Different stages of Avascular Necrosis AVN and surgical potential for each stage.

This table is for the different stages of avascular necrosis AVN in the hip, but can be a guide of other joints. It is clear that surgery can only be done in Stage 1, 2 or 3, after that joint replacement looks to be the only solution.

Stage

Clinical

Surgical potential

Stage 0 Theoretical stage:
Asymptomatic.
All diagnostic tests are normal.
Biopsy from histology - is the only
abnormality.
None Required:
Theoretical stage only
Not a clinical problem.
Stage 1 X-rays and CT-scan are normal
MRI and Tc99 and histology are abnormal.
Symptoms may or may not be present.

Surgery is possible / desirable.
Core-decompression possible.
Adult stem cell surgery possible.

Stage 2 X-Rays are abnormal -
With linear sclerosis or cysts.
There is no Subchondral lucency
Head of the femur is still spherical.
Surgery is possible / desirable.
Core-decompression possible.
Adult stem cell surgery possible
Stage 3 The femoral head starts to fail mechanically - With Trabecular collapse.
The radioluscent crescent sign is visible at the Subchondral endplate.
The femoral head itself is still spherical
Surgery is possible
Core-decompression possible.
Success depends on degree of changes.
Stage 3a Crescent <15% Surgery still possible.
Stage 3b Crescent 15-30% Increasing risk of failure of preventative surgery.
Stage 3c Crescent >30% Increasing risk of failure of preventative surgery.
Stage 4 Flattening of the femoral head is now seen Preventative surgery NO HELP
Medical Management.
Total Hip Replacement Required.
Stage 4a <15% of the surface is collapsed
Depression <4mm
Preventative surgery NO HELP
Medical Management.
Total Hip Replacement Required.
Stage 4b 15-30% collapse or 2-4mm depression Preventative surgery NO HELP
Medical Management.
Total Hip Replacement Required.
Stage 4c >30% Collapse or >4mm depression. Preventative surgery NO HELP
Medical Management.
Total Hip Replacement Required.
Stage 5 Any or all X-rays features may be present
There is a decrease in joint space.
Secondary Osteoarthritis is present with Sclerosis / Cysts / Osteophytes
Preventative surgery NO HELP
Medical Management.
Hip Replacement Required.
Stage 6 Extensive destruction Total Hip Replacement -
Where available / Possible.