La Magnetoterapia (o terapia magnetica) è una forma di terapia fisica che utilizza campi magnetici (statici o più spesso pulsati) a bassa o alta frequenza, con l’obiettivo di favorire processi di riparazione dei tessuti, ridurre il dolore e alleviare l’infiammazione. Viene impiegata in diversi ambiti, tra cui la riabilitazione ortopedica (problemi alle articolazioni, fratture, osteoartrite, ecc.) e la gestione del dolore muscolo-scheletrico.

Ecco gli elementi principali da sapere:

1. Campo magnetico

   • Può essere costante (statico) oppure variabile nel tempo (pulsato).
   • L’intensità (in millitesla, mT) e la frequenza (in hertz, Hz) sono parametri fondamentali.

2. Modalità di applicazione

   • Applicazione locale (su un’articolazione o un segmento corporeo specifico) o generale (tramite apparecchiature più ampie).
   • Sedute variabili da pochi minuti fino a un’ora, con cicli di trattamento ripetuti.

3. Benefici ipotizzati

   • Riduzione del dolore e dell’infiammazione.
   • Miglioramento della circolazione locale e possibile accelerazione del processo di guarigione (come nel caso di fratture).
   • Sostegno alla riabilitazione ortopedica e fisioterapica.

4. Evidenze scientifiche

   • Alcuni studi suggeriscono effetti positivi su dolore e infiammazione, specialmente in patologie croniche come l’osteoartrite.
   • L’efficacia può variare molto in base a: intensità, frequenza, durata del trattamento, tipo di patologia e caratteristiche individuali del paziente.
   • Non è considerata una “cura miracolosa” né sostituisce i trattamenti medici consolidati, ma può essere un utile supporto in un percorso riabilitativo più ampio.

5. Controindicazioni e precauzioni

   • È generalmente sicura, ma va usata con cautela in persone portatrici di pacemaker o altri dispositivi elettronici impiantati (rischio interferenze).
   • Consultare sempre un medico/fisioterapista prima di iniziare il trattamento.

C'è una relazione tra flusso magnetico (mT) e frequenza (Hz) ?

Non esiste una relazione “diretta” tra un valore di campo magnetico (espresso in Tesla, o in millitesla) e una frequenza in hertz, se non in contesti specifici. Nel caso più comune in cui si faccia riferimento alla risonanza magnetica nucleare (NMR/MRI), si utilizza la frequenza di Larmor, che mette in relazione il campo magnetico con la frequenza di precessione dei nuclei (per esempio, dell’idrogeno).

Frequenza di Larmor

La frequenza di Larmor fff per un nucleo di spin 1/2 (come il protone nell’idrogeno) è data dalla formula:

Quindi, se la domanda si riferisce al campo magnetico statico utilizzato in risonanza magnetica nucleare per nuclei di idrogeno, allora un campo di 25 mT corrisponde a una frequenza di risonanza di circa 1,06 MHz.

Ricerche

Le ricerche su magnetoterapia/PEMF (Pulsed ElectroMagnetic Fields) per il trattamento dell’osteoartrite (OA) — compresa quella di mani e ginocchia — mostrano che non esiste un’unica frequenza “universale” validata da tutti gli studi in modo unanime. Tuttavia, nella pratica clinica e nelle pubblicazioni scientifiche, si riscontrano range di frequenze spesso compresi tra 15 e 75 Hz, con valori di intensità del campo magnetico variabili (generalmente da pochi mT fino a decine di mT).

Di seguito alcuni punti di riferimento:

1. Range di frequenze più comuni

   • Molte apparecchiature per magnetoterapia a bassa frequenza (LF) utilizzano 15–25 Hz, 50 Hz o 75 Hz.
   • Esistono studi che hanno utilizzato frequenze anche di 1–100 Hz, ma i valori più usati per OA si concentrano spesso nel range 15–75 Hz.

2. Esempi di studi

   • Alcuni trial clinici su osteoartrite del ginocchio hanno utilizzato 50 Hz con intensità intorno a 0,8–2 mT.
   • Altri studi (ad es. su OA della mano) hanno utilizzato frequenze intorno ai 75 Hz con intensità anche superiori (fino a 10–30 mT e oltre).

1. Ampiezza (intensità) e frequenza sono parametri separati

   • La letteratura non indica solo la frequenza, ma anche l’ampiezza del campo e la forma d’onda (per esempio, forme d’onda pulsate a duty cycle specifici).
   • Per ottenere risultati consistenti, i protocolli di ricerca prestano attenzione a tutti questi parametri (frequenza, intensità, durata della seduta e numero di sedute settimanali).

2. Variabilità dei risultati

   • Gli effetti della magnetoterapia possono variare in base a molti fattori (stadio dell’osteoartrite, comorbidità del paziente, durata complessiva del trattamento, ecc.).
   • Non tutti gli studi concordano sull’efficacia clinica, sebbene diversi lavori suggeriscano un effetto antinfiammatorio e di riduzione del dolore.

In sintesi, la Magnetoterapia è un trattamento complementare che, se ben integrato in un percorso di cura personalizzato, può contribuire a ridurre il dolore e a favorire il recupero funzionale in varie patologie muscolo-scheletriche.

Bibliografia__________________________________________________________________________

Elvan Kanat, Alev Alp, Merih Yurtkuran, Magnetotherapy in hand osteoarthritis: A pilot trial, Complementary Therapies in Medicine, Volume 21, Issue 6, 2013, Pages 603-608, ISSN 0965-2299, https://doi.org/10.1016/j.ctim.2013.08.004 (https://www.sciencedirect.com/science/article/pii/S096522991300126X)

Abstract: Summary. Objective. To evaluate the effectiveness of magnetotherapy in the treatment of hand osteoarthritis (HO). Methods. In this randomized controlled single-blind follow-up study, patients with HO were randomly assigned into 2 groups (G1 and G2). The subjects in G1 (n=25) received 25Hz, 450pulse/s, 5–80G, magnetotherapy of totally 10 days and 20min/day combined with active range of motion/strengthening exercises for the hand. G2 (n=25) received sham-magnetotherapy for 20min/day for the same duration combined with the same hand exercises. Outcome measures were pain and joint stiffness evaluation, handgrip and pinchgrip strength (HPS), Duruöz and Auscan Hand Osteoarthritis Indexes (DAOI) and Short Form-36 Health Questionnaire (SF-36) administered at baseline, immediately after treatment and at the follow up. Results. When the groups were compared with each other, improvement observed in SF-36 Pain (p<0.001), SF-36 Social Function (p=0.030), SF-36 Vitality (p=0.002), SF-36 General Health (p=0.001), Pain at rest (p<0.001), Pain at motion (p<0.001), Joint stiffness (p<0.001), DAOI (p<0.001) were in favor of G1.. Conclusions. Changes in pain, function and quality of life scores showed significant advantage in favor of the applied electromagnetic intervention in patients with HO.

Zyss T. Magnetotherapy. Neuro Endocrinol Lett. 2008 Nov;29 Suppl 1:161-201. 

Abstract. Since antiquity, the phenomenon of magnetism has been known, and it has been tried for therapeutic purposes. Through history, people have made use of both natural sources of magnetic fields (magnetic iron ore) and artificial ones (magnets, electromagnets). It was as late as the 19th century that we started to produce time-varying magnetic fields, making numerous observations about its impact on humans, the nervous system included. A majority of these observations were cognitive in nature. There are, however, studies aimed at assessing the therapeutic results of the influence of magnetic fields, particularly of low frequencies. In terms of magnetotherapy with the use of a low-induction magnetic field, there are serious doubts concerning its effectiveness in general, including therapy for mental disorders. The year 1985 witnessed the introduction of transcranial magnetic stimulation (TMS) into medical practice as a diagnostic tool in neurology as well as in basic neurophysiologic and neuropsychological investigations. The 1990s began the epoch of investigations into possible applications of TMS in therapy of mental disorders, particularly depression. This work presents critical remarks and limitations of TMS, such as findings that its effectiveness is not particularly high. The traditional fixed stimulation of a definite area of the patient's head may lead to irritation of structures that, in a specific patient, may not be responsible for the symptoms of depression. The effectiveness could be improved only with the use of neuronavigation and prestimulation via functional neuroimaging diagnostics of the brain, which, however, would make TMS expensive and less practical.

Markov M. XXIst century magnetotherapy. Electromagn Biol Med. 2015 Sep;34(3):190-6. doi: 10.3109/15368378.2015.1077338.

Abstract. This paper discusses the state of the art therapeutic application of magnetic and electromagnetic fields (EMF) in treatment of various medical problems - from pain relief to musculoskeletal trauma, to vascular and endocrine disorders. The paper describes problems related to physical parameters of used fields, biophysical dosimetry, clinical protocols, and safety of the device operators. Clinical benefits and mechanisms of action are also discussed

Mayer Y, Shibli JA, Saada HA, Melo M, Gabay E, Barak S, Ginesin O. Pulsed Electromagnetic Therapy: Literature Review and Current Update. Braz Dent J. 2024 Oct 25;35:e246109. doi: 10.1590/0103-6440202406109. 

Abstract. This manuscript provides a comprehensive review of Pulsed Electromagnetic Fields (PEMFs), highlighting their therapeutic potential and historical evolution. PEMFs, recognized for their non-invasive and safe therapeutic benefits, interact with biological systems to influence processes such as DNA synthesis, gene expression, and cell migration. Clinically, PEMFs are applied in diverse treatments, including pain relief, inflammation management, and enhancing bone and wound healing. The manuscript delves into the historical development of PEMF technology, tracing its origins to the 19th century and exploring significant advancements, such as the discovery of the piezoelectric effect in bones. It presents detailed in-vitro and in-vivo studies demonstrating PEMFs' impact on cellular activities and their modulation of key biological pathways. Additionally, the review emphasizes PEMFs' applications in general medicine and dentistry, showcasing their role in promoting tissue healing, osseointegration in dental implants, and antimicrobial effects. The introduction of the Miniaturized Electromagnetic Device (MED) in dental implantology marks a significant advancement, enhancing implant stability and reducing inflammatory responses. Overall, the manuscript underscores PEMFs' promising applications in advancing patient care and treatment methodologies across medical and dental fields.

Osnovina IP, Alekseeva NV. Comparative evaluation of effectiveness of different magnetotherapy regimens in patients with osteoarthritis. Vopr Kurortol Fizioter Lech Fiz Kult. 2020;97(3):43-52. Russian. doi: 10.17116/kurort20209703143. 

Abstract.  Impulse low-frequency magnetotherapy is a modern method of treating diseases of the musculoskeletal system, including osteoarthritis. The effectiveness of the therapeutic effect largely depends on the biotropic characteristics of the magnetic fields - the type of magnetic field, induction, frequency, pulse shape, exposure, exposure zone. Aim of study: To conduct a comparative analysis of effectiveness of applying various modes of magnetotherapy using an impulse low-frequency magnetic field in patients with osteoarthritis. Materials and methods: A randomized, placebo-controlled clinical trial included 262 patients with grade II-III knee osteoarthritis according to the Kellgren-Lawrence classification. The 1st group included 56 patients who received local magnetic therapy on the knee using a running pulsed magnetic field (RPMF) - 20 mT, frequency 6.25 Hz, exposure time 20 min. The 2nd group included 99 patients who were exposed to a magnetic field using a combination of modes: 5 days - an impulse magnetic field (IMF) with induction of 2 mT, frequency of 100 Hz, then RPMF mode - 20 mT, frequency of 6.25 Hz, duration 20 min, number of procedures - 12. The third group included 97 patients who received placebo-magnetotherapy on the knee joint area. When analyzing the results, the VAS (100 mm) and WOMAC scales were used, as well as the subjective assessment of the treatment results by patients (5-point scale). Results: A pronounced symptom-modifying effect of magnetotherapy (according to VAS and WOMAC) was established in the form of a decrease in the severity of pain in patients with gonarthrosis (p<0.01). There was a significant improvement in pain and stiffness indices, as well as functional characteristics (WOMAC), more pronounced in patients who received a combined regime of exposure to a magnetic field (p<0.01). The use of magnetotherapy using various modes is safe for patients and does not cause serious adverse events. Conclusion: The application of magnetotherapy equipment, which allows the use of various biotropic characteristics of magnetic field, is an effective and safe technology for treatment of patients with osteoarthritis. Keywords: biotropic characteristics of magnetic field; impulse low-frequency magnetotherapy; osteoarthritis of knee joint; running magnetic field.

Shieh YY, Tsai FY. Static magnetotherapy for the treatment of insomnia. Int J Electron Healthc. 2008;4(3-4):339-49. doi: 10.1504/IJEH.2008.02267. 

Abstract. Magnets have been used for centuries to treat a number of physical disorders. The vast majority of research, however, on static magnet therapy for insomnia has been confined to the auricular type of therapy, with publications limited to Chinese journals. Most of these studies have depended on the subjective self-assessment of participants rather than objective scientific measurements. In this study, the authors report the positive preliminary results of insomnia treatment using pillows with embedded magnets, magnetic insoles and TriPhase bracelets. The analysis is based on objective actigraphic and polysomnographic data. A theory of accelerated transition from wakefulness to sleep is proposed to explain the process of insomnia relief through low-strength static magnetic fields. Analysis by functional Magnetic Resonance Imaging (fMRI) is used to further investigate the theory.

Woldańska-Okońska M, Koszela K. Chronic-Exposure Low-Frequency Magnetic Fields (Magnetotherapy and Magnetic Stimulation) Influence Serum Serotonin Concentrations in Patients with Low Back Pain-Clinical Observation Study. Int J Environ Res Public Health. 2022 Aug 8;19(15):9743. doi: 10.3390/ijerph19159743.

Abstract. (1) Background: The influence of serotonin on many regulatory mechanisms has not been sufficiently studied. The use of a physical method, assuming the possibility of its action on increasing the concentration of serotonin, may be the direction of therapy limiting the number of antidepressants used. The aim of the research was to study the effects of low-frequency magnetic fields of different characteristics on the circadian profile of serotonin in men with low back pain. (2) Methods: 16 men with back pain syndrome participated in the study. The patients were divided into two groups. In group 1, magnetotherapy (2.9 mT, 40 Hz, square wave, bipolar) was applied at 10.00 a.m. In group 2, the M2P2 magnetic stimulation program of the Viofor JPS device was used. Treatments in each group lasted 3 weeks, 5 days each, with breaks for Saturday and Sunday. The daily serotonin profile was determined the day before the exposure and the day after the last treatment. Blood samples (at night with red light) were collected at 8:00, 12:00, 16:00, 24:00, and 4:00. The patients did not suffer from any chronic or acute disease and were not taking any medications. (3) Results: In group 1, a significant increase in serotonin concentration was observed after 15 treatments at 4:00. In group 2, a significant increase in serotonin concentration was observed at 8:00 after the end of the treatments. In comparison between magnetotherapy and magnetic stimulation, the time points at which differences appeared after the application of serotonin occurred due to the increase in its concentrations after the application of magnetic stimulation. (4) Conclusions: Magnetotherapy and magnetic stimulation, acting in a similar way, increase the concentration of serotonin. Weak magnetic fields work similarly to the stronger ones used in TMS. It is possible to use them in the treatment of mental disorders or other diseases with low serotonin concentrations.