Fundamental and practical aspects of therapeutic uses
of pulsed electromagnetic fields (PEMFs).
Pulsed electromagnetic fields promote collagen production
in bone marrow fibroblasts via athermal mechanisms.
Modulation of collagen production in cultured fibroblasts
by a low-frequency pulsed magnetic field.
Results of pulsed electromagnetic fields (PEMFs) in
ununited fractures after external skeletal fixation.
Osteonecrosis of the femoral head treated by pulsed
electromagnetic fields (PEMFs): a preliminary report.
Treatment of therapeutically resistant non-unions with bone
grafts and pulsing electromagnetic fields.
Effects of a pulsed electromagnetic field on a mixed
chondroblastic tissue culture.
Biological effects of magnetic fields: studies with
microorganisms.
Influence of magnetic fields on calcium salts crystal
formation: an explanation of the 'pulsed electromagnetic field'
technique for bone healing.
Fundamental and practical aspects of therapeutic
uses of pulsed electromagnetic fields (PEMFs).
The beneficial therapeutic effects of selected low-energy, time-varying
magnetic fields, called PEMFs, have been documented with increasing
frequency since 1973. Initially, this form of athermal energy was used
mainly as a salvage for patients with long-standing juvenile and adult
nonunions. Many of these individuals were candidates for amputation.
Their clearly documented resistance to the usual forms of surgical
treatment, including bone grafting, served as a reasonable control in
judging the efficacy of this new therapeutic method, particularly when
PEMFs were the sole change in patient management. More recently, the
biological effectiveness of this approach in augmenting bone healing has
been confirmed by several highly significant double-blind and controlled
prospective studies in less challenging clinical circumstances.
Furthermore, double-blind evidence of therapeutic effects in other
clinical disorders has emerged. These data, coupled with well-controlled
laboratory findings on pertinent mechanisms of action, have begun to
place PEMFs on a therapeutic par with surgically invasive methods but at
considerably less risk and cost. As a result of these clinical
observations and concerns about electromagnetic "pollution",
interactions of nonionizing electromagnetic fields with biological
processes have been the subject of increasing investigational activity.
Over the past decade, the number of publications on these topics has
risen exponentially. They now include textbooks, speciality journals,
regular reviews by government agencies, in addition to individual
articles, appearing in the wide spectrum of peer-reviewed, scientific
sources. In a recent editorial in Current Contents, the editor reviews
the frontiers of biomedical engineering focusing on Science Citation
Index methods for identifying core research endeavors. Dr. Garfield
chose PEMFs from among other biomedical engineering efforts as an
example of a rapidly emerging discipline. Three new societies in the
bioelectromagnetics, bioelectrochemistry, and bioelectrical growth and
repair have been organized during this time, along with a number of
national and international committees and conferences. These activities
augment a continuing interest by the IEEE in the U.S. and the IEE in the
U.K. This review focuses on the principles and practice behind the
therapeutic use of "PEMFs". This term is restricted to time-varying
magnetic field characteristics that induce voltage waveform patterns in
bone similar to those resulting from mechanical deformation. These
asymmetric, broad-band pulses affect a number of biologic processes
athermally. Many of these processes appear to have the ability to modify
selected pathologic states in the musculoskeletal and other systems.
Bassett C. Dep. Orthopedic Surgery, Columbia
University, New York. Crit Rev Biomed Eng
Pulsed electromagnetic fields promote collagen
production in bone marrow fibroblasts via athermal mechanisms.
Primary and passaged cultures of fibroblasts (RBMFs) raised from the
bone marrow stroma of young rabbits were treated with pulsed
electromagnetic fields (PEMFs) from the start of each culture until 1
week after they became confluent. The PEMF treatment had no effect on
cell proliferation, estimated by phase contrast microscopy, by
3H-thymidine incorporation into DNA, or by total DNA assay. Collagen
production, estimated by conversion of 3H-proline to 3H-hydroxyproline
in nondialyzable material was markedly elevated in postconfluent
cultures, but not in cultures that had only just reached confluence.
About 65 of 3H-hydroxyproline was in low molecular weight form, and a
correlation between collagen breakdown and cyclic AMP (cAMP) levels in
RBMFs was demonstrated by adding dibutyryl cAMP or prostaglandin E3
(PGE2) to the culture medium concurrently with 3H-proline. The PEMF
apparatus caused an insufficient temperature rise (less than 0.1 degree
C) to account for these results. We propose that the rise in collagen
production is consistent with the hypothesis that PEMFs act by reducing
cAMP levels in RBMFs, and that thermal effects are insignificant.
Farndale R. et.al Calcif Tissue Int
Modulation of collagen production in cultured
fibroblasts by a low-frequency pulsed magnetic field.
Primary cultures of chicken tendon fibroblasts have been exposed for
various periods to a low-frequency, pulsed magnetic field, and the
effects on protein and collagen synthesis have been examined by
radioisotopic incorporation. Total protein synthesis was increased in
confluent cells treated with a pulsed magnetic field for the last 24 h
of culture as well as in cells treated for a total of 6 days. However,
in 6 day-treated cultures, collagen accumulation was specifically
enhanced as compared to total protein, whereas after short-term
exposure, collagen production was increased only to the same extent as
total protein. Levels of cyclic AMP were significantly decreased after
6-day pulsed magnetic field treatment, probably as a consequence of
diminished adenylate cyclase activity. Exposure to pulsed magnetic field
had no effect on cell proliferation or collagen phenotype. These results
indicate that a pulsed magnetic field can specifically increase
production of collagen, the major differentiated function of
fibroblasts, possibly by altering cyclic-AMP metabolism.
Murray J. et.al. Biochim Biophys Acta
Results of pulsed electromagnetic fields (PEMFs) in
ununited fractures after external skeletal fixation.
Of 147 patients with fractures of the tibia, femur and humerus, in whom
an average of 3.3 operations had failed to produce union, all were
treated with external skeletal fixation in situ and pulsed
electromagnetic fields (PEMFs). Of the 147, 107 patients united for an
overall success rate of 73%. Union of the femur occurred in 81% and the
tibia in 75%. Only five of 13 humeri united. Failure to achieve union
with PEMFs was most closely associated with very wide fracture gaps and
insecure skeletal fixation devices.
Marcer M. et.al. Clin Orthop
Osteonecrosis of the femoral head treated by pulsed
electromagnetic fields (PEMFs): a preliminary report.
This has been a preliminary report with a short-term follow-up of a
small number of observations (28 hips of 24 patients). The follow-ups
ranged from 6 to 36 months, with an average of 17.8 months. Only eleven
hips (in eleven patients) were followed an average of 8 months after
cessation of the treatment. It should be emphasized that this was a
"pilot" study, in which no control series was used to determine the
natural course of the disease in a comparable clinical setting. Of note
was the pain relief, in 19 of 23 patients with moderate to severe
pretreatment pain. Also there was an improved function, which suggests
that at least in approximately two thirds of the patients there was some
clinical benefit from this mode of treatment. In eight hips, clinical
conditions did not change; and in two they worsened, requiring further
treatment. Eighteen remaining hips were thought to have benefited by the
treatment. Six femoral heads that had already developed varying degrees
of collapse (Ficat Type III) collapsed further (1 to 2 mm), and two
round heads (Ficat II) progressed to off-round (Ficat III). This
preliminary study suggests that further exploration of pulsed
electromagnetic fields (PEMFs) is warranted in the treatment of
osteonecrosis of the femoral head.
Eftekhar N. et.al. Hip
Treatment of therapeutically resistant non-unions
with bone grafts and pulsing electromagnetic fields.
This study reviews the cases of eighty-three adults with ununited
fractures who were treated concomitantly with bone-grafting and pulsed
electromagnetic fields. An average of 1.5 years had elapsed since
fracture and the use of this combined approach. Nearly one-third of the
patients had a history of infection, and an average of 2.4 prior
operations had failed to produce bone union. Thirty-eight patients who
were initially treated with grafts and pulsed electromagnetic fields for
ununited fractures with wide gaps, synovial pseudarthrosis, and
malalignment achieved a rate of successful healing of 87 per cent.
Forty-five patients who had initially been treated unsuccessfully with
pulsing electromagnetic fields alone had bone-grafting and were
re-treated with pulsing electromagnetic fields. Ninety-three per cent of
these fractures healed. The residual failure rate after two therapeutic
attempts, one of which was operative, was 1.5 per cent. The median time
to union for both groups of patients was four months.
Bassett C. Et.al. J Bone Joint Surg Am
Effects of a pulsed electromagnetic field on a mixed
chondroblastic tissue culture.
A mixed tissue culture predominantly composed of chondroblastic tissue
was perturbed by a pulsed electromagnetic field (PEMF). Some cultures
were nonconfluent, and purposely retarded in growth to resemble an
atrophic nonunion, while others were grown to confluence in about
one-half the time as a model for a hypertrophic nonunion. These two
groups tested the effect of growth rate upon the products of cell
proliferation and differentiation. The slowly growing cultures were
stimulated to synthesize hydroxyproline. The rapidly growing cultures
showed a large increase in lysozyme activity, and increase in
hyaluronate and DNA, and a decrease in glycosaminoglycan. Exogenous
lysozyme further decreased the glycosaminoglycan synthesis in the
presence of PEMF. Chitotriose, a specific lysozyme inhibitor abolished
this effect. Cycloheximide, a protein synthesis inhibitor, did not
abolish the activation of lysozyme found in the matrix. Thus lysozyme
appears to be activated by PEMF. These observations of the rapidly
growing confluent cultures are consistent with events described in the
normal healing of a bone fracture or endochrondral growth. Thus, PEMF
appears to promote normal healing, probably by altering cartilaginous
lysozyme activity in the matrix, and possibly the sequence of events
leading to calcification.
Norton LA Clin Orthop
Biological effects of magnetic fields: studies with
microorganisms.
Five bacteria and one yeast were grown in magnetic fields of 50-900
gauss with frequencies of 0-0.3 HZ and square, triangular, or sine
waveform. Growth of these microorganisms could be stimulated or
inhibited depending upon the field strength and frequency of the pulsed
magnetic field. Spore germination and mutation frequency were unaffected
by the magnetic fields used in this study.
Moore R. Can J Microbiol
Influence of magnetic fields on calcium salts
crystal formation: an explanation of the 'pulsed electromagnetic field'
technique for bone healing.
In the search for a mechanism by means of which a magnetic field
deparalyses non-unions and enhances bone tissue formation, the influence
of continuous magnetic fields on the formation of calcium phosphate
crystal seeds has been investigated. From this perspective, an
explanation is given of a working mode in conventional equipment for
pulsed electromagnetic field treatment; this is compared with
multifunction equipment.
Madronero A J Biomed Eng
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