Equis ISSN 2398-2977

Magnetic field therapy

Synonym(s): Magnotherapy, Pulsed electromagnetic field therapy, PEMF

Contributor(s): Graham Munroe, Kate Hesse

Introduction

  • Pulsed electromagnetic field therapy (PEMF) has been used for over 30 years in treating equine musculoskeletal disorders, but its use is still controversial Musculoskeletal: physiotherapy.
  • An electromagnetic field is generated by the passage of an electrical current (low frequency and short pulse duration) through a circular coil of wires. The pulsed field is generated from an applicator and transmitted through tissues. It is absorbed by low impedance vascular tissues, such as muscle and nerves, or tissues which are edematous, contain effusions, or have recent haematoma. It has no heating effects within the tissues.
  • It is thought that PEMF therapy may have beneficial effects on damaged tissue cells, particularly at the cellular level, although this is not definitively confirmed. This may involve the restoration of cell membrane potential, transport, and ionic balance by either a direct ionic transport mechanism or activation of sodium/potassium pumps. PEMF therapy is said to: increase the number of WBC, histiocytes, and fibroblasts within wounds; improve the rate of dispersal of oedema; increase the absorption of haematoma; help resolve the inflammatory process; promote the orientation and early deposition of collagen and fibrin fibres; and stimulate osteogenesis.
  • It is known that bone can develop a piezoelectric potential on its external and internal surfaces and PEMF has been suggested as a technique that can improve bone healing and remodelling. It has been used for this for many years in human and equine medicine but most scientific studies have failed to show any significant improvement in either healing or remodelling.
  • In the horse it is used either within full-body rugs containing coils, to target tissues within the back, neck, pelvis or trunk, or as paired coils, of different sizes and often within plastic pads, that are strapped or bandaged to a limb to be treated for soft tissue or bony injuries.

Uses

  • It has been used in humans in the inflammatory healing phase of soft tissues, including following oral surgery, where it reduced healing times.
  • In the horse, various articles have been published describing effects on tendon healing, the healing of non union bone fractures, the stimulation of blood circulation in superficial and deep tissues, and the decrease in pain and muscle spasm.  In general, there is very little evidence in the human or equine literature of any significant effects on soft tissue structures and there is conflicting evidence in the horse as to its effect on non-union or slow healing fractures.

Advantages

  • Non-invasive.

Disadvantages

  • May have no significant effects.
  • Various commercial systems can be quite expensive to purchase.

Requirements

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Preparation

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Procedure

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Outcomes

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • Edner A et al (2015) Does a magnetic blanket induce changes in muscular blood flow, skin temperature and muscular tension in horses? Equine Vet J 47 (3), 302-307 PubMed.
  • Ibiwoye M O et al (2004) Bone mass is preserved in a critical sized osteotomy by low energy pulsed electromagnetic fields as quantitated by in vivo micro-computed tomography. J Orthop Res 22 (5), 1086-1093 PubMed.
  • Steyn P F et al (2000) Effect of a static magnetic field on blood flow to the metacarpus in horses. JAVMA 217 (6), 874-877 PubMed.
  • Ramey D W (1999) Magnetic and electromagnetic therapy in horses. Comp Cont Educ Pract Vet 21 (6), 553-560 VetMedResource.
  • Kobluk C N et al (1994) A scintigraphic investigation of magnetic field therapy on the equine third metacarpus. J Comp Orthop Traumatol 7 (1), 9-13 VetMedResource.
  • Sanders-Shamis M et al (1989) A preliminary investigation of the effect of selected electromagnetic field devices on healing of cannon bone osteotomies in horses. Equine Vet J 21 (3), 201-205 PubMed.
  • Watkins J P & Auer J A (1985) Healing of surgically created defects in the equine SDFT: effects of pulsing electromagnetic field therapy on collagen-type transformation and tissue morphologic reorganisation. Am J Vet Res 46 (10), 2097-2103 PubMed.


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