Bio-Medical Materials and Engineering - Volume 29, issue 4
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The aim of
Bio-Medical Materials and Engineering is to promote the welfare of humans and to help them keep healthy. This international journal is an interdisciplinary journal that publishes original research papers, review articles and brief notes on materials and engineering for biological and medical systems.
Articles in this peer-reviewed journal cover a wide range of topics, including, but not limited to: Engineering as applied to improving diagnosis, therapy, and prevention of disease and injury, and better substitutes for damaged or disabled human organs; Studies of biomaterial interactions with the human body, bio-compatibility, interfacial and interaction problems; Biomechanical behavior under biological and/or medical conditions; Mechanical and biological properties of membrane biomaterials; Cellular and tissue engineering, physiological, biophysical, biochemical bioengineering aspects; Implant failure fields and degradation of implants. Biomimetics engineering and materials including system analysis as supporter for aged people and as rehabilitation; Bioengineering and materials technology as applied to the decontamination against environmental problems; Biosensors, bioreactors, bioprocess instrumentation and control system; Application to food engineering; Standardization problems on biomaterials and related products; Assessment of reliability and safety of biomedical materials and man-machine systems; and Product liability of biomaterials and related products.
Abstract: Background: Contemporary total knee arthroplasty (TKA) provides remarkable clinical benefits. However, the normal function of the knee is not fully restored. Recent improvements in imaging and manufacturing have utilized the development of customized design to fit the unique shape of individual patients. Objective: The purpose of the present study is to investigate the preservation of normal knee biomechanics by using specific articular surface conformity in customized posterior stabilized (PS)-TKA. Methods: This includes customized PS-TKA, PS-TKA with conforming conformity (CPS-TKA), medial pivot conformity with PS-TKA (MPS-TKA), and PS-TKA with mimetic anatomy femoral and tibial articular surface (APS-TKA).…In this study, kinematics, collateral ligament force and quadriceps force were evaluated using a computational simulation under a deep knee bend condition. Results: A conventional TKA did not provide the normal internal tibial rotation with flexion leading to abnormal femoral rollback. The APS-TKA exhibited normal-like femoral rollback kinematics but did not exhibit normal internal tibial rotation. However, APS-TKA exhibited the most normal-like collateral ligament and quadriceps forces. Conclusions: Although the APS-TKA exhibited more normal-like biomechanics, it did not restore normal knee biomechanics owing to the absence of the cruciate ligament and post-cam mechanism.
Keywords: Patient-specific implant, total knee arthroplasty, conformity, finite element analysis
Abstract: The goal of the study was to determine material constants of cancellous tissue in a compression test taking into account stress-strain characteristics. The nineteen test samples were resected from a femoral head of a patient qualified for a hip replacement surgery. During the compression tests, load-displacement curves were evaluated and stress-strain characteristics (𝜎-𝜀) of the cancellous bone tissue were calculated. A special one-touch extensometer was used. The use of an extensometer improves the displacement measurement accuracy with respect to the measurement using standard crosshead. The obtained values of the mechanical parameters as well as the stress-strain curves are the basis…for further research going into the development of bone tissue constitutive equations.
Abstract: BACKGROUND: In vitro evaluation of cell–surface interactions for hard tissue implants have mostly been done using osteoblasts. However, when an implant is placed in the body, mesenchymal stem cells (MSCs) play a major role in new bone formation. Therefore, using MSCs in cell-surface investigations may provide more reliable information on the prediction of in vivo behavior of implants. OBJECTIVE: In this study, Mg doped TiN coatings ((Ti,Mg)N) were prepared and tested for their effect on MSC differentiation and mineralization. METHODS: MSCs were isolated from rat bone marrow (rBMSCs) and seeded onto bare Ti, TiN…and Mg containing (Ti,Mg)N surfaces. Cell proliferation, osteogenic differentiation (collagen type 1, alkaline phosphatase activity), calcium phosphate deposition (von Kossa staining, Scanning Electron Microscopy) analysis were conducted. RESULTS: Differentiation towards osteoblast lineage was significantly improved with the increment in Mg presence. Collagen type I deposition, mineralization, and the ALP activity were higher on high Mg containing (>10 at% Mg) surfaces but differentiation of rBMSCs were found to be delayed. CONCLUSIONS: Mg presence affected rBMSCs proliferation and differentiation positively in a dose-dependent manner. However, high Mg amounts delayed both proliferation and differentiation.
Abstract: BACKGROUND: The swelling properties and the drug-release sustainability of pre-gelatinized starches (𝛼-starch) tablets depend on the polymer characteristics. OBJECTBS: In order to clarify the drug release form, the natural polymers (NPs) were investigated. The relationship between drug release and swelling of natural polymers (NPs), the swelling processes of various starch polymers, were investigated using a drug-release test (DRT) and X-ray computed tomography (XCT). NPs consisting of various starches such as glutinous rice starch (GRS), corn starch (CS), and tapioca starch (TS) were used as additives for sustained drug-release tablets. Tablets consisted of 5% theophylline, 94% 𝛼-starch, and 1%…magnesium stearate and were compressed at 6 kN. DRTs were measured in distilled water at 37 °C, and the drug concentrations were measured using UV (271 nm). Swelling ratio (R ) profiles of the tablets during DRTs were evaluated based on XCT images. RESULTS: The order of the drug-release rate constant of the tablets was TS < GRS < CS. XCT images of the tablets were measured during the DRTs, and CS, GRS, and TS tablets swelled and showed increased gel-layers, and then finally disintegrated at 6, 9, and 11 h, respectively. CONCLUSION: The relationship between R profile and the % drug release of the tablets differed depending on the kind of NP used.
Abstract: The main advantage of a theoretical approach is essential knowledge of the mechanisms that allow us to comprehend the experimental conditions that we have to fulfill to be able to get the desired results. Based on our research in ultrathin crystal structures performed so far, superlattices, Q-wires and Q-dots, we will consider the materials that can act as carriers for medicines and tagged substances. For this purpose we established a shell-model of ultrathin crystals and investigated their fundamental characteristics. This could be considered as a form of nano-engineering. In this paper we will analyze application of nanomaterials in biomedicine, that…is to say we will present the recent accomplishments in basic and clinical nanomedicine. Achieving full potential of nanomedicine may be years or even decades away, however, potential advances in drug delivery, diagnosis, and development of nanotechnology-related drugs start to change the landscape of medicine. Site-specific targeted drug delivery (made possible by the availability of unique delivery platforms, such as dendrimers, nanoparticles and nanoliposomes) and personalized medicines (result of the advance in pharmacogenetics) are just a few concepts on the horizon of research. In this paper, especially, we have analyzed the changes in basic physical properties of spherical-shaped nanoparticles that can be made in several (nano)layers and have, at the same time, multiple applications in medicine. This paper presents a review of our current achievement in the field of theoretical physics of ultrathin films and possible ways to materialize the same in the field of nanopharmacy.
Keywords: Nanotechnology, nanomedicine, core-shells model, ultrathin film layers, drug deliveries
Abstract: BACKGROUND: Unilateral external fixators are widely used in orthopedics to stabilize fractured bones and in the treatment of limb deformities. The main value for evaluation of mechanical stability of the external fixator is fixator stiffness. The fixator stiffness is an important factor as it will influence the biomechanical environment to which fixator and regenerating tissues are exposed. OBJECTIVE: The main objective of this work was to monitor the transmission of stress and the change of displacement generated in fixator-bone system under three loading conditions during healing process. METHODS: In this study, a finite element model with…changing Young’s modulus of the callus is established, finite element analysis was used to investigating stress and deformation of fixator-bone system caused by axial load, torsional load and bending load during three healing stages. RESULTS: The results reveal that at different healing stages, stress distribution between the fixator and fractured bone is different, the position of displacement is mainly concentrated in the fracture site and proximal bone and with the increase of healing time, the deformation decreased. CONCLUSIONS: This work helps orthopedic doctors to monitor the progression of fracture healing and determine the appropriate time for removal of a fixation device and provide useful information.
Abstract: BACKGROUND: Lumbar spinal fusion in the interbody space is augmented with interbody fusion cages to provide structural support while arthrodesis occurs. Subsidence is a serious complication of interbody fusion. However, the biomechanical influence of anterior longitudinal ligament (ALL) and pedicle screws on subsidence has not been fully understood. OBJECTIVE: To investigate biomechanical effects of the hyperlordotic cages in different surgical conditions using finite element analysis. METHODS: Four surgical finite element (FE) models were constructed by inserting 15 degree lordosis cage at the L3-L4 disc space. The four surgical conditions were ALL intact (M1), ALL resected (M2),…ALL intact and bilateral pedicle screws (M3), and ALL resected and bilateral pedicle screws (M4). Follow loads were applied at the L2 vertebral body while the inferior surface of L5 was fixed. FEA was implemented to simulate the four motion modes and biomechanical properties of four fusion scenarios with hyperlordotic interbody cage were compared. RESULTS: The range of motion (ROM) and facet joint force (FJF) at L3-L4 decreased significantly after fusion during all the motion modes. The cage stress and endplate stress at L3-L4 increased significantly after fusion during all the motion modes. The cage stress and endplate stress at L3-L4 for M3 and M4 were smaller than that for M1 and M2 during all the motion modes. The FJF at L3-L4 for M3 and M4 were smaller than that for M1 and M2 during extension, bending, and rotation. CONCLUSIONS: ALL has little effect on the biomechanics after lumbar fusion with hyperlordotic interbody cage. The bilateral pedicle screws significantly decreased the stress in cage, stress in endplate at L3-L4, and lowered facet contact force except for flexion mode. The implication is that the supplemental bilateral pedicle screws are recommended whether or not the ALL is resected.
Keywords: Lumbar spine, biomechanics, lumbar fusion, hyperlordotic interbody cage, finite element analysis (FEA), bilateral pedicle screws, anterior longitudinal ligament (ALL), range of motion (ROM), subsidence, facet contact force
Abstract: BACKGROUND: The surrogate design and clinical diagnostic suggest that the pelvic dynamic response should be the basis of bone fracture mechanism study under side impact. Pelvic response indicators are the impact force, compression (C), viscous criterion (VC), bone stress, and bone strain. However, no evaluation of these indicators has been conducted. OBJECTIVE: To evaluate pelvic response indicators under side impact. METHODS: A sitting pelvic finite element (FE) complex model comprising bone, artery, ligaments, and soft tissue was constructed. The dynamic response of the model under side impact with initial velocity of 3 m/s was investigated and…material sensitivity analysis was complemented by changing bone elastic modulus. RESULTS: The pelvic FE model could predict response under side impact. Specifically, the indicators such as artery pressure and strain, together with the ligaments axial force and strain were provided. The sensitivity analysis showed the impact force, bone stress, and axial force were sensitive to the elastic modulus, whereas, C, VC, bone strain, and artery pressure were not. CONCLUSIONS: The sitting FE model in this study can predict pelvic dynamic response, and C, VC, bone strain and artery pressure are proposed for pelvic tolerance instead of impact force under side impact.
Keywords: Pelvic complex, side impact, dynamic response, material sensitivity analysis, finite element method
Abstract: BACKGROUND. The load transfer between the implant-bone interface depends on various factors, including loading type; material properties of the implant and prosthesis; and implant geometry, length, diameter, and shape. OBJECTIVE. The purpose of this study was to evaluate stress distribution in single tilted bone-level implants with different connections and peripheral bone under vertical and oblique loads using three-dimensional (3D) finite element analysis (FEA). METHOS. 3D models of four different implant systems and their abutments were created from the data (computer-aided design) of original implants and abutments scanned with an optical scanner. The implants were placed in…the bone block at degrees of 0°, 15°, and 30°. Then, a 3D model of the metal-ceramic crown was created and a 100-N total load was applied vertically and obliquely. RESULTS. Stress analyses showed variable results depending on the connection design and tilting angle; however, the tube in tube (TIT) connection type exhibited lower stress values in most loading and tilting simulations. CONCLUSIONS. Increase in tilting angle showed variable results in each connection design. The TIT connection design was found to be more successful in terms of stress distributions in the implant components and the peripheral bone.
Abstract: The pulse wave velocity (PWV) has been shown to be associated with the properties of blood vessel and a cardiovascular risk factor such as aneurysm. The global PWV estimation is applied in conventional clinical diagnosis. However, the geometry of blood vessel changes along the wave traveling path and the global PWV estimation may not always detect regional wall changes resulting from cardiovascular diseases. In this study, a fluid structure interaction (FSI) analysis was applied on arch-shaped aortas with and without aneurysm aimed at determining the effects of the number of aneurysm, aneurysm size and the modulus ratio (aneurysm to wall…modulus) on the pulse wave propagation and velocity. The characterization for each stage of aneurysmal aorta was simulated by progressively increasing aortic stiffness and aneurysm size. The pulse wave propagations and velocities were estimated from the two-dimensional spatial-temporal plot of the normalized wall displacement based on elastic deformation. The descending forward and arch reflected PWVs of aneurysmal aortic arch models were found up to 9.7% and 122.8%, respectively, deviate from the PWV of non-aneurysmal aortic arch model. The PWV patterns and magnitudes can be used to distinguish the characterization of the normal and aneurysmal aortic walls and shown to be relevant regional markers utilized in clinical diagnosis.