What is PEMF Therapy? Does it work?

Pulsed electromagnetic field (PEMF) therapy has been around for decades. Unfortunately, there is such confusion regarding the terminology and what constitutes PEMF that the history can be re-told many different ways.

Although the term PEMF is generic, the definition is that it is an active electromagnetic waveform delivered by an antenna. According to the United States Food and Drug Administration, in section 890.5290, a PEMF medical device is a prescription device, that transmits a therapeutic signal in the radio frequency bands of 13.56 or 27.12 for the adjunctive and palliative treatment of pain and edema in soft tissue, without generating heat. Importantly, for FDA approval one must prove the device is safe and electromagnetically compatible with its use, in addition to providing important signal output characteristics including peak output power, pulse width, pulse frequency, duty cycle, antennae output, specific absorption rates, characterization of deposited energy, electrical and magnetic fields with correct labeling, and clinical testing. This is a fairly high bar. The FDA codes to describe the above are ILX & PQY. The technologies are differentiated by the parameters of waveforms they emit such as antenna size, duration, and frequency of the application. These combined determine the strength and efficacy. Often overlooked, PEMF waveforms do not cause heat or membrane depolarization, and the signal must be detectable above background noise.

How did this get accomplished? In the 19^th century, English scientist Michael Faraday suggested that pulsing electromagnetic fields could induce an electrical field in a nearby conductor such as copper or even tissue. During the late 19^th and early 20^th centuries, many theories produced energy medicine devices, which were promoted without scientific evidence and had a wide array of operating characteristics, including heating tissue. Newer, modified, non-thermal devices were introduced by reducing the duty cycle to prevent it from heating tissue. Some previous PEMF devices consisted of a Helmholtz coil—a life-size, space-age-looking machine that produced a nearly uniform region of magnetic fields. The patient was placed inside this machine to deliver treatment. During the time of these inventions, many different trades were trying to find ways to use this technology.

In the 1970s, patients and orthopedic surgeons were frustrated by non-healing, or recalcitrant bone fractures. Clinicians began implanting electrodes directly into bone to provide direct electrical currents to treat non-union fractures. It was during this time that an electrochemist, Dr. Arthur Pilla, was traveling to San Diego for an electroceutical conference. The stranger sitting next to him on the plane was an orthopedic surgeon, Dr. Andrew Bassett. Dr. Bassett was reviewing his Kodachrome slides for his upcoming presentation at an orthopedic conference. Dr. Pilla was peeking at Dr. Bassett’s slides and thought he saw something obvious. He confidently said, “I see you are working on dendritic outgrowth from an electrode” (a process in electronics in which metal grows whiskers that cause shorts). Dr. Bassett said, “No, that was bone growing from an electrode.” The pair obviously hit it off and the rest they say is history. When they returned home, Dr. Pilla traveled to Dr. Bassett’s lab and proposed rather than surgically inserting electrodes into both sides of a fracture, why wouldn’t they simply pulse an electromagnetic field from the outside.  They ultimately succeeded and were able to heal non-union fractures. Dr. Pilla and another orthopedic surgeon, Dr. James Ryaby, went on to obtain regulatory approval for the first bone growth stimulator!

The bone growth stimulator (BGS) is a long-term, chronic treatment often used for many (> eight) hours per day for several months. This extensive treatment protocol was required because the BGS uses a less efficient signal waveform than the current Assisi signal, although it represented advanced thinking at the time. Randomized clinical trials to assess the BGS’s efficacy showed it to be about 70-80% successful as the transduction mechanism was unknown, so the dosimetry was poor. With more understanding of biological processes, scientists were able to target specific biochemical and electrical pathways associated with pain, edema, and tissue regeneration. Dr. Pilla was able to continue his life’s work and continually improve the BGS signal into the current day Assisi signal.

The strength of the magnetic fields generated by PEMF devices can vary dramatically from less than one Gauss to several thousand Gauss, which means that not all PEMF signals are alike, nor efficacious. And one PEMF device that proves it is efficacious and safe does not mean that all PEMF devices are efficacious or safe. The clinician must understand the difference between signals/fields and rely on human and animal research to validate specific devices for clinical conditions. Unfortunately, many PEMF systems today show a wide range of effectiveness. One must understand which signal/device they are using and for what condition.

Conscientiously, the Assisi signal has had decades of investigation and utilization from cell research, to lab animal research, to human research, and finally to veterinary research to substantiate its attributes. BGS/PEMF in general has been used on hundreds of thousands of patients without known adverse or side effects.