1. Trauma
Most humeral shaft fractures occur due to a fall or from a direct trauma. Typically, when we fall, we reach out our hands to brace ourselves. The force can be transmitted anywhere up the arm. Many of these scenarios result in wrist or forearm fractures, but the force may reach the arm and cause a humeral shaft fracture. Other times, there is a high-energy trauma, such as a motor vehicle accident, that will cause a humeral shaft fracture.
2. Medical Attention
Usually there will be pain and swelling at the fracture site. Most likely, you will be unable to lift the injured arm. You may have numbness on the back of your hand, and you may be unable to lift your thumb and fingers. This could be due to a radial nerve injury. The radial nerve spirals around the posterior portion of the humerus and comes into intimate contact with the bone. As you can imagine, a fracture with sharp edges could injure nerves. Many times the nerve will just be bruised, but it can sometimes be transected (cut in half) by the fracture.
3. Sling and Brace
The first line of treatment is to place the arm in a sling or splint. This will stabilize the fracture and prevent further displacement. By holding the fracture fragments still, the swelling and pain are reduced. If the fracture alignment is correct, the injury may heal with a fracture brace. This is a plastic brace composed of two half-shells. Once the swelling subsides somewhat, the fracture brace is placed on the arm and cinched up snugly with velcro straps. This puts pressure on the muscles to help keep the fracture in alignment, while allowing motion at the shoulder and elbow.
4. Surgery
There are certain conditions that require surgical intervention. These include poly-trauma injuries that involve multiple broken bones, and surgically fixing the humerus can allow the patient to be more mobile while the other injuries are being treated. Surgery can take the form of a plate-and-screws or a rod placed in the canal of the bone.
An open fracture is one where there is a wound overlying the fracture. This needs to be washed out to reduce the chances of infection. Pathologic fractures are fractures that break through a tumor. These should also be surgically stabilized because the tumor in the area may prevent healing, or may further weaken the bone. Note that fractures that involve radial nerve injury do not necessarily have to be taken to surgery. Most of the time, the nerve is bruised and will recover on its own. However, if the nerve is working and all of a sudden stops working once the splint is put on, then it could mean that the nerve is entrapped in the fracture site. A nerve exploration may be performed if that happens.
5. Non-Unions
Despite the doctors' best efforts, humeral shaft fractures sometimes do not heal (non-unions). In these cases, the best bet is surgery to put a plate and screws on the bone to compress them together. Sometimes a bone graft may be added to the fracture site to enhance healing.
