SUMMARY A rare acute injury caused by avulsion of the pectoralis major tendon and usually seen in weightlifters. Diagnosis is generally made clinically and is confirmed with MRI studies. Treatment is usually surgical repair when presenting acutely. Epidemiology Incidence rare injury (< 1 per 100,000 per year) that is increasing in incidence 75% of all reported cases have occurred since 1990 Demographics almost exclusively seen in males (20-40 years of age) often occurs in weightlifters commonly during bench-pressing Location most commonly occurs as a tendinous avulsion sternocostal head insertion of the pectoralis major tendon is the most common site of rupture Risk factors anabolic steroid use Etiology Pathophysiology mechanism excessive tension on a maximally eccentrically contracted muscle occurs during the downward portion of a bench press, with the arm in the final 30 degrees of humeral extension while pushing against heavy resistance tendon fails in a predictable sequence inferior fibers of sternocostal head fail first then superior fibers of the sternocostal head finally the clavicular head Anatomy Pectoralis major innervation lateral pectoral nerve (C5-C7) supplies clavicular head and upper portion of sternocostal head medial pectoral nerve (C8-T1) supplies the lower portion of the sternocostal head origin (two heads) clavicular head from medial clavicle and proximal sternum sternocostal head from distal sternum, costal cartilage ribs 1-6, external oblique aponeurosis sternocostal portion is larger (>80% of muscle volume) insertion humeral shaft just lateral to the bicipital groove action shoulder adduction and internal rotation, to a lesser extent forward flexion (chiefly the clavicular head) other one of four muscles connecting the upper limb to the thoracic wall other muscles include pectoralis minor subclavius serratus anterior Biomechanics inferior fibers of sternal head at maximal stretch during final 30 degrees of humeral extension position at which pectoralis major is most vulnerable to rupture (as with bench pressing) Classification Modified Tietjen (Anatomic) Classification Type Description I Muscle contusion or sprain II Partial tear III Complete tear (further subclassified by location) Location III-A Muscle origin III-B Muscle belly III-C Musculotendinous junction III-D Intra-tendinous rupture III-E Tendon avulsion off humerus (no bone) III-F Bony tendon avulsion off humerus Presentation History patient may report a sudden pop or tearing sensation with resisted adduction and internal rotation Symptoms pain and weakness of shoulder Physical exam inspection & palpation swelling and ecchymosis of anterolateral chest wall and/or proximal medial brachium if localized to the anterior brachium, then humeral attachment rupture is more likely than a musculotendinous junction rupture "dropped nipple" sign ipsilateral nipple will appear lower than the unaffected side due to medial retraction of muscle belly palpable defect and loss of anterior axillary contour accentuated by resisted adduction motion & strength weakness most pronounced in adduction and internal rotation to a lesser extent forward flexion Imaging Radiographs indications limited utility recommended views standard shoulder trauma series (true AP, scapular Y, and axillary lateral) findings most often normal may show loss of pectoralis major shadow or bony avulsion MRI indications investigation of choice can differentiate between complete and partial tears views requires dedicated sequence (standard shoulder MRI will not capture adequately) T2 sequence better for acute injuries T1 for evaluating chronic injuries findings useful in identifying the location and extent of the rupture (partial versus complete) may show avulsion of the pectoralis major tendon from the humerus integrity of clavicular head may mask partial rupture of sternocostal head Treatment Nonoperative initial sling immobilization, rest, ice, NSAIDs, physical therapy indications low-demand, sedentary, and elderly patients muscle belly tears, low-grade partial ruptures outcomes inferior to operative management for young, active individuals cosmetic disfigurement, significant deficit in strength (most pronounced with isokinetic adduction) and peak torque, delayed recovery, poor patient satisfaction, lower return to competitive sports Operative open primary repair indications gold standard for acute tears in high level athletes, and most young, active patients tendon avulsion, myotendinous junction tears outcomes reliable strength recovery, return to sport, and patient satisfaction may show improvement regardless of location of tear excellent success with all methods reconstruction indications chronic tears that cannot be adequately mobilized for primary repair primary repair may still be possible years after the injury persistent strength deficit in chronic tears outcomes reliable strength recovery and patient satisfaction, albeit generally inferior to primary repair still significantly better than nonoperative management in young, active patients Techniques Initial sling immobilization, rest, ice, NSAIDs, physical therapy technique sling in adduction and internal rotation, begin passive range of motion immediately as tolerated active assisted and active motion over the first 6 weeks transition to strengthening and unrestricted activity at 2-3 months Open primary repair approach standard deltopectoral approach repair technique all repair techniques have been shown to have comparably excellent success transosseous suture repair with cortical trough cortical button fixation suture anchor repair both PEAK screw and all suture available some evidence suggests that cortical button fixation and transosseous suture repair with cortical trough are superior to suture anchor repair direct repair may be indicated for tears at the muscle belly or myotendinous junction Reconstruction approach standard deltopectoral approach mobilization need to release adhesions superficial and deep to pectoralis major careful to avoid injury to the medial and lateral pectoral nerves during deep release supplemental fascial release may be necessary to mobilize the muscle belly in chronic situations graft options Achilles allograft (most common) advantages avoids donor site morbidity, excellent load characteristics, favorable dimensions, and good surgical outcomes reported Gracillis weave (allograft versus autograft) Complications Re-rupture (5-7%) failure most often occurs at suture-tendon interface Persistent pain incidence most common complication Residual weakness Cosmetic deformity