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Distal Humerus Fracture (Broken Elbow)

Elbow Anatomy

(Left) The elbow bones. The "distal humerus" is the lower end of the humerus (upper arm bone). (Right) The major nerves and ligaments of the elbow are highlighted.

A distal humerus fracture is a break in the lower end of the upper arm bone (humerus), one of the three bones that come together to form the elbow joint. A fracture in this area can be very painful and make moving the elbow impossible.

Most distal humerus fractures are caused by some type of high-energy event—such as receiving a direct blow to the elbow during a car collision. In an older person who has weaker bones, however, even a minor fall may be enough to cause a fracture.

Treatment for a distal humerus fracture usually involves surgery to restore the normal anatomy and motion of the elbow.

What is the anatomy of the elbow?

Your elbow is a joint made up of three bones:

  • The humerus (upper arm bone)
  • The radius (forearm bone on the thumb side)
  • The ulna (forearm bone on the pinky side)

The elbow joint bends and straightens like a hinge. It also helps you to turn your hand palm up (like accepting change from a cashier) or palm down (like typing or playing the piano).

The elbow consists of portions of all three bones:

  • The distal humerus is the lower end of the humerus. It forms the upper part of the elbow and makes it possible for your forearm to bend and straighten. 
  • The radial head is the knobby end of the radius where it meets the elbow. It glides up and down the front of the distal humerus when you bend your arm and rotates around the ulna when you turn your wrist up or down.
  • The olecranon is the part of the ulna that "cups" the lower end of the humerus, creating a hinge for elbow movement. The bony "point" of the olecranon can be easily felt beneath the skin because it is covered by just a thin layer of tissue.

The elbow is held together by its bony architecture, as well as ligaments, tendons, and muscles. Three major nerves cross the elbow joint.

What is a distal humerus fracture?

Distal Humerus Break

A distal humerus fracture occurs when there is a break anywhere within the distal region (lower end) of the humerus. The bone can crack just slightly or break into many pieces (comminuted fracture). The broken pieces of bone may line up straight or may be far out of place (displaced fracture).

In some cases, the bone breaks in such a way that bone fragments stick out through the skin or a wound penetrates down to the bone. This is called an open fracture. Open fractures are particularly serious because, once the skin is broken, infection in both the wound and the bone is more likely to occur. Immediate treatment is required to prevent infection.

Distal humerus fractures are uncommon; they account for just about 2 percent of all adult fractures. They can occur on their own, with no other injuries, but can also be a part of a more complex elbow injury.

What causes distal humerus fractures?

Distal humerus fractures are most often caused by:

  • Falling directly on the elbow
  • Receiving a direct blow to the elbow from something hard, like a baseball bat or a dashboard or car door during a vehicle collision
  • Falling on an outstretched arm with the elbow held tightly to brace against the fall. In this situation, the ulna (one of the forearm bones) is driven into the distal humerus and this causes it to break.

Distal humerus fractures are also sometimes caused by weak bone. This is most common in older patients whose bones have become weakened by osteoporosis. In these patients, a fracture may occur even after a minor fall.

What are the symptoms of a distal humerus fracture?

A distal humerus fracture may be very painful and can prevent you from moving your elbow. 

Other signs and symptoms of a fracture may include:

  • Swelling
  • Bruising
  • Tenderness to the touch
  • Stiffness
  • A feeling of instability in the joint, as if your elbow is going to "pop out"
  • In rare cases, the fractured bone may stick out of the skin (open fracture)