The effect of pulsed electromagnetic fields on osteoporosis at the knee in individuals with spinal cord injury.
Garland DE, Adkins RH, Matsuno NN, Stewart CA.
Rancho Los Amigos Medical Center, Downey, California 90242, USA.
The purpose of this study was to determine the effects of pulsed
electromagnetic fields on osteoporotic bone at the knee in individuals
with chronic spinal injury. The study consisted of 6 males with complete
spinal cord injury at a minimum of 2 years duration. Bone mineral
density (BMD) was obtained at both knees at initiation, 3 months, 6
months, and 12 months using dual energy X-ray absorptiometry. In each
case, 1 knee was stimulated using The Bone Growth Stimulator Model 3005
from American Medical Electronics, Incorporated and the opposite knee
served as the control. Stimulation ceased at 6 months. At 3 months BMD
increased in the stimulated knees 5.1% and declined in the control knees
6.6% (p < .05 and p < .02, respectively). By 6 months the BMD
returned to near baseline values and at 12 months both knees had lost
bone at a similar rate to 2.4% below baseline for the stimulated knee
and 3.6% below baseline for the control. There were larger effects
closer to the site of stimulation. While the stimulation appeared useful
in retarding osteoporosis, the unexpected exaggerated decline in the
control knees and reversal at 6 months suggests underlying mechanisms
are more complex than originally anticipated. The authors believe a
local as well as a systemic response was created.
J Spinal Cord Med. 1999 Winter;22(4):239-45.
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Effect of pulsed electromagnetic fields on bone formation and bone loss during limb lengthening.
Eyres KS, Saleh M, Kanis JA.
WHO Collaborating Centre for Metabolic Bone Disease, University of Sheffield Medical School, UK.
We examined the effect of pulsed electromagnetic fields (PEMFs) on
bone formation and disuse osteoporosis sustained during limb lengthening
in a double-blind study. Seven males (mean age 13 years, range 11-19
years) and six females (mean age 12 years, range 9-19 years) were
randomly allocated to receive either an active or an inactive PEMF coil.
Limb lengthening was performed by the Villarubbias technique using
either a unilateral or circular frame system. Sequential bone density
measurements were made using dual energy X-ray absorptiometry and
compared to traditional radiographs. Ten segments (eight tibial and two
femoral) in seven patients were lengthened under the influence of active
coils and eight segments (six tibial and two femoral) in six patients
using inactive coils. There was no difference in the rate nor the amount
of new bone formed at the site of distraction between the two groups.
Bone loss in the segments of bone distal to the lengthening sites was
observed in both groups but was significantly more marked using inactive
coils (BMD reduced by 23% +/- SEM 3% and 33% +/- 4% control values
after one and two months, respectively; p < 0.0001) than using active
coils (BMD reduced by 10% +/- 2% at 2 months). These differences were
greater at 12 months after surgery (reduced by 54% +/- 5% and 13% +/-
4%, respectively; p < 0.0001). Stimulation with pulsed
electromagnetic fields has no effect on the regenerate bone, but does
prevent bone loss adjacent to the distraction gap.
Bone. 1996 Jun;18(6):505-9.
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Effects of pulsed magnetic fields in the therapy of osteoporosis induced by ovariectomy in the rat.
Zati A, Gnudi S, Mongiorgi R, Giardino R, Fini M, Valdre G, Galliani I, Montagnani AM.
Institute Orthopaedic Rizzoli, University of Bologna.
This paper presents preliminary results on the effects of pulsed
electromagnetic fields (EMF) in the therapy of post menopausal
osteoporosis induced by ovariectomy in female rats aged ten months. In
particular, the effects of the intensity of pulsed EMF applied at
constant frequency has been studied. Magnetic fields pulsed at 50 Hz
were used having a positive sinusoidal wave form with a maximum
intensity of 30 and 70 Gauss. Treatment lasting one hour per day for 4
months showed that the pulsed EMF with 30 Gauss of maximum intensity are
able to slow down the bone mass loss, keeping it within some 10%; with
pulsed EMF with 70 Gauss of maximum intensity, instead, no significant
bone mass loss was observed.
Boll Soc Ital Biol Sper. 1993 Jul-Aug;69(7-8):469-75.
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Pulsed electromagnetic fields prevent osteoporosis in an ovariectomized female rat model: a prostaglandin E2-associated process.
Chang K, Chang WH.
Department of Biomedical Engineering, Chung-Yuan Christian University, Chung-Li, Taiwan, Republic of China.
With the use of Helmholtz coils and pulsed electromagnetic field
(PEMF) stimulators to generate uniform time varying electromagnetic
fields, the effects of extremely low frequency electromagnetic fields on
osteoporosis and serum prostaglandin E(2) (PGE(2)) concentration were
investigated in bilaterally ovariectomized rats. Thirty-five 3 month old
female Sprague-Dawley rats were randomly divided into five different
groups: intact (INT), ovariectomy (OVX), aspirin treated (ASP), PEMF
stimulation (PEMF + OVX), and PEMF stimulation with aspirin (PEMF + ASP)
groups. All rats were subjected to bilateral ovariectomy except those
in INT group. Histomorphometric analyses showed that PEMF stimulation
augmented and restored proximal tibial metaphyseal trabecular bone mass
(increased hard tissue percentage, bone volume percentage, and
trabecular number) and architecture (increased trabecular perimeter,
trabecular thickness, and decreased trabecular separation) in both PEMF +
OVX and PEMF + ASP. Trabecular bone mass of PEMF + OVX rats after PEMF
stimulation for 30 days was restored to levels of age matched INT rats.
PEMF exposure also attenuated the higher serum PGE(2) concentrations of
OVX rats and restored it to levels of INT rats. These experiments
demonstrated that extremely low intensity, low frequency, single pulse
electromagnetic fields significantly suppressed the trabecular bone loss
and restored the trabecular bone structure in bilateral ovariectomized
rats. We, therefore, conclude that PEMF may be useful in the prevention
of osteoporosis resulting from ovariectomy and that PGE(2) might relate
to these preventive effects. Copyright 2003 Wiley-Liss, Inc.
Bioelectromagnetics. 2003 Apr;24(3):189-98.
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Bone density changes in osteoporosis-prone women exposed to pulsed electromagnetic fields (PEMFs).
Tabrah F, Hoffmeier M, Gilbert F Jr, Batkin S, Bassett CA.
University of Hawaii School of Medicine, Straub Clinic and Hospital, Honolulu.
To determine the effect of a 72 Hz pulsating electromagnetic field
(PEMF) on bone density of the radii of osteoporosis-prone women, the
nondominant forearms of 20 subjects were exposed to PEMF 10 h daily for a
period of 12 weeks. Bone density before, during, and after the exposure
period was determined by use of a Norland-Cameron bone mineral
analyzer. Bone mineral densities of the treated radii measured by
single-photon densitometry increased significantly in the immediate area
of the field during the exposure period and decreased during the
following 36 weeks. A similar but weaker response occurred in the
opposite arm, suggesting a "cross-talk" effect on the nontreated radii,
from either possible arm proximity during sleep or very weak general
field effects. The data suggest that properly applied PEMFs, if scaled
for whole-body use, may have clinical application in the prevention and
treatment of osteoporosis.
J Bone Miner Res. 1990 May;5(5):437-42.
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Prevention of osteoporosis by pulsed electromagnetic fields.
Rubin CT, McLeod KJ, Lanyon LE.
Musculo-Skeletal Research Laboratory, Department of Orthopaedics, State University of New York, Stony Brook 11794.
Using an animal model, we examined the use of pulsed electromagnetic
fields, induced at a physiological frequency and intensity, to prevent
the osteoporosis that is concomitant with disuse. By protecting the left
ulnae of turkeys from functional loading, we noted a loss of bone of
13.0 per cent compared with the intact contralateral control ulnae over
an eight-week experimental period. Using a treatment regimen of one hour
per day of pulsed electromagnetic fields, we observed an osteogenic
dose-response to induced electrical power, with a maximum osteogenic
effect between 0.01 and 0.04 tesla per second. Pulse power levels of
more or less than these levels were less effective. The maximum
osteogenic response was obtained by a decrease in the level of
intracortical remodeling, inhibition of endosteal resorption, and
stimulation of both periosteal and endosteal new-bone formation. These
data suggest that short daily periods of exposure to appropriate
electromagnetic fields can beneficially influence the behavior of the
cell populations that are responsible for bone-remodeling, and that
there is an effective window of induced electrical power in which bone
mass can be controlled in the absence of mechanical loading.
J Bone Joint Surg Am. 1989 Mar;71(3):411-7.
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