The trapezium shape of the talar dome limits the use of 2-dimensional plain radiography for morphometric assessment because only 2 of the 4 required parameters can be measured. We used computed tomography data to measure the 4 morphologic parameters of the trochlea tali: anterior width, posterior width, trochlea tali length, and angle of trapezium shape. A total of 99 subjects underwent computed tomography scanning, and the left and right talus bones were both virtually modeled in 3 dimensions. The 4 morphologic parameters were measured 3 times each to obtain the intraclass correlation, and analysis of variance was used to check for any significant differences between the repeated measurements. The average intraclass correlation coefficient for the measurements for 2 to 3 trials was 0.94 ± 0.04. Statistical analyses were performed on the data from all 198 talus bones using SAS software, comparing male and female and left and right bones. All 4 morphometric values were greater in the male group. No significant differences were found between the left and right talus bones. A strong positive correlation was observed between the trochlea tali length and the anterior width. The angle of trapezium shape showed no correlation with the other 3 parameters. The measurements were compared with the dimensions of the current talar components of 4 total ankle arthroplasty implants. However, most of them did not perfectly match the trapezium shape of the talus from our population. We successfully analyzed the trapezium shape of the trochlea tali using reliable virtual 3-dimensional measurements. Compared with other published reports, our study showed a relatively smaller dimension of the trochlea tali than the European counterparts.
Scaffolds have been utilized in tissue regeneration to facilitate the formation and maturation of new tissues or organs where a balance between temporary mechanical support and mass transport (degradation and cell growth) is ideally achieved. Polymers have been widely chosen as tissue scaffolding material having a good combination of biodegradability, biocompatibility, and porous structure. Metals that can degrade in physiological environment, namely, biodegradable metals, are proposed as potential materials for hard tissue scaffolding where biodegradable polymers are often considered as having poor mechanical properties. Biodegradable metal scaffolds have showed interesting mechanical property that was close to that of human bone with tailored degradation behaviour. The current promising fabrication technique for making scaffolds, such as computation-aided solid free-form method, can be easily applied to metals. With further optimization in topologically ordered porosity design exploiting material property and fabrication technique, porous biodegradable metals could be the potential materials for making hard tissue scaffolds.
The use of open wedge high tibial osteotomy (HTO) to correct varus deformity of the knee is well established. However, the stability of the various implants used in this procedure has not been previously demonstrated. In this study, the two most common types of plates were analysed (1) the Puddu plates that use the dynamic compression plate (DCP) concept, and (2) the Tomofix plate that uses the locking compression plate (LCP) concept. Three dimensional model of the tibia was reconstructed from computed tomography images obtained from the Medical Implant Technology Group datasets. Osteotomy and fixation models were simulated through computational processing. Simulated loading was applied at 60:40 ratios on the medial:lateral aspect during single limb stance. The model was fixed distally in all degrees of freedom. Simulated data generated from the micromotions, displacement and, implant stress were captured. At the prescribed loads, a higher displacement of 3.25 mm was observed for the Puddu plate model (p<0.001). Coincidentally the amount of stresses subjected to this plate, 24.7 MPa, was also significantly lower (p<0.001). There was significant negative correlation (p<0.001) between implant stresses to that of the amount of fracture displacement which signifies a less stable fixation using Puddu plates. In conclusion, this study demonstrates that the Tomofix plate produces superior stability for bony fixation in HTO procedures.
This paper describes the fabrication of microfluidic cloth-based analytical devices (μCADs) using a simple wax patterning method on cotton cloth for performing colorimetric bioassays. Commercial cotton cloth fabric is proposed as a new inexpensive, lightweight, and flexible platform for fabricating two- (2D) and three-dimensional (3D) microfluidic systems. We demonstrated that the wicking property of the cotton microfluidic channel can be improved by scouring in soda ash (Na(2)CO(3)) solution which will remove the natural surface wax and expose the underlying texture of the cellulose fiber. After this treatment, we fabricated narrow hydrophilic channels with hydrophobic barriers made from patterned wax to define the 2D microfluidic devices. The designed pattern is carved on wax-impregnated paper, and subsequently transferred to attached cotton cloth by heat treatment. To further obtain 3D microfluidic devices having multiple layers of pattern, a single layer of wax patterned cloth can be folded along a predefined folding line and subsequently pressed using mechanical force. All the fabrication steps are simple and low cost since no special equipment is required. Diagnostic application of cloth-based devices is shown by the development of simple devices that wick and distribute microvolumes of simulated body fluids along the hydrophilic channels into reaction zones to react with analytical reagents. Colorimetric detection of bovine serum albumin (BSA) in artificial urine is carried out by direct visual observation of bromophenol blue (BPB) colour change in the reaction zones. Finally, we show the flexibility of the novel microfluidic platform by conducting a similar reaction in a bent pinned μCAD.
There is an increased interest in the use of polyether ether ketone (PEEK) for orthopedic and dental implant applications due to its elastic modulus close to that of bone, biocompatibility, and its radiolucent properties. However, PEEK is still categorized as bioinert due to its low integration with surrounding tissues. Many studies have reported on methods to increase the bioactivity of PEEK, but there is still one-preparation method for preparing bioactive PEEK implant where the produced implant with desirable mechanical and bioactivity properties is required. The aim of this review is to present the progress of the preparation methods for improvement of the bioactivity of PEEK and to discuss the strengths and weaknesses of the existing methods.
Fatigue assessment of the trabecular bone has been developed to give a better understanding of bone properties. While most fatigue studies are relying on uniaxial compressive load as the method of assessment, in various cases details are missing, or the uniaxial results are not very realistic. In this paper, the effect of three different load histories from physiological loading applied on the trabecular bone were studied in order to predict the first failure surface and the fatigue lifetime. The fatigue behaviour of the trabecular bone under uniaxial load was compared to that of multiaxial load using a finite element simulation. The plastic strain was found localized at the trabecular structure under multiaxial load. On average, applying multiaxial loads reduced more than five times the fatigue life of the trabecular bone. The results provide evidence that multiaxial loading is dominated in the low cycle fatigue in contrast to the uniaxial one. Both bone volume fraction and structural model index were best predictors of failure (p
In an open fracture, the external fixator is one of the definitive treatment options as it could provide the initial stabilisation of the fractured bone. Limited literature discussing on the biomechanical stability between unilateral, hybrid and Ilizarov configurations, principally in treating a femoral fracture. Thus, this study aims to analyse the biomechanical stability of different external fixators via the finite element method (FEM). The present study portrays that different configurations of fixators possess different biomechanical stability, hence leading to different healing rates and complication risks. For the methodology, three-dimensional models of three different external fixators were reconstructed where axial loads were applied on the proximal end of the femur, simulating the stance phase. From the results, the unilateral configuration provides better stability compared to the hybrid and Ilizarov, where it displaced the least with an average percentage difference of 50% for the fixator's frame and 23% for the bone. The unilateral configuration also produced the least interfragmentary movement (0.48 mm) as compared to hybrid (0.62 mm) and Ilizarov (0.61 mm) configurations. Besides, the strain and stress of the unilateral configuration were superior in terms of stability compared to the other two configurations. As a conclusion, the unilateral configuration had the best biomechanical stability as it was able to assist the bone healing process as well as minimising the risk of pin tract infection while treating a femoral fracture.
External fixators have been widely used in treating open fractures and have produced excellent outcomes, as they could successfully heal bones. The stability of external fixators lies greatly in their construction. Factors that associated with the stability of the external fixators includes stress, displacement, and relative micromotion. Three-dimensional (3D) models of bone and external fixators were constructed by using 3D modelling software, namely Materialise and SolidWorks, respectively. Three different configurations of external fixators namely Model 1, Model 2, and Model 3 were analysed. Three load cases were simulated to assess the abovementioned factors at the bone, specifically at the fracture site and at the external fixator. Findings showed that the double-cross configuration (Model 3) was the most promising in axial, bending, and torsion load cases as compared to the other two configurations. The no-cross configuration (Model 1) had the highest risk of complication due to high stress, relative micromotion, and displacement in the bending and torsion load cases. On the other hand, the single-cross configuration (Model 2) had the highest risk of complication when applied with axial load. In conclusion, the double-cross locking construct (Model 3) showed the biggest potential to be a new option for medical surgeons in treating patients associated with bone fracture. This new double-cross locking construct showed superior biomechanical stability as compared to single-cross and no-cross configurations in the axial, bending, and torsion load cases.
Osteoporosis and osteoarthritis are common pathological problems of the human bone tissue. There are some cases of pilon fractures associated with these 2 pathological conditions. In terms of treatment, for a normal and healthy bone with pilon fracture, the use of the Delta external fixator is a favorable option because it can allow early mobilization for patients and provide stability for the healing process. However, the stability of the external fixator differs when there is low bone stiffness, which has not been previously investigated. Therefore, this study was conducted to determine the stability of the external fixator to treat pilon fracture associated with osteoporosis and osteoarthritis, particularly to differentiate the stress distribution and micromovement of fracture fragment. Three-dimensional finite element models of the ankle and foot bones were reconstructed based on the computed tomography datasets. The bones consisted of 5 metatarsal, 3 cuneiform, and 1 each of cuboid, navicular, calcaneus, talus, fibula, and tibia bones. They were assigned with linear isotropic behavior. The ankle joint consisted of ligament and cartilage, and they were assigned with the use of linear links and the Mooney-Rivlin model, respectively. During simulation of the gait cycle, 70 N and 350 N were applied axially to the tibia bone to represent the swing and stance phases, respectively. The metatarsal and calcaneus bones were fixed to prevent any movement of the rigid body. The study found that the greatest von Mises stress value was observed at the pin-bone interface for the osteoporosis (108 MPa) model, followed by the osteoarthritis (87 MPa) and normal (44 MPa) models, during the stance phase. For micromovement, the osteoporosis model had the largest value at 0.26 mm, followed by the osteoarthritis (0.09 mm) and normal (0.03 mm) models. In conclusion, the greatest magnitudes of stress and micromovement were observed for the osteoporosis bone and extra care should be taken to treat pilon fracture associated with this pathological condition.
Complication rates of anterior cruciate ligament reconstruction (ACL-R) were reported to be around 15% although it is a common arthroscopic procedure with good outcomes. Breakage and migration of fixators are still possible even months after surgery. A fixator with optimum stability can minimise those two complications. Factors that affect the stability of a fixator are its configuration, material, and design. Thus, this paper aims to analyse the biomechanical effects of different types of fixators (cross-pin, interference screw, and cortical button) towards the stability of the knee joint after ACL-R. In this study, finite element modelling and analyses of a knee joint attached with double semitendinosus graft and fixators were carried out. Mimics and 3-Matic softwares were used in the development of the knee joint models. Meanwhile, the graft and fixators were designed by using SolidWorks software. Once the meshes of all models were finished in 3-Matic, simulation of the configurations was done using MSC Marc Mentat software. A 100-N anterior tibial load was applied onto the tibia to simulate the anterior drawer test. Based on the findings, cross-pin was found to have optimum stability in terms of stress and strain at the femoral fixation site for better treatment of ACL-R.
Immobilization of chlorhexidine (CHX) on stainless steel 316L (SS316L), assisted by a polydopamine film as an intermediate layer is projected as an approach in combating infection while aiding bone regeneration for coating development on orthopedic and dental implants. This study aimed to investigate the ability of CHX coating to promote apatite layer, osteoblast cells viability, adhesion, osteogenic differentiation and mineralization. Stainless steel 316L disks were pre-treated, grafted with a polydopamine film and immobilized with different concentrations of CHX (10-30mM). The apatite layer formation was determined through an in vitro simulated body fluid (SBF) test by ATR-FTIR and SEM-EDX analyses. The osteoblastic evaluations including cells viability, cells adhesion, osteogenic differentiation and mineralization were assessed with human fetal osteoblast cells through MTT assay, morphology evaluation under FESEM, ALP enzyme activity and Alizarin Red S assay. The apatite layer was successfully formed on the CHX coated disks, demonstrating potential excellent bioactivity property. The CHX coatings were biocompatible with the osteoblast cells at low CHX concentration (<20mM) with good adhesion on the metal surfaces. The increment of ALP activity and calcium deposition testified that the CHX coated disks able to support osteoblastic maturation and mineralization. These capabilities give a promising value to the CHX coating to be implied in bone regeneration area.
Glenoid conformity is one of the important aspects that could contribute to implant stability. However, the optimal conformity is still being debated among the researchers. Therefore, this study aims to analyze the stress distribution of the implant and cement in three types of conformity (conform, non-conform, and hybrid) in three load conditions (central, anterior, and posterior). Glenoid implant and cement were reconstructed using Solidwork software and a 3D model of scapula bone was done using MIMICS software. Constant load, 750 N, was applied at the central, anterior, and posterior region of the glenoid implant which represents average load for daily living activities for elder people, including, walking with a stick and standing up from a chair. The results showed that, during center load, an implant with dual conformity (hybrid) showed the best (Max Stress-3.93 MPa) and well-distributed stress as compared to other conformity (Non-conform-7.21 MPa, Conform-9.38 MPa). While, during eccentric load (anterior and posterior), high stress was located at the anterior and posterior region with respect to the load applied. Cement stress for non-conform and hybrid implant recorded less than 5 MPa, which indicates it had a very low risk to have cement microcracks, whilst, conform implant was exposed to microcrack of the cement. In conclusion, hybrid conformity showed a promising result that could compromise between conform and non-conform implant. However, further enhancement is required for hybrid implants when dealing with eccentric load (anterior and posterior).
An accurate measurement of intrinsic hand muscle strength (IHMS) is required by clinicians for effective clinical decision-making, diagnosis of certain diseases, and evaluation of the outcome of treatment. In practice, the clinicians use Intrins-o-meter and Rotterdam Intrinsic Hand Myometer for IHMS measurement. These are quite bulky, expensive, and possess poor interobserver reliability (37-52%) and sensitivity. The purpose of this study was to develop an alternative lightweight, accurate, cost-effective force measurement device with a simple electronic circuit and test its suitability for IHMS measurement. The device was constructed with ketjenblack/deproteinized natural rubber sensor, 1-MΩ potential divider, and Arduino Uno through the custom-written software. Then, the device was calibrated and tested for accuracy and repeatability within the force range of finger muscles (100 N). The 95% limit of agreement in accuracy from -1.95 N to 2.06 N for 10 to 100 N applied load and repeatability coefficient of ±1.91 N or 6.2% was achieved. Furthermore, the expenditure for the device construction was around US$ 53. For a practical demonstration, the device was tested among 16 participants for isometric strength measurement of the ulnar abductor and dorsal interossei. The results revealed that the performance of the device was suitable for IHMS measurement.
The main failure factors of cortical bone are aging or osteoporosis, accident and high energy trauma or physiological activities. However, the mechanism of damage evolution coupled with yield criterion is considered as one of the unclear subjects in failure analysis of cortical bone materials. Therefore, this study attempts to assess the structural response and progressive failure process of cortical bone using a brittle damaged plasticity model. For this reason, several compressive tests are performed on cortical bone specimens made of bovine femur, in order to obtain the structural response and mechanical properties of the material. Complementary finite element (FE) model of the sample and test is prepared to simulate the elastic-to-damage behavior of the cortical bone using the brittle damaged plasticity model. The FE model is validated in a comparative method using the predicted and measured structural response as load-compressive displacement through simulation and experiment. FE results indicated that the compressive damage initiated and propagated at central region where maximum equivalent plastic strain is computed, which coincided with the degradation of structural compressive stiffness followed by a vast amount of strain energy dissipation. The parameter of compressive damage rate, which is a function dependent on damage parameter and the plastic strain is examined for different rates. Results show that considering a similar rate to the initial slope of the damage parameter in the experiment would give a better sense for prediction of compressive failure.
Distinctive bioactivities possessed by luteolin (3', 4', 5, 7-tetrahydroxy-flavone) are advantageous for sundry practical applications. This paper reports the in vitro selection and characterization of single stranded-DNA (ssDNA) aptamers, specific for luteolin (LUT). 76-mer library containing 1015 randomized ssDNA were screened via systematic evolution of ligands by exponential enrichment (SELEX). The recovered ssDNA pool from the 8th round was amplified with unlabeled primers and cloned into PSTBlue-1 vector prior to sequencing. 22 of LUT-binding aptamer variants were further classified into one of the seven groups based on their N40 random sequence regions, wherein one representative from each group was characterized. The dissociation constant of aptamers designated as LUT#28, LUT#20 and LUT#3 was discerned to be 107, 214 and 109 nM, respectively with high binding affinity towards LUT. Prediction analysis of the secondary structure suggested discrete features with typical loop and stem motifs. Furthermore, LUT#3 displayed higher specificity with insignificant binding toward kaempferol and quercetin despite its structural and functional similarity compared to LUT#28 and LUT#20. Further LUT#3 can detect free luteolin within 0.2-1 mM in solution. It was suggested that LUT#3 aptamer were the most suitable for LUT recognition tool at laboratory scale based on the condition tested.
Previous works had successfully demonstrated the clinical effectiveness of unilateral external fixator in treating various types of fracture, ranging from the simple type, such as oblique and transverse fractures, to complex fractures. However, literature that investigated its biomechanical analyses to further justify its efficacy is limited. Therefore, this paper aimed to analyse the stability of unilateral external fixator for treating different types of fracture, including the simple oblique, AO32C3 comminuted, and 20 mm gap transverse fracture. These fractures were reconstructed at the distal diaphysis of the femoral bone and computationally analysed through the finite element method under the stance phase condition. Findings showed a decrease in the fixation stiffness in large gap fracture (645.2 Nmm-1 for oblique and comminuted, while 23.4 Nmm-1 for the gap fracture), which resulted in higher displacement, IFM and stress distribution at the pin bone interface. These unfavourable conditions could consequently increase the risk of delayed union, pin loosening and infection, as well as implant failure. Nevertheless, the stress observed on the fracture surfaces was relatively low and in controlled amount, indicating that bone unity is still allowable in all models. Briefly, the unilateral fixation may provide desirable results in smaller fracture gap, but its usage in larger gap fracture might be alarming. These findings could serve as a guide and insight for surgeons and researchers, especially on the biomechanical stability of fixation in different fracture types and how will it affect bone unity.
Previous research has primarily focused on pre-processing parameters such as design, material selection, and printing techniques to improve the strength of 3D-printed prosthetic leg sockets. However, these methods fail to address the major challenges that arise post-printing, namely failures at the distal end of the socket and susceptibility to shear failure. Addressing this gap, the study aims to enhance the mechanical properties of 3D-printed prosthetic leg sockets through post-processing techniques. Fifteen PLA + prosthetic leg sockets are fabricated and reinforced with four materials: carbon fiber, carbon-Kevlar fiber, fiberglass, and cement. Mechanical and microstructural properties of the sockets are evaluated through axial compression testing and scanning electron microscopy (SEM). Results highlight superior attributes of cement-reinforced sockets, exhibiting significantly higher yield strength (up to 89.57% more than counterparts) and higher Young's modulus (up to 76.15% greater). SEM reveals correlations between microstructural properties and socket strength. These findings deepen the comprehension of 3D-printed prosthetic leg socket post-processing, presenting optimization prospects. Future research can focus on refining fabrication techniques, exploring alternative reinforcement materials, and investigating the long-term durability and functionality of post-processed 3D-printed prosthetic leg sockets.
In medical image segmentation, manual segmentation is considered both labor- and time-intensive while automated segmentation often fails to segment anatomically intricate structure accordingly. Interactive segmentation can tackle shortcomings reported by previous segmentation approaches through user intervention. To better reflect user intention, development of suitable editing functions is critical. In this paper, we propose an interactive knee cartilage extraction software that covers three important features: intuitiveness, speed, and convenience. The segmentation is performed using multi-label random walks algorithm. Our segmentation software is simple to use, intuitive to normal and osteoarthritic image segmentation and efficient using only two third of manual segmentation's time. Future works will extend this software to three dimensional segmentation and quantitative analysis.
Hydroxyapatite is used extensively in hard tissue repair due to its biocompatibility and similarity to biological apatite, the mineral component of bone. It differs subtly in composition from biological apatite which contains other ions such as magnesium, zinc, carbonate and silicon (believed to play biological roles). Traditional methods of hydroxyapatite synthesis are time consuming and require strict reaction parameter control. This paper outlines synthesis of magnesium substituted hydroxyapatite using simple microwave irradiation of precipitated suspensions. Microwave irradiation resulted in a drastic decrease in ageing times of amorphous apatitic phases. Time taken to synthesize hydroxyapatite (which remained stable upon heat treatment at 900°C for 1h) reduced twelve folds (to 2h) as compared to traditionally required times. The effects of increasing magnesium concentration in the precursors on particle size, surface area, phase-purity, agglomeration and thermal stability, were observed using scanning electron microscopy, BET surface area analysis, X-ray diffraction and photo acoustic Fourier transform infra-red spectroscopy. Porous agglomerates were obtained after a brief heat-treatment (1h) at 900°C.
This work reports the modification of freeze/thaw poly(vinyl alcohol) hydrogel using citric acid as the bioactive molecule for hydroxyapatite formation in simulated body fluid. Inclusion of 1.3 mM citric acid into the poly(vinyl alcohol) hydrogel showed that the mechanical strength, crystalline phase, functional groups and swelling ability were still intact. Adding citric acid at higher concentrations (1.8 and 2.3 mM), however, resulted in physically poor hydrogels. Presence of 1.3 mM of citric acid showed the growth of porous hydroxyapatite crystals on the poly(vinyl alcohol) surface just after one day of immersion in simulated body fluid. Meanwhile, a fully covered apatite layer on the poly(vinyl alcohol) surface plus the evidence of apatite forming within the hydrogel were observed after soaking for seven days. Gel strength of the soaked poly(vinyl alcohol)/citric acid-1.3 mM hydrogel revealed that the load resistance was enhanced compared to that of the neat poly(vinyl alcohol) hydrogel. This facile method of inducing rapid growth of hydroxyapatite on the hydrogel surface as well as within the hydrogel network can be useful for guided bone regenerative materials.