Arm fractures occur from high-force impact injuries, such as falling on an outstretched arm or a motor vehicle accident. The forearm bones -- the radius and ulna -- are commonly fractured in adults and children. It is sometimes obvious that a bone is broken, particularly if it pokes through the skin. However, an arm fracture may not always be that easily detected. Consult a doctor immediately if you suspect an arm fracture.

Several types of arm fractures occur: closed, open or compound, comminuted, displaced and nondisplaced. Closed fractures are those that do not pierce the skin, while open or compound fractures break through the skin. Comminuted fractures are those in which the bone has broken into several pieces. Bone pieces move out of normal alignment with a displaced fracture, while the ends of the bone stay in position with a nondisplaced fracture.

Transverse fractures cause a clean break across the diameter of an arm bone. These injuries are usually the result of a high-impact force. Spiral fractures occur from a twisting force on the arm that causes the bone to splinter. A greenstick fracture typically occurs in a child's forearm. The growing bones are soft and may bend without breaking completely through the bone, much like what happens when you bend a fresh twig from a tree.

Diagnosis

Broken arm bones usually present with specific symptoms. Pain and a large bump typically occur at the site of the injury. The pain is typically sharp and often prevents movement of the arm. The mechanism of injury -- a fall on outstretched arm, a fall directly on the shoulder or upper arm, or a motor vehicle accident or sports accident -- can point toward a fracture. A snap or popping sound is often heard when the injury occurs. Swelling develops quickly after this injury, sometimes accompanied by bruising.

Arm fractures are usually diagnosed with x-rays. Pictures are taken from two angles, straight on and from the side. Bones are white on an x-ray, and a dark space along the length of a bone usually indicates a fracture. X-rays also show the type of fracture and whether it is comminuted or displaced.

Scaphoid Fracture

Some arm fractures are not immediately obvious. Scaphoid fractures, which involve a small bone at the base of your hand, typically happen with a fall and landing on an outstretched arm. According to a study published in 2011 by the "International Journal of Emergency Medicine," scaphoid fractures account for 2 to 7 percent of all fractures. The scaphoid bone has a very poor blood supply, which significantly impacts healing. These fractures are frequently missed with x-rays leading to a delayed diagnosis.

Symptoms of a scaphoid fracture can be subtle, such as pain at the base of your thumb with gripping or certain thumb movements. CT scans, bone scans and magnetic resonance imaging are often required to diagnosis this injury.

Radial Head Fracture

Radial head fractures can be missed after an arm injury. The radial head is part of the radius bone on the thumb side of the forearm. It is located in the elbow and is usually injured after a fall on an outstretched arm. Symptoms include elbow stiffness and pain with use of the arm.

This fracture does not always show up on initial x-rays, particularly if the bone pieces stay in place. However, an enlarged fat pad can be seen and is usually present with this injury. A radial head fracture diagnosis can be made based on mechanism of injury and the "fat pad sign."