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Item type:Publication, Access status: with files , Distal cortical notching significantly decreases tibial stability following tibial tubercle osteotomy: an in vitro porcine biomechanical study(Wiley, 2026-07-17); ; ; ; Purpose: Distalizing tibial tubercle osteotomy (dTTO) is an effective treatment for patella alta, yet complications can be severe. This study evaluates the biomechanical effects of distal cut orientation on tibial fracture risk. It was hypothesised that orthogonal cutting and cortical notching reduce tibial stability. Methods: A total of 61 porcine tibiae were tested in three setups. Four distal cut orientations were compared in a load-to-failure analysis (n = 32): oblique (Obl), orthogonal without notch (Orth), orthogonal 2-mm notch (Orth2), orthogonal 4-mm notch (Orth4) (each n = 8). Cyclic loading was evaluated in Obl, Orth and Orth2 (n = 17), followed by comparison of plate versus (2-hole one-third tubular plate) 3.5-mm screw fixation in Orth2 specimens (n = 12). Specimens were embedded in PMMA and axially loaded (MTS Bionix 358). Load-to-failure, stiffness and cycles until failure were recorded. Residual tibial thickness was measured. Linear regression analysed the relationship between residual thickness and failure load. Statistical analysis included t-tests and ANOVA (α = 0.05). Results: Obl showed the highest failure load (784.5 N ± 118.3), although the difference compared to Orth (538.8 N ± 229.5, p = 0.087) did not reach statistical significance. Notching significantly reduced load-to-failure (2-mm: 294.0 N ± 91.8; 4 mm: 274.6 N ± 96.5). In cyclic testing, Obl withstood most cycles until failure (5894 ± 2187) compared to Orth (3142 ± 808; p = 0.004), while Orth2 failed sooner (1400 ± 530, all p < 0.005). Osteosynthesis techniques did not affect failure load (p = 0.802). Stiffness and residual tibial thickness were comparable. Distal tibial thickness was associated with failure load in all groups (all p < 0.05). Conclusion: In this porcine model, cortical notching significantly reduced tibial stability and should be avoided during TTO. Oblique distal cuts demonstrated greater resistance to cyclic loading, while no significant difference was observed in static load-to-failure. Osteosynthesis technique did not affect load-to-failure. Level of Evidence: NA, cadaveric biomechanical study.Publicationtype: Journal Article25 6 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Evaluation of the capability of the simulated dual energy X-ray absorptiometry-based two-dimensional finite element models for predicting vertebral failure loads(2019-07); ; ; ; Prediction of the vertebral failure load is of great importance for the prevention and early treatment of bone fracture. However, an efficient and effective method for accurately predicting the failure load of vertebral bones is still lacking. The aim of the present study was to evaluate the capability of the simulated dual energy X-ray absorptiometry (DXA)-based finite element (FE) model for predicting vertebral failure loads. Thirteen dissected spinal segments (T11/T12/L1) were scanned using a HR-pQCT scanner and then were mechanically tested until failure. The subject-specific three-dimensional (3D) and two-dimensional (2D) FE models of T12 were generated from the HR-pQCT scanner and the simulated DXA images, respectively. Additionally, the areal bone mineral density (aBMD) and areal bone mineral content (aBMC) of T12 were calculated. The failure loads predicted by the simulated DXA-based 2D FE models were more moderately correlated with the experimental failure loads (R2 = 0.66) than the aBMC (R2 = 0.61) and aBMD (R2 = 0.56). The 2D FE models were slightly outperformed by the HR-pQCT-based 3D FE models (R2 = 0.71). The present study demonstrated that the simulated DXA-based 2D FE model has better capability for predicting the vertebral failure loads than the densitometric measurements but is outperformed by the 3D FE model. The 2D FE model is more suitable for clinical use due to the low radiation dose and low cost, but it remains to be validated by further in vitro and in vivo studies.Publicationtype: Journal Article142 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Variogram-based evaluations of DXA correlate with vertebral strength, but do not enhance the prediction compared to aBMD alone(2018-08-22); ; ; ; Ancillary evaluation of spinal Dual-energy X-ray Absorptiometry (DXA) via variogram-based texture evaluation (e.g., Trabecular Bone Score) is used for improving the fracture risk assessment, despite no proven relationship with vertebral strength. The purpose of this study was thus to determine whether classical variogram-based parameters (sill variance and correlation length) evaluated from simulated DXA scans could help predicting the in vitro vertebral strength. Experimental data of thirteen human full vertebrae (i.e., with posterior elements) and twelve vertebral bodies were obtained from two existing studies. Areal bone mineral density (aBMD) was calculated from 2D projection images of the 3D HR-pQCT scan of the specimens mimicking clinical DXA scans. Stochastic predictors, sill variance and correlation length, were calculated from their experimental variogram. Vertebral strength was measured as the maximum failure load of human vertebrae and vertebral bodies from mechanical tests. Vertebral strength correlated significantly with sill variance (r = 0.727) and correlation length (r = 0.727) for the vertebral bodies, and with correlation length (r = 0.593) for full vertebrae. However, the stochastic predictors improved the strength prediction made by aBMD alone by only 11% for the vertebral bodies while no improvement was observed for the full vertebrae. Despite a correlation, classical variogram parameters such as sill variance and correlation length do not enhance the prediction of in vitro vertebral strength beyond aBMD. It remains unclear why some variogram-based evaluations of DXA improve fracture prediction without a proven relationship with vertebral strength.Publicationtype: Journal Article126 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , The initial slope of the variogram, foundation of the trabecular bone score, is not or is poorly associated with vertebral strength(Wiley, 2016-08-01); ; ; ; Trabecular bone score (TBS) rests on the textural analysis of dual-energy X-ray absorptiometry (DXA) to reflect the decay in trabecular structure characterizing osteoporosis. Yet, its discriminative power in fracture studies remains incomprehensible because prior biomechanical tests found no correlation with vertebral strength. To verify this result possibly owing to an unrealistic setup and to cover a wide range of loading scenarios, the data from three previous biomechanical studies using different experimental settings were used. They involved the compressive failure of 62 human lumbar vertebrae loaded 1) via intervertebral discs to mimic the in vivo situation ("full vertebra"); 2) via the classical endplate embedding ("vertebral body"); or 3) via a ball joint to induce anterior wedge failure ("vertebral section"). High-resolution peripheral quantitative computed tomography (HR-pQCT) scans acquired from prior testing were used to simulate anterior-posterior DXA from which areal bone mineral density (aBMD) and the initial slope of the variogram (ISV), the early definition of TBS, were evaluated. Finally, the relation of aBMD and ISV with failure load (F exp ) and apparent failure stress (σ exp ) was assessed, and their relative contribution to a multilinear model was quantified via ANOVA. We found that, unlike aBMD, ISV did not significantly correlate with F exp and σ exp , except for the "vertebral body" case (r 2 = 0.396, p = 0.028). Aside from the "vertebra section" setup where it explained only 6.4% of σ exp (p = 0.037), it brought no significant improvement to aBMD. These results indicate that ISV, a replica of TBS, is a poor surrogate for vertebral strength no matter the testing setup, which supports the prior observations and raises a fortiori the question of the deterministic factors underlying the statistical relationship between TBS and vertebral fracture risk.Publicationtype: Journal Article160 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Effects of long-term alendronate treatment on bone mineralisation, resorption parameters and biomechanics of single human vertebral trabeculae(University of Wales, 2014); ; ; ; Due to their well-established fracture risk reduction, bisphosphonates are the most frequently used therapeutic agent to treat osteoporosis. Bisphosphonates reduce fracture risk by suppressing bone resorption, but the lower bone turnover could have a negative impact on bone quality at the tissue level. Here, we directly assess the structural and mechanical characteristics of cancellous bone from the lumbar vertebrae (L5) in non-treated osteoporotic controls (n = 21), mid-term alendronate-treated osteoporotic patients (n = 6), and long-term alendronate-treated osteoporotic patients (n = 7). The strength and toughness of single trabeculae were evaluated, while the structure was characterised through measurements of microdamage accumulation, mineralisation distribution, and histological indices. The alendronate-treated cases had a reduced eroded surface (ES/BS, p < 0.001) and a higher bone mineralisation in comparison to non-treated controls (p = 0.037), which is indicative of low turnover associated with treatment. However, the amount of microdamage and the mechanical properties were similar among the control and treatment groups. As the tissue mineral density (TMD) increased significantly with alendronate treatment compared to non-treated osteoporotic controls, the reduction in resorption cavities could counterbalance the higher TMD allowing the alendronate-treated bone to maintain its mechanical properties and resist microdamage accumulation. A multivariate analysis of the possible predictors supports the theory that multiple factors (e.g., body mass index, TMD, and ES/BS) can impact the mechanical properties. Our results suggest that long-term alendronate treatment shows no adverse impact on mechanical cancellous bone characteristics.Publicationtype: Journal ArticleScopus© Citations 15 64 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , New horizons for the in vivo assessment of major aspects of bone quality(Thieme, 2013); ; ; ; The Biomechanically founded individualised osteoporosis Assessment and treatment (BioAsset) consortium pursues experimental and clinical studies in the context of skeletal effects of bisphosphonate treatment. Here, first results using newly developed diagnostic methods in a set of vertebral bone specimen obtained from donors with documented bisphosphonate history ranging from 0 to more than 5 years of treatment are presented. A new thoracolumbar quantitative computed tomography (QCT) protocol covering T6 to L4 plus high-resolution QCT (HRQCT) assessment of T12 were compared with high-resolution peripheral QCT (HRpQCT) and micro-CT scans of excised specimens serving as gold standard techniques. Finite element (FE) modelling was performed. Material, ultrastructural, and micromechanical properties were tested on a set of single trabeculae obtained from the donor specimens. A newly developed quantitative ultrasound (QUS) device for measuring the anisotropy of cortical material properties at the tibia was designed and built. The thoraco - lumbar QCT protocol permitted in situ imaging with good image quality and automated segmentation of vertebral bodies in the whole range from T6 to L4. The duration of bisphosphonate treatment was significantly associated with increased levels of mineralization and this effect could be measured with HRQCT performed on excised specimens. Microstructural parameters contributed to vertebral bone strength modelled by FE analysis independently of bone mineral density. The new QUS tibia scanner permitted measuring the acoustical anisotropy of reference materials. Taken together, these results document that new methods developed in BioAsset permit a more comprehensive assessment of bone fragility. The set of donor specimens with a documented history of bisphosphonate treatment allows for the assessment of the effects of long-term treatment from the organ down to the tissue and material level. These results will ultimately be linked to the parallel clinical study to provide guidance for determining the optimum duration of bisphosphonate treatment to reduce the incidence of osteoporotic fractures. © Schattauer 2013.Publicationtype: Journal Article133 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Cementation and interface analysis of early failure cases after hip-resurfacing arthroplasty(Springer, 2012-01-11); ; ; ; Purpose: The use of inappropriate cementation techniques has been suggested as an adverse factor for the long-term survival of hip-resurfacing arthroplasty. Inadequate initial fixation, thermal osteonecrosis and interface biological reactions are possible causes of failure. We analysed morphological changes associated with the cementation technique in a large collection of retrieved femoral components. Methods: One hundred and fifty femoral components (mean time to failure of 8.3 months±11.0) obtained at revision surgery were analysed morphometrically and histopathologically. Cement mantle and penetration were quantified in six different regions of interest. Histopathological analysis of the bone-cement interface was performed on undecalcified processed bone tissue. Results: The vast majority of the cases differed substantially from laboratory-based cement-penetration depth recommendations. Fifty-nine cases had a fibrous membrane at the cement-bone interface. This membrane was significantly thicker in cases with osteonecrosis compared to cases viable bone. Conclusions: Our results demonstrate that most failures were cemented inappropriately. We suggest that poor cementation was an important adverse factor; however, the cause of the failures was obviously multifactorial. The thickness of the fibrous membrane at the cement-bone interface differed significantly between cases with osteonecrosis and specimens with viable bone tissue.Publicationtype: Journal Article8 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , 9 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Improvements in the hip resurfacing surgical technique influence its failure pattern(Science and Education Publishing, 2012); ; ; ; Publicationtype: Journal Article3 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Analysis of retrieved hip resurfacing arthroplasties reveals the interrelationship between interface hyperosteoidosis and demineralization of viable bone trabeculae(Elsevier, 2011-12-16); ; ; ; Retrieved hip resurfacing arthroplasties (HRA) revised for causes other than osteonecrosis enable further insights into bone-cement interactions within the interface with only minimal biomechanical stresses. Our primary objective was to investigate the mineralization changes at the trabecular bone interface in retrieved hips using bright field and polarized light microscopy and by quantitative backscattered electron imaging. Because superficial seams of non-mineralized bone tissue varied substantially, we defined hyperosteoidosis as an osteoid seam of more than 20μm thickness. We hypothesized that interface hyperosteoidosis might be caused by the demineralization of previously mineralized bone tissue. One hundred and thirty-one retrieved HRAs with viable bone remnant tissue were analyzed. Bone mineral density distribution obtained from backscattered signal intensities of the trabecular bone at the bone-cement interface was assessed in cases with and without interface hyperosteoidosis. In cases with interface hyperosteoidosis, the degree of trabecular mineralization was also analyzed in deeper areas of the femoral remnants. Thirty-four cases showed hyperosteoidosis at the bone-cement interface, mostly in female patients. Bone trabeculae with hyperosteoidosis displayed a mineral density distribution pattern suggestive of the demineralization of a previously mineralized bone matrix. Our results demonstrate the localized disorder of the mineralization pattern of bone trabeculae at the bone-cement interface in a group of retrieved HRAs. In previously well-fixed femoral components, potential adverse effects on the load-bearing bone due to a decreased degree of mineralization at the bone-cement interface may affect the durability of the implant's function. © 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.Publicationtype: Journal Article185