Pulsed magnetic field therapy for tibial non-union.
Interim results of a double-blind trial.
Pulsed Magnetic Field Therapy For Insomnia: A Double-Blind,
Placebo-Controlled Study
Pulsed electromagnetic fields increase growth factor
release by nonunion cells.
Comparative study of bone growth by pulsed electromagnetic
fields.
Long-term follow-up of fracture non-unions treated with
PEMF.
Augmentation of bone repair by pulsed elf magnetic fields.
The development and application of pulsed electromagnetic
fields (PEMFs) for ununited fractures and arthrodeses.
Pulsed electromagnetic field stimulation of MG63
osteoblast-like cells affects differentiation and local factor
production.
Pulsed magnetic field therapy for tibial non-union.
Interim results of a double-blind trial.
English patients with tibial fractures which had remained un-united for
at least 52 weeks were randomly allocated to either active or dummy
pulsed magnetic field stimulators and treated in full leg plasters for
24 weeks with a non-weight bearing conservative regimen, as is usual
with such techniques. Fractures in 5 of the 9 patients with working
machines united and fractures in 5 of the 7 patients with dummy machines
also united. These early results of this double-blind trial are
compatible with a difference in success rate at 24 weeks on active
treatment of + 33% to -61% (95% confidence limits) compared with the
success rate on the dummy stimulators. The high proportion of fractures
uniting in the control group suggests that conservative management of
non-union is effective and this may explain much of the success
attributed to pulsed magnetic field therapy.
Barker, A. et.al Lancet
Pulsed Magnetic Field Therapy For Insomnia: A
Double-Blind, Placebo-Controlled Study
This 4-week double-blind, placebo-controlled study assessed the efficacy
of impulse magnetic-field therapy for insomnia. One hundred one patients
were randomly assigned to either active treatment (n = 50) or placebo (n
= 51) and allocated to one of three diagnostic groups: (1) sleep
latency; (2) interrupted sleep; or (3) nightmares. Efficacy endpoints
were intensity of sleep latency, frequency of interruptions, sleepiness
after rising, daytime sleepiness, difficulty with concentration, and
daytime headaches. In the active-treatment group, the values of all
criteria were significantly lower at study end (P < .00001). The placebo
group also showed significant symptomatic improvement (P < .05), but the
differences between groups were highly significant (P < .00001). Seventy
percent (n = 34) of the patients given active treatment experienced
substantial or even complete relief of their complaints; 24% (n = 12)
reported clear improvement; 6% (n = 3) noted a slight improvement. Only
one placebo patient (2%) had very clear relief; 49% (n = 23) reported
slight or clear improvement; and 49% (n = 23) saw no change in their
symptoms. No adverse effects of treatment were reported.
Uni der Bundeswehr Munich, Germany.
Pulsed electromagnetic fields increase growth factor
release by nonunion cells.
The mechanisms involved in pulsed electromagnetic field stimulation of
nonunions are not known. Animal and cell culture models suggest
endochondral ossification is stimulated by increasing cartilage mass and
production of transforming growth factor-beta 1. For the current study,
the effect of pulsed electromagnetic field stimulation on cells from
human hypertrophic (n = 3) and atrophic (n = 4) nonunion tissues was
examined. Cultures were placed between Helmholtz coils, and an
electromagnetic field (4.5-ms bursts of 20 pulses repeating at 15 Hz)
was applied to 1/2 of them 8 hours per day for 1, 2, or 4 days. There
was a time-dependent increase in transforming growth factor-beta 1 in
the conditioned media of treated hypertrophic nonunion cells by Day 2
and of atrophic nonunion cells by Day 4. There was no effect on cell
number, [3H]-thymidine incorporation, alkaline phosphatase activity,
collagen synthesis, or prostaglandin E2 and osteocalcin production. This
indicates that human nonunion cells respond to pulsed electromagnetic
fields in culture and that transforming growth factor-beta 1 production
is an early event. The delayed response of hypertrophic and atrophic
nonunion cells (> 24 hours) suggests that a cascade of regulatory events
is stimulated, culminating in growth factor synthesis and release.
Guerkov H. et.al. Dep. of Orthopaedics, Univ. of
Texas Health Science Center. Clin Orthop
Comparative study of bone growth by pulsed
electromagnetic fields.
Pulsed electromagnetic fields have been widely used for treatment of
non-united fractures and congenital pseudarthrosis. Several electrical
stimulation systems such as air-cored and iron-cored coils and solenoids
have been used the world over and claimed to be effective. Electrical
parameters such as pulse shape, magnitude and frequency differ widely,
and the exact bone-healing mechanism is still not clearly understood.
The study attempts to analytically investigate the effectiveness of
various parameters and suggests an optimal stimulation waveform.
Mathematical analysis of electric fields inside the bone together with
Fourier analysis of induced voltage waveforms produced by commonly used
electrical stimulation wave-forms has been performed. A hypothesis based
on assigning different weightings to different frequencies for
osteogenic response has been proposed. Using this hypothesis
astonishingly similar effective values of electric fields have been
found in different systems. It is shown that effective electric field
rather than peak electric field is the main parameter responsible for
osteogenesis. The results are in agreement with experimental findings
made on human beings by different investigators.
Gupta T. et.al. Dep. Electrical Engineering,
Harcourt Butler Technological Institute, Kanpur, India. Med Biol Eng
Comput
Long-term follow-up of fracture non-unions treated
with PEMF.
One hundred thirty-nine established fracture non-unions were treated
using a pulsed electromagnetic field (PEMF) device that also recorded
patient usage. Patients who used the device less than an average of
three hours a day had a success rate of 35.7% (5/14), while those who
used the device in excess of three hours daily had an 80% success rate
(108/135). The difference in the success rate was statistically
significant at p less than .05. Treatment success was unaffected by long
versus short bone, open versus closed fractures, nonunion of nine to 12
months duration compared to one to ten years, age of patient (whether
less than or greater than age 60), gender, recalcitrant versus first
time treatment, infected versus non-infected non-unions, fracture gaps
up to 1cm, or weight bearing versus non-weight bearing. Ninety-seven
fractures in 90 patients
(90% follow-up) who averaged more than three hours of PEMF treatment
daily and were originally classified as healed were reevaluated
clinically and radiographically at four years following treatment
(range: 3.6-5.4 years; mean: 4.1 years). Eighty-nine (92%) maintained a
solid union. The success rate of PEMF treatment for nonunion repair
demonstrated no statistically significant change over long-term
follow-up.
Garland D. Et.al. University of Southern California
School of Medicine, Los Angeles, California. Contemp Orthop
Augmentation of bone repair by pulsed elf magnetic
fields.
Tibial osteotomies in rats were exposed for 2, 3, 5 and 8 weeks to a
pulsed extremely low frequency magnetic field. The shape of the pulse
was a double halfwave (50 Hz, 70 G). The rate of bone healing was
evaluated by light and electron microscopy. An increase of bone healing
was found in rats treated with magnetic fields persisting throughout the
tested time. The accelerated healing process produced a sequence of
morphological appearances identical to those of a normal fracture callus
being the enhancement of osteogenesis produced by an acceleration of
preliminary ossification.
Ottani V. et.al. Istituto di Anatomia Umana Normale,
Bologna, Italy. Anat Anz
The development and application of pulsed
electromagnetic fields (PEMFs) for ununited fractures and arthrodeses.
This article deals with the rational and practical use of surgically
noninvasive pulsed electromagnetic fields (PEMFs) in treating ununited
fractures, failed arthrodeses, and congenital pseudarthroses (infantile
nonunions). The method is highly effective (more than 90 per cent
success) in adult patients when used in conjunction with good management
techniques that are founded on biomechanical principles. When union
fails to occur with PEMFs alone after approximately four months, their
proper use in conjunction with fresh bone grafts insures a maximum
failure rate of 1 to 1.5 per cent. Union occurs because the weak
electric currents induced in tissues by the time-varying fields effect
calcification of the fibrocartilage in the fracture gap, thereby setting
the stage for the final phases of fracture healing by endochondral
ossification. The efficacy, safety, and simplicity of the method has
prompted its use by the majority of orthopedic surgeons in this country.
In patients with delayed union three to four months postfracture, PEMFs
appear to be more successful and healing, generally, is more rapid than
in patients managed by other conservative methods. For more challenging
problems such as actively infected nonunions, multiple surgical
failures, long-standing (for example, more than two years postfracture)
atrophic lesions, failed knee arthrodeses after removal of infected
prostheses, and congenital pseudarthroses, success can be expected in a
large majority of patients in whom PEMFs are used. Finally, as
laboratory studies have expanded knowledge of the mechanisms of PEMF
action, it is clear that different pulses affect different biologic
processes in different ways. Selection of the proper pulse for a given
pathologic entity has begun to be governed by rational processes
similar, in certain respects, to those applied to pharmacologic agents.
Bassett CA Clin Plast Surg & Orthop Clin North Am
Pulsed electromagnetic field stimulation of MG63
osteoblast-like cells affects differentiation and local factor
production.
Pulsed electromagnetic field stimulation has been used to promote the
healing of chronic non-unions and fractures with delayed healing, but
relatively little is known about its effects on osteogenic cells or the
mechanisms involved. The purpose of this study was to examine the
response of osteoblast-like cells to a pulsed electromagnetic field
signal used clinically and to determine if the signal modulates the
production of autocrine factors associated with differentiation.
Confluent cultures of MG63 human osteoblast-like cells were placed
between Helmholtz coils and exposed to a pulsed electromagnetic signal
consisting of a burst of 20 pulses repeating at 15 Hz for 8 hours per
day for 1, 2, or 4 days. Controls were cultured under identical
conditions, but no signal was applied. Treated and control cultures were
alternated between two comparable incubators and, therefore, between
active coils; measurement of the temperature of the incubators and the
culture medium indicated that application of the signal did not generate
heat above the level found in the control incubator or culture medium.
The pulsed electromagnetic signal caused a reduction in cell
proliferation on the basis of cell number and [3H]thymidine
incorporation. Cellular alkaline phosphatase-specific activity increased
in the cultures exposed to the signal, with maximum effects at day 1. In
contrast, enzyme activity in the cell-layer lysates, which included
alkaline phosphatase-enriched extracellular matrix vesicles, continued
to increase with the time of exposure to the signal. After 1 and 2 days
of exposure, collagen synthesis and osteocalcin production were greater
than in the control cultures. Prostaglandin E2 in the treated cultures
was significantly reduced at 1 and 2 days, whereas transforming growth
factor-beta1 was increased; at 4 days of treatment, however, the levels
of both local factors were similar to those in the controls. The results
indicate enhanced differentiation as the net effect of pulsed
electromagnetic fields on osteoblasts, as evidenced by decreased
proliferation and increased alkaline phosphatase-specific activity,
osteocalcin synthesis, and collagen production. Pulsed electromagnetic
field stimulation appears to promote the production of matrix vesicles
on the basis of higher levels of alkaline phosphatase at 4 days in the
cell layers than in the isolated cells, commensurate with osteogenic
differentiation in response to transforming growth factor-beta1. The
results indicate that osteoblasts are sensitive to pulsed
electromagnetic field stimulation, which alters cell activity through
changes in local factor production.
Lohmann C. et.al. Dep. Orthopaedics, University
Texas Health Science Center, San Antonio J Orthop Res
|
