**1. Introduction**

Necrosis of bone tissue is a nonspecific term that is related to conditions that cause major cell stress and cell death regularly due to interruption of the vascular supply. Frequently osteonecrosis (ON) is related to local traumatic events such as fractures that induce vascular injury; however, several non-traumatic causes have also been related. The first publications of ON were referred to avascular necrosis (AVN) of the femoral head and related in most cases to trauma. Later, other etiological factors were involved in the development of ON such as alcohol consumption, fat embolism, and steroid therapy. Likewise, coagulopathies, chronic osteoarthropathies, bone infections, and tumors are also causal factors associated with it.

AVN, aseptic necrosis, ischemic necrosis, subchondral AVN, and osteochondritis dissecans are synonyms used to denote ON. Vertebral AVN has been classically related to the intravertebral

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vacuum cleft (IVC) sign. This is represented by a transversal cleft of the vertebral body occupied by gas density observed in extension and not observed in flexion. Subsequently, with the advent of magnetic resonance imaging (MRI), the presence of fluid was demonstrated in association with osteoporotic vertebral collapse. In addition, ischemia was confirmed by histological analysis.

AVN of bone is otherwise characterized by massive necrosis of bone and bone marrow. This has been generally related to systemic factors such as alcohol abuse, glucocorticoid therapy, dyslipidemia, Gaucher disease or human immunodeficiency virus (HIV) infection, among others. AVN of the spine is known as Kümmel's disease (KD), usually related to osteoporotic vertebral fractures. Although the AVN associated with vertebral collapse hypothetically is a consequence of vascular damage, the pathogenesis, as well as the early diagnosis, the management protocols and prevention measures continue to be the research topics.
