The muscle is macerated and retracted. Abnormal increased fluid surrounding the biceps tendon in the intertubercular groove is an associated finding. Findings are diagnostic of compete tear of the pectoralis major tendon at the insertion site. Rupture of the tendon occurs when excessive force is applied while the muscle is in maximal eccentric contraction. The injury seems to be most common among weight lifters and high performance athletes, particularly football players.
Incomplete ruptures are more common than complete rupture.
Clinically, patients present with the characteristic history of excessive muscle stress or a direct blow to the shoulder region while the arm is in abduction and extension. The physical findings are related to the site and type of injury. Rupture occurring distally at or near the humerus usually causes ecchymosis and swelling in the arm or axilla. A more proximal rupture causes similar findings on the anterior chest wall. Range of motion in adduction, flexion and internal rotation of the shoulder is limited secondary to pain and weakness.