Pectoralis Major Rupture

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Pectoralis major tendon rupture is a rare shoulder injury, most commonly seen in weight lifters.  This injury is being seen more regularly due to the increased emphasis on healthy lifestyles.

Clinically Relevant Anatomy

Pectoralis major muscle is a very powerful shoulder muscle during its function – that of shoulder adductor, internal rotator, and flexor of the humerus. Origins of the pectoralis major include the clavicle, sternum, ribs, and external oblique fascia as well as cartilage of the first six ribs.The insertion of the pectoralis tendon onto the humerus occurs with the muscle twisting on itself so that the lowest fibers of the tendon insert at the highest location on the humerus.Wolfe et al have previously demonstrated that this attachment results in significant tension in the inferior portion of the pectoralis muscle and predisposes this portion to rupture when stretched and loaded. Wolfe and collegues measured excursion of individual pectoralis muscle fibers at seven different points along the origin by the use of finewires connected to humeral insertion and to dial gauges.Inferior fibers of the pectoralis major muscle lengthened disproportionately during the final 30 degrees of humeral extension. This attachment arrangement may result inpartial tears being much more common than that of com-plete ruptures.

Mechanism of Injury / Pathological Process

Although pectoralis tendon ruptures are most commonly seen in weight lifting, ruptures have also been reported in many other sporting activities such as boxing, football,rodeo, water skiing, and wrestling.These injuries tend to occur more commonly in patients during their second to fourth decade of life.To date, this rupture is a totally male dominated athletic injury with not even a single case study report of injury to the female athletic population.

Clinical Presentation

The diagnosis of pectoralis tears is generally not elusive. Patients often give a history of doing a maximal lift or effort and feeling something in the shoulder giving or ripping; while the injury is often accompanied by an audible “snap” or “pop”. Mild swelling and often ecchy-mosis follows. Bruising can be seen over the anterior lateral chest wall or in the proximal arm. Pain generally is not intense. Physical exam reveals a loss of the anterior axil-lary fold and normal pectoralis contour. Asking patients to press the hands together in a “prayer position” eliciting an isometric contraction will reveal asymmetry to the chest wall. This asymmetry can be easily confirmed by looking for medial movement of the nipple on the chest wall.Often a distinct deformity or hollow exists where the pectoralis muscle will move medial. Loss of strength is particularly notable to internal rotation of the arm when testing at neutral.

Diagnostic Procedures

• Plain radiographs report bony abnormalities
• Magnetic resonance imaging (MRI) can be especially helpful where a partial tear is suspected

Outcome Measures

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Management / Interventions

Conservative treatment

Historically, non-operative treatment has been advocated for older or sedentary individuals or for those with incom-plete tears. Wolf et al has reported up to a 26% loss of peak torque and a 39.9% work deficit in shoulder adduction in un-repaired ruptures. Furthermore, numerous studies have demonstrated that surgical treatment of complete pectoralis tendon ruptures has a defined advantage in regards to increased strength over that of non-operative treatment,especially in athletes.

Post-operative rehabilitation

Because no studies have been published that discuss pectoralis major tendon repair strain proper-ties, the amount of stress this tissue can tolerate prior to rupture or compromise in the post surgical patient is not fully understood.Therefore, post surgical rehabilitation soft tissue healing time frames following pectoralis tendon repair are based on clinical impression and empirical evidence in treating these athletes. Additionally, some general assumptions can be made based on previous literature related to soft tissue healing of other common tendon rupture repairs including the Rotator Cuff and Achilles tendon.

As with most post-operative rehabilitation, the ultimate goals following pectoralis major repair include:

1. maintaining structural integrity of the repaired soft tissues;
2. gradually restoring full functional range of motion;
3. restoring or enhancing full dynamic muscle control and stability;
4. return of full unrestricted upper extremity activities including activities of daily living and recreation and sporting athletic endeavors.

The ultimate goal is t return the patient to their preferred level of activity as quickly and safely as possible.

Key Evidence

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Resources

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Case Studies

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