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Pectoralis Major Tears

4409144273_7a4a8f24f8_o-500x376 Pectoralis Major Tears Ortho Handbook Sports Medicine | HB

Credit: camellia35 Flickr; #58 Pectoralis Major; #62 External Intercostal Muscle #63 Internal Intercostal Muscle

  • Bruising most often associated with tendinous avulsion, less commonly with musculotendinous junction or intramuscular tear
  • Pec tears are not always associated with ecchymosis
  • They are often missed in the ER
  • The clavicular head doesn’t tear as often as the sternal head; the defect from the sternal head will be hidden by the clavicular head when the arm is down by the side, so it will often be missed if you don’t get the arm up in the air
  • When ordering an MRI to evaluate pec tears, it is probably best to order chest wall and humerus MRI to include the entire origin through insertion
  • Issues
    • low publications number
    • few studies
      • In 2000, 150 cases identified in the literature, meta-analysis, largest series with 19 patients
      • in 2014, 365 cases identified, largest series with 40 patients
      • low incidence, no CPT code, often missed in the ER
  • Key anatomical factors

    • complex morphology
    • clavicular head
      • medial 1/2 of clavicle
    • sternal head
      • 2nd the 6th rib
    • anterior tendon
      • clavicular head and upper segment of SH
    • posterior tendon
      • lower segment of SH
    • 5.4 cm insertion – new studies suggest here is no twist
  • usually the injury occurs during the eccentric portion of the tear
  • Primary role

    • adductor and IR of the arm
      • forward flexion by the clavicular head
    • myofibers of varying length
      • allow differential shortening
  • Biomechanics of failure

    • humerus with forward flexion
      • fibers stay the same length (average 20%)
    • humerus in extension of 30 degrees
      • inferior fiber length (40% on average)
    • extended bench press position
      • muscle usually happens with inferior portion of SH head, then superior portion, and last would be CH
  • Risk factors

    • male
    • bench press
    • bi-modal
      • younger (20-40) and elderly
    • steroid use
      • stiffer tendon
      • collagen dysplasia
      • increased vascularity and cellularity
  • Classic signs and symptoms

    • acute setting
      • feeling a pop
      • ecchymosis
      • loss of anterior axillary fold
      • weakness
    • chronic setting
      • more subtle
  • Imaging

    • radiograph
    • ultrasound
      • inexpensive, quick
      • may be difficult due to patient’s pain level
      • fluid usually visible at the musculotendinous junction
      • 33% a normal distal pec tendon, so may be missed
    • MRI
      • sensitivity 100% for complete tears of both heads (acute and chronic)
      • specificity 100% for SH and 92% for CH
      • chronic partial tears had lowest sensitivity and specificity
      • much easier to predict at tendon bone interface, less accurate at myotendinous junction
      • axial oblique in line with the fibers is best for diagnosis
  • Injury Classification

    • Type 1 – muscle contusion
    • Type 2 – partial tears
    • Type 3 – Complete tears
      • A – muscle origin
      • B – muscle belly
      • C – MT junction
      • D – tendon
  • Timing of surgery

    • chronic tear will impact repair strategy
      • >14-36 days
      • some describe muscle retraction after 3 weeks of injury
      • mobilization of the muscle is preferred over reconstruction where possible, but sometimes not possible
  • Outcomes

    • nonoperative
      • considerations
        • elderly
        • location (muscle belly)
        • partial tears
        • chronic tears
      • subjective good results in this patient population
      • outcomes
        • cosmetic deformity
        • muscle weakness
        • 27% patient satisfaction
    • operative
      • both acute and chronic patients had high satisfaction
      • meta analysis by BAK KSSTA 2000
        • excellent results in 88% of surgical patients, 27% nonop
        • peak torque preserved in 99% of surgical patients, 56% of nonop
    • Surgical repair
      • acute
        • bone tunnels (older technique)
        • suture anchor
      • chronic tear
        • autograft and allograft options for reconstruction
    • Return to sport
      • all patients returned around 5.5 months, some difficulties in sport (about 20-25%)
    • Technique/fixatoin
      • bone trough best biomechanically, then cortical button, then suture anchor
      • bone trough can cause stress riser
      • other studies have shown no real difference

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