Bones are in a constant state of flux that consists of absorbing and replacing the cells that make up the bone. This gives bone a very large and natural capacity to heal themselves. A nonunion occurs when a bone that is broken fails to heal. Similarly a delayed union is when a fracture takes an inordinate amount of time to heal. Some bones and some patients more commonly experience problems with nonunions such as the elderly and those with more severe fractures. In some of these cases instead of trying to heal the bone, the damaged portion is actually replaced.
Causes of Nonunions
To understand the underlying causes for nonunions, it is important to understand how bones heal and what the ideal conditions are. Bones need stability and a nutrient rich blood supply to heal. A doctor might apply a cast or use plates and screws to increase the stability of the fracture. The blood brings healing components to the site where the healing needs to take place. Proper nutrition is essential.
Along those lines causes for nonunions can include infections, inadequate flow of blood to the bone, inadequate stabilization of the fracture, old age, diabetes, severe anemia, medications, and use of tobacco or nicotine. There are many risk factors involved and weighing with your doctor what needs to be done is important.
Some bones already have poor blood flow to them and so these are at higher risk for nonunions (upper thighbone and small wrist bone).
Symptoms
Pain at the site of a break long after the pain from a fracture has gone could be an indication of a nonunion. This pain can last months or years and be constantly present or only when that bone is moved.
Diagnosis
Several imaging tools can help the doctor find a nonunion such as X-rays, computed tomography, and magnetic resonance imaging. Following these images lets the doctor observe the healing of the bone. If there is persistent pain at the fracture site, a gap with no bone across the fracture site, no progress of healing over several imaging studies, or inadequate healing in a normal time period, the doctor may diagnose a nonunion. Blood tests may also be performed that might show infections or other conditions that may slow bone healing like anemia or diabetes.
Non-surgical Treatment
Some nonunions can be treated non-surgically. The most common non-surgical treatment is a bone stimulator. This small device delivers ultrasonic or pulsed electromagnetic waves that stimulate healing. The patient places the stimulator on the skin over the nonunion from 20 minutes to several hours daily. This treatment must be used every day to be effective.
Surgical Treatment
•Bone Graft - Bone grafts or bone graft substitutes can often "jump start" the healing process after normal healing has failed. A bone graft provides a lattice on which new bone may grow. Bone grafts also provide fresh bone cells and the naturally occurring chemicals the body needs for bone healing.
•A surgeon makes an incision and removes (harvests) pieces of bone from different areas on the patient. These are then transplanted to the nonunion site. The rim of the pelvis or "iliac crest" is most often used for harvesting bone. Although harvesting the bone is painful, the amount of bone removed does not cause functional, structural, or cosmetic problems.
•Allograft or Cadaver Bone Graft - An allograft avoids harvesting bone from the patient, and therefore, decreases the pain involved with treating the nonunion. Like a traditional bone graft, it provides scaffolding for the patient's bone to heal across the area of the nonunion. As time goes on, the patient's bone replaces the cadaver bone.
Bone grafts (or bone graft substitutes) alone provide no stability to the fracture site. Unless the nonunion is inherently stable, you may also need more surgical procedures (internal or external fixation).
Internal Fixation - Internal fixation stabilizes a nonunion. The surgeon attaches metal plates and screws to the outside of the bone or places a nail (rod) in the inside canal of the bone.
External fixation - External fixation stabilizes the injured bone. The surgeon attaches a scaffold-like rigid frame to the outside of the injured arm or leg. The frame is attached to the bone with wires or pins. External fixation may be used to increase the stability of the fracture site if instability helped cause the nonunion. External fixation can treat nonunions in a patient who also has bone loss and/or chronic infection.
-
*All literature found within this article has been abridged from the following sources:
