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Understanding Military Injuries Can Help Guide Patient Care

Musculoskeletal injuries are common in the military. The physical training required to achieve a certain level of strength and endurance can contribute to soft tissue trauma. Information gained from military studies benefits orthopedic surgeons and sports medicine professionals working with young adults and athletes who have similar problems.

In this report, injuries to the pectoralis major muscle are reviewed. Mechanisms of injury, anatomy, diagnosis, and treatment are discussed in detail. The pectoralis muscle is the large muscle across the chest that is most active when doing push-ups or lifting weights.

It is a two-part muscle that attaches above to the clavicle (collar bone) and down the length of the sternum (breast bone). It also attaches by a fairly narrow tendon (thin compared to the muscle size) to the upper arm next to the tendon insertion of the biceps muscle.

Injuries severe enough to rupture the tendon attachment occur most often when the muscle is fully contracted and then slowly lengthens against a weight. This mechanism of injury describes the bench press -- lifting overhead with arms out to the sides, elbows straight, and shoulders externally rotated.

Pectoralis major ruptures have also been reported as a result of work injuries. And this type of injury has been associated with a wide range of activities such as wrestling, sailing, water skiing, snow skiing, rugby and soccer, football, boxing, and even parachuting.

In younger adults, the injuries almost always occur in males between the ages of 20 and 40. Older adults might have this type of injury when they have to be helped by others when transferring from bed to chair and vice versa. Pressure under the arms against stiff, weak muscles while being lifted is enough to cause crush injuries and hematomas (pools of blood around or inside the muscle).

To help the reader understand the anatomy and function of this very large muscle, drawings were provided. The article includes a complete description of the muscle layers, blood supply, and nerve branches to each segment. There are differences among people, so not everyone has the exact same location of blood vessels and nerves.

However, no matter what the anatomical configuration, when the muscle is ruptured, it is clear to the examiner looking at the patient. First, the patient describes a pop or tearing sensation while bench pressing. There is pain right away and the arm gives way because it is suddenly too weak to hold up.

Early on after the injury, there is obvious swelling across the chest and/or under the armpit and bruising in the same areas. Touching or pressing the area is painful. Moving the arm is also painful. Unless the person has ruptured both pectoralis major muscles, there is an obvious difference in visual appearance when comparing the unhurt side with the involved side.

There may be a bulge on one side of the chest where the muscle has pulled away from the bone and bunched up. A common sign of pectoralis major rupture is the loss of the crease of skin in front of the arm pit. This area is called the axillary fold.

To confirm the diagnosis, it may be necessary to order X-rays, ultrasound studies, and/or MRIs. But most of the time, it is quite obvious what is the problem and further imaging studies aren't needed. X-rays are often negative unless there has been a bone fracture at the same time or a piece of bone (avulsion) has pulled away with the tendon rupture.

Ultrasound can show damage to the muscle and the presence of hematomas. MRIs help the surgeon see exactly where the damage has occurred and if the tendon is partially or fully ruptured. The MRI also shows the current location of the tendon and how far back it has pulled away (retracted) from the bone.

Since the insertion of the pectoralis major tendon is so close to the biceps tendon, the MRI clears up any confusion about what is included in the damage. All of this information can help when deciding what type of treatment is best.

Most of the time, surgery is required to repair the damage. It's during the operation that the surgeon gets a close up view and 100 per cent accuracy in the diagnosis. Only older adults are treated conservatively (nonoperative). With rest, support (arm in a sling), and the use of cold and later heat, these injuries can heal enough to allow the less active person to perform normal daily activities without pain.

In younger patients, whether the injury is fairly new (acute) or old (chronic), recovery is not likely without surgery. The tendon is returned to its normal position and reattached with sutures (stitches). There are several different ways to do this.

Some involve drilling holes in the bone, threading sutures or anchors through the holes and tissue to hold the tendon in place until it can reattach and accept tension during muscle contraction. The authors provide drawings, descriptions, and photos taken during the operation to explain the basic procedure.

Special problems are discussed such as the presence of scar tissue and adhesions in chronic injuries. When the tendon can't be pulled back and put in its original place, graft (donor) tissue is used to restore the natural length of the tendon.

With the proper follow-up and rehabilitation, pectoralis major muscle ruptures treated surgically can bring about excellent results. Recovery ranges from six weeks to 24 months. Most patients are able to resume normal activities, military involvement, and sports participation at the end of a year (some as early as four months postoperatively).

For physicians who would like to learn more about this topic and/or participate in a continuing medical education program, there is an on-line course available. This one-credit course meets the standards of the Accreditation Council for Continuing Medical Education (ACCME). It is available at http://ajsm-cme.sagepub.com.

References: CDR Matthew T. Provencher, MD, MC, USN, et al. Injuries to the Pectoralis Major Muscle. In The American Journal of Sports Medicine. August 2010. Vol. 38. No. 8. Pp. 1693-1705.

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