Papers by Keyword: Bone Cement

Abstract: Orthopedic cement is an essential component of cemented Total Hip Replacements (THR). It must ensure three essential functions: very good implant-cement adhesion, good bone-implant load transfer, and good antibiotic transport. The main objective of the present work is to study the fracture behavior of orthopedic cement in total hip replacements. The analysis is performed using the submodel technique. Two cases are being considered. The first case involves ordinary cracks, while the second case involves cracks emanating from cavities in the cement of the THR acetabular part. The effects of crack position and implant orientation on the variation of stress intensity factors (SIF) in the three failure modes are discussed. It has also been shown that the circumferential positions of cracks present a major risk of loosening of the prosthesis, especially when the defect is aligned with its axis.

Abstract: Bone cement is an indispensable material in orthopedic medicine. In Indonesia, the fulfillment of bone cement needs still depends on imports from other countries. Polymethyl methacrylate (PMMA) is one of the main ingredients of bone cement which can be made from suspension polymerization of methyl methacrylate monomer (MMA). Therefore, this study aims to develop a technique for producing bone cement from PMMA. The production of bone cement consists of (1) the manufacture of PMMA, (2) the mixing of solid mixtures, (3) the mixing of solid mixtures and liquid mixtures, and (4) the molding of bone cement composites. The concentrations of barium sulfate (BaSO₄) used were 7%, 9%, and 11% by weight. Composite products were analyzed by Scanning Electron Microscopy (SEM), Proton Nuclear Magnetic Resonance (H-NMR), and Compressive Strength. The increase of BaSO₄ can trigger more smooth surface of bone cement composite. The tacticity from H-NMR shows that the bone cement dominantly consists of syndiotactic (58.83-59.91%) molecular arrangement. The highest compressive strength was 84.2 MPa which was obtained in 9% BaSO4 weight.

Abstract: Bone cement is a material used in many orthopedic surgeries. Polymethyl Methacrylate (PMMA) is one of the acrylic-based bone cement materials. PMMA will be mixed with an activator (N, N-Dimethyl-p-toluidine (DMPT)), initiator (Benzoyl Peroxide (BPO)), radiopacifier / filler (BaSO₄), and Methyl Methacrylate monomer. Once the materials were mixed, the activator react with the initiator to form radicals and activate the bulk polymerization reaction between the MMA monomer and PMMA molecules. The bulk polymerization reaction occurs exothermically and increases the bulk temperature. Barium sulfate (BaSO4) is an inorganic compound that can be acted as both radiopacifier and filler in bone cement. The specific objective of this study was to describe the effect of BaSO₄ in bone cement composite formation. The solid material; PMMA, BPO, and BaSO4 were mixed firstly. The liquid portions; N, N-Dimethyl-p-toluidine (DMPT), and MMA were mixed and then poured into the solids one in a stainless-steel bowl. The bulk temperature was recorded after a one-minute mixing process. The samples were characterized by Gel Permeation Chromatography (GPC) and Differential Scanning Calorimetry (DSC). The highest setting temperature and setting time were 107.3°C and 10.6 min which was obtained in BaSO₄ content variables of 7% and 11%, respectively. The average molecular weight of the samples was 561.5-1,332.0 kDa. From the DSC result, the glass temperature of the samples was 119.17-119.87°C.

Abstract: Carbonate apatite is one of the most widely studied bioceramic material for its use as bone cement. On the previous study, it has already stated that CO₃Ap cement has good osteoconductivity which makes this cement could be replaced by bone. However, the mechanical strength of CO₃Ap cement is still low. This low mechanical strength is estimated due to the high porosity and absence of organic components. The aim of this study is to improve the mechanical strength of the CO₃Ap cement reinforced by gelatin as an organic component with genipin as a cross-linking agent (Gelapin). The powder phase of vaterite and DCPA at weight ratio 40:60 were mixed with 0.2 mol/L Na₂HPO₄, 5% (w/v) gelatin, and 20% (v/v) genipin using 0.5 liquid to powder (L/P) ratio. The liquid phase ratios of Na₂HPO₄ and Gelapin were 50:50, 70:30, and 90:10. For control group, Gelapin were didn’t mixed in the liquid. Diametral tensile strength was improving and statistically significant (p<0.05) on set cement with 50:50 liquid ratio, the average value was 6.02 ± 0.14 MPa whereas the average value of the control group was only 3.10 ± 0.15 MPa. For this instance, gelatin serves a polymer matrix so the carbonate apatite crystallites could be well distributed within it which then gives more flexibility and resistance for the cement. On the other hand, genipin was also successfully cross-linked the gelatin. This study showed that by reinforcing CO₃Ap cement using genipin cross-linked gelatin might be a good candidate for a bone substitute material.

Abstract: Generally, implants fixations in orthopedic surgery are insured by bone cement; which is generated mainly from polymer polymethylmethacrylate (PMMA). Since, the cement is identified as the weakest part among bone-cement-prosthesis assembly. Hence, the characterization of mechanical behaviour is of a crucial requirement for orthopaedic surgeon’s success. In this study, we investigates the failure behaviour of bone cement, under combined shear and compression loading, for the aim to determine the strengths of bone cement for different mode loading conditions. Therefore, experimental cylindrical specimens has been tested to assess different shear-compression stresses. Based on the mechanical tests, a finite elements model of cylindrical specimens was developed to evaluate stresses distribution in the bone cement under compression, shear and combined shear-compression loading. Results show that, the load which leading to the failure of the cement decreased with increasing of the specimen angle inclination with respect of loading direction.

Abstract: In this research, mechanical properties of bone cement containing micro-and nanohydroxyapatite (HAp) particles were studied. The bone cement was prepared from mixing between polymethyl methacrylate (PMMA) and methyl methacrylate (MMA). Hydroxyapatite powder was prepared from bovine bone. The bone was heated in hot water at 200 ^oc for the elimination of tissue, after which the bone was dried and calcined at 800 ^oc for 3 hrs. The calcined bone than was crushed into powder and ball-milled for 24 hrs. The micro-HAp particle was then obtained. The micro particles were then further milled employing the Vibro-milling machine for 2 hrs. The micro-and nanoHAp sizes are about 0.5 μm and 140 nm, respectively. The both size powders were treated with γ-methacrylic-propyl-tri-methoxy silane. The acetic acid was added to control the pH of the solution, until it reached 2.9 before they were mixed into the bone cement with equally wt%. The mixture was casted using the 304 stainless steel mold in order to obtain a cylindrical shape. The low vacuum scanning electron microscope (LV-SEM) and x-ray diffractometer (XRD) were employed to characterize the samples. The porosity of PMMA could be reduced by HAp particle additives. From compressive strength test, it was found that the mixture of bone cement and nanoHAp particle has shown higher compressive strength than pure PMMA bone cement that affected by porosity reduction and force distribution by HAp particles.

Abstract: When a patient is undergoing a total knee arthroplasty, the proximal tibia is cut with a certain depth for tibial tray mounting. Moreover, the proximal tibia plateau is then drilled distally to create a hole where the tibial tray stem is inserted. Due to the existence of tibial tray stem stuck into the central part of the proximal tibia, the development of stress around the stem becomes the interesting parameter to be investigated, especially in the cement. For this purpose, a simplified two-dimensional finite element model has been created. The focus of the result analysis was fixed only on the knee bend activity load due to the highest von Mises stress occurred in this activity. The highest von Mises stress of 52.80 MPa occurred in the tibial tray, and then followed by the cortical bone, cement, central cancellous bone, and edge cancellous bone with von Mises stresses were 34.56, 5.40, 1.41, and 1.26 MPa, respectively. In the field of displacement and true strain in the cement, the highest resultant of displacement of 0.2mm occurred in the top section of the cement. Around the posterior tip, the cement experienced the tensile strain of 0.02 and around the anterior tip the strain was the compressive strain with similar value.

Abstract: The injection behavior of β-tricalcium phosphate (Ca₃(PO₄)₂: β-TCP) based cement was improved through the granulation of β-TCP. Dense β-TCP granules were obtained by heat treatment after spray drying. The fraction of injected paste under loaded mass in the syringe was measured while varying the granular fraction of β-TCP and the heat treatment temperature. The increase in granular fraction and heating treatment temperature reduced the amount of setting agent required to wet the granules. As the surplus setting agent could be used in the powdery β-TCP to reduce the viscosity, improved injectability was achieved. Inappropriate setting by the excessive setting agent was not observed and the cements tested exhibited normal setting behavior by forming a brushite phase.

Abstract: The properties of brushite cement were manipulated by partially replacing β-tricalcium phosphate with dense granular hydroxyapatite (HA). The introduction of HA granules resulted in prolonged setting time as well as reduction of temperature rise during setting. The changes produced by addition of HA granule were useful for drug loading. HA granules, prepared by spray drying, could preserve a meaningful 4.5 wt% of gentamicin sulfate solution. However, HA granules with excessive setting agent resulted in formation of dicalcium phosphate instead of brushite.

Abstract: Brushite bone cement containing a drug was prepared using the dense granular β-tricalciump phospahte (β-TCP) as a starting material. The setting reaction was not significantly affected by loading antibiotics within the granules. Heat treatment of the granule at elevated temperature resulted in the suppression of temperature increase during setting, which provided benefits in drug loading. The amount of gentamicin sulfate infiltrated in the β-TCP granules was determined by thermogravimetric analysis and was found to be meaningful considering the MIC of microorganisms.