Pectoralis Major Tear Syndrome
The pectoralis major muscle is susceptible to trauma ranging from microscopic tears of the muscle substance after heavy exertion to macroscopic partial tearing of the muscle or, in extreme cases, full-thickness tearing with associated hematoma formation and cosmetic deformity.
Additionally, the pectoralis major tendon can rupture at its point of insertion into the crest of the greater tubercle of the humerus. A broad, thick, fan-like muscle, the pectoralis major arises from the anterior surface of the proximal clavicle, the anterior surface of the sternum, the cartilaginous attachments of the second through sixth and occasionally seventh ribs, and the aponeurotic band of the obliquus externus abdominis.
These muscle fibers overlap, with some running upward and laterally, others running horizontally, and others running downward and laterally, all ending in a broad flat tendon that inserts into the crest of the greater tubercle of the humerus.
The clinical presentation of pectoralis major tear syndrome is varied because of its several causes, with the severity of symptoms directly proportional to the amount of trauma sustained by the muscle, its tendons, or both.
Patients with pectoralis major tear syndrome present with the acute onset of anterior chest wall pain after trauma to the muscle sustained while performing activities such as bench pressing or rappelling down cliffs. The severity of pain is proportional to the amount of trauma sustained.
A patient with pectoralis muscle tear syndrome also may complain of varying degrees of weakness with internal rotation of the humerus. If complete tear of the muscle or rupture of the tendon occurs, the anterior chest wall bulges acutely with contraction of the muscle in a manner analogous to the Popeye’s bulge of Ludington sign associated with rupture of the biceps tendon.
If the rupture is not repaired promptly, further muscle retraction and calcification occur, worsening the functional disability and cosmetic deformity.
What are the Symptoms of Pectoralis Major Tear Syndrome
A patient with pectoralis major tear syndrome complains of the acute onset of pain in the anterior chest after trauma to the pectoralis major muscle, tendon, or both. If the trauma is significant, hematoma formation is clearly visible.
With rupture of the tendon at its insertion site into the humerus, impressive ecchymosis of the arm and anterior chest wall that may seem out of proportion to the amount of trauma perceived by the patient is present. Active internal rotation of the humerus against examiner resistance may reveal weakness.
If significant disruption of the muscle or rupture of the tendon occurs, the patient is unable to reach behind his or her back. As mentioned previously, if complete tear of the muscle or rupture of the tendon occurs, the anterior chest wall bulges with contraction of the pectoralis major against the unopposed torn distal muscle, tendon, or both.
Although not completely diagnostic of pectoralis major tear syndrome, this physical finding should prompt the examiner to order magnetic resonance imaging (MRI) of the affected proximal humerus and shoulder and anterior chest wall to further clarify and strengthen the diagnosis.
How is Pectoralis Major Tear Syndrome diagnosed?
MRI and ultrasound imaging of the shoulder, proximal humerus, and anterior chest wall provides the best information regarding pathological processes of these anatomical regions. Both MRI and ultrasound imaging are highly accurate and help identify abnormalities that may require urgent surgical repair, such as large complete muscle tears, tendon rupture, or both.
MRI and ultrasound imaging of the affected anatomy also helps the clinician rule out unsuspected pathological conditions that may harm the patient, such as primary and metastatic tumors. In patients who cannot undergo MRI, such as patients with pacemakers, computed tomography (CT) is a reasonable second choice.
Radionuclide bone scanning and plain radiography are indicated if fracture or bony abnormality such as metastatic disease of the proximal humerus, shoulder, or anterior chest wall is being considered in the differential diagnosis.
Screening laboratory tests consisting of complete blood cell count, erythrocyte sedimentation rate, and automated blood chemistry testing should be performed if the diagnosis of pectoralis major tear syndrome is in question.
Pectoralis major tear syndrome is a clinical diagnosis supported by a combination of clinical history, physical examination, radiography, and MRI.
Pain syndromes that may mimic pectoralis major tear syndrome include injuries to the pectoralis minor, subscapularis, or latissimus dorsi muscles and inferior glenohumeral ligament injuries.
Dislocation of the manubrium from the body of the sternum after acceleration/deceleration injuries also may confuse the diagnosis.
Fractures of all the bony origins of the pectoralis major muscles (e.g., the sternum and ribs and fractures of the anatomical or surgical neck of the humerus) may mimic the clinical presentation of pectoralis major tear syndrome.
Primary and metastatic tumors of the shoulder, humerus, and anterior chest wall and their surrounding structures remain an ever-present possibility and should be included as part of the differential diagnosis of patients with symptoms thought to result from pectoralis major tear syndrome.
Although the pain and functional disability associated with mild microscopic tears of the pectoralis major muscle may be treated conservatively with a combination of the nonsteroidal antiinflammatory drugs (NSAIDs) or cyclooxygenase-2 (COX-2) inhibitors and gentle physical therapy, more extensive tears and rupture of the pectoralis major tendon require urgent surgical repair if permanent cosmetic deformity and functional disability are to be avoided.
Failure to diagnose pectoralis major tear syndrome correctly puts the patient at risk for the missed diagnosis of other syndromes that may result in ongoing damage to the shoulder or lead to overlooked pathological processes in this anatomical region that may harm the patient, such as Pancoast tumor or primary or metastatic tumors of the shoulder, humerus, or anterior chest wall.
MRI is indicated in all patients thought to have pectoralis major tear syndrome, and aggressive treatment of surgically correctable causes of the symptoms is indicated on an urgent basis to avoid irreversible cosmetic deformity and functional disability.
Pectoralis major tear syndrome is an uncommon but easily recognized cause of anterior chest wall and shoulder pain.
A patient with complete pectoralis major muscle tear, tendon rupture, or both may present with hematoma and ecchymosis formation that seems out of proportion to the patient’s perception of the amount of trauma sustained; the patient often requires reassurance that he or she will not bleed to death. On rare occasions, the pectoralis major may rupture at its sternal origin.
Regardless of the site of rupture, patients with complete rupture of the pectoralis major musculotendinous unit should undergo urgent surgical repair and careful postoperative rehabilitation to avoid permanent cosmetic deformity and functional disability.