Role of pulsed electromagnetic fields after joint replacements

Although the rate of patients reporting satisfaction is generally high after joint replacement surgery, up to 23% after total hip replacement and 34% after total knee arthroplasty of treated subjects report discomfort or pain 1 year after surgery. Moreover, chronic or subacute inflammation is reported in some cases even a long time after surgery. Another open and debated issue in prosthetic surgery is implant survivorship, especially when related to good prosthesis bone ingrowth. Pulsed Electro Magnetic Fields(PEMFs) treatment, although initially recommended after total joint replacement to promote bone ingrowth and to reduce inflammation and pain, is not currently part of usual clinical practice. The purpose of this review was to analyze existing literature on PEMFs effects in joint replacement surgery and to report results of clinical studies and current indications. We selected all currently available prospective studies or RCT on the use of PEMFs in total joint replacement with the purpose of investigating effects of PEMFs on recovery, pain relief and patients’ satisfaction following hip, knee or shoulder arthroplasty. All the studies analyzed reported no adverse effects, and good patient compliance to the treatment. The available literature shows that early control of joint inflammation process in the first days after surgery through the use of PEMFs should be considered an effective completion of the surgical procedure to improve the patient’s functional recovery.

Promotional effects of exogenous stimulation with pulsed electromagnetic fields on skin wound healing in diabetic rats

Objective:The current study aims to identify the effects of exogenous application of pulsed electromagnetic fields on skin wound healing in diabetic rats, and thus provides experimental evidence for its more scientific clinical application in the future.Methods: The diabetic animal models were established via intraperitoneal injection of streptozotocin in 4-month-old male rats. Fourth eight rats were randomly assigned into the diabetes group (DM) and diabetes coupled with pulsed electromagnetic fields (DM+PEMF) group. Another 24 normal rats were used as the blank control group (Control). Then, all the rats in the three groups were subjected to dorsal surgery for the establishment of soft tissue wound model (circular wound with the diameter of 2 cm). Then, the rats in the DM+PEMF group were subjected to pulsed electromagnetic fields stimulation. Then, 6 rats in each group were sacrificed at Day 5, 12 and 19 post surgery. The glucose levels, wound closure, wound healing time and tissue tensile strength were examined and analyzed.Results: Pulsed electromagnetic fields significantly increased the wound closure rate in diabetic rats at Day 5, 12 and 19 post surgery, decreased overall wound healing period in diabetic rats, and also enhanced tissue tensile strength in diabetic rats at Day 5, 12 and 19 post surgery.Conclusion: Low-intensity pulsed electromagnetic fields can significantly accelerate diabetic wound healing process, and also improve diabetic tissue repair capacity. This study may be helpful for providing more scientific and reasonable experimental evidence for the treatment of pulsed electromagnetic fields on diabetic wound healing in clinics.

Low-frequency pulsed electromagnetic field pretreated bone marrow-derived mesenchymal stem cells promote the regeneration of crush-injured rat mental nerve

Bone marrow-derived mesenchymal stem cells （BMSCs） have been shown to promote the regeneration of injured peripheral nerves. Pulsed electromagnetic field （PEMF） reportedly promotes the proliferation and neuronal differentiation of BMSCs. Low-frequency PEMF can induce the neuronal differentiation of BMSCs in the absence of nerve growth factors. This study was designed to investigate the effects of low-frequency PEMF pretreatment on the proliferation and function of BMSCs and the effects of low-frequency PEMF pre-treated BMSCs on the regeneration of injured peripheral nerve using in vitro and in vivo experiments.In in vitro experiments, quantitative DNA analysis was performed to determine the proliferation of BMSCs, and reverse transcription-polymerase chain reaction was performed to detect S100 （Schwann cell marker）, glial fibrillary acidic protein （astrocyte marker）, and brain-derived neurotrophic factor and nerve growth factor （neurotrophic factors） mRNA expression. In the in vivo experiments, rat models of crush-injured mental nerve established using clamp method were randomly injected with low-frequency PEMF pretreated BMSCs, unpretreated BMSCs or PBS at the injury site （1 × 106 cells）. DiI-labeled BMSCs injected at the injury site were counted under the fluorescence microscope to determine cell survival. One or two weeks after cell injection, functional recovery of the injured nerve was assessed using the sensory test with von Frey filaments. Two weeks after cell injection, axonal regeneration was evaluated using histomorphometric analysis and retrograde labeling of trigeminal ganglion neurons. In vitro experiment results revealed that low-frequency PEMF pretreated BMSCs proliferated faster and had greater mRNA expression of growth factors than unpretreated BMSCs. In vivo experiment results revealed that compared with injection of unpretreated BMSCs, injection of low-frequency PEMF pretreated BMSCs led to higher myelinated axon count and axon density and more DiI-labeled neurons in the trigeminal ganglia, contributing to rapider functional recovery of injured mental nerve. These findings suggest that low-frequency PEMF pretreatment is a promising approach to enhance the efficacy of cell therapy for peripheral nerve injury repair.

The Effects of High-intensity Pulsed Electromagnetic Field on Proliferation and Differentiation of Neural Stem Cells of Neonatal Rats in vitro

The effects of high-intensity pulsed electromagnetic stimulation （HIPEMS） on proliferation and differentiation of neonatal rat neural stem cells in vitro were investigated. Neural stem cells derived from neonatal rats were exposed to 0.1 Hz, 0.5–10 Tesla （T） [8 groups of B–I, respectively], 5 stimuli of HIPEMF. The sham exposure controls were correspondingly established. Inverted phase contrast microscope was used to observe the cultured cells, MTT assay to detect the viability of the cells as expressed by absorbance （A） value, and flow cytometry to measure differentiation of neural stem cells. The results showed that A values of neural stem cells in both 3.0 T and 4.0 T groups were significantly higher than the other groups 24 to 168 h post HPEMS, indicating a strong promotion of the growth of neural stem cells （P〈0.05）. The A values of neural stem cells in the 6.0 T, 8.0 T, and 10.0 T groups were lower than the sham exposure control group, indicating a restraint of the growth of neural stem cells. The rate of neuron-specific enolase-positive neurons revealed by flow cytometry in HPEMS groups was the same as that in control group （P〉0.05）. It was suggested that 0.1 Hz, 5 pulses stimulation of HPEMS within certain scale of intensity （0.5–10.0 T）, significantly promoted the growth of neural stem cells with the rational intensity being 4.0 T.

Research on Strong Pulsed Electromagnetic Field Test Method by Time-frequency Combination

Many conventional methods of testing strong and pulsed electromagnetic fields,the ones used in radars for example,had deficiencies due to the difficulty in obtaining simultaneous information about the electromagnetic field's peak both in the time domain and in the frequency domain.With regard to this problem,after analyzing the time-domain and the frequency-domain characteristics of radar pulsed signals,we propose a new time-frequency combination test method based on the correction of the test parameters,as well as its correction method at different bandwidths.The test method is applied in a quick test of a high-power pulsed radar signal,and the corrected results have error less than 1 dB in both the time domain and the frequency domain,which indicates that the proposed time-frequency combined method is effective in testing strong and pulsed electromagnetic fields.

Cytogenetic Effects of Pulsing Electromagnetic Field on Domestic Pig Lymphocytes in Vitro

The effects of pulsing electromagnetic fields(PEMFs)on cells are very important subjects in the field of bioelectromagnetics.In this experiment,the cytogenetic effects of PEMF on domestic pig lymphocytes were tested in vitro.Pig lymphocytes in RPMI 1640 medium were exposed to PEMFs of 100 kHz and 200 kHz for 12,24 and 48 hours.Chromosomal aberrations(aneuploidy,breaks,gaps,et al)were significantly increased in exposed cultures,and of these aberrations,56%chromosomal or chromatid breaks and 42%gaps induced by PEMFs were the points of pig chromosomal fragile sites.The baseline frequency of sister chromatid exchange(SCE)increased after exposing lymphocytes continuously to PEMFs of 100 kHz and 200 kHz for 48 hours.These results suggested that the exposure to PEMFs might induce a type of DNA lesion and chromosomal aberrations.

Effect of pulsed electromagnetic frequency on the microstructure, wear and solid erosion resistance of CrAlN coatings deposited by arc ion plating

In this work,the chromium aluminum nitride(CrAlN)coatings were prepared on TC11 titanium alloy by composite magnetic field cathodic arc ion plating with controllable pulse electromagnetic combined with permanent magnet.The effects of electromagnetic frequency on the morphology,microstructure,nano-hardness and elastic modulus of the coatings were investigated by scanning electron microscope(SEM),X-ray diffraction(XRD)and nano-indenter.This paper has mainly studied the influence of CrAlN coatings which are prepared at various electromagnetic frequencies on the wear and erosion resistance through a series of wear and solid particle erosion experiments.It was found that the deposition rate of CrAlN coatings increases with the increase of electromagnetic frequency.And CrAlN coatings all preferentially grew along the(111)crystal plane.At 16.7 Hz,with the increase of pulsed electromagnetic frequency,the hardness is the highest(23.6 GPa)and the adhesion is the highest(41.5 N).In addition,the coating deposition exhibited the best wear and solid erosion resistance at 16.7 Hz and 33.3 Hz,the friction coefficient is about 0.35,and the erosion rate is about 0.2μm/g at 30°and less than 1μm/g at 90°,respectively.These results indicate that the CrAlN coating formed at an appropriate pulsed electromagnetic frequency can achieve excellent mechanical properties,wear and solid erosion resistance.

A Pulsed Electromagnet for Laser Wakefield Electron Acceleration Experiments

Laser Wakefield plasma acceleration of electrons to energies above 10 GeV, may be possible in the new high power Laser beam facilities. The design of an Electron Spectrometer with an electro-magnet with adjustable magnetic field is proposed for the characterization of electron energy spectrum with a precision better than 10% for the entire energy range from 0.5 GeV to 38 GeV. The expected precision in the measurement of the electron energy is calculated as a function of the magnetic field, of the electron energy and of the magnet length. To outline the advantages offered by a pulsed electromagnet with high magnetic fields, the mass and the electric power lost in the coils of a 4 m long electromagnet with continuous current and Iron yoke are calculated.

Pulsed electromagnetic field stimulation enhances neurite outgrowth in neural cells and modulates inflammation in macrophages

Nerve regeneration following traumas remains an unmet challenge.The application of pulsed electromagnetic field(PEMF)stimulation has gained traction for a minimally invasive regeneration of nerves.However,a sys-tematic exploration of different PEMF parameters influencing neuron function at a cellular level is not available.In this study,we exposed neuroblastoma F11 cells to PEMF to trigger beneficial effects on neurite outgrowth.Different carrier frequencies,pulse repetition frequencies,and duty cycles were screened with a custom ad hoc setup to find the most influential parameters values.A carrier frequency of 13.5 MHz,a pulse repetition frequency of 20 Hz,and a duty cycle of 10%allowed maximal neurite outgrowth,with unaltered viability with respect to non-stimulated controls.Furthermore,in a longer-term analysis,such optimal conditions were also able to in-crease the gene expression of neuronal expression markers NeuN and Tuj-1 and transcription factor Ngn1.Finally,the same optimal stimulation conditions were also applied to THP-1 macrophages,and both pro-inflammatory(TNF-α,IL-1β,IL-6,IL-8)and anti-inflammatory cytokines(IL-10,CD206)were analyzed.The optimal PEMF stimulation parameters did not induce differentiation towards an M1 macrophage phenotype,decreased IL-1β and IL-8 gene expression,decreased TNF-α and IL-8 cytokine release in M1-differentiated cells,increased IL-10 and CD206 gene expression,as well as IL-10 cytokine release in M0 cells.The specific PEMF stimulation regime,which is optimal in vitro,might have a high potential for a future in vivo translation targeting neural regeneration and anti-inflammatory action for treating peripheral nerve injuries.

The pulsed high magnetic field facility and scientific research at Wuhan National High Magnetic Field Center

Wuhan National High Magnetic Field Center(WHMFC)at Huazhong University of Science and Technology is one of the top-class research centers in the world,which can offer pulsed fields up to 90.6 T with different field waveforms for scientific research and has passed the final evaluation of the Chinese government in 2014.This paper will give a brief introduction of the facility and the development status of pulsed magnetic fields research at WHMFC.In addition,it will describe the application development of pulsed magnetic fields in both scientific and industrial research.

Inverse problem of pulsed eddy current field of ferromagnetic plates

To determine the wall thickness, conductivity and permeability of a ferromagnetic plate, an inverse problem is established with measured values and calculated values of time-domain induced voltage in pulsed eddy current testing on the plate. From time-domain analytical expressions of the partial derivatives of induced voltage with respect to parameters,it is deduced that the partial derivatives are approximately linearly dependent. Then the constraints of these parameters are obtained by solving a partial linear differential equation. It is indicated that only the product of conductivity and wall thickness, and the product of relative permeability and wall thickness can be determined accurately through the inverse problem with time-domain induced voltage. In the practical testing, supposing the conductivity of the ferromagnetic plate under test is a fixed value, and then the relative variation of wall thickness between two testing points can be calculated via the ratio of the corresponding inversion results of the product of conductivity and wall thickness. Finally, this method for wall thickness measurement is verified by the experiment results of a carbon steel plate.

Clinical efficacy of electromagnetic field therapy combined with traditional Chinese pain-reducing paste in myofascial pain syndrome

BACKGROUND Pulsed electromagnetic field(PEMF)therapy is widely used to treat myofascial pain syndrome(MPS).Damp-clearing and pain-reducing paste(DPP)comprises medical herbs and has been a traditional method of reducing myofascial pain in China for a long time,and it is usually administered with heating.However,the synergistic effect of PEMF therapy on heating-DPP in patients with MPS is unclear.AIM To investigate the synergistic effect of PEMF therapy plus heating-DPP in lumbar MPS.METHODS This double-blind,randomized,placebo-controlled trial was conducted on 120 patients with lumbar MPS who were randomly divided into an experimental group(EG,n=60)and a control group(CG,n=60).Patients in both groups were treated with heating-DPP combined with PEMF therapy;however,the electromagnetic function of the therapeutic apparatus used in the CG was disabled.Each treatment lasted for 20 min and was applied five times a week for two weeks.The short-form McGill Pain Questionnaire was applied at five time points:pretest,end of the first and second weeks of treatment,and end of the first and fourth week after completing treatment.Visual analog scale(VAS),present pain intensity index(PPI),and pain rating index(PRI;total,affective pain,and sensory pain scores)scores were then analyzed.RESULTS Compared with the CG,the VAS,PPI and PRI scores(total,affective pain and sensory pain scores)in the EG were significantly lower after treatment and during follow-up.CONCLUSION PEMF therapy combined with heating-DPP showed better efficacy than heating-DPP alone in reducing the overall intensity of pain and sensory and affective pain.

Enhancing cartilage repair with optimized supramolecular hydrogel-based scaffold and pulsed electromagnetic field

Functional tissue engineering strategies provide innovative approach for the repair and regeneration of damaged cartilage.Hydrogel is widely used because it could provide rapid defect filling and proper structure support,and is biocompatible for cell aggregation and matrix deposition.Efforts have been made to seek suitable scaffolds for cartilage tissue engineering.Here Alg-DA/Ac-β-CD/gelatin hydrogel was designed with the features of physical and chemical multiple crosslinking and self-healing properties.Gelation time,swelling ratio,biodegradability and biocompatibility of the hydrogels were systematically characterized,and the injectable self-healing adhesive hydrogel were demonstrated to exhibit ideal properties for cartilage repair.Furthermore,the new hydrogel design introduces a pre-gel state before photo-crosslinking,where increased viscosity and decreased fluidity allow the gel to remain in a semi-solid condition.This granted multiple administration routes to the hydrogels,which brings hydrogels the ability to adapt to complex clinical situations.Pulsed electromagnetic fields(PEMF)have been recognized as a promising solution to various health problems owing to their noninvasive properties and therapeutic potentials.PEMF treatment offers a better clinical outcome with fewer,if any,side effects,and wildly used in musculoskeletal tissue repair.Thereby we propose PEMF as an effective biophysical stimulation to be 4th key element in cartilage tissue engineering.In this study,the as-prepared Alg-DA/Ac-β-CD/gelatin hydrogels were utilized in the rat osteochondral defect model,and the potential application of PEMF in cartilage tissue engineering were investigated.PEMF treatment were proven to enhance the quality of engineered chondrogenic constructs in vitro,and facilitate chondrogenesis and cartilage repair in vivo.All of the results suggested that with the injectable self-healing adhesive hydrogel and PEMF treatment,this newly proposed tissue engineering strategy revealed superior clinical potential for cartilage defect treatment.

昼夜节律对PEMFs暴露小鼠血液流变学及红细胞脆性的影响

目的: 探讨昼夜节律对脉冲电磁场暴露小鼠血液流变学的影响.方法: 将30只雄性小鼠随机分为3组(n=10): 对照组、磁场A组和磁场B组.两磁场组饲养于强度为8×10-4 T的脉冲电磁场(pulsed electromagnetic fields,PEMFs)环境中(f=15 Hz),暴磁时间均为6 h/d(磁场A组为白天10∶00～16∶00,磁场B组为夜间22∶00～4∶00).对照组饲养于线圈中,但不暴磁.10 d后统一摘右眼取血,对血液流变学指标及红细胞脆性进行测定.结果: 磁场组与对照组比较,血液流变学特性以及红细胞脆性的差异均有统计学意义(P<0.05);两磁场组(A,B)之间比较,血液流变学各指标和开始溶血NaCl溶液浓度的差异具有显著性意义(P<0.05),而完全溶血的浓度差异不明显(P>0.05).结论: PEMFs可以改善小鼠血液流变特性,降低红细胞脆性,白天暴磁效果优于夜间,提示昼夜节律对其生物效应有影响.

Clinical update of pulsed electromagnetic fields on osteoporosis

Objective To understand the effects of low-frequency pulsed electromagnetic fields （PEMFs） on chronic bony pain, bone mineral density （BMD）, bone strength and biochemical markers of bone metabolism in the patients of osteoporosis. Data sources Using the key words “pulsed electromagnetic fields” and “osteoporosis”, we searched the PubMed for related studies published in English from January 1996 to December 2007. We also searched the China National Knowledge Infrastructure （CNKI） for studies published in Chinese from January 1996 to December 2007.Study selection Inclusion criteria： （1） all articles which referred to the effects of low-frequency pulsed magnetic fields on osteoporosis either in primary osteoporosis or secondary osteoporosis; （2） either observational studies or randomized controlled studies. Exclusion criteria： （1） articles on experimental studies about osteoporosis; （2） repetitive studies; （3） case reports; （4） meta analysis.Results Totally 111 related articles were collected, 101 of them were published in Chinese, 10 were in English. Thirty-four were included and the remaining 84 were excluded.Conclusions Low-frequency PEMFs relieves the pain of primary osteoporosis quickly and efficiently, enhances bone formation and increases BMD of secondary osteoporosis. But the effects of PEMFs on bone mineral density of primary osteoporosis and bone resorption were controversial.

Distributions of Electromagnetic Fields and Forced Flow and Their Relevance to the Grain Refinement in Al–Si Alloy Under the Application of Pulsed Magneto-Oscillation

Distributions of electromagnetic fields and induced forced flow inside a metal melt are crucial to understand the grain refinement of the metal driven by pulsed magneto-oscillation(PMO).In the present study,PMO-induced electromagnetic fields and forced flow in Ga-20 wt%In-12 wt%Sn liquid metal have been systematically investigated by performing numerical simulations and corresponding experimental measurements.The numerical simulations have been confirmed by magnetic and melt flow measurements.According to the simulated distribution of electromagnetic fields under the application of PMO,the strongest magnetic field,electric eddy current and Lorentz force with inward radial direction inside the melt are concentrated adjacent the sidewall of cylindrical melt at the cross section of middle height of coil.As a result,a global forced flow throughout the whole cylindrical column filled with Ga-20 wt%In-12 wt%Snmelt is initiated with a flow structure of two pair of symmetric vortexring.The PMO-induced electromagnetic fields and forced flow in Al-7 wt%Si melt have been numerically simulated.The contribution of electromagnetic fields and forced flow to the grain refinement of Al-7 wt%Sialloy under the application of PMO is discussed.It indicates that the forced flow may play a key role in the grain size reduction.

Role of Electromagnetic Stimulation in the Treatment of Osteonecrosis of the Femoral Head in Early Stages

Osteonecrosis of the femoral head is a disorder that leads to collapse and osteoarthritis in young patients. This study examines the effectiveness of pulsed electromagnetic fields [PEMF] in the treatment of osteonecrosis of the head in precollapse bone stages. A retrospective evaluation was done of 51 patients including 70 hips with symptomatic osteonecrosis of the hip treated with pulsed electromagnetic fields. Criteria for inclusion in the study group were evidence of osteonecrosis and absence of collapse of the femoral head. The average follow-up was 26 months (range, 18 - 90). Etiologies included idiopathic (40 cases), steroid use (26) and alcohol (4). To demonstrate the existence of osteonecrosis and its evolution, magnetic resonance imaging [MRI] and plain radiography techniques were used. Results: Procedures were radiological success in 80% of cases, and no progression to collapse in 88.57% of hips. Eight of the 70 hips had radiographic progression to collapse. This study suggests that selected PEMF reduce the incidence of progression of osteonecrosis of femoral head in early stage.

Microstructure Refinement of Al-5Ti-B Grain Refiner with Electromagnetic Energy

The influence of the electromagnetic energy on the microstructure of Al-5Ti-B grain reflner was discussed.In this study,the electromagnetic energy was applied above the liquid phase line temperature.Compared with Al-5Ti-B without electromagnetic energy applied,the experimental results show that the size of secondary particles is reduced and its size distribution becomes more uniform.Simultaneously,the secondary phase particles are uniformly spread in the matrix response to the electromagnetic energy.Moreover,when adding Al-5Ti-B with electromagnetic energy to the pure aluminum melt,it is clear that the electromagnetic energy has a signiflcantly impact on reflning properties of Al-5Ti-B.The mean size of pure aluminum is reduced by 27.6%in maximum with more uniform size distribution.The change in the microstructure is attributed to the electromagnetic energy changes the melt structure.With the electromagnetic energy entry into the system,the electromagnetic energy reduces the size of atomic clusters and increases the number of atomic clusters,thus the number of nuclei increases.

Non-Monochromatic Electromagnetic Radiation of Inhomogeneous Media

A coordinated physicomathematical model for the propagation of a soliton-like electromagnetic pulse in a heterogeneous medium is developed in the presence of strong discontinuities in the electromagnetic field. The model is based on the reduction of Maxwell’s equations to the well-studied wave equation. When the electromagnetic pulse was specified, its amplitude modulation was taken into account, as was the nonstationary broadening of the spectral line. Conditions for matching the momentum for the first initial boundary-value problem are obtained. The time dispersion of the electrical induction is taken into account in terms of the function of signal conditioning which takes account of the broadening of its spectral line and integration over the continuous spectrum. With this approach, it is not necessary to neglect spatial derivatives, and also to use spatial nonlocal relations to take account of the effect of surface charge, surface current, and spatial dispersion of electrical induction at the interfaces of adjacent media.

High-precision chaotic radial basis function neural network model:Data forecasting for the Earth electromagnetic signal before a strong earthquake

The Earth’s natural pulse electromagnetic field data consists typically of an underlying variation tendency of intensity and irregularities.The change tendency may be related to the occurrence of earthquake disasters.Forecasting of the underlying intensity trend plays an important role in the analysis of data and disaster monitoring.Combining chaos theory and the radial basis function neural network,this paper proposes a forecasting model of the chaotic radial basis function neural network to conduct underlying intensity trend forecasting by the Earth’s natural pulse electromagnetic field signal.The main strategy of this forecasting model is to obtain parameters as the basis for optimizing the radial basis function neural network and to forecast the reconstructed Earth’s natural pulse electromagnetic field data.In verification experiments,we employ the 3 and 6 days’data of two channels as training samples to forecast the 14 and 21-day Earth’s natural pulse electromagnetic field data respectively.According to the forecasting results and absolute error results,the chaotic radial basis function forecasting model can fit the fluctuation trend of the actual signal strength,effectively reduce the forecasting error compared with the traditional radial basis function model.Hence,this network may be useful for studying the characteristics of the Earth’s natural pulse electromagnetic field signal before a strong earthquake and we hope it can contribute to the electromagnetic anomaly monitoring before the earthquake.