Osteonecrosis of the femoral head is death of subchondral bone from loss of blood supply, linked to trauma, corticosteroids, alcohol and sickle cell disease. It is staged with Ficat and Arlet or Steinberg. Core decompression may help before collapse, and hip replacement is needed after collapse.

Western Health Orthopaedic Registrar presentation – Osteonecrosis of the femoral head by Dr Devinder Garewal

Osteonecrosis of the Hip | AVN, lateral radiograph of idiopathic avascular necrosis of the femoral head — Lateral radiograph of idiopathic avascular necrosis of the femoral head. Image by Mikael Häggström, M.D. Author info – Reusing images- Conflicts of interest: None Mikael Häggström, M.D.Consent note: Written informed consent was obtained from the individual, including online publication., Wikimedia Commons, CC0.

Osteonecrosis of the Hip | AVN, pathology of avascular necrosis of the femoral head, showing the zone of cell death beneath the articular cartilage — Pathology of avascular necrosis of the femoral head, showing the zone of cell death beneath the articular cartilage. Image by Mikael Häggström, M.D. Author info – Reusing images- Conflicts of interest: None Mikael Häggström, M.D.Consent note: Consent from the patient or patient’s relatives is regarded as redundant, because of absence of identifiable features (List of HIPAA identifiers) in the media and case information (See also HIPAA case reports guidance)., Wikimedia Commons, CC0.

Classification

Ficat Classification

Professor RP Ficat; Ficat Classification of Osteonecrosis of the Hip
- Normal hip with contra-lateral disease (Hungerford)
I
- Normal radiograph
- Diagnosis following MRI, bone scan or histology
II
- Radiographic changes of repair (osteoporosis / sclerosis / cysts)
- No osteochondral fracture
- Head spherical
III
- Wedge shaped ↑ density
- Mottled osteoporosis
- Subchondral lucent line® Crescent sign
- Head no longer spherical “out of round”
- Usually affects antero-lateral area of femoral head (best seen on lateral view)
IV
- Marked changes with secondary degenerative changes in the joint
- Collapse of subchondral bone & severe deformity of the head
Steinberg Classification
- Steinberg et al JBJS (Journal of Bone & Joint Surgery) 77B: 34-41,1995
  - Modified to assess extent of involvement
  - More accepted classification
- Steinberg Classification of Osteonecrosis of the Hip

* Normal hip with contra-lateral disease (Hungerford) * Suspicion but unable to confirm
I	* Normal radiograph * Diagnosis following MRI, bone scan or histology
II	* Radiographic changes of repair (osteoporosis / sclerosis) * No osteochondral fracture * Head spherical
III	* Wedge shaped ↑ density * Mottled osteoporosis * Subchondral lucent line (Crescent sign) * Head no longer spherical “out of round” * Usually affects antero-lateral area of femoral head (best seen on lateral view)
IV	* Flattening of the femoral head * On AP or lateral XRAYS * Now irreversible changes * Symptomatic treatment until arthroplasty
V	* joint narrowing with or without * acetabular involvement
VI	*advanced degenerative changes

These stages are further divided into mild (A), moderate (B) or severe (C)

Stage	Description
1 + 2	A mild: less than 15% involvement of head on XR or MRI B mod: 15- 30% C severe: more than 30%
3	A: subchondral collapse (crescent) less than 15% of artic surface B: 15- 30% C: more than 30%
4	A: less than 15% of surface has collapsed + depression is less than 2 mm B: 15- 30% collapsed or 2-4 mm depression C: more than 30% collapsed or more than 4mm depression
5	A, B or C average of femoral hd involvement as in stage 4

Classification of Osteonecrosis of the Hip

Head involvement = % of head on AP viewx % head on lateral view

Eg 25 % involvement may be 50 % AP & 50 % lateral

Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 10 October 2026.