Copyright 2002 American Academy of Orthopaedic Surgeons
Physical Fields

Broken bones are a common injury; an average of 6 million people in the United States will break a bone each year. Most of these broken bones heal without problems. However, about 300,000 are slow to heal or do not heal at all with traditional methods. For appropriate situations, there is another treatment option to consider the use of physical fields.

What are physical fields?

Physical fields include specific magnetic, electrical and sonic fields applied at an area of bone fracture to help healing. For a bone to heal properly, it needs three things:

  • A good blood supply after injury
  • Adequate stabilization
  • Sufficient new tissue formation

If one or more of these conditions is missing, a nonunion can occur. A nonunion occurs when there is no indication of healing for at least three months and no expectation of further healing. Other factors that can contribute to slow healing or nonunions include smoking, diabetes and certain glandular and renal disorders that decrease blood flow.

The use of physical fields can be a very effective treatment option for specific nonunion situations. But the technology isn't new; there are documented cases as far back as 1812 showing that physical field stimulation can help heal broken bones.

What happens in a fracture?

When a bone breaks, blood vessels also break, resulting in bleeding around the injury site. Cells in neighboring tissue send out chemical messages that encourage the growth of small blood vessels. Within days, a large number of these small vessels grow into the fracture area. Eventually, the cells divide and form different connective tissues such as cartilage, bone and fibrous tissue. However, if this process is delayed or if it fails to occur at all, a nonunion results.

How can physical fields help?

Physical field treatment is based on the concept of natural physiologic events that already exist in the body. It is natural for bone to bend slightly under normal physiological forces. Even normal walking and running can bend a long bone like the shinbone (tibia) slightly, perhaps as much as .03 to .04 inches. This bending causes small electrical charges. The same type of electrical charge is created by the application of a physical field. A physical field applied at the point of nonunion can be used to stimulate the production of more intracellular calcium, which appears to be a common denominator in healing the broken bone.

What are the types of physical field therapies?

There are four main types of physical field therapies. Which one to use depends on the condition of the nonunion fracture. The amount of energy transferred is comparable to a small battery and is not painful.

  • Direct Electrical Stimulation typically involves an implanted cathode and battery-based anode to deliver a constant electrical current.
  • Capacitive Coupling requires two surface electrodes placed on the skin across the fracture site. A 9-volt battery generates an electrical current. This device can be worn over a cast.
  • Pulsed Electromagnetic Fields (PEMFs) rely on magnetic coils that have a rechargeable battery power source. The coils receive a specific pulsed electrical current that results in a specific magnetic force. This device can also be worn over a cast.
  • Ultrasound is delivered through a device applied directly to the surface of the skin for 20 minutes a day. The device must be attached to a wall power source while in use.

Patients are typically treated for three to nine months, depending on fracture location, severity and time from injury. Some difficult fractures may need to be treated for longer periods. Most surgeons expect to see the fracture progress to healing within three to six months. There are no side effects.

What research is ongoing for physical field therapy?

Although physical field therapy has been around for decades, it is not as widely used as one would expect. To better define the role and value of physical field treatments, well-designed studies that will clarify both the physical and economic benefits are needed. As yet, there have not been enough studies that measure rates of return to work and specific activities. Another factor is cost. Although the devices can be expensive, the cost may be justified when compared to the cost of missed work due to a bone that won't heal.

Last reviewed: October 2002
AAOS does not endorse any treatments, procedures, products, or physicians referenced herein. This information is provided as an educational service and is not intended to serve as medical advice. Anyone seeking specific orthopaedic advice or assistance should consult his or her orthopaedic surgeon, or locate one in your area through the AAOS "Find an Orthopaedist" program on this website.
Copyright 2002 American Academy of Orthopaedic Surgeons
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