The effect on anterior column loading due to different vertebral augmentation techniques

Ananthakrishnan, Dheera; Berven, Sigurd; Deviren, Vedat; Cheng, Kevin; Lotz, Jeffrey C.; Xu, Zheng; Puttlitz, Christian M.

doi:10.1016/j.clinbiomech.2004.09.004

Cited by 58 publications

(39 citation statements)

References 22 publications

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“…Although these findings may suggest that the risk of fracture is increased adjacent to an augmented vertebra, new fractures may be the result of the natural progression of osteoporosis. Indeed, some recent studies refute earlier findings, concluding that subsequent vertebral fractures are the result of excessive loading and not the augmentation process [1,23,51]. Therefore, due to the conflicting conclusions drawn by previous studies, the need still exists to determine the effect of cement augmentation on vertebral mechanics.…”

Section: Introductioncontrasting

confidence: 39%

“…The mean endplate deformation for all specimens was 0.82 ± 0.025 mm at the maximum compressive load applied to the specimen, 1,620 ± 102 N. However, endplate deformation was not always equal between the caudal inferior and cranial superior endplate which abut a common disc (1) and high BV/TV and low endplate deformation (2) and thus be at risk of fracture following cement augmentation. Previous biomechanical in vitro tests [1,3,23] and finite element analyses [2,24,32,40,44,51] have reported conflicting results. The conflicting results between our experiment and previous finite element analyses may be attributed to differing injection volumes, loading parameters and inability to model the complex behavior of the intervertebral disc and 3D trabecular network.…”

Section: Discussionmentioning

confidence: 82%

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Differences in endplate deformation of the adjacent and augmented vertebra following cement augmentation

et al. 2009

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Section: Introductioncontrasting

confidence: 39%

Section: Discussionmentioning

confidence: 82%

Differences in endplate deformation of the adjacent and augmented vertebra following cement augmentation

et al. 2009

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“…The new fractures often seen in these patients could be due to the natural history of the osteoporosis [20][21][22], due to the increased load caused by a wedge-shaped fracture [13], or due to the increased stiffness of the augmented vertebral body [11,12,23].…”

Section: Introductionmentioning

confidence: 99%

A probabilistic finite element analysis of the stresses in the augmented vertebral body after vertebroplasty

et al. 2010

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Fractured vertebral bodies are often stabilized by vertebroplasty. Several parameters, including fracture type, cement filling shape, cement volume, elastic moduli of cement, cancellous bone and fractured region, may all affect the stresses in the augmented vertebral body and in bone cement. The aim of this study was to determine numerically the effects of these input parameters on the stresses caused. In a probabilistic finite element study, an osteoligamentous model of the lumbar spine was employed. Seven input parameters were simultaneously and randomly varied within appropriate limits for [110 combinations thereof. The maximum von Mises stresses in cancellous and cortical bone of the treated vertebral body L3 and in bone cement were calculated. The loading cases standing, flexion, extension, lateral bending, axial rotation and walking were simulated. In a subsequent sensitivity analysis, the coefficients of correlation and determination of the input parameters on the von Mises stresses were calculated. The loading case has a strong influence on the maximum von Mises stress. In cancellous bone, the median value of the maximum von Mises stresses for the different input parameter combinations varied between 1.5 (standing) and 4.5 MPa (flexion). The ranges of the stresses are large for all loading cases studied. Depending on the loading case, up to 69% of the maximum stress variation could be explained by the seven input parameters. The fracture shape and the elastic modulus of the fractured region have the highest influence. In cortical bone, the median values of the maximum von Mises stresses varied between 31.1 (standing) and 61.8 MPa (flexion). The seven input parameters could explain up to 80% of the stress variation here. It is the fracture shape, which has always the highest influence on the stress variation. In bone cement, the median value of the maximum von Mises stresses varied between 3.8 (standing) and 12.7 MPa (flexion). Up to 75% of the maximum stress variation in cement could be explained by the seven input parameters. Fracture shape, and the elastic moduli of bone cement and of the fracture region are those input parameters with the highest influence on the stress variation. In the model with no fracture, the maximum von Mises stresses are generally low. The present probabilistic and sensitivity study clearly showed that in vertebroplasty the maximum stresses in the augmented vertebral body and in bone cement depend mainly on the loading case and fracture shape. Elastic moduli of cement, fracture region and cancellous bone as well as cement volume have sometimes a moderate effect while number and symmetry of cement plugs have virtually no effect on the maximum stresses.

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“…Pérez-Higueras et al [16] observed 13 patients after vertebroplasty: three patients (23%) developed four new vertebral fractures in which two (50%) were adjacent vertebrae. This may be the consequence of the natural course of osteoporosis since existing fractures are strong, independent predictors of the risk of future vertebral fracture [1,20]. But these fractures may also have been provoked by the rigid reinforcement of the adjacent vertebral body with PMMA cement.…”

Section: Introductionmentioning

confidence: 99%

Adjacent vertebral failure after vertebroplasty: a biomechanical study of low-modulus PMMA cement

et al. 2007

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PMMA is the most common bone substitute used for vertebroplasty. An increased fracture rate of the adjacent vertebrae has been observed after vertebroplasty. Decreased failure strength has been noted in a laboratory study of augmented functional spine units (FSUs), where the adjacent, non-augmented vertebral body always failed. This may provide evidence that rigid cement augmentation may facilitate the subsequent collapse of the adjacent vertebrae. The purpose of this study was to evaluate whether the decrease in failure strength of augmented FSUs can be avoided using low-modulus PMMA bone cement. In cadaveric FSUs, overall stiffness, failure strength and stiffness of the two vertebral bodies were determined under compression for both the treated and untreated specimens. Augmentation was performed on the caudal vertebrae with either regular or low-modulus PMMA. Endplate and wedge-shaped fractures occurred in the cranial and caudal vertebrae in the ratios endplate:wedge (cranial:caudal): 3:8 (5:6), 4:7 (7:4) and 10:1 (10:1) for control, low-modulus and regular cement group, respectively. The mean failure strength was 3.3 ± 1 MPa with low-modulus cement, 2.9 ± 1.2 MPa with regular cement and 3.6 ± 1.3 MPa for the control group. Differences between the groups were not significant (p = 0.754 and p = 0.375, respectively, for low-modulus cement vs. control and regular cement vs. control). Overall FSU stiffness was not significantly affected by augmentation. Significant differences were observed for the stiffness differences of the cranial to the caudal vertebral body for the regular PMMA group to the other groups (p \ 0.003). The individual vertebral stiffness values clearly showed the stiffening effect of the regular cement and the lesser alteration of the stiffness of the augmented vertebrae using the low-modulus PMMA compared to the control group (p = 0.999). In vitro biomechanical study and biomechanical evaluation of the hypothesis state that the failure strength of augmented functional spine units could be better preserved using low-modulus PMMA in comparison to regular PMMA cement.

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The effect on anterior column loading due to different vertebral augmentation techniques

Cited by 58 publications

References 22 publications

Differences in endplate deformation of the adjacent and augmented vertebra following cement augmentation

Differences in endplate deformation of the adjacent and augmented vertebra following cement augmentation

A probabilistic finite element analysis of the stresses in the augmented vertebral body after vertebroplasty

Adjacent vertebral failure after vertebroplasty: a biomechanical study of low-modulus PMMA cement

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