Medial Epicondylitis
August 27, 2017
Intersection Syndrome
September 9, 2017

Pectoralis Major Tear/Rupture

 

Pectoralis Major Tear/Rupture

Description:

Tears and/or ruptures of the pectoralis major muscle are rare, with only 400 noted cases in the literature (1). They are becoming increasingly more common and almost exclusively occur in otherwise healthy males between the ages of 20 and 40 years old. This increase is potentially a result of greater participation in bodybuilding and weightlifting training(1). The majority of injuries take place at the musculotendinous junction, with only a small percentage occurring in the muscle belly(2).

Anatomy(3):

  • Location: Anterior Chest Wall
  • Origin:
    • Two heads: (1) Clavicular (2) Sternocostal
  • Insertion: lateral lip of the intertubercular groove of the humerus
  • Action: flexion (clavicular head), extension (sternocostal head), adduction, medial rotation of the humerus.
  • Innervation: lateral and medial pectoral nerves
  • Vascular supply: pectoral branch of the thoracoacromial trunk
  • One of four muscles that attach the upper limb to the thorax. Others include:
    • Serratus anterior
    • Pectoralis minor
    • Subclavius

PecMajorAnatomyFig1

Figure 1 and 2: Anatomy of pectoralis major and anterior chest muscles(5)

Injury Mechanism:

Injuries occur with excessive tension on a maximally eccentrically contracted muscle (3). The muscle is typically extended, abducted, and externally rotated during the downward deceleration phase of the bench press exercise(3). The inferior fibers of the sternal head are maximally stretched during the final 30 degrees of humeral extension and thus the most vulnerable to rupture in this position (i.e. final stage of bench press)(3). Tears/ruptures occur in four locations: (1) humeral insertion (2) musculotendinous junction (3) muscle belly (4) muscle tearing off the sternum (very rare). Patients will describe a “sharp tearing sensation”(3) or an audible snap/pop during resisted adduction and internal rotation.

There has been some association between increased risk of rupture and anabolic steroid use(1), with the weakening of tendons becoming a contributing factor (2). However, this injury can occur in individuals who do not use anabolic steroids.

Iatrogenic injury to the pectoralis major tendon can also occur during rotator cuff repair.

BenchPressFig2

Figure 2: point of maximal vulnerability during bench press (6)

Differential Diagnoses(4):

  • Long head of biceps tendon rupture
  • Shoulder dislocation
  • Proximal humerus fracture
  • Rotator cuff tendon tear
  • Subscapularis muscle tear
  • Medial pectoral nerve entrapment

 Exam:

Inspection(1)(2)(3):

  • Bruising, ecchymosis, swelling over anterior chest wall and/or proximal arm
  • Loss of anterior axillary fold crease
  • Asymmetry of normal chest contour

Palpation:

Palpable defect and deformity of the anterior axillary fold

Range of Motion:

  • Most useful sign(1): loss of anterior axillary fold with
    • Resisted adduction
    • Passive abduction

Strength:

  • Weakness with resisted adduction and internal rotation

PecMajorRupture

Figure 3: swelling and ecchymosis of left pectoralis major rupture.

Proximal arm ecchymosis is indicative of tendon rupture at humeral insertion(7)

Investigations(1)(3):

  • Diagnosis can typically be made clinically

Radiographs:

  • Obtain standard 3-shoulder views (true AP, scapular Y, and axillary lateral)
  • To rule out avulsion fractures, dislocations, other injuries
  • Usually normal

MRI:

  • To identify location and extent of injury

Ultrasound

  • Effectiveness is operator dependent and usually used if delay in obtaining MRI

Management(1)(3):

Conservative (nonoperative):

  • Immobilization with sling, rest, ice, analgesics
  • Strengthening program over 4-6 week period
  • Indicated for:
    • partial ruptures
    • low-demand athletes
    • musculotendinous and/or muscle belly injuries

Operative:

  • Open exploration and repair of tendon avulsion
  • Different techniques
    • Tendon-to-tendon suture
    • Bone trough repair
    • Anchor sutures
    • Transosseous sutures
    • Tendon reinsertion to clavipectoral fascia
  • Treatment of choice for high-level athletes
  • Post-operative rehabilitation:
    • Immobilization with sling with passive ROM: 3-4 weeks
    • Active assisted ROM: 3-6 weeks post-op
    • AROM: >6 weeks
    • Protected from normal life activities: 4-6 months post-op
    • Rehabilitation programs should always be individualized

Author: Alessandro Francella, MD (July 3, 2017 PR ND)

References:

  1. Bayon AO, Sandoval E, Mora MV. Acute Pectoralis Major Rupture Captured on Video. Case Reports in Orthopedics. 2016; 2016: 2482189.
  2. Kadu VV, Saindane KA, Godghate Ni, Godghate Ne. Pectoralis Major Tear: An Unusual and Rare Presentation. Journal of Orthopedic Case Reports. 2016 Sep-Oct; 6(4): 17-19.
  3. Allen, D. Pectoralis Major Rupture. Retrieved from: http://www.orthobullets.com/sports/3069/pectoralis-major-rupture
  4. Brukner P et al. Brukner & Khan’s Clinical Sports Medicine: Fourth Edition. McGraw Hill Medical. 2014: pp. 373

Images:

  1. Retrieved from: https://www.britannica.com/science/pectoralis-muscle
  2. Retrieved from: http://www.ptonthenet.com/articles/biomechanics-of-the-bench-press-4019
  3. Retrieved from: http://www.orthobullets.com/sports/3069/pectoralis-major-rupture