What is bone oedema?
Bone oedema is not a fracture and not a tumour. It means that fluid has built up inside the bone, in the spongy tissue – something like a bruise, only not under the skin but inside the bone itself. This is why it is called bone bruise in English. It usually cannot be seen on an X-ray and can only be detected with an MRI scan – which is why many people live with “unexplained” pain for months before the cause becomes clear.
Its symptoms are characteristic: deep, dull pain that worsens with weight-bearing, which may also be present at night and at rest. It is often disproportionately severe compared with the fact that nothing can be seen from the outside – no swelling and no discolouration. This experience of “nothing looks wrong with you” is itself distressing for many patients, because those around them do not understand why they cannot put weight on the limb.
Key point
Bone oedema is a condition that resolves – but slowly, typically over several months, and it hurts until then. This is precisely the aim of magnetotherapy (PEMF): to support the reduction of pain and oedema, and the resolution of the bone oedema while the body does its own work. It is not a quick fix, but a daily, home-based complementary treatment alongside other medical care.
Diagnosis first, treatment second
“Bone oedema” is in itself a finding, not a diagnosis. The same MRI image may be caused by a sports injury, transient osteoporosis or early bone necrosis – and these conditions differ greatly in their treatment, weight-bearing limits and outlook. Your orthopaedic doctor must first tell you what is behind it and how much weight you may put on the limb. Home magnetotherapy comes into play afterwards, under their guidance.
The main types of bone oedema
The same MRI finding may indicate very different things. This matters to you too, because the underlying cause determines how long it will last, how much weight you can put on it and what you can expect. The following three groups cover the vast majority of cases.
It develops after a blow, sprain, fall or sports accident: the bone trabeculae are damaged at microscopic level, and the area bleeds and becomes oedematous. It is often associated with ligament injury – in the knee, for example, it almost invariably appears on the impact surfaces of the femur and tibia alongside an anterior cruciate ligament tear.
This is the most common form and generally has the most favourable outcome. It gradually resolves over weeks to months, but the pain is real until then and can significantly delay an athlete’s return to sport.
There is no preceding event here: you have not knocked or fallen – the pain appears “by itself”, typically in the hip, knee, ankle or talus. It used to be called transient osteoporosis because the bone temporarily becomes less dense in the affected area.
It typically occurs in middle-aged men and in women in the third trimester of pregnancy. It is a self-limiting condition – in other words, it resolves on its own – but this may take 6–12 months, and it remains painful throughout. This is precisely why complementary treatment can be useful.
In the early stage of bone necrosis, the MRI image can be misleadingly similar to harmless bone oedema. The difference, however, is crucial: if the process progresses, bone necrosis may lead to collapse of the bone surface and joint damage.
This is why it matters who reviews the report. If your doctor suspects early bone necrosis, it requires close orthopaedic follow-up – magnetotherapy may still be considered as a complementary treatment, but under medical supervision and not instead of it.
How is magnetotherapy connected with bone oedema?
There is no heat and no sensation with pulsed electromagnetic fields (PEMF) – typically you feel nothing under the applicator. Its effect takes place at tissue level through electrical processes: the changing magnetic field induces a weak electric current in the bone, and the cells respond to it. Three processes matter in bone oedema.
The inside of the bone is a rigid box – the excess fluid inside it has nowhere to expand. This raises the pressure inside the bone, and that pressure itself causes pain. By affecting local circulation and ion movement across cell membranes, PEMF may help excess fluid drain from the area more easily.
This explains the observation that pain often improves before the MRI image shows a clear improvement.
Inflammatory signalling substances are released in the oedematous area of bone. They are not only responsible for pain but also place stress on the joint cartilage above them – which is why prolonged bone oedema may affect the condition of the joint in the long term.
Research suggests that PEMF treatment may favourably affect the local levels of these inflammatory signalling substances and may therefore indirectly protect the cartilage as well.4
This is magnetotherapy’s longest-known area of action: PEMF may favourably affect the activity of bone-forming cells (osteoblasts). This is the mechanism behind the use of bone stimulators for difficult-to-heal fractures for decades – and the same mechanism is involved when damaged bone trabeculae repair themselves.
If you would like to know more about bone fractures or osteoporosis, I have written about these separately: bone fractures and magnetotherapy, and osteoporosis.
Home treatment: which device is suitable?
This is the most important thing to know before choosing: not every Magnum device includes a bone-oedema programme. The dedicated “Bone oedema (bone bruise)” programme is available from the Magnum 2500 model upwards. The entry-level Magnum L and XL – although excellent devices for fractures, arthrosis and arthritis – are not suitable for this purpose.
| Device | Bone-oedema programme | Who do I primarily recommend it to? |
|---|---|---|
| Magnum L | – | Not suitable for bone oedema. A good choice for fractures, arthrosis and arthritis, however. |
| Magnum XL | – | Not suitable for bone oedema. It has beauty-care and tissue-regeneration programmes. |
| Magnum 2500 | ✓ | The entry point for bone-oedema treatment. If this is your only goal, it is sufficient. |
| Magnum XL Pro | ✓ | If you also want skin- and tissue-regeneration programmes alongside bone oedema. |
| Magnum 2 Pro Drive | ✓ | If you travel frequently. It runs on battery power and from a car cigarette lighter; it is worth complementing it with a Soft4 or MAT100 mat. |
| Magnum 3000 Pro | ✓ | A wider range of programmes, 1+1 mode. Also suitable for clinic use. |
| Magnum 3500 Pro | ✓ | The widest range: 2+2 mode, night programmes, and the highest intensity and penetration capability. |
Magnetotherapy devices suitable for bone-oedema treatment →
The category contains only those Magnum devices that actually include a dedicated bone-oedema programme. You do not need to browse programme lists: anything you find there is suitable for this purpose.
My advice when choosing
Do not choose based on the number of programmes. Ask yourself these two questions: (1) Is this my only complaint, or would I use it for something else too? (2) Will I use it at home, or while travelling as well? If the answers are “bone oedema only” and “at home”, then the Magnum 2500 does everything you need – the more expensive models offer programmes you will not use in this situation.
Before you start treatment
Magnetotherapy is generally well tolerated, and studies have not reported any significant side effects. In some situations, however, it cannot be used or may only be used with medical approval. Please read this through – and if any point applies to you, speak to your treating doctor first.
When should you not use it, or when should you ask your doctor first?
- Implanted electrical medical device – in the case of a pacemaker, implanted defibrillator (ICD), insulin pump, spinal cord or deep-brain stimulator, or cochlear implant, treatment must not be used, because the magnetic field may interfere with the device’s operation.
- Pregnancy – treatment is not recommended during pregnancy. This deserves particular attention because bone marrow oedema syndrome typically occurs in the third trimester of pregnancy – in this situation, treatment must be postponed until after delivery, in consultation with your doctor.
- Malignant disease – treatment must not be used in the case of known or suspected malignancy, or a tumour in the area being treated. If metastasis is suspected in the area affected by bone oedema, investigation is the first step.
- Active infection in the treatment area – it must not be used in the case of osteomyelitis, an infected joint or an open, infected wound; these require urgent medical care.
- Severe cardiac arrhythmia – if you have an unstable arrhythmia, ask your cardiologist for advice before starting treatment.
- Epilepsy – if you have a known tendency to seizures, treatment may only be started with the approval of a neurologist.
- Metal implant in the treatment area – this is not an absolute obstacle: treatment can generally be used alongside standard orthopaedic screws, plates and prostheses. However, because bone oedema often appears after surgery or a fracture, please consult the operating surgeon first.
Important information
The devices presented here are CE/MDR-certified medical devices intended to complement medical treatment. They do not replace orthopaedic assessment, weight-bearing instructions, physiotherapy or any prescribed medication. Clarifying the cause of bone oedema is always a medical task.
What do the studies tell us?
Bone oedema is not one of the most thoroughly researched areas. It is a rare condition, so studies involve small numbers of patients, and large placebo-controlled studies are practically non-existent. What we know comes from a few well-documented clinical observations – I summarise them below, together with their real limitations.
“Can it help if I have bone oedema in my ankle?”
This is where we have the most direct data. An Italian orthopaedic group treated patients with bone oedema of unknown origin in the talus for several hours a day over one month. The patients’ ankle and foot function scores improved from a moderate level before treatment to the excellent range by the end of the study, and this was accompanied by improvement on MRI. It was a small study without a control group – so we do not know exactly how much of the improvement came from treatment and how much from natural resolution – but both the result and the safety profile are noteworthy.1
“What if it is in my knee and the doctor mentioned bone necrosis?”
This is the most serious situation, and it is precisely here that the most encouraging data are available. Nearly thirty patients with early-stage bone necrosis of the knee were followed for two years. Alongside daily magnetotherapy, their pain fell to half or a third within six months, and this improvement remained two years later. But the most important figure is this: 86% of the treated knees avoided prosthetic surgery by the end of the second year. The size of the necrotic area decreased measurably in most cases.2
“How much do I need to use it for it to be worthwhile?”
This is the most inconvenient message, but I have to say it: a lot. In the studies that produced results, patients received treatment for 6–8 hours a day over 30–90 days. This is not twenty minutes twice a week. At the same time, this is exactly why a home device makes sense: nobody could manage this by travelling to a clinic – but at home, in the evening and while sleeping, it is realistically achievable.1,3
“I am an athlete – can I return sooner?”
I have no evidence for this, and I do not promise it. Reviews of the literature on sports-related bone oedema consider PEMF a useful complement for supporting oedema resolution and reducing pain – but there is no study that can safely determine the time of return. Your orthopaedic doctor and physiotherapist decide the pace of resuming weight-bearing, not the device.4
Where does the evidence stand today?
In summary: magnetotherapy appears in international treatment algorithms for bone oedema among conservative, surgery-avoiding options – but as a complementary treatment, not as first-line treatment.3 The data are encouraging and the method is safe, but the studies are small. Anyone who promises you more is saying more than the scientific literature supports.
Practical advice for everyday life
Build it into your evening, not your day
Several hours a day may sound alarming at first. In practice, most of my patients use it in the evening while watching television or during sleep – the applicator can be fitted, it does not heat up and it does not disturb them. Those who try to “fit in” twenty-minute sessions morning, midday and evening usually stop after a few weeks; those who tie it to their evening routine complete the course.
Do not stop based on pain alone
Pain often improves before the oedema has actually resolved. This is a trap: many people stop treatment at this point and return to full weight-bearing – then the symptoms return. The length of treatment and the timing of resuming weight-bearing are determined by the follow-up MRI and your doctor, not by how you feel.
Continue to reduce the load
The most important element of bone-oedema treatment remains reducing weight-bearing – no device can replace this. If your doctor has prescribed crutches, a walking stick or partial weight-bearing, continue this alongside magnetotherapy. The two work together, not instead of each other.
Frequently asked questions
It varies greatly and depends on the underlying cause. Traumatic bone oedema typically resolves within a few months. Bone marrow oedema syndrome is slower: it may take 6–12 months. The outcome of early bone necrosis cannot be predicted in advance, which is why close follow-up is needed. Improvement on MRI generally lags behind pain relief – this is normal.
No. These models do not have a dedicated bone-oedema programme. The Magnum 2500 is the entry-level model for bone oedema. The L and XL are excellent choices for fractures, arthrosis and arthritis, but do not choose them for bone oedema. The bone-oedema category contains only suitable devices.
The studies that produced results used 6–8 hours a day for 30–90 days. This is a lot, but it is realistically achievable at home with evening and overnight use – and this is precisely why a home device is better suited to this condition than clinic-based treatment. The device instructions and your treating doctor will specify the exact programme and duration.
It does not hurt, and typically you will not feel anything – PEMF does not heat the tissue or cause muscle contractions. Many people find this strange at first. The effect does not depend on sensation: the magnetic field acts within the tissue without sensory feedback.
Treatment can generally be used alongside standard orthopaedic metalwork – screws, plates, intramedullary nails and prostheses. What you must not do is use it near an implanted electrical device such as a pacemaker, defibrillator, insulin pump or stimulator. Because bone oedema often appears after surgery, please consult your operating surgeon in every case.
That is a fair question. There are two reasons. First, “on its own” usually means many months, and it hurts during that time – reducing the pain is itself a worthwhile goal. Second, prolonged bone oedema is not neutral for the joint: inflammatory signalling substances also place stress on the cartilage. And with early bone necrosis, it is particularly unwise to simply wait – the joint is at stake.
Essentially, they are the same thing, just different terminology. “Bone bruise” refers to traumatic bone oedema, and this is the term used in everyday language. “Bone oedema” and “bone marrow oedema” are broader terms: they cover every case in which fluid builds up inside the bone, even when it was not caused by an injury.
Summary – Quick overview
Sources
- Martinelli N, Bianchi A, Sartorelli E, Dondi A, Bonifacini C, Malerba F (2015). Treatment of bone marrow edema of the talus with pulsed electromagnetic fields: outcomes in six patients. Journal of the American Podiatric Medical Association, 105(1):27–32. PubMed: 25675223
- Marcheggiani Muccioli GM, Grassi A, Setti S, et al. (2013). Conservative treatment of spontaneous osteonecrosis of the knee in the early stage: pulsed electromagnetic fields therapy. European Journal of Radiology, 82(3):530–537. PubMed: 23219192
- Bone marrow edema of the knee: a narrative review (2024). Overview of the diagnosis and conservative treatment algorithm for knee bone oedema. PubMed Central: PMC11093815
- Applications and Future Perspective of Pulsed Electromagnetic Fields in Foot and Ankle Sport-Related Injuries (2023). Overview of PEMF applications in foot and ankle injuries, including bone oedema. Applied Sciences, 13(9):5807. MDPI: 10.3390/app13095807
- Massari L, Fini M, Cadossi R, Setti S, Traina GC (2006). Biophysical stimulation with pulsed electromagnetic fields in osteonecrosis of the femoral head. The Journal of Bone and Joint Surgery (American), 88 Suppl 3:56–60. PubMed: 17079368
