| S.No | Causes |
| 1 | Trauma |
| 2 | Iatrogenis (Use of glucocorticoids, Alcohol, chemotherapy) |
| 3 | Hematological (Thalassemia, Thrombophilia, hemophilia, myeloproliferative disorders) |
| 4 | Metabolic (Gaucher disease, hypercholesterolemia, pregnancy, chronic renal failure, Hyperparathyroidism, Cushing’s disease, gout/hyperuricemia, diabetes mellitus) |
| 5 | Autoimmune disease (systemic lupus erythematosus, rheumatoid arthritis) |
| 6 | Gastrointestinal (Chronic pancreatitis, inflammatiry bowel disease) |
| 7 | Orthopaedic (congenital hip dislocation) |
| 8 | Reduction of the perifocal oedema and of the dimensions of the two foci of the head of the left femur (blue arrows). The necrotic area present in the head of the right femur was unchanged (orange arrow). |