The latissimus dorsi muscle is a large and powerful muscle that covers a significant portion of the back and attaches to the arm near the shoulder joint. The latissimus is very active in adducting the arm during climbing or pull-ups. Occasionally, a patient may rupture the insertion of the latissimus dorsi muscle from the humerus (arm bone) near the shoulder. It is also possible to injure the muscle along the tendon or in the mid-substance. This may occur with a forced jerk of the arm, such as in water skiing, or with an eccentric (elongated) force as in the follow-through phase of throwing.
Initial treatment consists of rest and icing the injured area. A sling may be given for comfort. Small partial latissimus dorsi tendon injuries may be treated conservatively with shoulder exercises completed under the supervision of a physical therapist or athletic trainer. Treatment of complete tears is somewhat controversial. Tears in the mid-belly and at the muscle-tendon junction are not favorable to repair. For the active athlete with a tear at the bony insertion, surgical reattachment of the tendon to the humerus is a possible treatment option. Depending on the needs of the athlete, good functional outcomes have been reported with surgical or nonoperative treatment. Without surgery, the loss of normal armpit contour and some weakness of the shoulder will persist. Repair within the first few weeks provides a better result and is technically easier to perform. After surgery and immobilization for six weeks, physical therapy is needed to regain shoulder motion and strength.
Frequent Signs and Symptoms
- A pop, rip, or tearing sensation combined with severe or sharp, often burning, pain in the armpit or upper back at the time of injury
- Tenderness, swelling, warmth, and/or redness over and around armpit, side, and back
- Bruising that develops several days after injury
- Pain when trying to raise the arm, weakness trying to pull down or extend the arm
- Loss of contour of the posterior armpit region and a bulging below the shoulder blade
- Loss of firmness when pushing on the area where the tendon ruptured (a defect between the ends of the tendon and bone where they separated from each other)
Etiology (Causes)
- Sudden episode of strenuous activity
- Direct blow or jerk to the arm
- Eccentric overload in throwing
Risk Factors
- Excessive climbing, hanging, pull ups
- Wrestling
- Poor physical conditioning (strength and flexibility)
- Previous tendinopathy
- Oral anabolic steroid use