PEMF for
Avascular Necrosis.

August 2026 · 12 min read · Clinical Protocol

What Is Avascular Necrosis of the Femoral Head?

Avascular necrosis (AVN), also called osteonecrosis of the femoral head (ONFH), is the death of bone tissue caused by an interruption of its blood supply. Without circulation the bone's internal structure weakens and, at a certain point, the femoral head collapses — changing from spherical to flattened. From the moment of collapse, cartilage wear progresses quickly and most patients reach total hip arthroplasty within two to three years.

The most common causes are prolonged corticosteroid therapy, heavy alcohol consumption, trauma (hip fracture or dislocation), sickle cell disease, and idiopathic cases where no cause is identified. In a series of 95 patients published in Clinical Orthopaedics and Related Research, 46 cases were attributed to steroids and 44 were idiopathic (PubMed 2670386). The mean age in that series was 38 — and that is what makes this condition so difficult: it is a young population, for whom a hip replacement means at least one revision operation later in life.

Corticosteroid-associated AVN is of particular relevance in the Philippines, where high-dose dexamethasone and methylprednisolone were widely used in severe COVID-19 protocols between 2020 and 2022. Steroid exposure is the single most frequently reported non-traumatic risk factor for AVN in the orthopedic literature, and patients exposed during that period are within the typical latency window for presentation now.

The Ficat Staging System — Everything Depends on It

Stage	Imaging finding	Structural status	What the PEMF evidence shows
Ficat I	Normal X-ray; MRI shows marrow changes	Femoral head intact and round	The stage with the strongest reported results (94% joint preservation, I–II combined)
Ficat II	Sclerosis or cystic change on X-ray; no collapse	Intact but structurally weakened	Reported more effective here than in advanced lesions
Ficat III	Crescent sign; the head begins to flatten	Subchondral collapse present	12 of the 15 hips that went on to replacement were at this stage
Ficat IV	Articular collapse and secondary osteoarthritis	Joint surface destroyed	0 of 79 hips improved; 23% progressed further

A normal X-ray does not rule out AVN. At Stage I the plain film is almost always normal, and MRI is the only test that will find it — which is precisely the stage at which there is something to do.

How PEMF Acts on Bone Tissue

PEMF (Pulsed Electromagnetic Field) is a non-invasive treatment in which a coil generates an alternating magnetic field that induces a small electrical current in the tissue. The field passes through soft tissue and bone without significant absorption, so it reaches the femoral head — a deep structure that light- or heat-based modalities do not reach.

At the cellular level the theoretical basis combines two effects described in the literature: osteogenesis (new bone formation by osteoblasts) and a chondroprotective effect on articular cartilage. This is the rationale proposed by the University of Ferrara group as an explanation for why biophysical stimulation might delay progression of the necrosis (PubMed 17079368).

An important boundary, stated plainly: this mechanism is local and reparative, not vascular. There is no evidence that PEMF reopens the occluded vessels or restores blood supply to the femoral head. What is attributed to it is support for bone remodelling in the region surrounding the necrosis, and through that, possible slowing of structural deterioration. An orthopedic surgeon will notice that distinction immediately, and a page that blurs it loses credibility.

What the Research Actually Shows

Evidence exists, but it is old, retrospective, and includes not a single randomised controlled trial. These are the four principal clinical studies — including the one that found no benefit:

• Massari et al. 2006, Journal of Bone and Joint Surgery (American), University of Ferrara, Italy. Retrospective analysis of 76 hips in 66 patients with Ficat I–III disease, treated with PEMF 8 hours per day for an average of 5 months. Results: 94% of Ficat I–II hips were preserved from surgery; 15 hips required total hip arthroplasty, 12 of them Ficat III; radiographic progression occurred in 20 hips (26%); pain disappeared entirely within 60 days in 35 patients (53%). Limitation: retrospective, no control group (PubMed 17079368).
• New York Orthopaedic Hospital / Columbia Presbyterian 1989, Clinical Orthopaedics and Related Research. 118 hips in 95 patients treated between 1979 and 1985, assessed by Steinberg staging. In Stages 0–III (15 hips), no hip progressed and 9 of 15 improved. In Stage IV (79 hips), 23% progressed and none improved. Overall progression was 16%, with 87% of hips already collapsed on entry (PubMed 2670386).
• University of Rhode Island 1989, Clinical Orthopaedics and Related Research. A comparison of core decompression with PEMF. Both reduced clinical and radiographic progression, and PEMF appeared more effective in Ficat II hips than in more advanced lesions (PubMed 2582669).
• Friedrich-Schiller-Universität Jena 2014, The Open Orthopaedics Journal — the negative result. A prospective (non-randomised) cohort study, n=35 patients / 40 hips, testing an invasive electromagnetic field (an implanted bipolar induction screw) added to curettage and bone grafting. At 12 months, total hip arthroplasty had been performed in 18% of the treatment group versus 22% of controls — not a significant difference. Both clinical scores improved in both groups, with no significant difference between them (PubMed 24987486). This is an invasive modality and materially different from external PEMF, but it is the only prospective work in the field and cannot be skipped.

Where PEMF Fits in the Standard Care Pathway

• Diagnosis is by MRI, the most sensitive test, which detects Stage I disease while the X-ray is still normal.
• Load reduction and risk-factor removal — adjusting steroid dosing in coordination with the prescribing physician, stopping alcohol, and treating the underlying disease — are an integral part of management.
• In early stages, joint-preserving surgery is considered, principally core decompression, sometimes combined with bone grafting.
• In advanced stages — after collapse and cartilage wear — total hip arthroplasty is the accepted treatment.
• PEMF is integrated into a broader treatment plan and is not a substitute for medical evaluation. It has been examined as an adjunct intended to delay or avoid surgery in early disease, not as a standalone therapy.

Clinical Protocol

1. Confirm the diagnosis and stage first. An MRI report and a documented Ficat stage are required. Without a documented stage there is no treatment decision — and a patient at Stage III or above is referred back to the orthopedic surgeon.
2. Patient position: supine or side-lying, the affected hip accessible to the coil. No undressing is required.
3. Coil placement over the groin and hip so the field covers the femoral head.
4. Session length: approximately 30 minutes in clinic. Note an important gap: in the 2006 study the exposure was 8 hours per day using a portable device — a far higher dose than any clinic protocol, and one of the main reasons the numbers from that study cannot be transferred directly to a weekly clinic session.
5. Clinic frequency: 1–2 times per week, at the practitioner's discretion.
6. Course length: at the practitioner's discretion and not fewer than 3 sessions. First assessment after at least 3 sessions.
7. Outcome measures: groin pain on a VAS, hip range of motion, walking distance, and imaging follow-up by the orthopedic surgeon — not in the clinic.
8. Stopping criteria: worsening pain, limb shortening, or reduced range of motion require immediate cessation and referral.

Comparison with the Alternatives

Parameter	PEMF	Core decompression	Analgesic medication	Total hip arthroplasty
Invasiveness	None	Surgical (minimally invasive)	None	Major surgery
Stage studied	Ficat I–II only	Ficat I–II	Any stage (symptomatic)	Ficat III–IV
Evidence quality	Low — retrospective, no RCT	Moderate — series and comparisons	Moderate for pain, not for disease	High
Effect on disease course	Not proven; joint preservation reported in early stage	May delay progression	None — symptomatic only	Replaces the joint
Pain relief	53% pain-free within 60 days (n=66)	After surgical recovery	Immediate, temporary	Substantial after rehabilitation
Session cost (Philippines)	₱1,500–₱2,500 per session	Surgical admission	Ongoing medication cost	Surgical admission + revision later
Practitioner time in clinic	Hands-free — does not require continuous direct supervision	—	—	—

Clinic System or Home Device?

In this indication the question matters more than usual, because the dose in the 2006 study was 8 hours per day — a dose no clinic can deliver. There are three distinct categories, not two:

Category	Who it suits	Field intensity and protocols	Possible treatment frequency
Clinical PEMF system	Patients under practitioner supervision after diagnosis	The highest of the three; full coil range and an indication-specific protocol library	1–2 times per week
Medical-grade home device	Home rehabilitation, or as a complement to clinic care	More powerful than common consumer home devices and less powerful than the clinical system; preset programmes, simple operation, usable while reading or watching television	Daily, and even twice daily
Consumer wellness product	Not relevant to a medical indication	Mats and pads — consumer products, not medical equipment, with no defined indication	—

Intensity versus frequency: the difference between the routes is not only intensity but cumulative dose. Clinic treatment runs 1–2 times per week; at home, treatment can be daily or twice daily — and in an indication where the literature itself used prolonged daily exposure, that is a substantive difference rather than a sales argument. The technology has been tested in controlled clinical trials, and devices carrying FDA 510(k) clearance for pain and oedema reduction exist on the market — two things absent from most consumer home devices, which rely on infrared or laser light that is absorbed in the superficial layers of the skin, whereas a magnetic field passes through tissue and bone without significant absorption.

⚠ A home device is not a substitute for diagnosis and not a substitute for orthopedic follow-up. It must never be used to defer investigation or imaging surveillance. Regulatory clearance always applies to a specific model rather than to the technology as a whole, and it has an expiry date — ask to see the current certificate for the model offered to you and its validity date.

Frequently Asked Questions

Does PEMF cure avascular necrosis?

No — there is no evidence for that. PEMF does not restore blood supply and does not reverse tissue that has already died. What the literature describes is preservation of 94% of hips at Ficat I–II in a retrospective series of 76 hips, meaning avoidance of surgery within the follow-up period — not cure. After collapse, no benefit was found at all.

Can it save me from a hip replacement?

Only in early-stage disease, and only as a possibility rather than a promise. In Ficat I–II, 94% joint preservation was reported; of the 15 hips that went on to replacement, 12 were already Stage III at the start of treatment. In the only prospective study there was no significant difference in replacement rates (18% versus 22%). The decision about surgery belongs to the orthopedic surgeon alone.

Can I stop my steroids if I start PEMF?

No, under no circumstances. Stopping corticosteroid therapy without medical supervision can be dangerous and is sometimes life-threatening. Steroids are the most common risk factor for AVN — 46 of 95 patients in the 1989 series — but any change in dose is made solely by the physician who prescribed it.

When must a patient seek urgent orthopedic assessment?

Four signs require an orthopedic surgeon or emergency department the same day: sudden sharp groin pain that does not settle at rest or wakes the patient from sleep; inability to bear weight; a sense that the leg has shortened or the hip is catching; and fever, chills or swelling in the area. In addition, any new hip pain in a patient on prolonged steroid therapy or after hip trauma warrants an MRI, even if the X-ray is normal.

Which patients should not receive PEMF?

Absolute contraindications are an implanted pacemaker or defibrillator, pregnancy, active malignancy in the treatment field, active epilepsy, and acute infection at the treatment site. A metal implant in the hip requires consultation with the operating orthopedic surgeon before treatment begins. In any chronic medical condition, consultation with the treating physician before starting is mandatory, not advisory.

What This Means for a Philippine Clinic

AVN is a referral-driven indication rather than a volume indication, and that is exactly where its business value lies. A clinic that screens correctly — accepting patients only with an MRI report and a documented stage, and returning Stage III and above to the surgeon — becomes a standing referral destination for orthopedic surgeons in its area. Treatment is delivered hands-free and does not require continuous direct supervision, so the revenue is generated while the practitioner is treating another patient in a parallel room: it does not compete with the manual-therapy fee but is added to it, and therefore raises the value of a clinic hour.

70+ Israeli clinics serving a population of 9M — now expanding to the Philippines. Each system ships with clinical staff training, an indication-specific protocol book, and ongoing technical and clinical support.

References

1. Massari L, Fini M, Cadossi R, et al. Biophysical stimulation with pulsed electromagnetic fields in osteonecrosis of the femoral head. J Bone Joint Surg Am. 2006;88 Suppl 3:56-60 — PubMed 17079368
2. Effects of pulsed electromagnetic fields on Steinberg ratings of femoral head osteonecrosis. Clin Orthop Relat Res. 1989;(249):199-208 — PubMed 2670386
3. The conservative treatment of osteonecrosis of the femoral head. A comparison of core decompression and pulsing electromagnetic fields. Clin Orthop Relat Res. 1989;(249):209-218 — PubMed 2582669
4. Invasive electromagnetic field treatment in osteonecrosis of the femoral head: a prospective cohort study. Open Orthop J. 2014;8:125-129 — PubMed 24987486 (non-significant result)
5. Osteonecrosis of the femoral head treated by pulsed electromagnetic fields (PEMFs): a preliminary report. The Hip. 1983:78-92 — PubMed 6671918

Hebrew original: painfree.org.il. This page is informational and is not medical advice; it does not replace diagnosis, treatment or follow-up by a treating physician.