Injury to the Vertebral Endplate-Disk Complex Associated with Osteoporotic Vertebral Compression Fractures

Ortiz, A. Orlando; Bordia, Ritu

doi:10.3174/ajnr.a2223

Cited by 40 publications

(45 citation statements)

References 14 publications

(14 reference statements)

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“…), the superior endplate was much more often affected than the inferior endplate, and the progression of failure involved appreciable deformation in only the half of the vertebral body exhibiting endplate collapse. These similarities are consistent with prior evidence that fractures occur more often in the superior versus inferior endplate and that the former is thinner and is supported by less robust trabecular bone . The role of the central endplate in vertebral failure due to anterior flexion has been controversial, in part because the majority of prior studies of endplate deflection have used only compressive loading.…”

Section: Discussionsupporting

confidence: 83%

Quantitative, 3D Visualization of the Initiation and Progression of Vertebral Fractures Under Compression and Anterior Flexion

Jackman

Hussein

Curtiss

et al. 2015

Journal of Bone and Mineral Research

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The biomechanical mechanisms leading to vertebral fractures are not well understood. Clinical and laboratory evidence suggests that the vertebral endplate plays a key role in failure of the vertebra as a whole, but how this role differs for different types of vertebral loading is not known. Mechanical testing of human thoracic spine segments, in conjunction with time-lapsed micro–computed tomography, enabled quantitative assessment of deformations occurring throughout the entire vertebral body under axial compression combined with anterior flexion (“combined loading”) and under axial compression only (“compression loading”). The resulting deformation maps indicated that endplate deflection was a principal feature of vertebral failure for both loading modes. Specifically, the onset of endplate deflection was temporally coincident with a pronounced drop in the vertebra’s ability to support loads. The location of endplate deflection, and also vertebral strength, were associated with the porosity of the endplate and the microstructure of the underlying trabecular bone. However, the location of endplate deflection and the involvement of the cortex differed between the two types of loading. Under the combined loading, deflection initiated, and remained the largest, at the anterior central endplate or the anterior ring apophysis, depending in part on health of the adjacent intervertebral disc. This deflection was accompanied by outward bulging of the anterior cortex. In contrast, the location of endplate deflection was more varied in compression loading. For both loading types, the earliest progression to a mild fracture according to a quantitative morphometric criterion occurred only after much of the failure process had occurred. The outcomes of this work indicate that for two physiological loading modes, the vertebral endplate and underlying trabecular bone are critically involved in vertebral fracture. These outcomes provide a strong biomechanical rationale for clinical methods, such as algorithm-based qualitative (ABQ) assessment, that diagnose vertebral fracture on the basis of endplate depression.

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Section: Discussionsupporting

confidence: 83%

Quantitative, 3D Visualization of the Initiation and Progression of Vertebral Fractures Under Compression and Anterior Flexion

Jackman

Hussein

Curtiss

et al. 2015

Journal of Bone and Mineral Research

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“…These observations further indicate that the subchondral trabecular bone is critically involved in endplate deflection and vertebral failure. The disparity between superior and inferior endplate deflection supports previous findings that superior endplates are more susceptible to failure . The larger endplate deflection underlying the NP versus AF may reflect regional variations in endplate thickness, trabecular microstructure, and intra‐discal pressure .…”

Section: Discussionsupporting

confidence: 82%

Endplate deflection is a defining feature of vertebral fracture and is associated with properties of the underlying trabecular bone

Jackman

Hussein

Adams

et al. 2014

Journal Orthopaedic Research

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Endplate deflection frequently occurs with vertebral failure, but the relationship between the two remains poorly defined. This study examined associations between endplate deflection under compressive loading and characteristics of the neighboring subchondral bone and intervertebral disc (IVD). Ten L1 vertebrae with adjacent IVDs were dissected, compressed axially in a stepwise manner to failure, and imaged with micro-computed tomography before each loading step. From the images, deflection was measured across the surface of each endplate at each step. Trabecular microstructure and endplate volume fraction were evaluated in 5mm regions just under the superior endplate. IVDs were assessed using computed tomography and histology. A marked increase in superior endplate deflection coincided with a drop in the load-displacement curve. Endplate deflection was higher in regions with less robust bone microstructure (p<0.009), though these associations tended to weaken as loading progressed. Immediately following the ultimate point, endplate deflection was higher in regions underlying the nucleus pulposus vs. annulus fibrosus (p=0.035), irrespective of disc grade (p=0.346). These results indicate that a sudden increase in endplate deflection signals that the mechanical competence of the vertebra has been compromised. The mechanisms of endplate failure likely relate to anatomical features of the endplate, neighboring trabecular bone, and IVD.

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“…18,20,35 However, it is unclear whether endplate disruption is exacerbated by vertebroplasty and if the magnitude of subsidence is dependent on endplate thickness and the underlying trabecular bone. In this study, we developed techniques to understand whether vertebroplasty increases subsidence in endplates surrounding the treated level.…”

Section: Discussionmentioning

confidence: 99%

Effects of vertebroplasty on endplate subsidence in elderly female spines

Nagaraja¹,

Awada²,

Dreher³

et al. 2015

SPI

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OBJECT The aim in this study was to quantify the effects of vertebroplasty on endplate subsidence in treated and adjacent vertebrae and their relationship to endplate thickness and underlying trabecular bone in elderly female spines. METHODS Vertebral compression fractures were created in female cadaveric (age range 51–88 years) thoracolumbar spine segments. Specimens were placed into either the control or vertebroplasty group (n = 9/group) such that bone mineral density, trabecular microarchitecture, and age were statistically similar between groups. For the vertebroplasty group, polymethylmethacrylate bone cement was injected into the fractured vertebral body under fluoroscopy. Cyclic compression (685–1370 N sinusoid) was performed on all spine segments for 115,000 cycles. Micro-CT scans were obtained before and after cyclic loading to quantify endplate subsidence. Maximum subsidence was compared between groups in the caudal endplate of the superior adjacent vertebra (SVcau); cranial (TVcra) and caudal (TVcau) endplates of the treated vertebra; and the cranial endplate of the inferior adjacent vertebra (IVcra). In addition, micro-CT images were used to quantify average endplate thickness and trabecular bone volume fraction. These parameters were then correlated with maximum endplate subsidence for each endplate. RESULTS The maximum subsidence in SVcau endplate for the vertebroplasty group (0.34 ± 0.58 mm) was significantly (p < 0.05) greater than for the control group (−0.13 ± 0.27 mm). Maximum subsidence in the TVcra, TVcau, and IVcra endplates were greater in the vertebroplasty group, but these differences were not significant (p > 0.16). Increased subsidence in the vertebroplasty group manifested locally in the anterior region of the SVcau endplate and in the posterior region of the TVcra and TVcau endplates (p < 0.10). Increased subsidence was observed in thinner endplates with lower trabecular bone volume fraction for both vertebroplasty and control groups (R2 correlation up to 62%). In the SVcau endplate specifically, these 2 covariates aided in understanding subsidence differences between vertebroplasty and control groups. CONCLUSIONS Bone cement injected during vertebroplasty alters local biomechanics in elderly female spines, resulting in increased endplate disruption in treated and superior adjacent vertebrae. More specifically, bone cement increases subsidence in the posterior regions of the treated endplates and the anterior region of the superior caudal endplate. This increased subsidence may be the initial mechanism leading to subsequent compression fractures after vertebroplasty, particularly in vertebrae superior to the treated level.

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Injury to the Vertebral Endplate-Disk Complex Associated with Osteoporotic Vertebral Compression Fractures

Cited by 40 publications

References 14 publications

Quantitative, 3D Visualization of the Initiation and Progression of Vertebral Fractures Under Compression and Anterior Flexion

Quantitative, 3D Visualization of the Initiation and Progression of Vertebral Fractures Under Compression and Anterior Flexion

Endplate deflection is a defining feature of vertebral fracture and is associated with properties of the underlying trabecular bone

Effects of vertebroplasty on endplate subsidence in elderly female spines

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