Displaying publications 1 - 20 of 46 in total

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  1. A finite element study: Finding the best configuration between unilateral, hybrid, and ilizarov in terms of biomechanical point of view
    Abd Aziz AU, Abdul Wahab AH, Abdul Rahim RA, Abdul Kadir MR, Ramlee MH
    Injury, 2020 Nov;51(11):2474-2478.
    PMID: 32798038 DOI: 10.1016/j.injury.2020.08.001
    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.
  2. Age estimation based on bone length using 12 regression models of left hand X-ray images for Asian children below 19 years old
    Darmawan MF, Yusuf SM, Abdul Kadir MR, Haron H
    Leg Med (Tokyo), 2015 Mar;17(2):71-8.
    PMID: 25456051 DOI: 10.1016/j.legalmed.2014.09.006
    Age estimation was used in forensic anthropology to help in the identification of individual remains and living person. However, the estimation methods tend to be unique and applicable only to a certain population. This paper analyzed age estimation using twelve regression models carried out on X-ray images of the left hand taken from an Asian data set for subjects under the age of 19. All the nineteen bones of the left hand were measured using free image software and the statistical analysis were performed using SPSS. There are two methods to determine age in this study which are single bone method and all bones method. For single bone method, S-curve regression model was found to have the highest R-square value using second metacarpal for males, and third proximal phalanx for females. For age estimation using single bone, fifth metacarpal from males and fifth proximal phalanx from females can be used due to the lowest mean square error (MSE) value. To conclude, multiple linear regressions is the best techniques for age estimation in cases where all bones are available, but if not, S-curve regression can be used using single bone method.
  3. Fulltext Anthropometric measurements of the human distal femur: a study of the adult Malay population
    Hussain F, Abdul Kadir MR, Zulkifly AH, Sa'at A, Aziz AA, Hossain G, et al.
    Biomed Res Int, 2013;2013:175056.
    PMID: 24294597 DOI: 10.1155/2013/175056
    The distal femurs of 100 subjects (50 men, 50 women) from the Malay population aged between 19 and 38 years were scanned to measure the anterior-posterior (AP) and medial-lateral (ML) width. The mean AP values were 64.02 ± 3.38 mm and 57.33 ± 3.26 mm for men and women, respectively, and the mean ML values were 74.91 ± 3.52 mm and 64.53 ± 3.07 mm. We compared our data to that published previously for the Chinese and Indian populations. It was found that the Malay population had smaller distal femur than that of the Chinese but was larger than that of the Indian population (P < 0.05). In conclusion, although it is well established that Asians have a smaller distal femur size than that of the Western population, the variations in different Asian ethnicities may need to be considered when designing the appropriate knee implant.
  4. Arabinoxylan/graphene-oxide/nHAp-NPs/PVA bionano composite scaffolds for fractured bone healing
    Aslam Khan MU, Haider A, Abd Razak SI, Abdul Kadir MR, Haider S, Shah SA, et al.
    J Tissue Eng Regen Med, 2021 04;15(4):322-335.
    PMID: 33432773 DOI: 10.1002/term.3168
    The importance of bone scaffolds has increased many folds in the last few years; however, during bone implantation, bacterial infections compromise the implantation and tissue regeneration. This work is focused on this issue while not compromising on the properties of a scaffold for bone regeneration. Biocomposite scaffolds (BS) were fabricated via the freeze-drying technique. The samples were characterized for structural changes, surface morphology, porosity, and mechanical properties through spectroscopic (Fourier transform-infrared [FT-IR]), microscopic (scanning electron microscope [SEM]), X-ray (powder X-ray diffraction and energy-dispersive X-ray), and other analytical (Brunauer-Emmett-Teller, universal testing machine Instron) techniques. Antibacterial, cellular, and hemocompatibility assays were performed using standard protocols. FT-IR confirmed the interactions of all the components. SEM illustrated porous and interconnected porous morphology. The percentage porosity was in the range of 49.75%-67.28%, and the pore size was 215.65-470.87 µm. The pore size was perfect for cellular penetration. Thus, cells showed significant proliferation onto these scaffolds. X-ray studies confirmed the presence of nanohydroxyapatite and graphene oxide (GO). The cell viability was 85%-98% (BS1-BS3), which shows no significant toxicity of the biocomposite. Furthermore, the biocomposites exhibited better antibacterial activity, no effect on the blood clotting (normal in vitro blood clotting), and less than 5% hemolysis. The ultimate compression strength for the biocomposites increased from 4.05 to 7.94 with an increase in the GO content. These exciting results revealed that this material has the potential for possible application in bone tissue engineering.
  5. Assessment of compressive failure process of cortical bone materials using damage-based model
    Ng TP, R Koloor SS, Djuansjah JRP, Abdul Kadir MR
    J Mech Behav Biomed Mater, 2017 02;66:1-11.
    PMID: 27825047 DOI: 10.1016/j.jmbbm.2016.10.014
    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.
  6. Biomechanical analysis of the wrist arthroplasty in rheumatoid arthritis: a finite element analysis
    Bajuri MN, Abdul Kadir MR, Murali MR, Kamarul T
    Med Biol Eng Comput, 2013 Feb;51(1-2):175-86.
    PMID: 23124814 DOI: 10.1007/s11517-012-0982-9
    The total replacement of wrists affected by rheumatoid arthritis (RA) has had mixed outcomes in terms of failure rates. This study was therefore conducted to analyse the biomechanics of wrist arthroplasty using recently reported implants that have shown encouraging results with the aim of providing some insights for the future development of wrist implants. A model of a healthy wrist was developed using computed tomography images from a healthy volunteer. An RA model was simulated based on all ten general characteristics of the disease. The ReMotion ™ total wrist system was then modelled to simulate total wrist arthroplasty (TWA). Finite element analysis was performed with loads simulating the static hand grip action. The results show that the RA model produced distorted patterns of stress distribution with tenfold higher contact pressure than the healthy model. For the TWA model, contact pressure was found to be approximately fivefold lower than the RA model. Compared to the healthy model, significant improvements were observed for the TWA model with minor variations in the stress distribution. In conclusion, the modelled TWA reduced contact pressure between bones but did not restore the stress distribution to the normal healthy condition.
  7. Biomechanical analysis of three different types of fixators for anterior cruciate ligament reconstruction via finite element method: a patient-specific study
    Zainal Abidin NA, Abdul Wahab AH, Abdul Rahim RA, Abdul Kadir MR, Ramlee MH
    Med Biol Eng Comput, 2021 Sep;59(9):1945-1960.
    PMID: 34392448 DOI: 10.1007/s11517-021-02419-6
    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.
  8. Biomechanical and bioactivity concepts of polyetheretherketone composites for use in orthopedic implants-a review
    Abdullah MR, Goharian A, Abdul Kadir MR, Wahit MU
    J Biomed Mater Res A, 2015 Nov;103(11):3689-702.
    PMID: 25856801 DOI: 10.1002/jbm.a.35480
    The use of polyetheretherketone (PEEK) composites in the trauma plating system, total replacement implants, and tissue scaffolds has found great interest among researchers. In recent years (2008 afterward), this type of composites has been examined for suitability as substitute material over stainless steel, titanium alloys, ultra high molecular weight polyethylene, or even biodegradable materials in orthopedic implant applications. Biomechanical and bioactivity concepts were contemplated for the development of PEEK orthopedic implants and a few primary clinical studies reported the clinical outcomes of PEEK-based orthopedic implants. This study aims to review and discuss the recent concepts and contribute further concepts in terms of biomechanical and bioactivity challenges for the development of PEEK and PEEK composites in orthopedic implants.
  9. Biomechanical evaluation of three different configurations of external fixators for treating distal third tibia fracture: Finite element analysis in axial, bending and torsion load
    Abdul Wahab AH, Wui NB, Abdul Kadir MR, Ramlee MH
    Comput Biol Med, 2020 12;127:104062.
    PMID: 33096298 DOI: 10.1016/j.compbiomed.2020.104062
    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.
  10. Deposition of nanostructured fluorine-doped hydroxyapatite-polycaprolactone duplex coating to enhance the mechanical properties and corrosion resistance of Mg alloy for biomedical applications
    Bakhsheshi-Rad HR, Hamzah E, Kasiri-Asgarani M, Jabbarzare S, Iqbal N, Abdul Kadir MR
    Mater Sci Eng C Mater Biol Appl, 2016 Mar;60:526-537.
    PMID: 26706560 DOI: 10.1016/j.msec.2015.11.057
    The present study addressed the synthesis of a bi-layered nanostructured fluorine-doped hydroxyapatite (nFHA)/polycaprolactone (PCL) coating on Mg-2Zn-3Ce alloy via a combination of electrodeposition (ED) and dip-coating methods. The nFHA/PCL composite coating is composed of a thick (70-80 μm) and porous layer of PCL that uniformly covered the thin nFHA film (8-10 μm) with nanoneedle-like microstructure and crystallite size of around 70-90 nm. Electrochemical measurements showed that the nFHA/PCL composite coating presented a high corrosion resistance (R(p)=2.9×10(3) kΩ cm(2)) and provided sufficient protection for a Mg substrate against galvanic corrosion. The mechanical integrity of the nFHA/PCL composite coatings immersed in SBF for 10 days showed higher compressive strength (34% higher) compared with the uncoated samples, indicating that composite coatings can delay the loss of compressive strength of the Mg alloy. The nFHA/PCL coating indicted better bonding strength (6.9 MPa) compared to PCL coating (2.2 MPa). Immersion tests showed that nFHA/PCL composite-coated alloy experienced much milder corrosion attack and more nucleation sites for apatite compared with the PCL coated and uncoated samples. The bi-layered nFHA/PCL coating can be a good alternative method for the control of corrosion degradation of biodegradable Mg alloy for implant applications.
  11. Effects of Blood Flow Restriction Training on Muscle Strength and Pain in Patients With Knee Injuries: A Meta-Analysis
    Li S, Shaharudin S, Abdul Kadir MR
    Am J Phys Med Rehabil, 2021 Apr 01;100(4):337-344.
    PMID: 33727516 DOI: 10.1097/PHM.0000000000001567
    BACKGROUND: Due to the pain caused by knee injuries, low-load resistance training with blood flow restriction (L-BFR) may be a potential adjuvant therapeutic tool in the rehabilitation of knee injuries. This review aimed to analyze the effectiveness of L-BFR training modality in knee rehabilitation.

    DESIGN: A meta-analysis was conducted to determine the potential impact of blood flow restriction on patients with knee injuries. PubMed, EBSCO, and Web of Science databases were searched for eligible studies from January 2000 until January 2020. The mean differences of the data were analyzed using Revman 5.3 software with a 95% confidence interval.

    RESULTS: Nine studies fulfilled the inclusion criteria. These studies involved 179 patients who received L-BFR, 96 patients who underwent high-load resistance training, and another 94 patients who underwent low-load resistance training. The analysis of pooled data showed that patients in both the L-BFR (standardized mean difference, 0.83 [0.53, 1.14], P < 0.01) and high-load resistance training (standardized mean difference, -0.09 [-0.43, 0.24], P = 0.58) groups experienced an increase in muscle strength after the training. In addition, pain score was significantly reduced in the L-BFR group compared with the other two groups (standardized mean difference, -0.61 [-1.19, -0.03], P = 0.04).

    CONCLUSIONS: Muscle strength increased after L-BFR and high-load resistance training compared with low-load resistance training. Furthermore, pain score was significantly reduced after L-BFR. Hence, L-BFR is a potential intervention to be applied in rehabilitation of knee injuries.

  12. Effects of conform, non-conform, and hybrid conformity toward stress distribution at the glenoid implant and cement: A finite element study
    Abdul Wahab AH, Mohamad Azmi NA, Abdul Kadir MR, Md Saad AP
    Int J Artif Organs, 2022 Feb;45(2):200-206.
    PMID: 33645338 DOI: 10.1177/0391398821999391
    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).
  13. Effects of different implant-abutment connections on micromotion and stress distribution: prediction of microgap formation
    Saidin S, Abdul Kadir MR, Sulaiman E, Abu Kasim NH
    J Dent, 2012 Jun;40(6):467-74.
    PMID: 22366313 DOI: 10.1016/j.jdent.2012.02.009
    The aim of this study was to analyse micromotion and stress distribution at the connections of implants and four types of abutments: internal hexagonal, internal octagonal, internal conical and trilobe.
  14. Fulltext Enhancement of the Mechanical Properties of Hydroxyapatite/Sulphonated Poly Ether Ether Ketone Treated Layer for Orthopaedic and Dental Implant Application
    Sharifi R, Almasi D, Sudin IB, Abdul Kadir MR, Jamshidy L, Amiri SM, et al.
    Int J Biomater, 2018;2018:9607195.
    PMID: 30154853 DOI: 10.1155/2018/9607195
    The mechanical properties of coated layers are one of the important factors for the long-term success of orthopeadic and dental implants. In this study, the mechanical properties of the porous coated layer were examined via scratch and nanoindentation tests. The effect of compression load on the porous coated layer of sulphonated poly ether ether ketone/Hydroxyapatite was studied to determine whether it changes its mechanical properties. The water contact angle and surface roughness of the compressed coated layer were also measured. The results showed a significant increase in elastic modulus, with mean values ranging from 0.464 GPa to 1.199 GPa (p<0.05). The average scratch hardness also increased significantly from 69.9 MPa to 95.7 MPa after compression, but the surface roughness and wettability decreased significantly (p<0.05). Simple compression enhanced the mechanical properties of the sulphonated poly ether ether ketone/hydroxyapatite coated layer, and the desired mechanical properties for orthopaedic and dental implant application can be achieved.
  15. Finite element analysis of Puddu and Tomofix plate fixation for open wedge high tibial osteotomy
    Raja Izaham RM, Abdul Kadir MR, Abdul Rashid AH, Hossain MG, Kamarul T
    Injury, 2012 Jun;43(6):898-902.
    PMID: 22204773 DOI: 10.1016/j.injury.2011.12.006
    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.
  16. Finite element analysis of different surgical approaches in various occlusal loading locations for zygomatic implant placement for the treatment of atrophic maxillae
    Ishak MI, Abdul Kadir MR, Sulaiman E, Abu Kasim NH
    Int J Oral Maxillofac Surg, 2012 Sep;41(9):1077-89.
    PMID: 22575179 DOI: 10.1016/j.ijom.2012.04.010
    The aim of this study was to compare two different types of surgical approaches, intrasinus and extramaxillary, for the placement of zygomatic implants to treat atrophic maxillae. A computational finite element simulation was used to analyze the strength of implant anchorage for both approaches in various occlusal loading locations. Three-dimensional models of the craniofacial structures surrounding a region of interest, soft tissue and framework were developed using computed tomography image datasets. The implants were modelled using computer-aided design software. The bone was assumed to be linear isotropic with a stiffness of 13.4 GPa, and the implants were assumed to be made of titanium with a stiffness of 110 GPa. Masseter forces of 300 N were applied at the zygomatic arch, and occlusal loads of 150 N were applied vertically onto the framework surface at different locations. The intrasinus approach demonstrated more satisfactory results and could be a viable treatment option. The extramaxillary approach could also be recommended as a reasonable treatment option, provided some improvements are made to address the cantilever effects seen with that approach.
  17. Finite element analysis of the wrist in stroke patients: the effects of hand grip
    Ramlee MH, Beng GK, Bajuri N, Abdul Kadir MR
    Med Biol Eng Comput, 2018 Jul;56(7):1161-1171.
    PMID: 29209961 DOI: 10.1007/s11517-017-1762-3
    The provision of the most suitable rehabilitation treatment for stroke patient remains an ongoing challenge for clinicians. Fully understanding the pathomechanics of the upper limb will allow doctors to assist patients with physiotherapy treatment that will aid in full arm recovery. A biomechanical study was therefore conducted using the finite element (FE) method. A three-dimensional (3D) model of the human wrist was reconstructed using computed tomography (CT)-scanned images. A stroke model was constructed based on pathological problems, i.e. bone density reductions, cartilage wane, and spasticity. The cartilages were reconstructed as per the articulation shapes in the joint, while the ligaments were modelled using linear links. The hand grip condition was mimicked, and the resulting biomechanical characteristics of the stroke and healthy models were compared. Due to the lower thickness of the cartilages, the stroke model reported a higher contact pressure (305 MPa), specifically at the MC1-trapezium. Contrarily, a healthy model reported a contact pressure of 228 MPa. In the context of wrist extension and displacement, the stroke model (0.68° and 5.54 mm, respectively) reported a lower magnitude than the healthy model (0.98° and 9.43 mm, respectively), which agrees with previously reported works. It was therefore concluded that clinicians should take extra care in rehabilitation treatment of wrist movement in order to prevent the occurrence of other complications. Graphical abstract ᅟ.
  18. Flexible microfluidic cloth-based analytical devices using a low-cost wax patterning technique
    Nilghaz A, Wicaksono DH, Gustiono D, Abdul Majid FA, Supriyanto E, Abdul Kadir MR
    Lab Chip, 2012 Jan 7;12(1):209-18.
    PMID: 22089026 DOI: 10.1039/c1lc20764d
    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.
  19. Geometric variable designs of cam/post mechanisms influence the kinematics of knee implants
    Fallahiarezoodar A, Abdul Kadir MR, Alizadeh M, Naveen SV, Kamarul T
    Knee Surg Sports Traumatol Arthrosc, 2014 Dec;22(12):3019-27.
    PMID: 25149643 DOI: 10.1007/s00167-014-3227-7
    PURPOSE: Reproducing the femoral rollback through specially designed mechanism in knee implants is required to achieve full knee function in total knee arthroplasty. Most contemporary implants use cam/post mechanism to replace the function of Posterior Cruciate Ligament. This study was aimed to determine the most appropriate cam and post designs to produce normal femoral rollback of the knee.

    METHODS: Three different cams (triangle, ellipse, and circle) and three different posts (straight, convex, concave) geometries were considered in this study and were analysed using kinematic analyses. Femoral rollback did not occur until reaching 50° of knee flexion. Beyond this angle, two of the nine combinations demonstrate poor knee flexion and were eliminated from the study.

    RESULTS: The combination of circle cam with concave post, straight post and convex post showed 15.6, 15.9 and 16.1 mm posterior translation of the femur, respectively. The use of ellipse cam with convex post and straight post demonstrated a 15.3 and 14.9 mm femoral rollback, whilst the combination of triangle cam with convex post and straight post showed 16.1 and 15.8 mm femoral rollback, respectively.

    CONCLUSION: The present study demonstrates that the use of circle cam and convex post created the best femoral rollback effect which in turn produces the highest amount of knee flexion. The findings of the study suggest that if the design is applied for knee implants, superior knee flexion may be possible for future patients.

    LEVEL OF EVIDENCE: IV.

  20. In vitro and in vivo degradation evaluation of novel iron-bioceramic composites for bone implant applications
    Ulum MF, Arafat A, Noviana D, Yusop AH, Nasution AK, Abdul Kadir MR, et al.
    Mater Sci Eng C Mater Biol Appl, 2014 Mar 1;36:336-44.
    PMID: 24433920 DOI: 10.1016/j.msec.2013.12.022
    Biodegradable metals such as magnesium, iron and their alloys have been known as potential materials for temporary medical implants. However, most of the studies on biodegradable metals have been focusing on optimizing their mechanical properties and degradation behavior with no emphasis on improving their bioactivity behavior. We therefore investigated the possibility of improving iron biodegradation rate and bioactivity by incorporating various bioactive bioceramics. The iron-based bioceramic (hydroxyapatite, tricalcium phosphate and biphasic calcium phosphate) composites were prepared by mechanical mixing and sintering process. Degradation studies indicated that the addition of bioceramics lowered the corrosion potential of the composites and slightly increased their corrosion rate compared to that of pure iron. In vitro cytotoxicity results showed an increase of cellular activity when rat smooth muscle cells interacted with the degrading composites compared to pure iron. X-ray radiogram analysis showed a consistent degradation progress with that found in vivo and positive tissue response up to 70 days implantation in sheep animal model. Therefore, the iron-based bioceramic composites have the potential to be used for biodegradable bone implant applications.
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