It is necessary to distinguish:
- The fracture lesions which are always found with certainty notion traumatic (new or old)
- Chronic lesions with onset of osteonecrosis subchondral more or less extensive, described in the literature under different terminologies (osteochondrosis, osteochondritis, osteonecrosis).
This distinction seems to us essential because etiology, radiographic appearance, treatment and prognosis of such lesions are sometimes totally different.