Rupture of the Pectoralis Major Muscle: Diagnosis and Treatment
Geoffrey P. Griffiths, MD; F. Harlan Selesnick, MD
THE PHYSICIAN AND SPORTSMEDICINE - VOL 25 - NO. 8 - AUGUST 97
In Brief: Correct diagnosis of complete or partial ruptures of the pectoralis major muscle complex is important because of the muscle's vital role in shoulder function. Three case reports are used here to support a discussion of diagnosis and treatment. The diagnosis can usually be made with a history and physical exam, but magnetic resonance imaging can help pinpoint the site of a tear. Nonoperative treatment is generally preferred for partial tears; operative treatment may be necessary to restore full function in complete tears. Rehabilitation involves a gradual progression from pendulum exercises to range-of-motion exercises to strengthening, and patients can usually return to full activity in 3 to 6 months.
Ruptures of the pectoralis major muscle complex are relatively rare; more common causes of shoulder pain include rotator cuff tears, impingement syndrome, and shoulder instability. Swelling can obscure the defect, making diagnosis difficult, so the clinician must have a high degree of suspicion. Failure to recognize and treat a complete avulsion or tear can lead to significant functional disability.
The usual mechanism of injury involves an actively contracting muscle overburdened by a load or extrinsic force that exceeds tissue tolerance (1). A rupture may also be caused by a direct blow. The majority of complete ruptures reported in the literature are in athletes, with weight lifting by far the most often-cited precipitating activity (2-4).
Localizing the tear is important for classification and treatment (see "Anatomy of the Pectoralis Major," below), and treatment options vary depending on the site and nature of the injury. The degree of rupture can be termed incomplete (partial) or complete; many patients who have pectoralis major muscle injuries have incomplete ruptures. Tears located at the proximal origin of the muscle are least common. They occur more often in the muscle belly, at the musculotendinous junction, and at or near the distal insertion on the humerus.
In this article, we describe complete pectoralis major muscle injuries in three patients, two of whom were treated operatively and one of whom was treated nonoperatively.
A 42-year-old right-handed acupuncturist was manipulating a patient with a twisting internal rotation of his left upper arm when he felt a sudden snap and marked pain in his left axilla. He presented to our office several hours after the injury, supporting his left arm with his uninjured hand.
On examination the skin was intact, and a moderate degree of swelling with some ecchymosis had developed around the shoulder area. He reported tenderness on palpation over the anterior aspect of the proximal humerus and the entire axillary area. There was a suggestion of a loss of the anterior axillary contour that was best visualized when the patient's arm was in a passively abducted position, but this was difficult to fully appreciate because of the edema. All ranges of active motion were painful and weak relative to the opposite side, but pain and weakness were greatest during adduction and internal rotation.
A detailed neurocirculatory exam was normal, and a radiographic trauma series, consisting of an anteroposterior view in the scapular plane, a lateral scapular Y-view, and an axillary view, showed no bony abnormalities. A presumptive diagnosis of complete distal rupture or avulsion of the pectoralis major was confirmed by magnetic resonance imaging (MRI, figure 1a).
The patient's arm was immobilized with a sling until operative treatment was given. With a standard deltopectoral approach to the shoulder, a complete rupture of the distal tendon was identified. The tendon was mobilized and secured with five suture anchors (figures 1b and 1c). Postoperatively, he advanced in a physical therapy program and returned to his profession in 4 months.
A 25-year-old right-handed National Basketball Association player was playing basketball on vacation when he fell, pinning his left arm behind his body and injuring his left shoulder. The local emergency department diagnosed a shoulder sprain.
On examination several days later, he reported significant loss of motion and weakness on adduction. No deformity existed along the axilla, but there was moderate bruising. X-rays were unremarkable. The patient's MRI revealed extensive tearing of the pectoralis major muscle near the musculotendinous junction, with a large amount of fluid collecting in the tissue planes within the muscle and spreading distally to the tendinous insertion.
The operative procedure and findings were similar to those in case 1, with a deltopectoral surgical approach, and repair of the ruptured distal tendon with suture anchors.
Postoperative care included immobilization of the patient's arm in a sling for 4 weeks, followed by an aggressive rehabilitation program. Isokinetic strength testing done 3 months after surgery demonstrated only a 12% deficit with both external and internal rotation of the injured side. The patient returned to full competition at that point (figure 2). He completed the season without difficulties, and continues as a starting player 3 1/2 years postoperatively.
A 31-year-old right-handed professional jai alai player reported a popping sensation and immediate, severe pain after releasing the ball at high speed from his cesta basket. The pain was mainly in the right anterior chest wall. He denied having dyspnea.
One day after the injury, physical examination revealed a fullness in the right pectoral region along with ecchymosis along the chest wall. There was no tenderness at the distal insertion of the tendon on the humerus. Radiographs were unremarkable. An MRI (figure 3) demonstrated a large pectoralis major tear in the muscle belly with no involvement of the tendon or musculotendinous junction.
Because there was no gross displacement and the patient desired nonoperative care, he was treated conservatively. His arm was immobilized for 10 days, after which a physical therapy program was initiated. He returned to full pain-free competition at 3 months.
The histories in these three cases are typical for this injury. The majority of ruptures occur in the third and fourth decades (4). The patient often describes an audible pop, snap, or tearing sensation, which is usually accompanied by immediate, marked pain and weakness. The role of anabolic steroid use in this condition is unknown, and none of the patients in our series admitted steroid use.
Mechanism of injury. The most common mechanism of injury occurs when excessive force is brought to bear on the pectoralis major muscle complex indirectly through the arm. An attempt to break a fall with an outstretched hand can apply this type of indirect force to the muscle-tendon unit, resulting in a rupture (1).
Physical findings. With these injuries, the physical examination will likely reveal a painful limitation of motion, swelling and ecchymosis, and weakness, especially in adduction and internal rotation.
Findings vary depending on the site of the rupture. If the muscle is injured at or near its origin, the swelling and ecchymosis will be along the anterior chest wall. The injured muscle belly may retract toward the axillary fold, causing the fold to be enlarged (5). A distal avulsion often disrupts the normal contour of the anterior axillary area. A thin or absent axillary fold may be obvious, but a large hematoma, some retained fibers, or fascia may mask the defect of the anterior axillary wall (4). An effort to contract the muscle against resistance will accentuate the deformity.
In chronic cases of pectoralis major rupture, the defect will be more prominent, with obvious asymmetry as compared with the opposite side. Without treatment, weakness in adduction and internal rotation will persist.
Imaging studies. The diagnosis can usually be made after a complete and careful history and exam. Radiographs are unremarkable in most circumstances. Occasionally, other tests and imaging modalities can be used, especially for differentiating partial from complete ruptures. MRI provides excellent detail and clarity, giving important information regarding the specific location of the injury (muscle substance, musculotendinous junction, or tendon insertion). Liu et al (2) used isokinetic muscle testing, computed tomography scanning, and ultrasonography to delineate a chronic injury.
Conservative treatment. Nonoperative treatment is the preferred choice for partial tears and consists of immobilization, rest, cryotherapy, compression for control of the hematoma, and analgesia. Progressive Codman pendulum exercises can be initiated at 1 to 2 weeks postinjury, followed by active and active assisted range-of-motion exercises at 4 to 6 weeks. A strengthening program can be started once full pain-free motion has returned. This usually requires 6 to 8 weeks from the time of the injury.
Surgical approaches. Multiple surgical procedures have been described, including direct end-to-end repair at the musculotendinous junction or muscle substance and stabilization of the tendon to the bone through drill holes or suture anchors.
Complete tears can be treated surgically or nonsurgically, but some authors feel that for complete ruptures surgical repair is essential to restore complete function and contour, especially in young, active patients (2). In one of the largest series reported in the literature, Park and Espiniella (6) reported that only 58% of patients who had nonoperative treatment for complete ruptures showed good results. In the same series, 90% of the surgically treated patients had excellent or good results. Wolfe et al (7) reported a 26% peak torque deficit and 40% work deficit on isokinetic testing in a conservatively treated patient. In a bilateral injury the surgically repaired side had one third more peak torque. According to Kretzler and Richardson (8), the majority of reports in the literature showed that full strength was achieved only with operative repair.
Postoperative management consists of sling immobilization for 4 weeks, with pendulum exercises allowed immediately. After the period of immobilization, range-of-motion exercises can be started, followed by a progression to strengthening similar to the conservative treatment program described above. Return to competition or unrestricted sports participation is usually possible 3 to 6 months postsurgery, when the patient's full range of motion and normal strength have returned.
Anatomy of the Pectoralis Major
An appreciation of the anatomy of the pectoralis major is important for understanding the nature of injuries to this muscle complex (figure A). The origin of the muscle complex comprises two parts, often described as two "heads" or lamina. The upper (clavicular) portion arises from the proximal clavicle and the upper portion of the sternum, while the inferior (sternocostal) portion arises from the distal end of the sternum, the ribs, and the aponeurosis of the external oblique muscles. The tendons of insertion rotate around each other so that the lower portion inserts at a site proximal to the upper portion at the humerus.
The main functions of the pectoralis major include shoulder adduction, internal rotation, and flexion. Pectoralis major muscle tears can occur in the muscle belly, at the musculotendinous junction, or at or near the distal insertion into the humerus. The least common site is the proximal origin of the muscle.
Dr Griffiths is an orthopedic surgeon completing a sports medicine fellowship in Miami. Dr Selesnick is team physician for the Miami Heat basketball team, and is an orthopedic surgeon in private practice in Miami. Address correspondence to Geoffrey P. Griffiths, MD, 6262 Sunset Dr, Ste 503, Miami, FL 33143.