Publication Date: 2025
The Archives Of Bone And Joint Surgery (23454644)13(10)pp. 607-610
Publication Date: 2025
The Archives Of Bone And Joint Surgery (23454644)13(8)pp. 497-508
Objectives: Radial head fractures often require prosthetic replacement, but post-surgical complications like radial neck osteolysis, capitellum osteopenia, and ulnohumeral osteoarthritis can arise due to altered elbow biomechanics. This study used the finite element method to evaluate how radial head prostheses (RHPs) shape and material affect elbow joint biomechanics. Methods: A 3D elbow model was developed, including bones, ligaments, and cartilage. Implants featuring two geometries (anatomical vs. axisymmetric) and three materials (polymethylmethacrylate [PMMA], polyether ether ketone [PEEK], and Cobalt) were tested. Bones were considered isotropic and heterogeneous, ligaments and implants linear elastic, and cartilages were considered hyperplastic materials. Stress distributions, contact stresses, and contact areas were assessed during elbow flexion and forearm rotation. Results: During forearm rotation, Cobalt RHPs exhibited lower stresses in the radial neck, indicating higher stress shielding, and all axisymmetric implants showed increased edge loadings. In rotation, only the PMMA anatomic RHP showed close contact stresses to the intact model, while all other models resulted in lower stress levels. In flexion, anatomical designs produced more uniform stress distributions in the radial neck that resembled intact conditions and matched intact capitellum contact stresses, in contrast to axisymmetric designs. The reduction in the contact area in the ulnohumeral cartilage was most noticeable with all axisymmetric RHPs in flexion. Conclusion: The lower contact areas, higher contact stresses, and lower stresses at the radial neck observed in the presence of most axisymmetric RHPs and anatomic Cobalt RHP can be correlated to postoperative complications. The findings suggest that polymeric anatomical RHPs may be superior to conventional metallic axisymmetric options in preserving elbow biomechanics and reducing postoperative complications. However, their long-term effects need to be further explored. Level of evidence: VI. © 2025 BY THE ARCHIVES OF BONE AND JOINT SURGERY and 2025 Mashhad University of Medical Sciences.
Publication Date: 2023
Computers in Biology and Medicine (00104825)167
Even though, proximal tibia is a common site of giant cell tumor and bone fractures, following tumor removal, nonetheless very little attention has been paid to affecting factors on the fracture risk. Here, nonlinear voxel-based finite element models based on computed tomography images were developed to predict bone fracture load with defects with different sizes, which were located in the medial, lateral, anterior, and posterior region of the proximal tibia. Critical defect size was identified using One-sample t-test to assess if the mean difference between the bone strength for a defect size was significantly different from the intact bone strength. Then, the defects larger than critical size were reconstructed with cement and the mechanics of the bone-cement interface (BCI) was investigated to find the regions prone to separation at BCI. A significant increase in fracture risk was observed for the defects larger than 20 mm, which were located in the medial, lateral and anterior regions, and defects larger than 25 mm for those located in the posterior region of the proximal tibia. Furthermore, it was found that the highest and lowest fracture risks were associated with defects located in the medial and posterior regions, respectively, highlighting the importance of selecting the initial location of a cortical window for tumor removal by the surgeon. The results of the BCI analysis showed that the location and size of the cement had a direct impact on the extent of damage and its distribution. Identification of critical regions susceptible to separation at BCI, can provide critical comments to surgeons in selecting the optimal cement augmentation technique, which may ultimately prevent unnecessary surgical intervention, such as using screws and pins. © 2023 Elsevier Ltd
Publication Date: 2021
The Archives Of Bone And Joint Surgery (23454644)9(1)pp. 1-4
Publication Date: 2020
Journal of Medical and Biological Engineering (16090985)40(4)
The article “The Great Need of a Biomechanical-Based Approach for Surgical Methods of Giant Cell Tumor: A Critical Review”, written by Azadeh Ghouchani, Gholamreza Rouhi was originally published Online First without open access. After publication in volume [37], issue [4], page [454–467] the author decided to opt for Open Choice and to make the article an open access publication. Therefore, the copyright of the article has been changed to © The Author(s) [2018] and the article is forthwith distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits use, duplication, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. © 2018, Taiwanese Society of Biomedical Engineering.
Publication Date: 2020
Scientific Reports (20452322)10(1)
The distal femur is the predominant site for benign bone tumours and a common site for fracture following tumour removal or cementation. However, the lack of conclusive assessment criterion for post-operative fracture risk and appropriate devices for cement augmentation are serious concerns. Hence, a validated biomechanical tool was developed to assess bone strength, depending on the size and location of artificially created tumorous defects in the distal femora. The mechanics of the bone–cement interface was investigated to determine the main causes of reconstruction failure. Based on quantitative-CT images, non-linear and heterogeneous finite element (FE) models of human cadaveric distal femora with simulated tumourous defects were created and validated using in vitro mechanical tests from 14 cadaveric samples. Statistical analyses demonstrated a strong linear relationship (R2 = 0.95, slope = 1.12) with no significant difference between bone strengths predicted by in silico analyses and in vitro tests (P = 0.174). FE analyses showed little reduction in bone strength until the defect was 35% or more of epiphyseal volume, and reduction in bone strength was less pronounced for laterally located defects than medial side defects. Moreover, the proximal end of the cortical window and the most interior wall of the bone–cement interface were the most vulnerable sites for reconstruction failure. © 2020, The Author(s).
Publication Date: 2020
Australasian Physical and Engineering Sciences in Medicine (18795447)
Lack of quantitative, biomechanical criteria to predict the risk of fracture for a bone affected by giant cell tumor (GCT) has made the decision for the necessary surgical technique a dilemma. The purpose of this study is to critically assess the usefulness of quantitative computed tomography (QCT) based structural rigidity analysis (QCSRA) and QCT-based finite element analysis (FEA) in predicting the fracture risk for long bones reconstructed with bone cement. QCSRA, QCT-based FEA, and in-vitro mechanical tests on five pairs of cadaveric distal femora were employed to quantitatively assess the compressive failure load of the human femur affected by GCT and reconstructed with bone cement. QCT was utilized to investigate the bone’s structural rigidity properties as well as to generate heterogeneous finite element models using written material mapping codes. In order to validate the QCSRA and QCT-based FEA results, their outcomes were compared with the results of in-vitro mechanical tests on human cadavers. Results of this study demonstrated an acceptable correlation between QCSRA fracture loads and fracture loads found in in-vitro mechanical tests on cadavers (R2 = 0.85). Also, QCSRA procedure is developed in order to estimate the axial stiffness and the maximum bending stiffness of the bone, employing the QCT-scans. It is shown that these two features, describing the structural rigidity, are linked to the experimental fracture loads (R2 = 0.72 for axial stiffness, R2 = 0.79 for maximum bending stiffness). Moreover, a good correlation was found between the fracture loads determined by QCT-based FEA and the experimental in-vitro fracture loads (R2 = 0.92). Results of this study confirm the usefulness of the applications of QCSRA and QCT-based FEA as clinically tools for predicting the failure load of a long bone. © 2020, Australasian College of Physical Scientists and Engineers in Medicine.
Publication Date: 2019
Computers in Biology and Medicine (00104825)112
Cement augmentation following benign bone tumor surgery, i.e. curettage and cementation, is recommended in patients at high risk of fracture. Nonetheless, identifying appropriate cases and devices for augmentation remains debatable. Our goal was to develop a validated biomechanical tool to: predict the post-surgery strength of a femoral bone, assess the precision and accuracy of the predicted strength, and discover the mechanisms of reconstruction failure, with the aim of finding a safe biomechanical fixation. Tumor surgery was mimicked in quantitative-CT (QCT) scanned cadaveric human distal femora, and subsequently tested in compression to measure bone strength (FExp). Finite element (FE) models considering bone material non-homogeneity and non-linearity were constructed to predict bone strength (FFE). Analyses of contact, damage, and crack initiation at the bone-cement interface (BCI) were completed to investigate critical failure locations. Results of paired t-tests did not show a significant difference between FExp and FFE (P > 0.05); linear regression analysis resulted in good correlation between FExp and FFE (R2 = 0.94). Evaluation of the models precision using linear regression analysis yielded R2 = 0.89, with the slope = 1.08 and intercept = −324.16 N. FE analyses showed the initiation of damage and crack and a larger cement debonding area at the proximal end and most interior part of BCI, respectively. Therefore, we speculated that devices that reinforce critical failure locations offer the most biomechanical advantage. The QCT-based FE method proved to be a reliable tool to predict distal femoral strength, identify some causes of reconstruction failure, and assist in a safer selection of fixation devices to reduce post-operative fracture risk. © 2019 Elsevier Ltd
Publication Date: 2018
The Archives Of Bone And Joint Surgery (23454644)6(2)pp. 85-89
Publication Date: 2017
Journal of Medical and Biological Engineering (16090985)37(4)pp. 454-467
There are many unanswered questions about giant cell tumor (GCT) treatment and not enough attention is paid to the biomechanics of the current treatment methods. Treatment methods have not changed much, and the best method remains controversial to some degree, due to the lack of adequate clinical and biomechanical investigations. Biomechanical tests, including in vitro mechanical experiments combined with finite element analysis, are very helpful in assessing the efficiency of the surgical methods employed and in determining the optimal method of surgery. Tests can be tailored to meet a patient’s needs, while limiting postoperative complications. One of the complications, following tumor surgery, is the frequency of postoperative fractures. In order to prevent postoperative fractures, defect reconstruction is recommended. The reconstruction usually consists of defect infilling with bone cement, and in the case of large defects cement augmentation is employed. Whether cement augmentation is essential and offers enough mechanical strength and what is the best fixation device for cement augmentation are areas of debate. In this article, the biomechanical studies comparing different methods of tumor surgery and cement augmentation, highlighting the areas needing more attention to advance GCT treatment, are critically reviewed. Based on our review, we recommend a biomechanical criterion for the essence of defect reconstruction, which must include patient specific factors, in addition to the tumor geometrical properties. © 2017, Taiwanese Society of Biomedical Engineering.
Publication Date: 2011
Iranian Journal of Medical Physics (17357241)8(2)
Introduction: Due to limitations of current treatments for degenerative disc disease, arthroplastic methods to repair the diseased disc have been proposed. The artificial disc is a mobile implant for degenerative disc replacement that attempts to lessen the degeneration of the adjacent elements following interbody fusion procedures. Because the success of artificial disc replacement depends on maintenance or restoration of the mechanical function of the intervertebral disc, it is useful to study the initial mechanical performance of the disc after implantation in the spine. Materials and Methods: A three-dimensional finite element model of the L3-L4 disc was analyzed. The model took into account the material nonlinearities and it imposed different loading conditions. In this study, we validated the model by comparison of its predictions with several sets of experimental data; we determined the optimal Young's modulus as well as the Poissan ratios for the artificial disc under different loading conditions. Results: The artificial disc was subjected to three loading conditions: 1) compression, 2) bending and 3) torsion. In each case, optimum elastic parameters were determined. Then, by using the root mean square method, optimum parameters for all loading conditions (and therefore minimum error) were calculated. Discussion and Conclusion: The results of this study suggest that a well-designed elastic arthroplastic disc preferably has Young's modulus values of 18.63 MPa and 1.19 MPa for the annulus and nucleus sections, respectively. Elastic artificial disc with such properties can then achieve the goal of restoring the disc height and mechanical function of a normal disc under different loading conditions.
Publication Date: 2011
Proceedings of SPIE - The International Society for Optical Engineering (1996756X)8285
A three-dimensional finite element model (FEM) of the L3-L4 motion segment using ABAQUS v 6.9 has been developed. The model took into account the material nonlinearities and is imposed different loading conditions. In this study, we validated the model by comparison of its predictions with several sets of experimental data. Disc deformation under compression and segmental rotational motions under moment loads for the normal disc model agreed well with the corresponding in vivo studies. By linking ABAQUS with MATLAB 2010.a, we determined the optimal Young s modulus as well as the Poisson's ratio for the artificial disc under different physiologic loading conditions. The results of the present study confirmed that a well-designed elastic arthroplastic disc preferably has an annulus modulus of 19.1 MPa and 1.24 MPa for nucleus section and Poisson ratio of 0.41 and 0.47 respectively. Elastic artificial disc with such properties can then achieve the goal of restoring the disc height and mechanical function of intact disc under different loading conditions and so can reduce low back pain which is mostly caused due to disc degeneration. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).
