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Fractures of the Humeral Shaft

A break of the middle of the arm bone

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Updated August 06, 2012

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mid shaft humerus fracture

Fracture of the shaft of the humers.

Image © Jonathan Cluett, M.D.
The humerus is the bone that connects the shoulder to the elbow. This segment of the body is called the arm, and together with the hand and the forearm, makes up the upper extremity. The humerus is a strong bone, that is capped with the ball of the ball-and-socket shoulder joint on the top, and has a hinge of the elbow joint on the bottom. Fractures of the humerus are divided into three types: proximal humerus fractures of the shoulder, mid-shaft humerus fractures, and distal humerus fractures of the elbow.

Mid-Shaft Humerus Fractures

A mid-shaft humerus fracture typically does not involve the shoulder or elbow joints. This type of fracture represents about 3% of all broken bones. The most common cause of a humeral shaft fracture is a fall, but high-energy injuries (motor vehicle collisions, sports injuries) and penetrating trauma (gunshot wounds) also can cause this injury. Many humeral shaft fractures occur as a result of weakening on the bone from osteoporosis.

Fractures of the humerus can be scary injuries, and the x-rays often look frightening to patients. Because there is only one bone connecting the shoulder to the elbow, patients often feel as though their extremity is not attached. Patients should be reassured, that there is much more than bone holding on to the extremity, and that the vast majority of mid-shaft humerus fractures heal without surgery.

Treatment of Humeral Shaft Fractures

There are several treatment options for these fractures, but the most common is non-surgical treatment. Fortunately, gravity does wonders to align the humerus, and simply allowing the arm to hang by the side is often the best treatment for a humerus fracture. Furthermore, any surgical treatment has significant risks. Minimizing the chance of complication is one reason to consider non-surgical treatment.

Reasons to consider surgical treatment include multiple fractures, open fractures, injuries to blood vessels or nerves, and failure of healing with nonsurgical treatment (nonunion).

  • Fracture Bracing
    The most common treatment for a humeral shaft fracture is called a fracture brace, often referred to as a Sarmiento brace, named after the physician who popularized this treatment method. Usually the fracture treated in a splint or sling for a week to allow swelling to subside, and then a fracture brace is fit to the patient. The brace looks like a clam shell, and holds the humerus in alignment. An advantage of the fracture brace, is that as healing progresses, patients can begin to use their shoulder and elbow.
  • Metal Plates
    The most common surgery for treatment of a humerus fracture is to place a large metal plate along the humerus, and secure it with screws. Use of a plate and screws is the most successful way to surgically heal a humeral shaft fracture. The concern of surgery is that risks of nerve injury and nonunion are higher with surgical treatments than with non-surgical treatments.
  • Rods
    An intramedullary rod is a metal rod that is placed down the hollow center of the bone. The advantage of the metal rod, is the surgery is less invasive, and the surgeon is staying away from the important nerves that travel down the arm. The concern with a rod, is that healing rates are not as high, and nonunion is a common complication.
Healing of a mid-shaft humerus fracture takes several months, but often exercises to improve mobility of the shoulder and elbow joints are initiated much sooner. The two complications often seen are injuries to the radial nerve and nonunion of the fracture.

Injuries to the radial nerve occur because this important nerve tightly wraps around the middle of the humerus. The radial nerve can be injured at the time of the fracture or during treatment of the fracture. Radial nerve injuries cause numbness on the back of the hand, and difficulty straightening (extending) the wrist and fingers. Most radial nerve injuries will improve with time, but your doctor will follow this carefully to determine if any further treatment is needed.

Nonunion is a difficult problem, and occurs when the fracture does not heal. There are a number of reasons why a nonunion may occur. Interestingly, one of the most common reasons for nonunion is surgery. When you have surgery, the soft-tissues surrounding the fracture are further disrupted, and this can compromise blood flow to the site of the fracture. One reason to avoid surgery, is to prevent the risk of nonunion. However, if a nonunion does occur, then surgery is almost always needed to stimulate a healing response of the bone.

Source:

Carroll EA, et al. "Management of Humeral Shaft Fractures" J Am Acad Orthop Surg July 2012 vol. 20 no. 7 423-433.

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