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What is osteonecrosis
Osteonecrosis (avascular necrosis, AVN) is the death of a section of bone tissue due to interrupted blood supply. Living bone constantly remodels; when blood flow stops, bone cells die, the structure breaks down, and ordinary loading triggers collapse — sinking of the joint surface.
Typical locations
Femoral head (most common). Femoral condyles (knee osteonecrosis). Humeral head. Talus. Scaphoid. Less often — vertebral body.
Risk groups
Men aged 30–50 — 4× more often than women. Bilateral in 40–80% (especially with systemic causes). Etiology unknown in 30%.
Why it's urgent
From early stage to collapse — often 6–18 months. After head collapse, restoration is impossible. Therefore, on suspicion — immediate MRI and urgent consultation.
Main causes
Glucocorticoids
Prolonged prednisolone or analog use (> 2 g cumulative). The most common non-traumatic cause. Often after COVID-19 courses, systemic disease, transplantation.
Alcohol
Chronic abuse alters fat metabolism and bone microcirculation. Risk is dose-dependent.
Trauma
Femoral neck fractures, hip dislocations, fractures of the talus and scaphoid disrupt end-arterial blood supply. May develop weeks to months after injury.
Hematologic disease
Sickle cell disease, antiphospholipid syndrome, thrombophilias, leukemia — disrupt microcirculation in marrow sinuses.
Decompression sickness
"Caisson disease" in divers and caisson workers. Gas emboli block bone capillaries.
Idiopathic
Unknown cause in 30%. A diagnosis of exclusion after ruling out all known factors.
ARCO stages
Stage 0 and I
Normal X-ray. MRI shows bone marrow edema and "double line." Clinically — load-related pain, possibly asymptomatic. Regenerative treatment — maximum efficacy.
Stage II
X-ray shows sclerotic and lucent zones. Head shape preserved. Moderate pain. Regenerative treatment — core decompression + BMAC, high efficacy.
Stage III
Subchondral fracture — "crescent sign." Beginning of collapse. Increasing pain. Regenerative treatment feasible in early cases, often combined with orthopedic offloading.
Stage IV
Complete head collapse, acetabular changes, secondary arthrosis. Endoprosthesis indicated. Regenerative treatment only as part of a comprehensive palliative approach.
Osteonecrosis diagnosis
MRI — method of choice
99% sensitivity at early stages, when X-ray is still normal. Detects bone marrow edema, "double line," first signs of necrosis. Mandatory on any suspicion.
X-ray
Not informative at early stages. Useful for stage II–IV: sclerosis, crescent sign, collapse. X-ray dynamics is a key progression criterion.
Lab screening
Cause identification: coagulation panel (thrombophilia), lipid profile, immune workup, systemic disease tests. Critical for preventing involvement of the second joint.
Osteonecrosis: treatment options and what is known about them
The treatment plan is made by the clinic doctor after an examination and a review of your images. The table shows the options usually discussed for this diagnosis and how well they have been studied.
| Option | What to expect | How well studied |
|---|---|---|
| Load management, weight loss | Takes load off the affected area; if overweight, losing 5–10% noticeably reduces pain | Moderate evidence |
| Painkillers and NSAIDs | Ease pain during flare-ups; long-term use is limited by side effects | Moderate evidence |
| BMAC / MFAT | Cell preparations from bone marrow or fat; more expensive, no proven advantage over PRP | Limited or conflicting evidence |
| PRP / CGF | Concentrate from your own blood; may reduce pain, growth of new tissue has not been shown | Little data |
| Core decompression or hip replacement | If conservative treatment does not help or there is an indication | When indicated — the doctor decides |
We send your request to several partner clinics. Some will suggest conservative treatment or injections, others surgery; each clinic quotes its own conditions and price. We help you compare the options.
Regenerative methods: realistic expectations
In avascular necrosis everything depends on the stage. In early stages, before the femoral head collapses, offloading and core decompression are used; in some studies adding bone marrow concentrate (BMAC) improved results, but the data are still limited. After collapse and joint destruction, regenerative methods do not help — hip replacement is usually discussed.
When surgery is discussed. In the early stage — core decompression of the femoral head (sometimes combined with BMAC); in the late stage — hip replacement.
If an injection helps, the effect usually builds up over 6–12 weeks, and the result is assessed after 2–3 months. No clinic can guarantee a result.
Recovery and timelines
After an outpatient injection procedure, most patients return to normal activity within 1–3 days. Sport and heavy loads are resumed according to the physician’s plan, usually after 2–6 weeks, alongside therapeutic exercise. The effect is assessed after 6–12 weeks. After surgery, rehabilitation takes longer and depends on the operation.
Who it is not suitable for and possible risks
Contraindications
- Active infection — at the injection site or systemic, with fever.
- Active cancer or ongoing chemotherapy.
- Blood clotting disorders or a low platelet count. Anticoagulants are discussed with the physician.
- Pregnancy and breastfeeding — the procedure is usually postponed.
- A corticosteroid injection into the same area in recent weeks.
- Severe stage IV osteoarthritis with axial deformity and joint destruction — joint replacement is usually discussed instead.
Possible risks
- Pain and swelling at the injection site for 1–3 days.
- Bruising where blood or fat tissue is taken.
- Rarely, infection. The procedure is therefore performed under sterile conditions with ultrasound or X-ray guidance.
- The effect may be absent or smaller than expected.
If any of these apply to you, mention it in your request. The coordinator will check with the clinic physician whether treatment is possible. Contact a coordinator.
Scientific evidence
Studies of regenerative methods show mixed results. Clinic physicians rely on research including the following:
- Hernigou P et al. Treatment of osteonecrosis with autologous bone marrow grafting. Clin Orthop Relat Res, 2002.
- Evans JT et al. How long does a hip replacement last? A systematic review and meta-analysis of case series and national registry reports with more than 15 years of follow-up. Lancet, 2019.
Next steps: Treatment methods · Treatment cost · How treatment in Germany is organised
Frequently asked questions
RegenPAS is a patient service centre in Munich, not a clinic. We review your images and symptoms and send a request to several partner clinics at once. Clinics that can accept you send their own conditions and price; prices differ between clinics, and you choose the option that suits you. The coordinator replies within 24 hours, and a clinic physician’s preliminary opinion follows in 1–3 business days. We then arrange the appointment, visa invitation, interpreter, transfers and accommodation. Treatment decisions are made by the clinic physician. Contact a coordinator.
Your MRI (or CT, X-ray) report and the images if you have them, plus a short description of your symptoms and previous treatment. Send them via the form on the website — the assessment is free and without obligation: the coordinator replies within 24 hours, and the clinic physician’s preliminary opinion follows in 1–3 business days.
The cost depends on the method, the diagnostics needed and the clinic itself: prices differ between clinics. We request offers from several clinics and send you their conditions and quotes so you can compare. Price guidance is on the treatment cost page. For an outpatient procedure, 2–3 days in Munich are usually enough: examination, procedure and follow-up visit.