Understanding Pulsed Electromagnetic Field Therapy (PEMF)

At ARC Veterinary Physiotherapy we use PEMF therapy for many of our clients to support healing and reduce pain. But how does it actually work? I'll try my best to keep things simple but I apologise if it gets a little complicated.

PEMF is an electromagnet, basically a magnet that runs on electricity. The machine consists of a power unit and several applicators containing magnets. PEMF has a base frequency (measured in Hz) and a pulsing frequency (measured in pulses per second), which can be adjusted to produce a variety of therapeutic effects.

When a cell in the body is damaged, the cell membrane potential is reduced, meaning that it cannot function properly as the electrical potential between the inside and outside of the cell has changed and signals cannot be passed through properly. The PEMF machine generates a low-level electromagnetic field which encourages the body to re-establish a normal cellular voltage within the cell, enabling the body to heal by transporting ions across the membrane and restoring its function. Therefore, it only has an effect on the damaged cells.

The movement of electrons within our body affects cellular physiology by causing ions to move towards the electrodes. The movement of these ions through ion channels in the organelles and plasma membrane play important roles such as nerve signal propagation, energy production, and muscle contraction.

PEMF encourages an increased release of calcium ions (Ca2+), as the concentration is increased Ca2+ will then bind to calmodulin which produces short bursts of nitric oxide. Nitric oxide is a molecule that could probably have a whole blog post of its own but to simplify it in this case, nitric oxide will bind to other substances causing an upregulation of endogenous anti-inflammatory responses, enhancing blood flow, and increasing the production of growth factors responsible for tissue repair.

PEMF for Pain Relief:

PEMF can disrupt the brain's ability to transmit pain signals by decreasing the nerve cell potential from -70mV to a hyper-polarization level of -90mV. This means that the cell voltage is too low when the pain signal is detected for the synapse to trigger the release of chemical transmitters, blocking the pain signal. See the graph below.

Graph from Writtle University College and (Warnke 1983) showing the change in nerve cell potential.

PEMF for Bone Healing:

There is also lots of available research suggestive of the use of PEMF to improve bone healing by increasing the structural integrity of the bone. It increases the expression of bone cells (osteoblasts) promoting differentiation and osteogenesis (formation of new bone). PEMF may also have a pro-anabolic effect on the bone and cartilage matrix providing a chondroprotective effect on the joint environment, reducing inflammation.

Other Effects:

PEMF can also reduce pain by reducing inflammation. It does this by causing constriction of the blood vessels, reducing prostaglandins and inflammatory cytokines, and reducing pain and inflammation. Changing the setting of PEMF can also have the opposite effect and cause dilation of the blood vessels through the increase of nitric oxide. This increases blood flow and encourages an increased flow of nutrients and removal of toxins in and out of the tissues. Re-establishing the injured cell membrane. PEMF may also help to increase the growth of new neurons improving neurological cases.

Let's talk about the research:

Pinna et al., (2012) studied the effect of PEMF on 25 dogs with osteoarthritis (OA). The dogs received 20 PEMF treatments over 3 weeks and were assessed and scored for lameness, pain on palpation, and ROM before, during, immediately after, 4 months, and 12 months after the treatment. Radiographs were also taken and scored before and after the treatment. By the end of the treatment, 92% of the dogs in the PEMF group had an improved lameness score. Additionally, the reduction of the percentage of dogs with pain on palpation was statistically significant compared to the control group. Radiographic signs of OA remained unchanged in both treatment and control groups, although owner satisfaction was improved in the PEMF group. Overall this study has produced favourable results for the use of PEMF in dogs with OA to reduce pain and improve lameness.

A study in humans investigated the effect of PEMF therapy on chronic lower back pain. 36 patients were split into a PEMF or placebo group and provided with treatment 3 times a week for 3 weeks. Pain scores were measured before, immediately after, and 1 and 4 weeks after. The percentage of pain improvement was significantly greater in the PEMF than in the placebo group at all of the time points. A 38% reduction in pain was observed in the PEMF group in comparison to only 22% in the placebo group. These results are similar to the effects of painkillers (NSAIDs) and chiropractic manipulation. This study produced positive results for the use of PEMF for back pain in humans, which is especially important considering how frequently animals also suffer from back pain.

Finally, a study by Inoue et al., (2002) looked at the effect of PEMF on bone healing of an osteotomy gap in the canine tibia. 6 dogs received PEMF therapy for 1 hour daily for 8 weeks and 6 dogs were assigned to a control group. The dogs within the PEMF group started to weight-bear the affected limb much earlier than the control group. The periosteal callus area also increased earlier within the PEMF group. Maximum torque and torsional stiffness were also greater within the PEMF group. This study has produced positive results suggesting the use of PEMF to encourage new bone formation, decreased porosity, and provides a higher mechanical strength encouraging its use for bone healing in animals.

More PEMF research:

Fini, M., Torricelli, P., Giavaresi, G., Aldini, N.N., Cavani, F., Setti, S., Nicolini, A., Carpi, A. and Giardino, R. (2008) 'Effect of pulsed electromagnetic field stimulation on knee cartilage, subchondral and epiphyseal trabecular bone of aged Dunkin Hartley guinea pigs'. Biomedicine and Pharmacotherapy, 62, 709-715

Overall, PEMF therapy appears to be very effective for a range of conditions within our animals. If you have any questions or would like to know more about the therapies we offer please don't hesitate to get in contact with us!

Tel: 07527310689

Email: info@arcvetphysio.co.uk

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Instagram: @arcvetphysio

References

Cheing, G.L.-Y., Li, X., Huang, L., Kwan, R.L.-C., Cheung, K.-K. (2014) Pulsed electromagnetic fields (PEMF) promote early wound healing and myofibroblast proliferation in diabetic rats. Bioelectromagnetics. 35(3), 161–169.

Gaynor, J.S., Hagberg, S., Gurfein, B.T. (2018) Veterinary applications of pulsed electromagnetic field therapy. Research in Veterinary Science. 119, 1–8.

Markov, M.S. (2007) Pulsed electromagnetic field therapy history, state of the art and future. The Environmentalist. 27(4), 465–475.

Inoue N, Ohnishi I, Chen D, Deitz LW, Schwardt JD, Chao EYS. Effect of pulsed electromagnetic fields (PEMF) on late-phase osteotomy gap healing in a canine tibial model. Journal of Orthopaedic Research 2002;20:1106–14. https://doi.org/10.1016/S0736-0266(02)00031-1.

Lee, P.B., Kim, Y.C., Lim, Y.J., Lee, C.J., Choi, S.S., Park, S.H., Lee, J.G. and Lee, S.C. (2006) 'Efficacy of pulsed electromagnetic therapy for chronic lower back pain: a randomized, double-blind, placebo-controlled study'. The Journal of International Medical Research, 34, (2), 160-167.

Markov, M.S. (2007) Pulsed electromagnetic field therapy history, state of the art and future. The Environmentalist. 27(4), 465–475.

Pinna, S., Landucci, F., Tribuiani, A.M. and Carli, F. (2012) The effects of pulsed electromagnetic field in the treatment of osteoarthritis in dogs: clinical study'. Pakistan Veterinary Journal, 33, 96-100.

Warnke, U. (1983) Possible role of PMF in reduction of pain, Elsevier Biomedical Press.