Pectoralis Major Tears
The Pectoralis Major muscle is the big muscle in the chest. The muscle extends from the midline of the chest across the shoulder and inserts into the humerus, the bone of the upper arm via a tendon. The muscle provides power to the upper arm.
Uncommonly the Pectoralis Major ruptures. This usually occurs after significant trauma such as a fall at high speed or a tackle, but can occur when training with heavy weights. It specifically occurs when the patient is bench pressing too heavy a weight, and pushes the weight up from a fully extended position. The condition is more common in persons who take anabolic steroids as this can weaken the attachment of the muscle into the bone. The rupture usually occurs where the tendon of the muscle inserts into the bone. Uncommonly it can tear through the muscle itself.
The injury is usually very obvious with loss of the contour of the chest wall muscles and loss of the front muscle fold of the armpit. There is usually upper arm bruising which appears within 24 hours of the injury.
This injury causes significant weakness of upper arm function and a cosmetic deformity of the chest wall. The only way to address the problem is surgically and surgery needs to be done as soon as possible after the injury. Prior to surgery an MRI of the shoulder and chest is required to make sure that the tear of the Pectoralis Major is at the insertion into the bone and that the tendon is completely torn rather than partially torn. Rarely the Pectoralis Major can tear in the muscle belly itself, making it surgically irrepairable. On occasions, it may be difficult to diagnose the exact position of the tear, and the surgeon will recommend an exploration of the muscle. If the tear is complete, and off the bone, it can be repaired, but if the tear is in the substance of the muscle belly then it cannot be repaired.
Leaving surgery for longer than 4 weeks can make the outcome less reliable. Trying to repair a tear of long standing duration is very difficult and rarely successful. On occasions in chronic tears we can supplement the repair with tendons harvested from the leg but again the outcome of this surgery is extremely variable and is better to avoid.
The surgical procedure generally entails a 4 cm incision about the shoulder. The muscle is usually repaired to the humerus bone after making a small trough in the bone into which the muscle is attached with non dissolvable stitches. Occasionally small screws are used.
Surgery usually involves a night in hospital and approximately 6 weeks of immobilization in a sling. For around 6 months after surgery you have to be careful with the shoulder and avoid heavy lifting, overhead activity and all sports. During this period physiotherapy is required to strengthen the Pectoralis Major muscle. The muscle does not fully heal to the bone for 6 months hence the need to avoid lifting and sport for that period of time.
After about 6 months you can resume full activity with care understanding that the muscle is never quite as strong as prior to the injury. Surgery carries a 90% success rate.