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Electromagnetic Fields in Biological Systems
A series of magnetic pulses induces electrical fields, which stimulate bone repair (e.g.,
72 mT, 50 Hz). There are several PEMF stimulation devices approved by the FDA that
are widely available to patients for use. These devices are considered to provide additive
support to bone growth and repair (Grana, Marcos, and Kokubu 2008). The effectiveness of PEMF in the management of osteoarthritis has been investigated with different
outcomes. In a meta-analysis, it has been concluded that pulsed EMFs improve clinical
scores and function in patients with osteoarthritis of the knee and should be considered
adjuvant therapies in the management of osteoarthritis (Vavken et al. 2009). In a study
including 57 cases of tibial pseudarthrosis, surgical treatment was combined with PEMF
in 22 cases. Of the PEMF treated group (22), 20 (91%) fractures healed, and two (9%)
did not. From the not PEMF treated group (35), 29 (83%) healed, and six (17%) did not.
PMT was considered clinically relevant both with regard to healing and time to union
(Cebrián et al. 2010).
Studies have also investigated the effectiveness of PEMF in healing soft-tissue
wounds, suppressing inflammatory responses at the cell membrane level to alleviate pain, and increasing range of motion. Pieber, Herceg, and Paternostro-Sluga
(2010) reported on two small and three large studies describing analgesic benefits
of PEMF treatment, whereas in one large study, no beneficial effect could be found.
Kroeling et al. (2009) concluded that the current evidence for PEMF shows that these
modalities might be more effective in treating neck pain than placebo but not compared to other interventions.
6.2.3.3 Static Magnetic Fields
Magnetic devices that are offered for medical treatment include magnetic bracelets,
insoles, magnetic straps for wrist and knee, back and neck braces, and pads, pillows,
and mattresses.
Two main types of magnets exist:
1. Static or permanent magnets in which the magnetic field is generated by the spin
of electrons within the ferromagnetic material itself
2. Magnet coils either cylindrical with concentric windings or flat with spiral windings in which the magnetic field is generated by electric currents
Permanent magnets can be of compact material and are marketed in various strengths,
typically with inductions at their surface between 5 and 500 mT. In addition, magnetic
foils (plastic foils coated with magnetic particles) are offered with surface fields of less
than 1 mT. However, it needs to be noted that the fields are very inhomogeneous and
amplitudes decrease very rapidly with distance.
Costantino et al. (2007) treated wrist and hand fractures with permanent magnets
inserted into a plaster cast of hand and wrist fractures and reported on reduced union
time of 35%, however, with no control group. Permanent magnets (necklace) were
not more effective for pain relief than placebo (Pieber, Herceg, and Paternostro-Sluga
2010; Pittler, Brown, and Ernst 2007; Finegold 2006; Flamm 2006). In a book, Colbert
et al. (2009) analyzed 56 studies, 42 in patients and 14 in healthy volunteers. The most
common indication was osteoarthritis of the knee, and other applications concerned