A 53-year-old physically active man presented to the Emergency Department with a history of pain in the right arm and anterior right-sided chest wall after bench-pressing exercises during a routine workout one week before.
On physical examination, demonstrated swelling and ecchymosis, with functional limitation in shoulder adduction and internal rotation.
Given the clinical findings, a magnetic resonance imaging (MRI) study was performed (Fig.1 and Fig.2). The MRI revealed a musculotendinous junction tear of the sternal head of the right pectoralis major muscle. The respective muscle belly was retracted by up to 5 cm and the gap was filled with fluid (Fig.3). There was also intramuscular oedema involving the sternal head of the pectoralis major muscle.
The humeral pectoralis major tendon insertion was intact.
The superior clavicular head and the inferior abdominal head of the pectoralis major muscle were normal.
The rest of the surrounding muscles had normal size and signal intensity.
(To view the MRI study, please refer to videos 1 and 2.)
Background
The pectoralis major muscle is a fan-shaped muscle with three heads (clavicular, sternal, and abdominal) [1]. The clavicular head is the most superior and arises from the medial half of the clavicle. The sternal head arises from the manubrium, body of the sternum and 1st to 6th costal cartilages of ribs. The abdominal head arises from the aponeurosis of the external oblique muscle.
The muscle fibres insert into a common tendon onto the lateral ridge of the bicipital groove of the humerus. The tendon measures about 5 cm in mediolateral length and 4 cm in craniocaudal width [2].
This complex muscle works as a strong adductor and internal rotator at the shoulder joint [1,2].
Clinical Perspective
Pectoralis major muscle injuries are rare. Nevertheless, the frequency of these injuries has been increasing due to sports-related trauma and the growing popularity of weight-lifting training regimens [2,3].
Pectoralis major muscle injuries are commonly seen in young, active males aged 20-40 years [3].
Patients typically present with acute pain and weakness during muscular loading, and ecchymosis and swelling in the axilla and upper arm. Although the diagnosis is usually suspected clinically, assessment of the extent and location of the injury is limited in the acute setting [2,4].
Imaging Perspective
A targeted MR examination provides the anatomic detail necessary to characterize pectoralis major injuries.
A pectoralis major injury may occur at the muscle origin or belly, at the musculotendinous junction, within the tendon, or at the humeral insertion of the tendon with or without bone avulsion [2,3].
Most tears occur at the humeral insertion, followed by the musculotendinous junction [3,5].
The extent of the injury can be described in terms of thickness and width of tendon involvement [3]. The thickness refers to the anteroposterior dimension (partial versus full), and the width indicates the craniocaudal length (complete versus incomplete).
Outcome
Treatment depends on the clinical scenario and anatomic characteristics of the injury.
Patients with injuries at the muscle origin or belly are usually treated conservatively [2,3]. Patients with tears between the musculotendinous junction and the site of humeral tendinous insertion are managed by surgical repair [2,3].
Take Home Message / Teaching Points
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Tear of the pectoralis major muscle at the musculotendinous junction
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The patient is a 53-year-old male who presented with right arm and right chest wall pain after weightlifting (particularly bench press). The current MRI images show:
1. Near the humeral attachment of the pectoralis major, there is a local abnormal signal. On the T2-weighted sequence, it appears as a high signal, suggesting soft tissue injury and possible tearing or fluid infiltration.
2. Partial disruption of the tendon continuity is observed, accompanied by edema and signs of bleeding in the surrounding area, correlating with clinical swelling and subcutaneous bruising.
3. There is a signal alteration in the musculotendinous junction compared to normal structures, and some fibrous bundles show abnormal changes, indicating varying degrees of muscle or tendon tear.
4. No obvious bone abnormalities or clear fractural lesions are observed.
In addition, mild edema in the surrounding soft tissue is consistent with local injury. Overall imaging features suggest damage to the pectoralis major tendon–muscle belly complex, with the most pronounced tear near the humeral insertion.
In summary, based on the patient’s history of injury during weight training and the MRI evidence of clear abnormal signals in the pectoralis major tendon, a pectoralis major tendon tear is the most likely diagnosis.
Considering the patient’s history (injury during bench press), clinical symptoms (weakness in shoulder adduction and internal rotation, local swelling and bruising), and MRI findings (soft tissue discontinuity at the pectoralis major tendon or musculotendinous junction near its insertion), the most likely diagnosis is a pectoralis major tendon tear. If further confirmation of the range and specific degree of the tear is needed, additional imaging studies or surgical exploration may be considered.
Depending on the location and severity of the pectoralis major tendon tear, the following treatment strategies can be chosen:
Rehabilitation/Exercise Prescription (FITT-VP Principle):
Throughout rehabilitation, closely monitor any changes in swelling and pain. If notable discomfort occurs, adjust the training plan or seek medical attention promptly. For patients over fifty who remain active, special attention should be paid to cardiovascular and bone health; bone density tests and cardiac function evaluations may be needed to develop a safer exercise program.
Disclaimer: This report is for reference only and cannot replace face-to-face consultation or professional medical advice. Specific treatment plans and rehabilitation guidelines should be carried out under the supervision of a specialist or rehabilitation therapist.
Tear of the pectoralis major muscle at the musculotendinous junction
