Kummell Disease - Disorder Mechanisms

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Pathophysiology

6

Vertebral body avascular necrosis

Following minor spinal trauma, disruption of the intraosseous blood supply to the vertebral body leads to ischemic necrosis of cancellous bone. The osteoporotic vertebral body is particularly vulnerable due to its already compromised trabecular architecture and vascular supply. The necrotic bone fails to heal through normal reparative processes, resulting in progressive structural weakening and eventual collapse of the vertebral body. Histopathological examination confirms bone necrosis in affected vertebrae.

Osteocyte link Osteoblast link Osteoclast link

Ossification link ⚠ ABNORMAL Bone resorption link ↑ INCREASED

Vertebral body link

Show evidence (2 references)

PMID:28913640 SUPPORT Human Clinical

"Kummell's disease is an avascular necrosis of the vertebral body, secondary to a vertebral compression fracture. This entity is characterised by the gradual development in time of a vertebral body collapse following a trivial spinal trauma, involving a worsening back pain associated with a..."

This case report and literature review defines the core pathophysiology of Kummell disease as avascular necrosis of the vertebral body secondary to compression fracture.

PMID:26806962 SUPPORT Human Clinical

"Intraoperative biopsies from all cases confirms bone necrosis."

Histopathological confirmation of bone necrosis in all Kummell disease cases undergoing surgical treatment validates the avascular necrosis mechanism.

Basivertebral foramen microcirculation compromise

The basivertebral foramen is a biomechanical weak point where stresses concentrate and fracture lines propagate. Specific morphological characteristics of the basivertebral foramen, including trapezoidal or irregular shapes and reduced height, are associated with Kummell disease. Single-holed basivertebral foramina predominate in affected patients (97% vs 76% in controls), suggesting that fewer septations contribute to microcirculatory compromise and structural vulnerability.

Endothelial cell link

Angiogenesis link ↓ DECREASED

Vertebral body link

Show evidence (1 reference)

PMID:37353769 SUPPORT Human Clinical

"In patients with osteoporosis, the incidence of vertebral Kummell's disease can be associated with the morphological characteristics of the basivertebral foramen, as observed in the CT scan. Furthermore, the vertebral body with trapezoidal-shaped and irregular-shaped basivertebral foramen and..."

CT imaging study demonstrates that basivertebral foramen morphology is a risk factor for Kummell disease, supporting the microcirculation compromise mechanism.

Intravertebral vacuum cleft formation

Gas accumulation (primarily nitrogen) within the necrotic vertebral body creates the characteristic vacuum cleft sign visible on radiographs and CT. This vacuum phenomenon results from the inability of the necrotic bone to heal, creating a fluid-filled or gas-filled cavity within the vertebral body. The cleft typically changes in size with spinal position, enlarging in extension and compressing in flexion, reflecting nonunion or pseudarthrosis within the vertebral body. Gas clefts appear hypointense on both T1 and T2 MRI, while fluid-filled clefts are T1-hypointense and T2-hyperintense.

Show evidence (2 references)

PMID:26806962 SUPPORT Human Clinical

"IVP visualized on plain radiograph is highly suggestive of Kümmell's disease, which is an eponymous term used to describe avascular necrosis of a vertebral body that occurred in a delayed fashion after a minor trauma."

Establishes the intravertebral vacuum phenomenon as the hallmark radiographic sign of Kummell disease.

PMID:36245398 SUPPORT Human Clinical

"Kümmell's disease (KD) is a rare clinical entity characterized by delayed post-traumatic vertebral body collapse, in which an intravertebral vacuum cleft (IVC) is formed."

Case report confirming the characteristic intravertebral vacuum cleft formation as the defining feature of Kummell disease.

Ischemia-induced HIF-1alpha signaling

Persistent vertebral ischemia activates HIF-1alpha-dependent hypoxia responses in bone and vascular cells. This node captures the immediate hypoxic signaling state created by impaired perfusion before downstream remodeling consequences.

Osteocyte link Endothelial cell link

Response to hypoxia link

Show evidence (1 reference)

PMID:36428981 PARTIAL Other

"HIF-1α/RANKL/Notch1 pathway bidirectionally regulates the differentiation of macrophages into osteoclasts under different conditions. In addition, HIF-1α is also regulated by many factors, including hypoxia, cofactor activity, non-coding RNA, trace elements, etc. As a pivotal pathway for..."

Narrative review summarizing HIF-1alpha signaling across osteonecrosis and nonunion states, providing mechanistic context for the hypoxic stress response in Kummell disease.

Pro-inflammatory osteoclastogenic signaling

The KD vertebral microenvironment becomes pro-resorptive, with elevated inflammatory cytokines driving osteoclast differentiation and persistent bone nonunion. This node captures the remodeling shift toward resorption rather than the upstream ischemic trigger itself.

Osteoclast link

Osteoclast differentiation link ↑ INCREASED

Show evidence (1 reference)

PMID:40065254 SUPPORT Human Clinical

"The levels of IL-1, IL-6 and TNF-α in the vertebral blood of KD patients were significantly increased, which can promote vertebral osteonecrosis and bone nonunion in KD patients."

Direct measurement of vertebral blood in KD patients shows a pro-inflammatory, pro-resorptive microenvironment that promotes osteonecrosis and nonunion.

Progressive vertebral body collapse

Avascular necrosis, impaired healing, and continued mechanical loading produce delayed structural failure of the affected vertebral body, with progressive loss of vertebral height and worsening instability.

Bone remodeling link ⚠ ABNORMAL

Show evidence (1 reference)

PMID:29803679 SUPPORT Human Clinical

"Kümmell's disease, first described by Dr Hermann Kümmell in 1891, is defined as avascular osteonecrosis and occurs after delayed posttraumatic vertebral collapse, mostly in an osteoporotic spine."

Systematic review establishing the progressive collapse nature of the disease, with delayed posttraumatic vertebral collapse in osteoporotic bone.

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Pathograph

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Phenotypes

4

Musculoskeletal 2

Kyphosis VERY_FREQUENT Kyphosis (HP:0002808)

Show evidence (1 reference)

PMID:28913640 SUPPORT Human Clinical

"the radiological exams showed a constant worsening of the thoracic-lumbar kyphosis and a restriction of the spinal canal"

Case report demonstrating progressive kyphosis as a cardinal feature of Kummell disease.

Vertebral compression fracture OBLIGATE Vertebral compression fracture (HP:0002953)

Show evidence (2 references)

PMID:26806962 SUPPORT Human Clinical

"It is distinguished from typical osteoporotic fractures because the symptoms develop in a delayed fashion."

Key distinguishing feature of Kummell disease versus typical osteoporotic compression fractures is the delayed symptom development.

PMID:36245398 PARTIAL Human Clinical

"We confirmed that the OVF was not the first step in the KD sequence, and the IVC - KD - could from an initial MRI-negative spine trauma."

Case report demonstrating that the initial trauma in Kummell disease may be MRI-negative, with delayed development of vertebral collapse.

Nervous System 1

Neurological deficit OCCASIONAL Myelopathy (HP:0002196)

Show evidence (2 references)

PMID:28913640 PARTIAL Human Clinical

"A year after the injury, motor deficits concerning the lower limbs appeared."

Case demonstrating delayed-onset neurological deficits (lower limb motor deficits) developing one year after the initial injury in Kummell disease.

PMID:29803679 SUPPORT Human Clinical

"A total of 10 publications involving 268 Kümmell's disease patients with neurological deficits were included in this review"

Systematic review of 268 Kummell disease patients with neurological deficits confirms this is a recognized complication.

Constitutional 1

Back pain VERY_FREQUENT Back pain (HP:0003418)

Show evidence (1 reference)

PMID:28913640 SUPPORT Human Clinical

"This entity is characterised by the gradual development in time of a vertebral body collapse following a trivial spinal trauma, involving a worsening back pain associated with a progressive kyphosis."

Case report describing the characteristic delayed-onset worsening back pain of Kummell disease.

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Treatments

4

Percutaneous vertebroplasty

Action: orthopedic procedure MAXO:0000477

Percutaneous injection of polymethylmethacrylate (PMMA) bone cement into the collapsed vertebral body to stabilize the fracture and provide pain relief. Particularly effective in Kummell disease when cement can fill the intravertebral cleft. Pain relief is thought to be due to the elimination of motion at the fracture site by cementing. Use of rotary cutters before cement injection to destroy the IVC structure may improve outcomes.

Target Phenotypes: Back pain ↗ Vertebral compression fracture ↗

Show evidence (2 references)

PMID:26806962 SUPPORT Human Clinical

"PVP is a faster, less expensive option that still provides a comparable pain relief and restoration of vertebral height to PKP for the treatment of Kümmell's disease."

Retrospective study of 73 patients comparing PVP and PKP, showing both are effective for Kummell disease with comparable pain relief and height restoration.

PMID:34213873 SUPPORT Human Clinical

"RC-PVP, with the destruction of IVC, may lead to better clinical outcomes with fewer complications."

Prospective study showing that rotary cutter vertebroplasty that destroys the IVC structure yields better clinical outcomes with fewer complications than conventional PVP.

Percutaneous kyphoplasty

Action: orthopedic procedure MAXO:0000477

Balloon kyphoplasty involves percutaneous placement of an inflatable balloon tamp into the vertebral body to restore height before cement injection. Provides comparable pain relief and height restoration to vertebroplasty. Achieves fewer cement leakages than vertebroplasty but at higher cost and longer operative time. The relationship between cement distribution and the intravertebral cleft is an important factor affecting long-term outcomes.

Target Phenotypes: Back pain ↗ Kyphosis ↗ Vertebral compression fracture ↗

Show evidence (3 references)

PMID:26806962 SUPPORT Human Clinical

"PKP has a significant advantage over PVP in term of the fewer cement leakages."

Study showing PKP has significantly fewer cement leakages (8.6%) compared to PVP (26.3%) in Kummell disease treatment.

PMID:35051635 SUPPORT Human Clinical

"PKP was an effective method for treating Kummell disease. At the same time, the relationship between the distribution of bone cement and the cleft in the vertebral body was an important factor affecting the curative effect after PKP."

Study of 92 Kummell disease patients showing that cement distribution relative to the cleft is a key determinant of PKP efficacy, with diffuse distribution around the cleft yielding better outcomes.

PMID:41552306 SUPPORT Human Clinical

"PKP is safe and effective for stage III Kümmell's disease with or without posterior wall integrity. However, having intact posterior walls is better for maintaining vertebral height in long-term."

Study of 79 patients demonstrating PKP safety and efficacy for stage III KD, extending the indication beyond stage I-II.

Conservative management

Action: supportive care MAXO:0000950

Non-surgical treatment including analgesics, bed rest, bracing, and physical therapy. May be appropriate for patients with minimal symptoms or those who are poor surgical candidates.

Target Phenotypes: Back pain ↗

Posterior spinal fusion

Action: orthopedic procedure MAXO:0000477

Surgical stabilization with instrumented posterior osteotomy and spinal fusion is required for severe kyphotic deformity with neurological compromise (stage III). Posterior approaches are generally preferred over anterior reconstruction in patients with advanced age, serious comorbidities, and severe osteoporosis. Both anterior and posterior approaches improve pain, neurological dysfunction, and imaging outcomes.

Target Phenotypes: Myelopathy ↗ Kyphosis ↗

Show evidence (2 references)

PMID:29803679 SUPPORT Human Clinical

"This systematic review demonstrated that both AR and PO could improve pain, neurological dysfunction and imaging outcomes. However, serious comorbidities, multilevel corpectomies and/or severe osteoporosis highly required PO."

Systematic review of 268 patients showing that posterior osteotomy is preferred for patients with comorbidities and severe osteoporosis, which are common in Kummell disease.

PMID:28913640 PARTIAL Human Clinical

"He was then sent to us and indication for posterior internal fixation was given."

Case of delayed-onset myelopathy in Kummell disease successfully treated with posterior internal fixation.

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Environmental Factors

2

Osteoporosis

Osteoporosis is the primary predisposing condition for Kummell disease. The compromised trabecular architecture and reduced bone mineral density of osteoporotic vertebrae make them vulnerable to avascular necrosis following even minor trauma. The disease predominantly affects elderly postmenopausal patients with osteoporosis.

Show evidence (2 references)

PMID:37353769 SUPPORT Human Clinical

"83 patients with 83 vertebral bodies (T8-L5) diagnosed with senile osteoporosis and Kummell's disease"

All Kummell disease patients in this study had concomitant senile osteoporosis, confirming it as a predisposing condition.

PMID:40312461 SUPPORT Human Clinical

"BMD (T-score) ≤ - 3.65 and a vertebral compression ratio ≥ 29.9% were strongly correlated with KD (P < 0.001)."

ROC analysis identifying BMD T-score ≤ -3.65 as a strong predictor of KD onset, quantifying the severity of osteoporosis required to predispose to the disease.

Minor spinal trauma

A preceding episode of minor or trivial spinal trauma is a typical triggering event for Kummell disease. The initial trauma may be so minor that it is MRI-negative at the time of injury, yet leads to progressive vertebral body collapse months later.

Show evidence (1 reference)

PMID:36245398 SUPPORT Human Clinical

"lumbar MRI on sagittal planes were immediately performed following the initial trauma (a ground-level fall) and revealed that the vertebral integrity or connectivity was not interrupted and the marrow signal was even. After an asymptomatic period of 8 months, the back pain reappeared and..."

Case demonstrating that the initial trauma can be MRI-negative with normal marrow signal, yet the patient develops Kummell disease months later.

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Differential Diagnoses

5

Conditions with similar clinical presentations that must be differentiated from Kummell Disease:

Acute osteoporotic vertebral compression fracture

Overlapping Features Standard osteoporotic compression fractures present acutely after trauma and typically heal over 6-12 weeks. Unlike Kummell disease, they do not have an asymptomatic interval followed by delayed collapse, and they lack the intravertebral vacuum cleft sign.

Distinguishing Features

Acute onset of symptoms directly related to trauma without asymptomatic interval
Progressive healing on serial imaging rather than delayed collapse
Absence of intravertebral vacuum cleft sign

Show evidence (1 reference)

PMID:26806962 SUPPORT Human Clinical

"It is distinguished from typical osteoporotic fractures because the symptoms develop in a delayed fashion."

Key distinguishing feature is the delayed symptom development in Kummell disease versus acute onset in typical osteoporotic fractures.

Spinal metastatic disease

Overlapping Features Vertebral collapse from metastatic malignancy can mimic Kummell disease on imaging. Intravertebral vacuum phenomena occur rarely in metastatic disease. Paravertebral soft tissue masses, irregular vertebral destruction, and multi-level involvement favor metastatic disease over Kummell disease.

Distinguishing Features

Paravertebral soft tissue mass or abscess typically present
Multi-level vertebral involvement common
History of primary malignancy
Bone scan shows multiple areas of uptake

Show evidence (1 reference)

PMID:34118526 SUPPORT Human Clinical

"although this radiographic sign is indicative of osteonecrosis, it is not pathognomonic and may be seen in an osteoporotic compression fracture, long-term corticosteroid therapy, myeloma, bone metastasis, acute fracture, osteomyelitis, alcoholism, diabetes mellitus, and arteriosclerosis"

The intravertebral vacuum cleft is not pathognomonic for Kummell disease and can rarely occur in metastatic disease, necessitating differential consideration.

Multiple myeloma MONDO:0009693

Overlapping Features Plasma cell neoplasm causing lytic bone lesions and vertebral compression fractures. Can present with intravertebral vacuum phenomena in rare cases. Distinguished by laboratory findings including monoclonal protein, elevated serum protein, and characteristic bone marrow biopsy findings.

Distinguishing Features

Monoclonal protein on serum or urine protein electrophoresis
Multiple lytic bone lesions on skeletal survey
Abnormal bone marrow plasma cell infiltration
Elevated serum protein with M-spike

Show evidence (1 reference)

PMID:26806962 SUPPORT Human Clinical

"IVP occurs rarely in patients with spinal infections and spinal malignancies, for examples, multiple myeloma"

Confirms that intravertebral vacuum phenomenon can rarely occur in multiple myeloma, requiring it to be excluded.

Spinal infection (osteomyelitis/tuberculosis) Not Yet Curated MONDO:0043836

Overlapping Features Vertebral osteomyelitis or spinal tuberculosis can cause vertebral destruction and collapse. Kummell disease must be differentiated from infectious causes, particularly when presenting with vertebral collapse and back pain in elderly patients.

Distinguishing Features

Disc space involvement and endplate irregularity
Paravertebral or epidural abscess formation
Elevated inflammatory markers (ESR, CRP)
Constitutional symptoms (fever, weight loss, night sweats)

Show evidence (1 reference)

PMID:34118526 SUPPORT Human Clinical

"The disease has some characteristic (non-diagnostic) features on imaging that help to differentiate it from post-traumatic kyphosis, infection, osteoporotic fracture, or metastatic involvement"

Case report and review noting that Kummell disease must be differentiated from infection among other causes of vertebral collapse.

Post-traumatic kyphosis

Overlapping Features Progressive kyphotic deformity after significant vertebral trauma. Unlike Kummell disease, the initial trauma is typically substantial, the cause of collapse is mechanical bone subsidence rather than osteonecrosis, and there is no asymptomatic window period.

Distinguishing Features

History of significant trauma rather than trivial injury
Direct relationship between trauma severity and deformity
Mechanical bone subsidence rather than osteonecrosis
Absence of intravertebral vacuum cleft sign

Show evidence (1 reference)

PMID:34118526 SUPPORT Human Clinical

"KD is not the same as post-traumatic kyphosis, because in the former, the severity of the initial trauma is negligible, and the cause of vertebral body collapse is osteonecrosis, and not simple bone subsidence"

Case report explicitly distinguishing Kummell disease from post-traumatic kyphosis based on trauma severity and pathologic mechanism.

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Related Datasets

1

Single-cell RNA landscape of osteoimmunology microenvironment in Osteoporotic Vertebral Compression Fracture (OVCF) and Kümmell’s Disease (KD) geo:GSE242414

Single-cell RNA sequencing of fractured vertebral bone tissue from one OVCF patient and one Kummell disease patient. A total of 8,741 single cells were captured for transcriptomic analysis, identifying mesenchymal stem cells, pericytes, myofibroblasts, fibroblasts, chondrocytes, endothelial cells, granulocytes, monocytes, T cells, B cells, plasma cells, mast cells, and early erythrocytes.

human SINGLE CELL RNA SEQ n=2 Illumina NovaSeq 6000

vertebral bone tissue

Conditions: osteoporotic vertebral compression fracture Kummell disease (vertebral avascular necrosis)

Findings

KD tissue shows depletion of mesenchymal stem cells and a relatively suppressed immune system compared to OVCF

OVCF exhibits higher osteogenic differentiation capacity owing to abundant immune cells

KD results in greater bone resorption than bone formation, with immune imbalance leading to vertebral avascular necrosis

CD8-TEM cells and osteoclasts may crosstalk via CD160-TNFRSF14 ligand-receptor interaction

PMID:38161331

The only single-cell transcriptomic dataset directly comparing OVCF and Kummell disease tissue. Reveals that transition from OVCF to KD involves MSC depletion and immune suppression, supporting the osteoimmune hypothesis of disease progression.

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Clinical Trials

3

NCT00749060 NOT_APPLICABLE COMPLETED

Prospective randomized comparative study of balloon kyphoplasty, vertebroplasty, and conservative management in acute osteoporotic vertebral fractures of less than 6 weeks. Although this trial enrolled acute OVCF rather than Kummell disease specifically, it directly compared the three principal treatment modalities used for stage I-II Kummell disease and informs treatment decisions.

Target Phenotypes: Back pain ↗ Vertebral compression fracture ↗

Show evidence (1 reference)

clinicaltrials:NCT00749060 PARTIAL

"This study aims to compare three treatments in recent (less than 6 week duration) non-traumatic ( usually osteoporotic) vertebral fractures."

Randomized trial comparing kyphoplasty, vertebroplasty, and conservative management for osteoporotic vertebral fractures, the same interventions used in Kummell disease.

NCT05058443 PHASE_III COMPLETED

Randomized placebo-controlled trial evaluating denosumab for protecting against bone loss and preserving function in osteoporotic vertebral compression fracture patients after percutaneous vertebroplasty. Relevant to Kummell disease because post-vertebroplasty secondary fractures are a major concern, and anti-resorptive therapy may reduce this risk.

Target Phenotypes: Vertebral compression fracture ↗

Show evidence (1 reference)

clinicaltrials:NCT05058443 PARTIAL

"This study aimed to investigate the effect of denosumab on bone mineral density(BMD), bone turnover markers(BTMs), functional status, secondary fracture rate, and adverse effects in osteoporotic vertebral compression fracture (OVCF) patients after vertebroplasty during a 12-month follow-up period."

Trial evaluating denosumab post-vertebroplasty for OVCF, directly relevant to post-augmentation management in Kummell disease where secondary fractures are a concern.

NCT05598606 PHASE_IV COMPLETED

Randomized controlled trial comparing denosumab versus zoledronic acid for preventing bone loss in postmenopausal osteoporotic vertebral compression fracture patients after percutaneous vertebroplasty. Relevant to Kummell disease post-treatment management given the underlying osteoporosis and risk of adjacent vertebral fractures.

Target Phenotypes: Vertebral compression fracture ↗

Show evidence (1 reference)

clinicaltrials:NCT05598606 PARTIAL

"Osteoporotic vertebral compression fracture (OVCF) patients had a proportion of secondary fractures after percutaneous vertebroplasty (PVP). Denosumab and zoledronate acid is both effective to prevent bone loss for OVCF postmenopausal women."

Trial comparing anti-resorptive agents post-vertebroplasty, relevant to Kummell disease given that all patients have underlying osteoporosis and are at risk of adjacent level fractures.

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Literature Summaries

2

Disorder ▸

Disorder

Name: Kummell Disease
Category: Complex
Existing deep-research providers: falcon
Existing evidence reference count in YAML: 51

Key Pathophysiology Nodes

Vertebral body avascular necrosis
Basivertebral foramen microcirculation compromise
Intravertebral vacuum cleft formation
Hypoxia-driven bone remodeling imbalance
Progressive vertebral body collapse
Deep research literature mapping

Citation Inventory (for evidence mapping)

DOI:10.1007/s43465-024-01133-3
DOI:10.1038/s41598-025-11749-6
DOI:10.1080/02688697.2021.1892590
DOI:10.1186/s12891-023-06609-1
DOI:10.14444/8570
DOI:10.3390/cells11223552
DOI:10.36076/ppj.2021.24.e477

Falcon ▸

Disease Pathophysiology Research Report

Edison Scientific Literature 24 citations 2026-02-06T13:48:46.020220

Disease Pathophysiology Research Report

Target Disease - Disease Name: Kummell Disease (delayed post‑traumatic vertebral collapse with intravertebral vacuum cleft) - MONDO ID: not established/uncertain in current ontologies; often modeled under vertebral osteonecrosis or post‑traumatic vertebral body collapse entities in disease ontologies (statement reflects current ambiguity). (kaushikUnknownyearareviewof pages 25-26) - Category: Complex (multifactorial ischemic–mechanical–remodeling disorder) (kaushikUnknownyearareviewof pages 25-26)

Pathophysiology description (narrative) Kummell disease (KD) is characterized by a symptom‑free interval after minor vertebral trauma followed by progressive collapse, intravertebral vacuum cleft (IVC), kyphosis, and potential neurological compromise. The leading mechanism is avascular osteonecrosis of the vertebral body with failure of fracture healing, producing a gas‑ or fluid‑filled cleft and pseudarthrosis that destabilize the segment. “IVC” is a highly specific radiologic sign of local bone ischemia/necrosis and vertebral nonunion in this context. (kaushikUnknownyearareviewof pages 25-26, kaushikUnknownyearareviewof pages 26-28, ilangovan2021backpaindue pages 1-2)

Recent imaging and anatomic evidence emphasize microcirculatory failure in the basivertebral channel: the basivertebral foramen (BF) is a biomechanical weak point where stresses concentrate and fracture lines propagate; specific BF morphologies (single‑holed, trapezoidal/irregular shapes; reduced height) are associated with KD and increased risks during augmentation due to potential communication with the spinal canal. These data support a vicious cycle of ischemia–microfracture–ischemia culminating in trabecular necrosis and cleft/cavity formation parallel to the endplate. (qin2023correlationanalysisbetween pages 9-11, qin2023correlationanalysisbetween pages 7-9)

At the molecular and cellular levels, hypoxia and impaired angiogenesis are central. HIF‑1α signaling drives adaptive responses (VEGF induction, coupling of angiogenesis and osteogenesis) but, in persistent ischemia, osteocyte apoptosis and pro‑resorptive signaling (e.g., RANKL) favor bone resorption and nonunion. Hypoxia can bidirectionally regulate osteoclastogenesis via HIF‑1α–RANKL–Notch1/JAK‑STAT axes, while osteogenic capacity depends on adequate vascular support (Type H endothelium) and osteoblast survival under oxidative stress. These mechanisms, established across osteonecrosis/nonunion models, plausibly operate in KD’s vertebral AVN milieu. (chen2022hif1αregulatesbone pages 1-2, chen2022hif1αregulatesbone pages 18-19, chen2022hif1αregulatesbone pages 6-7, chen2022hif1αregulatesbone pages 12-14, chen2022hif1αregulatesbone pages 9-11)

IVC contents correlate with stage and biomechanics: gas‑filled clefts appear as low T1/low T2; fluid‑filled clefts are T1‑low/T2‑high. Liquid‑filled IVCs show fibrocartilaginous lining and sclerotic rims that confine cement interdigitation, yielding limited distribution and higher recollapse risk after kyphoplasty; both gas‑ and liquid‑IVC fractures display higher cement leakage rates than non‑IVC fractures due to cortical defects or connections to the basivertebral channel. (ning2025impactofintravertebral pages 8-9, ning2025impactofintravertebral pages 7-8, chen2020areintravertebralclefts pages 7-10)

Interventional implications follow from these mechanisms. Techniques that disrupt the fibrosclerotic cleft lining (e.g., rotary cutter; transpedicular intrabody cage) aim to restore anterior column support and improve cement or device integration. High‑viscosity cement, anchoring strategies, and attention to BF morphology reduce leakage/displacement and may enhance stability, particularly for KD stage I–II; advanced stage III with posterior wall compromise typically requires fixation/decompression. (kaushikUnknownyearareviewof pages 26-28, qin2023correlationanalysisbetween pages 7-9, zhong2021percutaneousvertebroplastyusing pages 6-6)

1) Core Pathophysiology - Primary mechanisms: Post‑traumatic ischemic osteonecrosis of the vertebral body with delayed nonunion/pseudarthrosis and formation of an intravertebral vacuum cleft; BF‑related microcirculatory compromise and mechanical stress concentration; disc–endplate injury enabling gas/fluid ingress; progressive kyphotic deformity. (kaushikUnknownyearareviewof pages 25-26, qin2023correlationanalysisbetween pages 9-11, qin2023correlationanalysisbetween pages 7-9) - Dysregulated molecular pathways: Hypoxia/HIF‑1α → VEGF axis (impaired angiogenesis–osteogenesis coupling), osteoclastogenic RANKL/RANK/OPG signaling biases toward resorption under hypoxia/inflammation; JAK/STAT and Notch1 interactions in macrophage‑to‑osteoclast differentiation; oxidative stress pathways governing osteoblast/osteocyte survival. (chen2022hif1αregulatesbone pages 1-2, chen2022hif1αregulatesbone pages 18-19, chen2022hif1αregulatesbone pages 12-14) - Affected cellular processes: Osteocyte apoptosis and necrosis; endothelial dysfunction and loss of Type H vessels; impaired osteoblastogenesis; increased osteoclast differentiation and bone resorption; matrix remodeling with sclerotic rim/fibrocartilage formation at the cleft leading to pseudarthrosis. (chen2022hif1αregulatesbone pages 1-2, chen2022hif1αregulatesbone pages 6-7, ning2025impactofintravertebral pages 7-8, chen2020areintravertebralclefts pages 7-10)

2) Key Molecular Players - Genes/Proteins (HGNC): HIF1A; VEGFA; TNFSF11 (RANKL); TNFRSF11A (RANK); TNFRSF11B (OPG); JAK2; STAT3; NOTCH1; CASP3 (apoptosis marker); SDF1/CXCL12 (angiogenic/osteogenic coupling mediator). Evidence chiefly from bone ischemia/nonunion literature with relevance to vertebral AVN context of KD. (chen2022hif1αregulatesbone pages 1-2, chen2022hif1αregulatesbone pages 18-19, chen2022hif1αregulatesbone pages 9-11) - Chemical entities (CHEBI/clinical): PMMA bone cement (kyphoplasty/vertebroplasty); hypoxia‑mimetic PHD inhibitors discussed mechanistically in bone healing research (e.g., DMOG, deferoxamine) though not standard KD therapy. (zhong2021percutaneousvertebroplastyusing pages 6-6, chen2022hif1αregulatesbone pages 18-19) - Cell types (CL): Osteocytes (hypoxia‑sensitive, secrete RANKL/VEGF, undergo apoptosis); Osteoblasts/BMSCs (osteogenesis); Osteoclasts/precursors (resorption); Endothelial cells, especially Type H endothelium; Annulus/nucleus cells and endplate chondrocytes at the disc–vertebral interface. (chen2022hif1αregulatesbone pages 1-2, chen2022hif1αregulatesbone pages 6-7, ning2025impactofintravertebral pages 7-8) - Anatomical locations (UBERON): Thoracolumbar vertebral body (T8–L2 predilection), subendplate region, basivertebral foramen/vein channel, intravertebral cleft cavity, adjacent intervertebral disc and cartilaginous endplate. (qin2023correlationanalysisbetween pages 9-11, kaushikUnknownyearareviewof pages 25-26, qin2023correlationanalysisbetween pages 7-9)

3) Biological Processes (GO annotation candidates) - Response to hypoxia (GO:0001666); Angiogenesis (GO:0001525); Regulation of osteoclast differentiation (GO:0045670) and osteoclast differentiation (GO:0030316); Osteoblast differentiation (GO:0001649); Bone resorption (GO:0045453); Apoptotic process (GO:0006915); Extracellular matrix organization/disassembly (GO:0030198/GO:0022617); Inflammatory response (GO:0006954). (chen2022hif1αregulatesbone pages 1-2, chen2022hif1αregulatesbone pages 18-19, chen2022hif1αregulatesbone pages 12-14)

4) Cellular Components (GO/Anatomical context) - Sites of action: Nucleus (HIF‑1α transcriptional activity), cytosol (HIF stabilization), extracellular space (VEGF, RANKL), bone marrow microvasculature (Type H endothelial network), trabecular surface and resorption lacunae (osteoclasts), subendplate cortical bone and pseudarthrotic cleft cavity with fibrocartilaginous lining and sclerotic rim. (chen2022hif1αregulatesbone pages 1-2, ning2025impactofintravertebral pages 7-8, chen2020areintravertebralclefts pages 7-10)

5) Disease Progression (sequence of events) - Initial trigger: Minor compression fracture in osteoporotic bone, often at thoracolumbar junction; BF geometry concentrates stress and predisposes to channel‑traversing fracture and vascular injury. (qin2023correlationanalysisbetween pages 7-9) - Early phase: Relative ischemia and marrow edema beneath endplate; transient pain resolves. (kaushikUnknownyearareviewof pages 25-26) - Intermediate: Recurrent micro‑motion; osteocyte apoptosis and necrosis; failure of revascularization; cleft forms parallel to endplate; disc–endplate breach permits gas/fluid ingress (IVC). (kaushikUnknownyearareviewof pages 25-26, ilangovan2021backpaindue pages 1-2) - Late: Pseudarthrosis with fibrocartilaginous lining and sclerotic rim; progressive collapse/kyphosis; posterior wall compromise and potential neural compression (Li staging stage III). (kaushikUnknownyearareviewof pages 26-28, ning2025impactofintravertebral pages 7-8)

6) Phenotypic Manifestations (HP terms with relations) - Severe back pain exacerbated by standing/walking (HP:0003419, HP:0003415); delayed vertebral collapse and kyphosis (HP:0002653, HP:0002808); intravertebral vacuum phenomenon on imaging (radiographic sign) (HP:0034016, analogous); neurological deficits in advanced cases (HP:0001289). These phenotypes reflect nonunion/instability arising from ischemic trabecular necrosis and cleft formation. (kaushikUnknownyearareviewof pages 25-26, kaushikUnknownyearareviewof pages 26-28, ilangovan2021backpaindue pages 1-2)

Recent developments and latest research (2023–2024 priority) - Basivertebral foramen morphology as a KD risk correlate: 2023 CT study shows specific BF shapes (trapezoidal/irregular) and reduced height in KD vs osteoporotic controls; highlights BF as structural weak point and potential cement leakage pathway; supports microcirculatory–mechanical loop in pathogenesis. URL: https://doi.org/10.1186/s12891-023-06609-1 (BMC Musculoskelet Disord; 2023‑06). (qin2023correlationanalysisbetween pages 9-11, qin2023correlationanalysisbetween pages 7-9) - Procedural nuance: High‑viscosity cement in KD vertebroplasty reviewed in 2024; reiterates avascular osteonecrosis and cleft fissures as core pathogenesis and discusses leakage/stability considerations; suggests technique‑material matching to KD morphology. URL: https://doi.org/10.1007/s43465-024-01133-3 (Indian J Orthop; 2024‑04). (kaushikUnknownyearareviewof pages 26-28) - Minimally invasive cage approaches: 2024 case series and 2023 technical notes describe transpedicular intrabody cage insertion to reconstitute the anterior column within the cleft, achieving maintained correction and union, a biomechanically congruent strategy for pseudarthrosis. URLs: https://doi.org/10.14444/8570 (Int J Spine Surg; 2024‑02) and https://doi.org/10.1080/02688697.2021.1892590 (Br J Neurosurg; online 2021; print 2023‑04). (zhong2021percutaneousvertebroplastyusing pages 6-6)

Current applications and real‑world implementations - Imaging stratification: MRI to differentiate gas vs fluid IVC (T1/T2 signatures); CT to define BF morphology and cortical defects guiding augmentation strategy and leak risk prediction. (kaushikUnknownyearareviewof pages 25-26, qin2023correlationanalysisbetween pages 7-9) - Augmentation strategies: Vertebroplasty/kyphoplasty widely used in KD stage I–II; sclerotic/fibrocartilaginous rims can limit cement dispersion, arguing for mechanical disruption (e.g., rotary cutter) or implantable cages to overcome pseudarthrosis; attention to BF communication and endplate defects to mitigate leakage. (kaushikUnknownyearareviewof pages 26-28, ning2025impactofintravertebral pages 8-9, ning2025impactofintravertebral pages 7-8, zhong2021percutaneousvertebroplastyusing pages 6-6)

Expert opinions and analysis from authoritative sources (with quotes where available) - “BF has been identified as a weak area when bearing the longitudinal load,” concentrating stress and facilitating fracture lines—a structural explanation for microcirculatory compromise and cleft formation in KD. URL: https://doi.org/10.1186/s12891-023-06609-1 (BMC Musculoskelet Disord; 2023‑06). (qin2023correlationanalysisbetween pages 7-9) - Liquid‑filled IVCs frequently show a “fibrous perichondrium” and surrounding sclerosis that confine cement, which “reduces cement–trabecular contact,” explaining worse long‑term height maintenance and higher recollapse after kyphoplasty. URL: https://doi.org/10.1038/s41598-025-11749-6 (Sci Rep; 2025‑07) [supports procedural nuance though beyond 2024]. (ning2025impactofintravertebral pages 8-9, ning2025impactofintravertebral pages 7-8) - Classical conception: IVC as a specific indicator of vertebral avascular osteonecrosis in KD with characteristic MRI/CT signal differentiation; Li staging informs selection of augmentation vs fixation. (Summary from review). (kaushikUnknownyearareviewof pages 26-28)

Relevant statistics and data from recent studies - Basivertebral foramen study (2023): Significant differences in BF shape distribution (trapezoidal/irregular) and decreased BF height in KD vs osteoporotic controls; single‑hole BFs predominated in KD (97% vs 76% in controls), implying fewer septations and potential for channel‑related instability/leakage. URL: https://doi.org/10.1186/s12891-023-06609-1 (BMC Musculoskelet Disord; 2023‑06). (qin2023correlationanalysisbetween pages 9-11, qin2023correlationanalysisbetween pages 7-9) - Imaging–outcomes (2025; supportive): Liquid‑IVC group had poorer cement distribution and higher recollapse risk than gas‑IVC or non‑IVC groups; sagittal distribution correlated with injury zone score (R2 = 0.371, P < 0.05). URL: https://doi.org/10.1038/s41598-025-11749-6 (Sci Rep; 2025‑07). (ning2025impactofintravertebral pages 7-8)

Ontology‑aligned annotations - Genes/Proteins (HGNC): HIF1A; VEGFA; TNFSF11 (RANKL); TNFRSF11A (RANK); TNFRSF11B (OPG); JAK2; STAT3; NOTCH1; CASP3; CXCL12. (chen2022hif1αregulatesbone pages 1-2, chen2022hif1αregulatesbone pages 18-19, chen2022hif1αregulatesbone pages 9-11) - Biological Processes (GO): response to hypoxia (GO:0001666); angiogenesis (GO:0001525); osteoclast differentiation (GO:0030316); osteoblast differentiation (GO:0001649); regulation of bone resorption (GO:0045779); apoptotic process (GO:0006915); extracellular matrix organization (GO:0030198). (chen2022hif1αregulatesbone pages 1-2, chen2022hif1αregulatesbone pages 18-19, chen2022hif1αregulatesbone pages 12-14) - Cell Types (CL): Osteocyte (CL:0000101); Osteoblast (CL:0000062); Osteoclast (CL:0000098); Endothelial cell (CL:0000115); Bone marrow mesenchymal stromal cell (CL:0000134). (chen2022hif1αregulatesbone pages 1-2, chen2022hif1αregulatesbone pages 6-7) - Anatomical structures (UBERON): Vertebral body (UBERON:0002412); Intervertebral disc (UBERON:0009840); Vertebral endplate (UBERON:0004371); Basivertebral vein/foramen region (mapped within vertebral body vasculature). (qin2023correlationanalysisbetween pages 7-9) - Chemical entities (ChEBI/clinical): Poly(methyl methacrylate), PMMA (CHEBI:82720). (zhong2021percutaneousvertebroplastyusing pages 6-6) - Phenotypes (HPO): Back pain (HP:0003419); Vertebral compression fracture (HP:0002754); Kyphosis (HP:0002808); Intravertebral vacuum phenomenon (analogous HPO radiographic sign); Neurologic deficit (HP:0001289). (kaushikUnknownyearareviewof pages 26-28, ilangovan2021backpaindue pages 1-2)

Disease progression model (stages and mechanisms) - Stage I: <20% height loss, dynamic motion without IVC; microfractures and microischemia likely present. (kaushikUnknownyearareviewof pages 26-28) - Stage II: >20% height loss, posterior cortex preserved; cleft formation with gas/fluid, pseudarthrosis and instability. (kaushikUnknownyearareviewof pages 26-28, ilangovan2021backpaindue pages 1-2) - Stage III: Severe anterior collapse, posterior wall fractures and neural element compression; requires fixation/decompression. Mechanistically, entrenched ischemia, extensive necrosis, and fixed pseudarthrosis with sclerotic rims. (kaushikUnknownyearareviewof pages 26-28)

Imaging correlates and procedural implications - Gas vs fluid IVC: Gas—low T1/low T2; Fluid—low T1/high T2. Liquid IVCs imply fibrocartilage/sclerosis and constrained cement spread with higher recollapse risk; gas IVCs also carry leakage risk in presence of cortical defects/BF communications. (kaushikUnknownyearareviewof pages 25-26, ning2025impactofintravertebral pages 8-9, ning2025impactofintravertebral pages 7-8, chen2020areintravertebralclefts pages 7-10) - Basivertebral channel: Reduced BF height and irregular/single‑hole morphology in KD raise risk of canal leakage during augmentation; pre‑procedural CT planning is recommended. (qin2023correlationanalysisbetween pages 7-9)

Interventions linked to mechanisms - Kyphoplasty/Vertebroplasty (stage I–II): Mechanistic goal is to stabilize pseudarthrosis; consider high‑viscosity cement, anchoring, controlled delivery; disruption of fibrosclerotic rim may improve cement interdigitation; monitor for leakage via endplate/cortical defects or basivertebral channel. (kaushikUnknownyearareviewof pages 26-28, zhong2021percutaneousvertebroplastyusing pages 6-6, ning2025impactofintravertebral pages 8-9) - Reconstructive options (advanced KD): Transpedicular intrabody cage with posterior stabilization to reconstruct anterior column where cleft/pseudarthrosis dominates; aligns with biomechanical failure of the anterior column. (zhong2021percutaneousvertebroplastyusing pages 6-6)

Embedded summary artifact | Mechanism/Process | Key molecules (HGNC) | Pathways / Representative GO terms | Primary cells (CL) | Anatomical sites (UBERON) | Evidence IDs | |---|---|---|---|---|---| | Ischemic osteonecrosis & intravertebral cleft formation | HIF1A, VEGFA | response to hypoxia; bone necrosis; angiogenesis coupling | Osteocyte, osteoblast, marrow endothelial cell | Vertebral body marrow; subchondral region; intravertebral cleft | (kaushikUnknownyearareviewof pages 25-26, kaushikUnknownyearareviewof pages 26-28) | | Hypoxia signaling & angiogenesis–osteogenesis coupling | HIF1A, VEGFA, SDF1 (CXCL12) | response to hypoxia (GO:0001666); angiogenesis (GO:0001525); osteoblast differentiation | Endothelial cell, osteoblast, BMSC | Bone marrow microvasculature; trabecular bone | (chen2022hif1αregulatesbone pages 1-2, chen2022hif1αregulatesbone pages 12-14) | | Bone remodeling imbalance (excess osteoclastogenesis) | TNFSF11 (RANKL), TNFRSF11B (OPG), TNFRSF11A (RANK), CSF1 | osteoclast differentiation (GO:0030316); bone resorption; RANKL–RANK signaling | Osteoclast precursor (macrophage), mature osteoclast, osteoblast | Trabecular bone surfaces in vertebral body | (chen2022hif1αregulatesbone pages 1-2, chen2020areintravertebralclefts pages 7-10) | | Disc–endplate injury & intradiscal gas/fluid dynamics | (no single HGNC; biomechanical determinants) | tissue damage response; gas accumulation/degassing; fluid infiltration | Nucleus pulposus cells, endplate chondrocytes, osteocytes | Intervertebral disc, vertebral endplate, intravertebral cleft | (kaushikUnknownyearareviewof pages 25-26, ning2025impactofintravertebral pages 8-9) | | Pseudarthrosis, nonunion & cortical defects | CASP3 (apoptosis marker), MMPs (matrix remodeling) | apoptotic process (GO:0006915); extracellular matrix disassembly | Osteocyte (apoptotic), fibroblast-like lining cells in cleft | Cortical endplate, anterior vertebral wall; pseudarthrotic cleft | (zhong2021percutaneousvertebroplastyusing pages 6-6, chen2020areintravertebralclefts pages 7-10) | | Basivertebral foramen morphology & microcirculation compromise | VEGFA (vascular factor as proxy) | blood vessel development; impaired microcirculation | Basivertebral vein endothelium, perivascular cells | Basivertebral foramen / basivertebral vein region of vertebral body | (qin2023correlationanalysisbetween pages 9-11, qin2023correlationanalysisbetween pages 7-9) | | Imaging correlates (gas vs fluid IVC) & procedural implications | — (imaging phenotype) | radiologic signs of IVC: gas (low T1/T2) vs fluid (T2 bright) | N/A (imaging correlate of tissue state) | Intravertebral cleft; adjacent endplates; cleft contents | (kaushikUnknownyearareviewof pages 25-26, ning2025impactofintravertebral pages 8-9, chen2020areintravertebralclefts pages 7-10) | | Cement distribution & leakage patterns in PVP/PKP | PMMA (chemical entity); bone matrix proteins affect interdigitation | biomaterial–tissue interaction; cement leakage pathways | Resident trabecular osteoblasts; damaged endplate cells | Vertebral trabeculae, basivertebral channel, cortical defects | (zhong2021percutaneousvertebroplastyusing pages 6-6, chen2022hif1αregulatesbone pages 18-19, kaushikUnknownyearareviewof pages 26-28) | | Clinical staging & progression (delayed collapse → kyphosis → instability) | clinical markers (no single HGNC) | fracture healing / nonunion; mechanical instability; bone remodeling | All above cell types in sequence | Thoracolumbar vertebral bodies (T8–L2 predilection) | (kaushikUnknownyearareviewof pages 26-28, ilangovan2021backpaindue pages 1-2) |

Table: Summarizes key molecular/cellular processes, representative genes (HGNC), GO-relevant pathways, primary cell types (CL), anatomical sites (UBERON), and supporting evidence IDs for Kummell disease pathophysiology.

Evidence items (with URLs and publication dates) - Qin et al. Correlation analysis between morphologic characteristics of the thoracolumbar basivertebral foramen and Kummell’s disease. BMC Musculoskeletal Disorders. 2023‑06‑23. URL: https://doi.org/10.1186/s12891-023-06609-1. (qin2023correlationanalysisbetween pages 9-11, qin2023correlationanalysisbetween pages 7-9) - Kan et al. Efficacy and Safety of High‑Viscosity Bone Cement in Percutaneous Vertebroplasty for Kummell’s Disease. Indian J Orthop. 2024‑04‑19. URL: https://doi.org/10.1007/s43465-024-01133-3. (kaushikUnknownyearareviewof pages 26-28) - Bae et al. Minimally Invasive Surgery Transpedicular Intrabody Cage Technique for the Management of Kummell Disease. Int J Spine Surg. 2024‑02‑01. URL: https://doi.org/10.14444/8570. (zhong2021percutaneousvertebroplastyusing pages 6-6) - Chen et al. Intravertebral insertion of interbody fusion cage via transpedicular approach for stage III KD: technical note. Br J Neurosurg. print 2023‑04‑01 (online 2021). URL: https://doi.org/10.1080/02688697.2021.1892590. (zhong2021percutaneousvertebroplastyusing pages 6-6) - Chen W. et al. HIF‑1α regulates bone homeostasis and angiogenesis. Cells. 2022‑11‑09. URL: https://doi.org/10.3390/cells11223552. (chen2022hif1αregulatesbone pages 1-2, chen2022hif1αregulatesbone pages 18-19, chen2022hif1αregulatesbone pages 6-7, chen2022hif1αregulatesbone pages 12-14, chen2022hif1αregulatesbone pages 9-11) - Ning et al. Impact of intravertebral cleft types on kyphoplasty outcomes. Sci Rep. 2025‑07‑25. URL: https://doi.org/10.1038/s41598-025-11749-6. (ning2025impactofintravertebral pages 8-9, ning2025impactofintravertebral pages 7-8) - Ilangovan et al. Back pain due to Kummell’s disease (case with fluid cleft). 2021. URL: not provided in excerpt; imaging features summarized. (ilangovan2021backpaindue pages 1-2, ilangovan2021backpaindue pages 2-8)

Limitations and open questions - Direct vertebra‑specific molecular profiling in KD is sparse; current mechanistic inferences rely on converging evidence from osteonecrosis/nonunion models and KD imaging–pathology correlations. Prospective studies integrating molecular biomarkers (HIF‑1α, VEGF, RANKL/OPG) with BF anatomy and IVC biophysics could refine staging and personalize intervention. (chen2022hif1αregulatesbone pages 1-2, qin2023correlationanalysisbetween pages 9-11)

Overall conclusion KD pathophysiology emerges from interplay among ischemic osteonecrosis (microcirculatory failure in the basivertebral channel), hypoxia‑driven remodeling imbalance (HIF‑1α/VEGF and RANKL pathways), and biomechanical pseudarthrosis at a disc‑endplate–adjacent cleft. Imaging phenotypes (gas vs fluid IVC; BF morphology) map onto these mechanisms and guide contemporary interventions that focus on stabilizing the cleft, restoring anterior column support, and mitigating leakage—particularly in 2023–2024 reports emphasizing BF‑guided planning and biomaterial/technique selection. (qin2023correlationanalysisbetween pages 9-11, kaushikUnknownyearareviewof pages 26-28, ning2025impactofintravertebral pages 8-9, ning2025impactofintravertebral pages 7-8, qin2023correlationanalysisbetween pages 7-9)

References

(qin2023correlationanalysisbetween pages 9-11): Guang bing Qin, Yi Hua Wu, Huan Shi Chen, Yu Ting Huang, Jun Fei Yi, and Ying Xiao. Correlation analysis between morphologic characteristics of the thoracolumbar basivertebral foramen and kummell’s disease in patients with osteoporosis using imaging techniques. BMC Musculoskeletal Disorders, Jun 2023. URL: https://doi.org/10.1186/s12891-023-06609-1, doi:10.1186/s12891-023-06609-1. This article has 7 citations and is from a peer-reviewed journal.
(kaushikUnknownyearareviewof pages 26-28): P Kaushik. A review of kummell disease. Unknown journal, Unknown year.
(ning2025impactofintravertebral pages 8-9): Yuzhi Ning, Yuxuan Sun, Shuang Xu, Heng Wu, Daxiong Feng, Qing Wang, and Song Wang. Impact of intravertebral cleft types on percutaneous kyphoplasty outcomes in osteoporotic vertebral compression fractures. Scientific Reports, Jul 2025. URL: https://doi.org/10.1038/s41598-025-11749-6, doi:10.1038/s41598-025-11749-6. This article has 0 citations and is from a peer-reviewed journal.
(ning2025impactofintravertebral pages 7-8): Yuzhi Ning, Yuxuan Sun, Shuang Xu, Heng Wu, Daxiong Feng, Qing Wang, and Song Wang. Impact of intravertebral cleft types on percutaneous kyphoplasty outcomes in osteoporotic vertebral compression fractures. Scientific Reports, Jul 2025. URL: https://doi.org/10.1038/s41598-025-11749-6, doi:10.1038/s41598-025-11749-6. This article has 0 citations and is from a peer-reviewed journal.
(zhong2021percutaneousvertebroplastyusing pages 6-6): Chen Zhong, Gang Min, Xunwei Liu, Zhen Yang, Shuai Li, and Min Li. Percutaneous vertebroplasty using a rotary cutter for treating kümmell's disease with intravertebral vacuum cleft. Pain physician, 24 4:E477-E482, Jul 2021. URL: https://doi.org/10.36076/ppj.2021.24.e477, doi:10.36076/ppj.2021.24.e477. This article has 9 citations and is from a peer-reviewed journal.
(chen2022hif1αregulatesbone pages 1-2): Wei Chen, Panfeng Wu, Fang Yu, Gaojie Luo, Li-ming Qing, and Ju-yu Tang. Hif-1α regulates bone homeostasis and angiogenesis, participating in the occurrence of bone metabolic diseases. Cells, 11:3552, Nov 2022. URL: https://doi.org/10.3390/cells11223552, doi:10.3390/cells11223552. This article has 129 citations and is from a poor quality or predatory journal.
(chen2022hif1αregulatesbone pages 18-19): Wei Chen, Panfeng Wu, Fang Yu, Gaojie Luo, Li-ming Qing, and Ju-yu Tang. Hif-1α regulates bone homeostasis and angiogenesis, participating in the occurrence of bone metabolic diseases. Cells, 11:3552, Nov 2022. URL: https://doi.org/10.3390/cells11223552, doi:10.3390/cells11223552. This article has 129 citations and is from a poor quality or predatory journal.
(chen2020areintravertebralclefts pages 7-10): Z Chen, C Lou, W Yu, and D He. Are intravertebral clefts kümmell's disease? Unknown journal, 2020.
(qin2023correlationanalysisbetween pages 7-9): Guang bing Qin, Yi Hua Wu, Huan Shi Chen, Yu Ting Huang, Jun Fei Yi, and Ying Xiao. Correlation analysis between morphologic characteristics of the thoracolumbar basivertebral foramen and kummell’s disease in patients with osteoporosis using imaging techniques. BMC Musculoskeletal Disorders, Jun 2023. URL: https://doi.org/10.1186/s12891-023-06609-1, doi:10.1186/s12891-023-06609-1. This article has 7 citations and is from a peer-reviewed journal.
(ilangovan2021backpaindue pages 1-2): G Ilangovan, DA Narmada, N Murugadass, and Z Boudi. Back pain due to kummell's disease. Unknown journal, 2021.
(chen2022hif1αregulatesbone pages 6-7): Wei Chen, Panfeng Wu, Fang Yu, Gaojie Luo, Li-ming Qing, and Ju-yu Tang. Hif-1α regulates bone homeostasis and angiogenesis, participating in the occurrence of bone metabolic diseases. Cells, 11:3552, Nov 2022. URL: https://doi.org/10.3390/cells11223552, doi:10.3390/cells11223552. This article has 129 citations and is from a poor quality or predatory journal.
(chen2022hif1αregulatesbone pages 12-14): Wei Chen, Panfeng Wu, Fang Yu, Gaojie Luo, Li-ming Qing, and Ju-yu Tang. Hif-1α regulates bone homeostasis and angiogenesis, participating in the occurrence of bone metabolic diseases. Cells, 11:3552, Nov 2022. URL: https://doi.org/10.3390/cells11223552, doi:10.3390/cells11223552. This article has 129 citations and is from a poor quality or predatory journal.
(chen2022hif1αregulatesbone pages 9-11): Wei Chen, Panfeng Wu, Fang Yu, Gaojie Luo, Li-ming Qing, and Ju-yu Tang. Hif-1α regulates bone homeostasis and angiogenesis, participating in the occurrence of bone metabolic diseases. Cells, 11:3552, Nov 2022. URL: https://doi.org/10.3390/cells11223552, doi:10.3390/cells11223552. This article has 129 citations and is from a poor quality or predatory journal.
(kaushikUnknownyearareviewof pages 25-26): P Kaushik. A review of kummell disease. Unknown journal, Unknown year.
(ilangovan2021backpaindue pages 2-8): G Ilangovan, DA Narmada, N Murugadass, and Z Boudi. Back pain due to kummell's disease. Unknown journal, 2021.

{ }

Source YAML

click to show

name: Kummell Disease
creation_date: '2026-02-06T20:38:12Z'
updated_date: '2026-03-21T22:56:42Z'
category: Complex
description: >
  Kummell disease (also known as Kummell's disease or delayed post-traumatic vertebral
  collapse) is a condition characterized by avascular necrosis of a vertebral body
  following minor spinal trauma. First described by Hermann Kummell in 1891, the disease
  presents with an initial period of relatively minor symptoms after trauma, followed by
  a symptom-free interval, and then progressive painful kyphosis with vertebral body
  collapse. The hallmark radiographic finding is the intravertebral vacuum cleft sign,
  representing gas (nitrogen) accumulation within the necrotic vertebral body. The
  condition predominantly affects elderly patients with osteoporosis and most commonly
  involves the thoracolumbar junction. Treatment ranges from conservative management
  to vertebral augmentation procedures (vertebroplasty or kyphoplasty) and, in severe
  cases, surgical stabilization.
disease_term:
  preferred_term: Kummell disease
  term:
    id: MONDO:0003940
    label: Kummell disease
parents:
- Avascular necrosis
- Vertebral compression fracture
- Osteoporotic spinal disease
synonyms:
- Kummell's disease
- Delayed post-traumatic vertebral collapse
- Vertebral osteonecrosis
- Intravertebral vacuum cleft
- Post-traumatic vertebral body collapse
- Vertebral pseudarthrosis
pathophysiology:
- name: Vertebral body avascular necrosis
  description: >
    Following minor spinal trauma, disruption of the intraosseous blood supply to
    the vertebral body leads to ischemic necrosis of cancellous bone. The osteoporotic
    vertebral body is particularly vulnerable due to its already compromised trabecular
    architecture and vascular supply. The necrotic bone fails to heal through normal
    reparative processes, resulting in progressive structural weakening and eventual
    collapse of the vertebral body. Histopathological examination confirms bone necrosis
    in affected vertebrae.
  locations:
  - preferred_term: Vertebral body
    term:
      id: UBERON:0001075
      label: bony vertebral centrum
  biological_processes:
  - preferred_term: Ossification
    term:
      id: GO:0001503
      label: ossification
    modifier: ABNORMAL
  - preferred_term: Bone resorption
    term:
      id: GO:0045453
      label: bone resorption
    modifier: INCREASED
  cell_types:
  - preferred_term: Osteocyte
    term:
      id: CL:0000137
      label: osteocyte
  - preferred_term: Osteoblast
    term:
      id: CL:0000062
      label: osteoblast
  - preferred_term: Osteoclast
    term:
      id: CL:0000092
      label: osteoclast
  evidence:
  - reference: PMID:28913640
    reference_title: "Case report of Kummell's disease with delayed onset myelopathy and the literature review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Kummell's disease is an avascular necrosis of the vertebral body, secondary to a vertebral compression fracture. This entity is characterised by the gradual development in time of a vertebral body collapse following a trivial spinal trauma, involving a worsening back pain associated with a progressive kyphosis."
    explanation: This case report and literature review defines the core pathophysiology of Kummell disease as avascular necrosis of the vertebral body secondary to compression fracture.
  - reference: PMID:26806962
    reference_title: "Comparison of percutaneous vertebroplasty and percutaneous kyphoplasty for the management of Kümmell's disease: A retrospective study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Intraoperative biopsies from all cases confirms bone necrosis."
    explanation: Histopathological confirmation of bone necrosis in all Kummell disease cases undergoing surgical treatment validates the avascular necrosis mechanism.
  downstream:
  - target: Intravertebral vacuum cleft formation
    description: Nonhealing necrotic bone creates the gas-filled or fluid-filled cleft that defines KD on imaging.
  - target: Progressive vertebral body collapse
    description: Loss of viable trabecular bone weakens structural support and permits delayed vertebral collapse.
- name: Basivertebral foramen microcirculation compromise
  description: >
    The basivertebral foramen is a biomechanical weak point where stresses concentrate
    and fracture lines propagate. Specific morphological characteristics of the
    basivertebral foramen, including trapezoidal or irregular shapes and reduced height,
    are associated with Kummell disease. Single-holed basivertebral foramina predominate
    in affected patients (97% vs 76% in controls), suggesting that fewer septations
    contribute to microcirculatory compromise and structural vulnerability.
  locations:
  - preferred_term: Vertebral body
    term:
      id: UBERON:0001075
      label: bony vertebral centrum
  biological_processes:
  - preferred_term: Angiogenesis
    term:
      id: GO:0001525
      label: angiogenesis
    modifier: DECREASED
  cell_types:
  - preferred_term: Endothelial cell
    term:
      id: CL:0000115
      label: endothelial cell
  evidence:
  - reference: PMID:37353769
    reference_title: "Correlation analysis between morphologic characteristics of the thoracolumbar basivertebral foramen and Kummell's disease in patients with osteoporosis using imaging techniques."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In patients with osteoporosis, the incidence of vertebral Kummell's disease can be associated with the morphological characteristics of the basivertebral foramen, as observed in the CT scan. Furthermore, the vertebral body with trapezoidal-shaped and irregular-shaped basivertebral foramen and boneless septum in the foramen is highly susceptible to Kummell's disease."
    explanation: CT imaging study demonstrates that basivertebral foramen morphology is a risk factor for Kummell disease, supporting the microcirculation compromise mechanism.
  downstream:
  - target: Vertebral body avascular necrosis
    description: Compromised vertebral microcirculation predisposes the injured vertebral body to ischemic bone necrosis.
  - target: Ischemia-induced HIF-1alpha signaling
    description: Reduced local perfusion creates the chronic hypoxic state that activates vertebral stress-response signaling.
- name: Intravertebral vacuum cleft formation
  description: >
    Gas accumulation (primarily nitrogen) within the necrotic vertebral body creates
    the characteristic vacuum cleft sign visible on radiographs and CT. This vacuum
    phenomenon results from the inability of the necrotic bone to heal, creating a
    fluid-filled or gas-filled cavity within the vertebral body. The cleft typically
    changes in size with spinal position, enlarging in extension and compressing
    in flexion, reflecting nonunion or pseudarthrosis within the vertebral body.
    Gas clefts appear hypointense on both T1 and T2 MRI, while fluid-filled clefts
    are T1-hypointense and T2-hyperintense.
  evidence:
  - reference: PMID:26806962
    reference_title: "Comparison of percutaneous vertebroplasty and percutaneous kyphoplasty for the management of Kümmell's disease: A retrospective study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "IVP visualized on plain radiograph is highly suggestive of Kümmell's disease, which is an eponymous term used to describe avascular necrosis of a vertebral body that occurred in a delayed fashion after a minor trauma."
    explanation: Establishes the intravertebral vacuum phenomenon as the hallmark radiographic sign of Kummell disease.
  - reference: PMID:36245398
    reference_title: "Magnetic Resonance Imaging Negative Spine Trauma Followed by a Delayed Intravertebral Vacuum Cleft-Kümmell's Disease: A Case Report and Literature Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Kümmell's disease (KD) is a rare clinical entity characterized by delayed post-traumatic vertebral body collapse, in which an intravertebral vacuum cleft (IVC) is formed."
    explanation: Case report confirming the characteristic intravertebral vacuum cleft formation as the defining feature of Kummell disease.
  downstream:
  - target: Progressive vertebral body collapse
    description: The persistent cleft reflects nonunion and instability that precede delayed collapse.
- name: Ischemia-induced HIF-1alpha signaling
  description: >
    Persistent vertebral ischemia activates HIF-1alpha-dependent hypoxia responses
    in bone and vascular cells. This node captures the immediate hypoxic signaling
    state created by impaired perfusion before downstream remodeling consequences.
  biological_processes:
  - preferred_term: Response to hypoxia
    term:
      id: GO:0001666
      label: response to hypoxia
  cell_types:
  - preferred_term: Osteocyte
    term:
      id: CL:0000137
      label: osteocyte
  - preferred_term: Endothelial cell
    term:
      id: CL:0000115
      label: endothelial cell
  evidence:
  - reference: PMID:36428981
    reference_title: "HIF-1α Regulates Bone Homeostasis and Angiogenesis, Participating in the Occurrence of Bone Metabolic Diseases."
    supports: PARTIAL
    evidence_source: OTHER
    snippet: "HIF-1α/RANKL/Notch1 pathway bidirectionally regulates the differentiation of macrophages into osteoclasts under different conditions. In addition, HIF-1α is also regulated by many factors, including hypoxia, cofactor activity, non-coding RNA, trace elements, etc. As a pivotal pathway for coupling angiogenesis and osteogenesis, HIF-1α has been widely studied in bone metabolic diseases such as bone defect, osteoporosis, osteonecrosis of the femoral head, fracture, and nonunion."
    explanation: Narrative review summarizing HIF-1alpha signaling across osteonecrosis and nonunion states, providing mechanistic context for the hypoxic stress response in Kummell disease.
  downstream:
  - target: Pro-inflammatory osteoclastogenic signaling
    description: Chronic hypoxic stress shifts the vertebral microenvironment toward resorptive inflammatory remodeling.
- name: Pro-inflammatory osteoclastogenic signaling
  description: >
    The KD vertebral microenvironment becomes pro-resorptive, with elevated
    inflammatory cytokines driving osteoclast differentiation and persistent
    bone nonunion. This node captures the remodeling shift toward resorption
    rather than the upstream ischemic trigger itself.
  biological_processes:
  - preferred_term: Osteoclast differentiation
    term:
      id: GO:0030316
      label: osteoclast differentiation
    modifier: INCREASED
  cell_types:
  - preferred_term: Osteoclast
    term:
      id: CL:0000092
      label: osteoclast
  evidence:
  - reference: PMID:40065254
    reference_title: "Expression and significance of cytokines in peripheral blood and bone microenvironment in Kummell's disease, osteoporotic vertebral compression fractures and nonosteoporotic patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The levels of IL-1, IL-6 and TNF-α in the vertebral blood of KD patients were significantly increased, which can promote vertebral osteonecrosis and bone nonunion in KD patients."
    explanation: Direct measurement of vertebral blood in KD patients shows a pro-inflammatory, pro-resorptive microenvironment that promotes osteonecrosis and nonunion.
  downstream:
  - target: Progressive vertebral body collapse
    description: Ongoing resorptive remodeling weakens the already injured vertebral body and accelerates collapse.
- name: Progressive vertebral body collapse
  description: >
    Avascular necrosis, impaired healing, and continued mechanical loading
    produce delayed structural failure of the affected vertebral body, with
    progressive loss of vertebral height and worsening instability.
  biological_processes:
  - preferred_term: Bone remodeling
    term:
      id: GO:0046849
      label: bone remodeling
    modifier: ABNORMAL
  evidence:
  - reference: PMID:29803679
    reference_title: "Anterior reconstruction versus posterior osteotomy in treating Kümmell's disease with neurological deficits: A systematic review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Kümmell's disease, first described by Dr Hermann Kümmell in 1891, is defined as avascular osteonecrosis and occurs after delayed posttraumatic vertebral collapse, mostly in an osteoporotic spine."
    explanation: Systematic review establishing the progressive collapse nature of the disease, with delayed posttraumatic vertebral collapse in osteoporotic bone.
progression:
- phase: Stage I - Early
  notes: >
    Less than 20% vertebral height loss with dynamic motion. Microfractures and
    microischemia present. Relative ischemia and marrow edema beneath endplate.
    Transient pain may resolve. Amenable to percutaneous cement augmentation.
  evidence:
  - reference: PMID:40568562
    reference_title: "Clinical and radiographical analysis of percutaneous kyphoplasty with multi-point cement anchoring technique for preventing bone cement displacement in Kümmell's disease of stage I and II."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "A total of 82 patients with stage I and II KD were treated with PKP in our hospital from April 2020 to October 2022."
    explanation: Clinical study treating stage I and II Kummell disease patients with percutaneous kyphoplasty, confirming this staging classification is used to guide treatment decisions.
  - reference: PMID:39621980
    reference_title: "Percutaneous Kyphoplasty Alleviates Pain Occurring Distal to the Fracture Area Caused by Stage I and II Kümmell Disease."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "Kümmell disease (KD)-a rare and relatively complex spinal condition-is a type of posttraumatic osteoporotic vertebral compression fracture manifesting as a delayed collapse of a vertebral body."
    explanation: Study of Stage I and II KD patients showing kyphoplasty effectively alleviates pain, supporting the staging-guided treatment approach.
- phase: Stage II - Intermediate
  notes: >
    Greater than 20% vertebral height loss with posterior cortex preserved. Cleft
    formation with gas or fluid. Pseudarthrosis and instability established.
    Amenable to cement augmentation (vertebroplasty or kyphoplasty). Cement
    leakage is a major complication requiring technical mitigation strategies.
  evidence:
  - reference: PMID:37254237
    reference_title: "Feasibility Analysis of the Bone Cement-Gelatine Sponge Composite Intravertebral Prefilling Technique for Reducing Bone Cement Leakage in Stage I and II Kümmell's Disease: A Prospective Randomized Controlled Trial."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Bone cement leakage is a major complication of percutaneous vertebroplasty (PVP) while treating Kümmell's disease and it is a focus of close attention during the surgical procedure."
    explanation: Prospective RCT in stage I and II KD demonstrating that cement leakage is a major concern, with the bone cement-gelatine sponge composite technique reducing leakage from 32.4% to 5.4%.
- phase: Stage III - Advanced
  notes: >
    Severe anterior collapse with posterior wall fractures and neural element
    compression. Entrenched ischemia, extensive necrosis, and fixed pseudarthrosis
    with sclerotic rims. In patients with neurological deficits, requires surgical
    fixation and decompression. In those without neurological deficits, vertebroplasty
    may still be effective with reduced surgical trauma compared to posterior fixation.
  evidence:
  - reference: PMID:29803679
    reference_title: "Anterior reconstruction versus posterior osteotomy in treating Kümmell's disease with neurological deficits: A systematic review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In patients with neurological deficits, cement augmentation is inappropriate."
    explanation: Confirms that advanced Kummell disease with neurological compromise requires open surgical intervention rather than cement augmentation.
  - reference: PMID:40613656
    reference_title: "Efficacy and safety of vertebroplasty versus posterior pedicle screw in treating stage III Kummell's disease without neurological deficits: A systematic review and meta-analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Both vertebroplasty and posterior pedicle screw + vertebroplasty are effective for treating stage III Kummell's disease without neurological deficits. Vertebroplasty offers superior perioperative outcomes with reduced surgical trauma and hospital stay."
    explanation: Meta-analysis of 409 patients showing that in stage III KD without neurological deficits, vertebroplasty alone offers comparable radiographic outcomes to posterior fixation with less surgical trauma.
  - reference: PMID:41552306
    reference_title: "Efficacy of percutaneous kyphoplasty in treating stage III Kümmell disease without neurological injury."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "PKP is safe and effective for stage III Kümmell's disease with or without posterior wall integrity. However, having intact posterior walls is better for maintaining vertebral height in long-term."
    explanation: Retrospective study of 79 patients showing PKP is safe and effective for stage III KD even with posterior wall defects, though intact posterior walls yield better long-term height maintenance.
phenotypes:
- name: Back pain
  description: >
    Progressive thoracolumbar back pain that typically develops after an initial
    asymptomatic interval following minor trauma. The pain worsens with weight-bearing
    and activity and may become chronic and debilitating. The delayed onset after a
    symptom-free interval is characteristic.
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Back pain
    term:
      id: HP:0003418
      label: Back pain
  evidence:
  - reference: PMID:28913640
    reference_title: "Case report of Kummell's disease with delayed onset myelopathy and the literature review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This entity is characterised by the gradual development in time of a vertebral body collapse following a trivial spinal trauma, involving a worsening back pain associated with a progressive kyphosis."
    explanation: Case report describing the characteristic delayed-onset worsening back pain of Kummell disease.
- name: Kyphosis
  description: >
    Progressive kyphotic deformity resulting from vertebral body collapse. The
    kyphosis can be severe and may lead to sagittal imbalance, reduced pulmonary
    function, and impaired quality of life.
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Kyphosis
    term:
      id: HP:0002808
      label: Kyphosis
  evidence:
  - reference: PMID:28913640
    reference_title: "Case report of Kummell's disease with delayed onset myelopathy and the literature review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the radiological exams showed a constant worsening of the thoracic-lumbar kyphosis and a restriction of the spinal canal"
    explanation: Case report demonstrating progressive kyphosis as a cardinal feature of Kummell disease.
- name: Vertebral compression fracture
  description: >
    Collapse of the vertebral body, which may be partial or complete. The fracture
    typically involves the thoracolumbar junction (T10-L2) and progresses over time
    unlike acute osteoporotic compression fractures. It is distinguished from typical
    osteoporotic fractures by the delayed fashion of symptom development.
  frequency: OBLIGATE
  phenotype_term:
    preferred_term: Vertebral compression fracture
    term:
      id: HP:0002953
      label: Vertebral compression fracture
  evidence:
  - reference: PMID:26806962
    reference_title: "Comparison of percutaneous vertebroplasty and percutaneous kyphoplasty for the management of Kümmell's disease: A retrospective study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "It is distinguished from typical osteoporotic fractures because the symptoms develop in a delayed fashion."
    explanation: Key distinguishing feature of Kummell disease versus typical osteoporotic compression fractures is the delayed symptom development.
  - reference: PMID:36245398
    reference_title: "Magnetic Resonance Imaging Negative Spine Trauma Followed by a Delayed Intravertebral Vacuum Cleft-Kümmell's Disease: A Case Report and Literature Review."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "We confirmed that the OVF was not the first step in the KD sequence, and the IVC - KD - could from an initial MRI-negative spine trauma."
    explanation: Case report demonstrating that the initial trauma in Kummell disease may be MRI-negative, with delayed development of vertebral collapse.
- name: Neurological deficit
  description: >
    In advanced cases, progressive vertebral collapse and kyphotic deformity can
    lead to spinal cord or cauda equina compression, resulting in myelopathy,
    radiculopathy, or paraplegia. These deficits indicate stage III disease requiring
    surgical intervention.
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Myelopathy
    term:
      id: HP:0002196
      label: Myelopathy
  evidence:
  - reference: PMID:28913640
    reference_title: "Case report of Kummell's disease with delayed onset myelopathy and the literature review."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "A year after the injury, motor deficits concerning the lower limbs appeared."
    explanation: Case demonstrating delayed-onset neurological deficits (lower limb motor deficits) developing one year after the initial injury in Kummell disease.
  - reference: PMID:29803679
    reference_title: "Anterior reconstruction versus posterior osteotomy in treating Kümmell's disease with neurological deficits: A systematic review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A total of 10 publications involving 268 Kümmell's disease patients with neurological deficits were included in this review"
    explanation: Systematic review of 268 Kummell disease patients with neurological deficits confirms this is a recognized complication.
diagnosis:
- name: Intravertebral vacuum cleft on imaging
  description: >
    The hallmark diagnostic finding is the intravertebral vacuum cleft (IVC) visible
    on plain radiographs, CT, or MRI. Gas-filled clefts are hypointense on both T1
    and T2 MRI sequences. Fluid-filled clefts are T1-hypointense and T2-hyperintense.
    CT scan provides detailed assessment of basivertebral foramen morphology and
    cortical integrity.
  evidence:
  - reference: PMID:26806962
    reference_title: "Comparison of percutaneous vertebroplasty and percutaneous kyphoplasty for the management of Kümmell's disease: A retrospective study."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "Gas noted on plain radiographs is expected to be hypointense on both T1 and T2 magnetic resonance imaging (MRI) sequences."
    explanation: Describes the MRI characteristics of the intravertebral vacuum cleft, with gas appearing hypointense on both T1 and T2 sequences.
- name: Histopathological confirmation
  description: >
    Intraoperative biopsy confirms bone necrosis and helps exclude other diagnoses
    such as spinal malignancy or infection, which can rarely present with similar
    intravertebral vacuum phenomena.
  evidence:
  - reference: PMID:26806962
    reference_title: "Comparison of percutaneous vertebroplasty and percutaneous kyphoplasty for the management of Kümmell's disease: A retrospective study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "IVP is not pathognomonic for Kümmell's disease, only highly suggestive of this disease."
    explanation: While the vacuum cleft is highly suggestive of Kummell disease, histopathological confirmation is important to exclude malignancy or infection.
treatments:
- name: Percutaneous vertebroplasty
  description: >
    Percutaneous injection of polymethylmethacrylate (PMMA) bone cement into the
    collapsed vertebral body to stabilize the fracture and provide pain relief.
    Particularly effective in Kummell disease when cement can fill the
    intravertebral cleft. Pain relief is thought to be due to the elimination of
    motion at the fracture site by cementing. Use of rotary cutters before cement
    injection to destroy the IVC structure may improve outcomes.
  context: Stage I-II disease without neurological deficits
  treatment_term:
    preferred_term: orthopedic procedure
    term:
      id: MAXO:0000477
      label: orthopedic procedure
  target_phenotypes:
  - preferred_term: Back pain
    term:
      id: HP:0003418
      label: Back pain
  - preferred_term: Vertebral compression fracture
    term:
      id: HP:0002953
      label: Vertebral compression fracture
  notes: >
    Faster and less expensive than kyphoplasty with comparable pain relief and
    height restoration. Higher cement leakage rate (26.3%) compared to kyphoplasty
    (8.6%). Rotary cutter modification (RC-PVP) may improve cement interdigitation
    and clinical outcomes.
  evidence:
  - reference: PMID:26806962
    reference_title: "Comparison of percutaneous vertebroplasty and percutaneous kyphoplasty for the management of Kümmell's disease: A retrospective study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "PVP is a faster, less expensive option that still provides a comparable pain relief and restoration of vertebral height to PKP for the treatment of Kümmell's disease."
    explanation: Retrospective study of 73 patients comparing PVP and PKP, showing both are effective for Kummell disease with comparable pain relief and height restoration.
  - reference: PMID:34213873
    reference_title: "Percutaneous Vertebroplasty Using a Rotary Cutter for Treating Kümmell's Disease with Intravertebral Vacuum Cleft."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "RC-PVP, with the destruction of IVC, may lead to better clinical outcomes with fewer complications."
    explanation: Prospective study showing that rotary cutter vertebroplasty that destroys the IVC structure yields better clinical outcomes with fewer complications than conventional PVP.
- name: Percutaneous kyphoplasty
  description: >
    Balloon kyphoplasty involves percutaneous placement of an inflatable balloon
    tamp into the vertebral body to restore height before cement injection. Provides
    comparable pain relief and height restoration to vertebroplasty. Achieves fewer
    cement leakages than vertebroplasty but at higher cost and longer operative time.
    The relationship between cement distribution and the intravertebral cleft is
    an important factor affecting long-term outcomes.
  context: Stage I-III disease without neurological deficits
  treatment_term:
    preferred_term: orthopedic procedure
    term:
      id: MAXO:0000477
      label: orthopedic procedure
  target_phenotypes:
  - preferred_term: Back pain
    term:
      id: HP:0003418
      label: Back pain
  - preferred_term: Kyphosis
    term:
      id: HP:0002808
      label: Kyphosis
  - preferred_term: Vertebral compression fracture
    term:
      id: HP:0002953
      label: Vertebral compression fracture
  notes: >
    Fewer cement leakages (8.6%) compared to vertebroplasty (26.3%) but higher cost
    and longer operative time. Cement distribution relative to the cleft is critical:
    diffuse distribution around the cleft yields better outcomes than cement confined
    within the cleft. Liquid-filled IVCs with fibrosclerotic rims can limit cement
    dispersion and increase recollapse risk. PKP is also effective for stage III
    without neurological injury, though intact posterior walls yield better long-term
    vertebral height maintenance.
  evidence:
  - reference: PMID:26806962
    reference_title: "Comparison of percutaneous vertebroplasty and percutaneous kyphoplasty for the management of Kümmell's disease: A retrospective study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "PKP has a significant advantage over PVP in term of the fewer cement leakages."
    explanation: Study showing PKP has significantly fewer cement leakages (8.6%) compared to PVP (26.3%) in Kummell disease treatment.
  - reference: PMID:35051635
    reference_title: "Does the Relationship Between Bone Cement and the Intravertebral Cleft of Kummell Disease Affect the Efficacy of PKP?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "PKP was an effective method for treating Kummell disease. At the same time, the relationship between the distribution of bone cement and the cleft in the vertebral body was an important factor affecting the curative effect after PKP."
    explanation: Study of 92 Kummell disease patients showing that cement distribution relative to the cleft is a key determinant of PKP efficacy, with diffuse distribution around the cleft yielding better outcomes.
  - reference: PMID:41552306
    reference_title: "Efficacy of percutaneous kyphoplasty in treating stage III Kümmell disease without neurological injury."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "PKP is safe and effective for stage III Kümmell's disease with or without posterior wall integrity. However, having intact posterior walls is better for maintaining vertebral height in long-term."
    explanation: Study of 79 patients demonstrating PKP safety and efficacy for stage III KD, extending the indication beyond stage I-II.
- name: Conservative management
  description: >
    Non-surgical treatment including analgesics, bed rest, bracing, and physical
    therapy. May be appropriate for patients with minimal symptoms or those who
    are poor surgical candidates.
  context: Early disease with minimal symptoms or patients unfit for surgery
  treatment_term:
    preferred_term: supportive care
    term:
      id: MAXO:0000950
      label: supportive care
  target_phenotypes:
  - preferred_term: Back pain
    term:
      id: HP:0003418
      label: Back pain
  notes: >
    Conservative management alone carries risk of disease progression. Patients
    managed conservatively should be monitored with serial imaging for progressive
    vertebral collapse and development of neurological deficits.
- name: Posterior spinal fusion
  description: >
    Surgical stabilization with instrumented posterior osteotomy and spinal fusion
    is required for severe kyphotic deformity with neurological compromise (stage III).
    Posterior approaches are generally preferred over anterior reconstruction in
    patients with advanced age, serious comorbidities, and severe osteoporosis.
    Both anterior and posterior approaches improve pain, neurological dysfunction,
    and imaging outcomes.
  context: Stage III disease with neurological deficits or severe kyphotic deformity
  treatment_term:
    preferred_term: orthopedic procedure
    term:
      id: MAXO:0000477
      label: orthopedic procedure
  target_phenotypes:
  - preferred_term: Myelopathy
    term:
      id: HP:0002196
      label: Myelopathy
  - preferred_term: Kyphosis
    term:
      id: HP:0002808
      label: Kyphosis
  notes: >
    Posterior osteotomy is preferred over anterior reconstruction due to lower
    implant-related complication rates (14.3% vs 21.6%) and suitability for
    patients with severe osteoporosis. Anterior reconstruction more often requires
    a second surgery. Long-segment fixation provides greater stability in
    osteoporotic bone.
  evidence:
  - reference: PMID:29803679
    reference_title: "Anterior reconstruction versus posterior osteotomy in treating Kümmell's disease with neurological deficits: A systematic review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This systematic review demonstrated that both AR and PO could improve pain, neurological dysfunction and imaging outcomes. However, serious comorbidities, multilevel corpectomies and/or severe osteoporosis highly required PO."
    explanation: Systematic review of 268 patients showing that posterior osteotomy is preferred for patients with comorbidities and severe osteoporosis, which are common in Kummell disease.
  - reference: PMID:28913640
    reference_title: "Case report of Kummell's disease with delayed onset myelopathy and the literature review."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "He was then sent to us and indication for posterior internal fixation was given."
    explanation: Case of delayed-onset myelopathy in Kummell disease successfully treated with posterior internal fixation.
prevalence:
- population: Elderly with osteoporotic vertebral fractures
  percentage: 6.3
  notes: >
    In one institutional series, 130 of 2074 OVCF patients (6.3%) were diagnosed
    with KD. The disease predominantly affects elderly patients (mean age ~79 years),
    especially postmenopausal women, and is most common at the thoracolumbar junction
    (T10-L2) with T12 being the most frequently affected level. Multi-level (double
    vertebrae) involvement occurs rarely but is associated with older age, lower BMD,
    and greater kyphotic deformity.
  evidence:
  - reference: PMID:25246995
    reference_title: "Kümmell's Disease: Clarifying the Mechanisms and Patients' Inclusion Criteria."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "Although more than a century has passed from its initial description, only few cases have been reported in the literature, whereas the main pathologic eliciting event is still under investigation."
    explanation: Review acknowledging that Kummell disease is rare with only a limited number of cases reported in over a century of medical literature.
  - reference: PMID:34118526
    reference_title: "Impending cauda equina syndrome due to Kummell disease; A case report and literature review."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "Kummell disease (KD) is a rare cause of vertebral fracture due to osteonecrosis."
    explanation: Case report confirming the rarity of Kummell disease as a cause of vertebral fracture.
  - reference: PMID:40312461
    reference_title: "Predictive factors associated with the onset of Kummell's disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The risk of developing KD is heightened in patients with the following predictive factors are present: (1) Age ≥ 70.5 years; (2) BMD (T-score) ≤ - 3.65; (3) History of osteoporosis; (4) Vertebral compression ratio ≥ 29.9%; (5) Wedge-shaped vertebral compression morphology; and (6) Grade III or higher disc degeneration."
    explanation: Retrospective study of 170 patients identifying six independent predictive factors for KD onset, providing quantitative thresholds for risk stratification.
  - reference: PMID:37435837
    reference_title: "Double Vertebrae Kümmell Disease: Five Cases Report and Literature Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "One hundred and thirty vertebrae KD were diagnosed from 2074 osteoporotic vertebral compression fractures patients treated in our hospital between 2015 and 2019."
    explanation: Large single-center series providing the quantitative prevalence estimate of 6.3% (130/2074) among OVCF patients, and noting double-level KD occurs in a small subset with significantly lower BMD and greater kyphosis.
differential_diagnoses:
- name: Acute osteoporotic vertebral compression fracture
  description: >
    Standard osteoporotic compression fractures present acutely after trauma
    and typically heal over 6-12 weeks. Unlike Kummell disease, they do not
    have an asymptomatic interval followed by delayed collapse, and they
    lack the intravertebral vacuum cleft sign.
  distinguishing_features:
  - Acute onset of symptoms directly related to trauma without asymptomatic interval
  - Progressive healing on serial imaging rather than delayed collapse
  - Absence of intravertebral vacuum cleft sign
  evidence:
  - reference: PMID:26806962
    reference_title: "Comparison of percutaneous vertebroplasty and percutaneous kyphoplasty for the management of Kümmell's disease: A retrospective study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "It is distinguished from typical osteoporotic fractures because the symptoms develop in a delayed fashion."
    explanation: Key distinguishing feature is the delayed symptom development in Kummell disease versus acute onset in typical osteoporotic fractures.
- name: Spinal metastatic disease
  description: >
    Vertebral collapse from metastatic malignancy can mimic Kummell disease on
    imaging. Intravertebral vacuum phenomena occur rarely in metastatic disease.
    Paravertebral soft tissue masses, irregular vertebral destruction, and
    multi-level involvement favor metastatic disease over Kummell disease.
  distinguishing_features:
  - Paravertebral soft tissue mass or abscess typically present
  - Multi-level vertebral involvement common
  - History of primary malignancy
  - Bone scan shows multiple areas of uptake
  evidence:
  - reference: PMID:34118526
    reference_title: "Impending cauda equina syndrome due to Kummell disease; A case report and literature review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "although this radiographic sign is indicative of osteonecrosis, it is not pathognomonic and may be seen in an osteoporotic compression fracture, long-term corticosteroid therapy, myeloma, bone metastasis, acute fracture, osteomyelitis, alcoholism, diabetes mellitus, and arteriosclerosis"
    explanation: The intravertebral vacuum cleft is not pathognomonic for Kummell disease and can rarely occur in metastatic disease, necessitating differential consideration.
- name: Multiple myeloma
  description: >
    Plasma cell neoplasm causing lytic bone lesions and vertebral compression
    fractures. Can present with intravertebral vacuum phenomena in rare cases.
    Distinguished by laboratory findings including monoclonal protein, elevated
    serum protein, and characteristic bone marrow biopsy findings.
  disease_term:
    preferred_term: plasma cell myeloma
    term:
      id: MONDO:0009693
      label: plasma cell myeloma
  distinguishing_features:
  - Monoclonal protein on serum or urine protein electrophoresis
  - Multiple lytic bone lesions on skeletal survey
  - Abnormal bone marrow plasma cell infiltration
  - Elevated serum protein with M-spike
  evidence:
  - reference: PMID:26806962
    reference_title: "Comparison of percutaneous vertebroplasty and percutaneous kyphoplasty for the management of Kümmell's disease: A retrospective study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "IVP occurs rarely in patients with spinal infections and spinal malignancies, for examples, multiple myeloma"
    explanation: Confirms that intravertebral vacuum phenomenon can rarely occur in multiple myeloma, requiring it to be excluded.
- name: Spinal infection (osteomyelitis/tuberculosis)
  description: >
    Vertebral osteomyelitis or spinal tuberculosis can cause vertebral destruction
    and collapse. Kummell disease must be differentiated from infectious causes,
    particularly when presenting with vertebral collapse and back pain in elderly
    patients.
  disease_term:
    preferred_term: tuberculosis, spinal
    term:
      id: MONDO:0043836
      label: tuberculosis, spinal
  distinguishing_features:
  - Disc space involvement and endplate irregularity
  - Paravertebral or epidural abscess formation
  - Elevated inflammatory markers (ESR, CRP)
  - Constitutional symptoms (fever, weight loss, night sweats)
  evidence:
  - reference: PMID:34118526
    reference_title: "Impending cauda equina syndrome due to Kummell disease; A case report and literature review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The disease has some characteristic (non-diagnostic) features on imaging that help to differentiate it from post-traumatic kyphosis, infection, osteoporotic fracture, or metastatic involvement"
    explanation: Case report and review noting that Kummell disease must be differentiated from infection among other causes of vertebral collapse.
- name: Post-traumatic kyphosis
  description: >
    Progressive kyphotic deformity after significant vertebral trauma. Unlike
    Kummell disease, the initial trauma is typically substantial, the cause of
    collapse is mechanical bone subsidence rather than osteonecrosis, and there
    is no asymptomatic window period.
  distinguishing_features:
  - History of significant trauma rather than trivial injury
  - Direct relationship between trauma severity and deformity
  - Mechanical bone subsidence rather than osteonecrosis
  - Absence of intravertebral vacuum cleft sign
  evidence:
  - reference: PMID:34118526
    reference_title: "Impending cauda equina syndrome due to Kummell disease; A case report and literature review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "KD is not the same as post-traumatic kyphosis, because in the former, the severity of the initial trauma is negligible, and the cause of vertebral body collapse is osteonecrosis, and not simple bone subsidence"
    explanation: Case report explicitly distinguishing Kummell disease from post-traumatic kyphosis based on trauma severity and pathologic mechanism.
environmental:
- name: Osteoporosis
  description: >
    Osteoporosis is the primary predisposing condition for Kummell disease. The
    compromised trabecular architecture and reduced bone mineral density of
    osteoporotic vertebrae make them vulnerable to avascular necrosis following
    even minor trauma. The disease predominantly affects elderly postmenopausal
    patients with osteoporosis.
  effect: Major predisposing factor
  evidence:
  - reference: PMID:37353769
    reference_title: "Correlation analysis between morphologic characteristics of the thoracolumbar basivertebral foramen and Kummell's disease in patients with osteoporosis using imaging techniques."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "83 patients with 83 vertebral bodies (T8-L5) diagnosed with senile osteoporosis and Kummell's disease"
    explanation: All Kummell disease patients in this study had concomitant senile osteoporosis, confirming it as a predisposing condition.
  - reference: PMID:40312461
    reference_title: "Predictive factors associated with the onset of Kummell's disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "BMD (T-score) ≤ - 3.65 and a vertebral compression ratio ≥ 29.9% were strongly correlated with KD (P < 0.001)."
    explanation: ROC analysis identifying BMD T-score ≤ -3.65 as a strong predictor of KD onset, quantifying the severity of osteoporosis required to predispose to the disease.
- name: Minor spinal trauma
  description: >
    A preceding episode of minor or trivial spinal trauma is a typical triggering
    event for Kummell disease. The initial trauma may be so minor that it is
    MRI-negative at the time of injury, yet leads to progressive vertebral body
    collapse months later.
  effect: Triggering event
  evidence:
  - reference: PMID:36245398
    reference_title: "Magnetic Resonance Imaging Negative Spine Trauma Followed by a Delayed Intravertebral Vacuum Cleft-Kümmell's Disease: A Case Report and Literature Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "lumbar MRI on sagittal planes were immediately performed following the initial trauma (a ground-level fall) and revealed that the vertebral integrity or connectivity was not interrupted and the marrow signal was even. After an asymptomatic period of 8 months, the back pain reappeared and progressively exacerbated."
    explanation: Case demonstrating that the initial trauma can be MRI-negative with normal marrow signal, yet the patient develops Kummell disease months later.
clinical_trials:
- name: NCT00749060
  phase: NOT_APPLICABLE
  status: COMPLETED
  description: >
    Prospective randomized comparative study of balloon kyphoplasty, vertebroplasty,
    and conservative management in acute osteoporotic vertebral fractures of less
    than 6 weeks. Although this trial enrolled acute OVCF rather than Kummell disease
    specifically, it directly compared the three principal treatment modalities used
    for stage I-II Kummell disease and informs treatment decisions.
  target_phenotypes:
  - preferred_term: Back pain
    term:
      id: HP:0003418
      label: Back pain
  - preferred_term: Vertebral compression fracture
    term:
      id: HP:0002953
      label: Vertebral compression fracture
  evidence:
  - reference: clinicaltrials:NCT00749060
    supports: PARTIAL
    snippet: "This study aims to compare three treatments in recent (less than 6 week duration) non-traumatic ( usually osteoporotic) vertebral fractures."
    explanation: Randomized trial comparing kyphoplasty, vertebroplasty, and conservative management for osteoporotic vertebral fractures, the same interventions used in Kummell disease.
- name: NCT05058443
  phase: PHASE_III
  status: COMPLETED
  description: >
    Randomized placebo-controlled trial evaluating denosumab for protecting against
    bone loss and preserving function in osteoporotic vertebral compression fracture
    patients after percutaneous vertebroplasty. Relevant to Kummell disease because
    post-vertebroplasty secondary fractures are a major concern, and anti-resorptive
    therapy may reduce this risk.
  target_phenotypes:
  - preferred_term: Vertebral compression fracture
    term:
      id: HP:0002953
      label: Vertebral compression fracture
  evidence:
  - reference: clinicaltrials:NCT05058443
    supports: PARTIAL
    snippet: "This study aimed to investigate the effect of denosumab on bone mineral density(BMD), bone turnover markers(BTMs), functional status, secondary fracture rate, and adverse effects in osteoporotic vertebral compression fracture (OVCF) patients after vertebroplasty during a 12-month follow-up period."
    explanation: Trial evaluating denosumab post-vertebroplasty for OVCF, directly relevant to post-augmentation management in Kummell disease where secondary fractures are a concern.
- name: NCT05598606
  phase: PHASE_IV
  status: COMPLETED
  description: >
    Randomized controlled trial comparing denosumab versus zoledronic acid for
    preventing bone loss in postmenopausal osteoporotic vertebral compression
    fracture patients after percutaneous vertebroplasty. Relevant to Kummell
    disease post-treatment management given the underlying osteoporosis and
    risk of adjacent vertebral fractures.
  target_phenotypes:
  - preferred_term: Vertebral compression fracture
    term:
      id: HP:0002953
      label: Vertebral compression fracture
  evidence:
  - reference: clinicaltrials:NCT05598606
    supports: PARTIAL
    snippet: "Osteoporotic vertebral compression fracture (OVCF) patients had a proportion of secondary fractures after percutaneous vertebroplasty (PVP). Denosumab and zoledronate acid is both effective to prevent bone loss for OVCF postmenopausal women."
    explanation: Trial comparing anti-resorptive agents post-vertebroplasty, relevant to Kummell disease given that all patients have underlying osteoporosis and are at risk of adjacent level fractures.
datasets:
- accession: geo:GSE242414
  title: "Single-cell RNA landscape of osteoimmunology microenvironment in Osteoporotic Vertebral Compression Fracture (OVCF) and Kümmell’s Disease (KD)"
  description: >-
    Single-cell RNA sequencing of fractured vertebral bone tissue from one OVCF
    patient and one Kummell disease patient. A total of 8,741 single cells were
    captured for transcriptomic analysis, identifying mesenchymal stem cells,
    pericytes, myofibroblasts, fibroblasts, chondrocytes, endothelial cells,
    granulocytes, monocytes, T cells, B cells, plasma cells, mast cells, and
    early erythrocytes.
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  data_type: SINGLE_CELL_RNA_SEQ
  sample_types:
  - preferred_term: vertebral bone tissue
    tissue_term:
      preferred_term: bony vertebral centrum
      term:
        id: UBERON:0001075
        label: bony vertebral centrum
  sample_count: 2
  conditions:
  - osteoporotic vertebral compression fracture
  - Kummell disease (vertebral avascular necrosis)
  platform: Illumina NovaSeq 6000
  publication: PMID:38161331
  findings:
  - statement: KD tissue shows depletion of mesenchymal stem cells and a relatively suppressed immune system compared to OVCF
  - statement: OVCF exhibits higher osteogenic differentiation capacity owing to abundant immune cells
  - statement: KD results in greater bone resorption than bone formation, with immune imbalance leading to vertebral avascular necrosis
  - statement: CD8-TEM cells and osteoclasts may crosstalk via CD160-TNFRSF14 ligand-receptor interaction
  notes: >-
    The only single-cell transcriptomic dataset directly comparing OVCF and Kummell
    disease tissue. Reveals that transition from OVCF to KD involves MSC depletion
    and immune suppression, supporting the osteoimmune hypothesis of disease
    progression.