by Veterinary Practice News Editors | April 17, 2009 4:06 pm
Biophysical treatments such as pulsed electromagnetic field (PEMF) therapy are pushing patient recovery in new dimensions. Enthusiasm for these techniques is mounting, as evidence and applications expand.
For magnetic fields to influence cellular behavior, signal transduction must take place across the cell membrane.1 PEMFs appear to alter a variety of membrane components capable of affecting transmembrane signaling, such as ion channels, ligand binding and alternations in receptor distribution and density.2
Decades ago, the U.S. Food and Drug Administration approved PEMF for the treatment of nonunion fractures.
More recently, a 2006 study in Connective Tissue Research indicated that an exposure of eight or 16 hours of PEMF significantly accelerated apoptosis in osteoclasts in vitro, suggesting a potential application for osteoporosis.3
PEMF applied to a rat Achilles’ tendon repair model revealed an increase in tensile strength at the repair site.4
Biophysical stimulation with PEMF after arthroscopic reconstruction of the anterior cruciate ligament limited the expected but potentially damaging post-surgical joint inflammation. It also shortened recovery time.5
Chondrocytes exposed to PEMFs adopted a spherical shape and retracted their processes, although the clinical significance of these changes remains unclear.6
PEMF applied to either the cervical or lumbar spine after fusion surgery accelerated arthrodesis.7
Long-term (38-day) exposure to a pulsed magnetic field promoted peripheral nerve regeneration in a rat model involving a crush injury of the sciatic nerve.8
Applying a pulsed magnetic field to transplanted fibrosarcoma tumors in rats that received mitomycin C potentiated the antitumor effects of chemotherapy.9
PEMF augmented bone marrow cytotoxicity of cyclophosphamide in mice, which may have clinical relevance if it allows dosage reduction.10 Pulsed magnetic fields significantly enhanced the activity and number of tumoricidal nonparenchymal liver cells.11
In a rat model of rheumatoid arthritis, PEMF therapy reduced levels of alpha-2-macroglobulin, a protein associated with destruction of articular cartilage.12
Furthermore, these researchers demonstrated equivalency to ibuprofen in joint edema reduction.
PEMF therapy significantly improved wound healing in a diabetic mouse model by up-regulating fibroblast growth factor-2, stimulating angiogenesis.13
An uncontrolled pilot study showed Pulsed Signal Therapy (PST) offered short-term analgesic benefits in 50 percent of patients experiencing refractory neuropathic pain secondary to peripheral neuropathy.14 PST varies from PEMF in that the device produces a magnetic field with a magnitude of 1.25mT and a frequency range between 1 Hz and 30 Hz.15,16
PST supposedly induces a small electrical signal similar to the physiologic signals normally occurring in healthy tissue.17
A 2002 report in Veterinary Anesthesia and Analgesia evaluated PEMF application post-ovariohysterectomy for changes in vital signs, pain score and behavior.18 This pilot study indicated that PEMF may have potentiated morphine analgesia.
Patients with active hemorrhage should not receive PEMF therapy, nor should those with electrical implants or pregnant patients.19
One might also consider avoiding PEMF therapy in patients who have received gold bead implants, or “permanent acupuncture,” since those who still practice this technique often replace the gold wire with tiny stainless steel balls that wander through tissue planes.
Given the relative safety, ease of administration and non-invasiveness of PEMFs, they provide an attractive option for speeding tissue healing, restoring function and reducing the need for anti-inflammatories and analgesics.20
5. Benazzo F, Zanon G, Pederzini L, et al. Effects of biophysical stimulation in patients undergoing arthroscopic reconstruction of anterior cruciate ligament: prospective, randomized and double blind study. Knee Surg Sports Traumatol Arthosc. 2008: in press.
12. Dortch AB and Johnson MT. Characterization of pulsed magnetic field therapy in a rat model for rheumatoid arthritis. Presented at Rocky Mountain Bioengineering Symposium and International ISA Biomedical Sciences Instrumentation Symposium April 7-9 2006, Terre Haute, Indiana, www.isa.org.
13. Callaghan MJ, Chang E, Seiser N, et al. Pulsed electromagnetic fields accelerate normal and diabetic wound healing by increasing endogenous FGF-2 release. Plastic and Reconstructive Surgery. 2008;121(1):130-141.
14. Weintraub MI and Cole SP. Pulsed magnetic field therapy in refractory neuropathic pain secondary to peripheral neuropathy: electrodiagnostic parameters—pilot study. Neurorehabilitation and Neural Repair. 2004;18(1):42-46.
15. Weintraub MI and Cole SP. Pulsed magnetic field therapy in refractory neuropathic pain secondary to peripheral neuropathy: electrodiagnostic parameters – pilot study. Neurorehabilitation and Neural Repair. 2004;18(1):42-46.
20. Zorzi C, Dall-Oca C, Cadossi R, et al. Effect of pulsed electromagnetic fields on patients’ recovery after arthroscopic surgery: prospective, randomized and double-blind study. Knee Surg Sports Traumatol Arthrosc. 2007;15:830-834.
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