A 43-year old man presents with left shoulder pain after performing a bench press 2 days earlier. He reports he had immediate pain, felt a “pop” in the shoulder, and was unable to lift the bar any higher. On physical examination, he has pain to palpation over the anterior shoulder with ecchymosis into the axilla. The patient has weakness with adduction of the humerus on the left side as compared with the right side. He has no asymmetry of the chest wall bilaterally. Magnetic resonance imaging (MRI) of the left chest wall is performed and demonstrates a full-thickness rupture of the pectoralis major tendon distally with 4 cm of retraction (Figure).
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The pectoralis major (PM) muscle is located on the anterior chest wall. The muscle originates from the sternum adjacent to the first through sixth ribs and inserts on the proximal humerus just lateral and distal to the bicipital groove. The primary function of the PM is forward flexion, internal rotation, and adduction of the humerus.
The most common mechanism of injury is a bench press maneuver when the shoulder is extended and externally rotated.1 During a PM injury, patients will often describe a popping sensation followed by pain and weakness of the arm. Initially, the physical examination may reveal ecchymosis in the axilla without any obvious deformity to the contour of the PM. The patient’s arm can be positioned in abduction and external rotation to accentuate the pectoralis deformity.1,2
Magnetic resonance imaging (MRI) is the gold standard study to confirm the diagnosis of a PM tear. Imaging of the chest wall (not of the shoulder) performed in a prone position to reduce respiratory motion interference is recommended.1,2
Operative treatment is recommended in active patients who are not older than 65 years to preserve shoulder adduction strength. The PM is generally repaired back down to bone using suture anchors within 2 to 4 weeks of injury. Surgical repair more than 8 weeks from time of injury leads to worse outcomes because the tendon retracts and becomes harder to repair.1,2
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor in chief of the Journal of Orthopaedics for Physician Assistants.
1. Kowalczuk M, Elmaraghy A. Pectoralis major rupture: evaluation and management. J Am Acad Orthop Surg. 2022 Jan 12. [Online ahead of print] doi:10.5435/JAAOS-D-21-00541
2. Brown SM, Cole WW 3rd, Provencher MT, Mary MK. Pectoralis major injuries presentation, diagnosis, and management. JBJS Rev. 2021;9(5). doi:10.2106/JBJS.RVW.20.00097