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What is a humerus fracture?

The upper arm bone (the humerus) is the bone that runs between the elbow and the shoulder. Humerus fractures account for a remarkably small proportion of total bone fractures: only three percent.

The humerus is a strong bone, analogous to the femur in the leg (which is the strongest bone in the body). It  does not absorb the intensity of stress that the forearm bones do when you fall and catch yourself with your hands, since the humerus is farther up the chain of bones. Nonetheless, falling down is responsible for the bulk of humerus fractures. People with osteoporosis, whose bones have been made thin and porous through mineral loss, are especially vulnerable to humerus fractures.

Of all humerus fractures, only ten percent cause substantial bone displacement. This means that most humerus fractures can be treated non-surgically by immobilizing and stabilizing them. Of the ones that do need surgery, many are closer to the elbow (toward the humerus’ distal end).  

Anatomy of the upper arm

The bone of the upper arm connects to the shoulder blade at its proximal end and with the radius and ulna at its distal end. It consists of the following:

  • The humerus (the upper arm bone; it is a very strong bone)
  • The radius (the forearm bone on the inside of your arm)
  • The ulna (the forearm bone on the outside of your arm)
  • The scapula (the shoulder blade, a triangular bone protected by a lot of muscle)

Types of humerus fractures

Humerus fractures can be divided into three main types:

  • Proximal humerus fracture—If your fracture is near the shoulder joint (where the humerus connects with the scapula), then you have a proximal humerus fracture. Since this type of fracture can mean that the humerus ball, which inserts into the shoulder blade’s socket, is broken, rotator cuff damage is sometimes associated with it.
  • Diaphyseal humerus fracture—These are mid-shaft fractures that are generally treated nonsurgically.
  • Distal humerus fracture—This fracture of the humerus at or near the elbow is far more common in children than in adults. It generally requires surgery to heal properly.

Symptoms

Different types of humerus fractures have somewhat different symptoms since they occur in different locations, but they are generalizable. If you fracture your humerus, the portion of it that you have fractured will hurt intensely, swell and feel stiff. If your nerves have been damaged by the fracture, your hand and wrist will likely be weak and experience strange sensations. If you have fractured your distal humerus, your elbow may feel unstable, as if the joint were going to separate.

The symptoms of humerus fracture may be mistaken for the symptoms of other medical conditions (proximal ulna fracture, rotator cuff tear, etc.). Make sure you consult a doctor to determine if you have a humerus fracture and get the appropriate treatment. 

Causes

A humerus fracture generally is the result of a fall or a blow to the arm. The following are some potential causes:

  • Indirect blow to the humerus—If you fall down and land on your arm, and it is outstretched with the elbow locked, the ulna can be forced into the distal humerus (the portion of the humerus that makes up a part of the elbow), causing a distal humerus fracture.
  • Direct blow to the humerus—If you fall directly on any area of your humerus, are hit there by an object or are in an automobile accident, you can fracture it at that point. 
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