junction
D	Tendon avulsion off humerus (no bone)
E	Bony tendon avulsion off humerus
F	Tendinous rupture

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 that 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 prounounced 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
- indication
  - investigation of choice
- technique
  - 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
  - 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
  - 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 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
- 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

Surgical Technique

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 scew and all suture available
        
        some evidence suggests that cortical button fixation and are superior to
        
        direct repair may be indicated for tears at the muscle belly or myotendinous junction
  - outcomes
    - excellent success with all methods
    - some evidence suggests that cortical button fixation and transosseous suture repair with cortical trough are superior to suture anchor repair
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 is most often suture-tendon interface
Persistent pain (most common)
Residual weakness
Cosmetic deformity

significant