Updated December 16, 2014.

A humerus fracture is an injury to the bone of the upper arm. The upper arm bone, the humerus, connects the shoulder to the elbow. Humerus fractures are generally divided into three types of injuries:

• Proximal Humerus Fractures
  Proximal humerus fractures occur near the shoulder joint. The shoulder joint is a ball-and-socket joint, with the ball being the top of the humerus bone. Fractures of this ball are considered proximal humerus fractures. These fractures may involve the insertion of the important rotator cuff tendons. Because these tendons are important to shoulder motion, treatment may depend on the position of these tendon insertions.

• Mid-Shaft Humerus Fractures
  Mid-shaft humerus fractures occur away from the shoulder and elbow joints. Most humeral shaft fractures will heal without surgery, but there are some situations that require surgical intervention. These injuries are commonly associated with injury to one of the large nerves in the arm, called the radial nerve. Injury to this nerve may cause symptoms in the wrist and hand (see below).
• Distal Humerus Fractures
  Distal humerus fractures are uncommon injuries in adults. These fractures occur near the elbow joint. These fractures most often require surgical treatment unless the bones are held in proper position. This type of fracture is much more common in children, but the treatment is very different in this age group.

How do humerus fractures occur?
Humerus fractures can occur by many different mechanisms, but are most commonly caused by falls.
What is the treatment for a humerus fracture?
The good news is that most humerus fractures will heal without surgery. The majority of patients can be treated with a sling or brace, and with time the fracture will heal.

Casting is not possible with most types of humerus fractures.

Surgery may be required when the bone fragments are far out of position. Determining when the alignment is acceptable depends on a number of factors. Fractures close to the shoulder and elbow joints, especially fractures that extend into the joint, are more likely to require surgery. Conversely, fractures in the center of the shaft of the bone rarely require surgery, even with the bone fragments appear not perfectly aligned.

Why does numbness over the back of the hand often occur with humerus fractures?
One of the commonly associated problems with humerus fractures is injury to the radial nerve. The radial nerve is one of the major nerves of the upper extremity. This nerve travels from the spinal cord, wraps around the humerus bone, and travels all the way down to the hand. When the humerus is injured, this nerve is often damaged, although the damage is almost always temporary. Patients may notice abnormal sensation over the back of the hand, and weakness of some of the muscles of the hand and wrist. Over 90% of patients with humerus fractures and radial nerve damage will have complete recovery of the nerve within 3 to 4 months.