**2. Historical background**

AVN frequently associated with vertebral compression fractures (CF) in osteoporosis is called KD, first described by Herman Kümmell, a German surgeon in 1895. Also at that time, A.A. Verneuil, French, referred to some clinical cases with similar manifestations, so that occasionally this syndrome was named "Kümmell-Verneuil disease." The cases described by Kümmel had a history of minor spinal trauma, with asymptomatic periods from months to years and angular kyphotic spinal deformities of the lower thoracic or upper lumbar regions and the T12 segment with progressive painful [1, 2]. Kümmell hypothesized that there was no traumatic CF in all the patients; however, it seemed very likely that most of them had a history of minimal trauma with influence on local nutrition and progressive atrophy [3]. It should be mentioned that these observations described by Kümmell were performed before the advent of X-rays, and once these were used, the existence of the disease was questioned in "normal" radiographic studies with uncertain quality. Years later, the collapse of the delayed vertebral body was demonstrated; however, diagnostic criteria in the early stages of the disease were associated with negative radiographic findings [2, 4, 5].

Steel also classified the KD in five progressive stages [2]. Initially, it is characterized by hyperflexion of the radiographically normal vertebral column, namely, the *initial insult*. Subsequently, a second *post-traumatic stage* is categorized by minimal manifestations of the low back without functional limitation. This is followed by a *latent stage*, relative well-being, lasting weeks to months, with no significant symptoms. Then, the *stage of recrudescence*, the patient manifests pain in the back, develops gibbous and loss of progressive stature, in addition to peripheral pain. In the *terminal stage*, the patient develops a progressive back pain located in the region of the pathological fracture with angular kyphosis and compression of the spinal [2]. The cases of AVN without a history of spinal trauma should not be termed KD. **Table 1** summarizes the clinical cases of KD reported in the literature.

A frequently representative feature of vertebral ON has been named IVC sign. This was first described as a horizontal cleft with gas density in radiographic studies [6]. This entity has


vacuum cleft (IVC) sign. This is represented by a transversal cleft of the vertebral body occu

histological analysis.

20 Osteonecrosis

**2. Historical background**

T12 segment with progressive painful [

associated with negative radiographic findings [

the spinal [

Steel also classified the KD in five progressive stages [

**Table 1** summarizes the clinical cases of KD reported in the literature.

described as a horizontal cleft with gas density in radiographic studies [

pied 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

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 man

AVN frequently associated with vertebral compression fractures (CF) in osteoporosis is called KD, first described by Herman Kümmell, a German surgeon in 1895. Also at that time, A.A. Verneuil, French, referred to some clinical cases with similar manifestations, so that occasion

ally this syndrome was named "Kümmell-Verneuil disease." The cases described by Kümmel had a history of minor spinal trauma, with asymptomatic periods from months to years and angular kyphotic spinal deformities of the lower thoracic or upper lumbar regions and the

matic CF in all the patients; however, it seemed very likely that most of them had a history

mentioned that these observations described by Kümmell were performed before the advent of X-rays, and once these were used, the existence of the disease was questioned in "normal" radiographic studies with uncertain quality. Years later, the collapse of the delayed vertebral body was demonstrated; however, diagnostic criteria in the early stages of the disease were

hyperflexion of the radiographically normal vertebral column, namely, the *initial insult*. Subsequently, a second *post-traumatic stage* is categorized by minimal manifestations of the low back without functional limitation. This is followed by a *latent stage*, relative well-being, lasting weeks to months, with no significant symptoms. Then, the *stage of recrudescence*, the patient manifests pain in the back, develops gibbous and loss of progressive stature, in addi

tion to peripheral pain. In the *terminal stage*, the patient develops a progressive back pain located in the region of the pathological fracture with angular kyphosis and compression of

A frequently representative feature of vertebral ON has been named IVC sign. This was first

2]. The cases of AVN without a history of spinal trauma should not be termed KD.

2, 4, 5].

2]. Kümmell hypothesized that there was no trau

2]. Initially, it is characterized by

1,

of minimal trauma with influence on local nutrition and progressive atrophy [

agement protocols and prevention measures continue to be the research topics.






6]. This entity has

3]. It should be

also been called post-traumatic vertebral ON [3, 5, 7], IVC [8, 9], vertebral pseudarthrosis [10], delayed post-traumatic vertebral body collapse [11, 12] and nonunion of VCF [10, 13].
