Papers by Keyword: Bone Cement

Abstract: Healing of rat tibia after intramedullary implantation of MgO was analysed by Environmental Scanning Electron Microscopy (ESEM) and Energy-Dispersive X-ray spectroscopy (EDX). The results indicated the formation of hydroxyl-apatite (HA) in the entire intramedullary space after 1 week of healing. Then, corroded Mg, MgO and MgCO₃ were incubated with DMEM in vitro for 24 h and the surface of the material was analysed by EDX and Time-of-Flight Secondary Ion Mass (ToF-SIMS). The chemical analysis of the Mg corrosion products indicate that HA is formed at the material surface and that MgCO₃ was an efficient catalyzer of HA formation

Abstract: Polymethylmethacrylate (PMMA) cement has been used in orthopedics for more than 70 years. The advantages of PMMA bone cement include high compressive strength, stickiness, deformable ability and rapid self-setting. But the heat produced during polymerization would hinder the recovery. In order to improve the properties, in this research we added tetracalcium phosphate (TTCP) into polymethylmethacrylate cement as TP cement. A serious of characterizations including thermal property study, compression strength and micor-CT evaluation were carried out. According to the results, the polymerization heat was significantly reduced for the TP cement. The compressive strength was also enhanced with TTCP addition. TP-10 had better properties. As to thermal tests, TP-40 showed better results. Micro CT was used to monitor the composition inside the materials, and the results showed that TTCP was well dispersed in the PMMA matrix. The composite PMMA bone cement adding with tetracalcium phosphate seemed to be a potential candidate as low temperature product.

Abstract: The cause of the degradation was analyzed by applying the highly humid conditions during the storage of cement composed of β-tricalcium phosphate (β-TCP) and monocalcium phosphate monohydrate (MCPM). For the β-TCP and MCPM stored separately under the humid environment, the mild increase in the setting time was observed, and the product after the setting was entirely dicalcium phosphate dihydrate (CaHPO₄2H₂O: DCPD). However, for the β-TCP and MCPM stored mixed under the same condition, the setting time significantly increased with the period of storage, and the product contained dicalcium phosphate (CaHPO₄: DCP) as major phase, resulting in the loss of setting ability. The formation of DCP could be because of the weak driving force for setting, caused by a feeble supply of water from moisture. As the formation of DCPD requires stronger driving force to overcome the activation barrier, sufficient amount of water is essential. Humid environment during the storage decreased the driving force by the formation of DCP, and the driving force to produce DCPD was lost during the actual setting.

Abstract: Bone cement has been used for over half a century, to successfully anchor artificial joints. From its emergence there have appeared a number of types of bone cement, with the 2 major classes being bone cement with or without active substances. The one with the added antibiotics is used primarily in the treatment and revision surgery of infected total hip arthroplasty (THA), as well as a prophylactic method in primary THA in patients with high risks for this complication. The purpose of this study is to determine the mechanical properties of bone cement with added antibiotics. Over a period of 2 years, a number of 41 cases were chosen for this study: 25 with revision surgery for THA, where bone cement with antibiotics was used, and 16 with primary THA, where regular bone cement was used. A number of studies have been performed on the mechanical properties of the 2 types of cement, which determined that the cement with antibiotics presents a slightly lower compressive strength, tensile strength, elastic modulus and fatigue strength compared with regular cement. These variations, however, become more pronounced as the quantity of the antibiotic goes up. The mechanical properties of the cement with antibiotics are similar with those of the regular cement, when low doses of antibiotics are used and become more evident as the doses go up. In conclusion, the antibiotic bone cement is a trustworthy tool in the surgeon’s arsenal against infection, with minimal detriments from the mechanical view.

Abstract: Several bone cements were prepared in two ways of mixing (manual and vacuum bowl). Wear behavior, friction coefficient were studied by ball on disc method. Nano-hardness and Young`s modulus was studied by instrumented indentation. Obtained results were summarized by taking into account their way preparation, antibiotics content and testing conditions. There was found no significant time dependence of saline acting on Young`s modulus and nano-hardness values. Friction coefficient in saline was less than half in compare to dry sliding conditions

Abstract: An important breakthrough of orthopedic surgery is to use bone cement to fill the space between an artificial joint and bone tissue, which allows the artificial joint to stabilize on human bone tissues. However, surgery failure cases due to bone cement utilization and side effects still exist at present. Therefore, the purpose of this study is to investigate bone cement characteristics, such as coagulation time, consolidation time, maximal exothermic temperature and anti-compressive strength, etc. under different mixture ratios. Our results showed that the smaller the ratio of polymethyl methacrylate and methyl methacrylate (PMMA/MMA), the lower exothermic temperature and the stronger anti-compressive resistance. These results are helpful to reduce incidences of post surgery side effects. Of note, bone cement supplement decreases corresponding to loading and operating time, which will become a major challenge for orthopedic surgery.

Abstract: Vertebroplasty has been widely accepted in treatment of osteoporotic vertebral fractures. Polymerization of bone cement stabilizes the fractured vertebra by increasing its mechanical strength, thereby providing symptomatic pain relief. Many factors affect the reaction of polymerization of polymethylmethacrylate and, therefore, the reaction rate and injection permeability of bone cement. This may increase the probability of a surgeon missing the crucial period, leading to the increase of the risks of uneven cement distribution, cement leakage and premature hardening of cement. Hypothermic manipulation of bone cement is expected to reduce reaction rate and hence, extending the handling time. However, in a manner of reducing the environmental temperature of bone cement, there are still uncertainties on handling time, cement distribution pattern and injection permeability of cement. This study is thus designed to investigate the efficacy of temperature control for enhancing applicability and safety of bone cement.

Abstract: Self-setting calcium phosphate cement (CPC) has been used in bone repair and substitution due to their excellent biocompatibility, bioactive as well as simplicity of preparation and use. The inherent brittleness and slow degradation are the major disadvantages for the use of calcium phosphate cements. To improve the degradation for the traditional CPC, the apatite cement formula incorporated with β-tricalcium phosphate (β-TCP) with varying concentration were studied and the effect of the pH value of liquid phase on the properties of this new calcium phosphate cement formula was evaluated. The apatite cements containing β-TCP for 10 and 40 wt.% were mixed into the aqueous solution with different pH values and then aging in absolute humidity at 37°C for 7 days. The setting time and phase analysis of the biphasic calcium phosphate were determined as compared to the apatite cement. For proper medical application, the compressive strength, the phase analysis and the degradation of the CPC samples at pH 7.0 and 7.4 were evaluated after soaking in the simulated body fluid (SBF) at 37°C for 7 days. The results indicated that the properties of the samples such as the setting time, the compressive strength related to the phase analysis of the set cements. The high degradation of the CPC was found in the cement with increasing β-TCP addition due to the phase after setting. Apatite formation with oriented plate-like morphology was also found to be denser on the surface of the biphasic bone cements after soaking in SBF for 7 days. The obtained results indicated that the cement containing β-TCP mixed with the liquid phase at pH 7.4 could be considered as a highly biodegradable and bioactive bone cement, as compared to the traditional CPC.

Abstract: The properties of calcium phosphate cements are influenced both by presence of setting aids in cement paste and also by surface properties and particle size distribution of solid phase. In this study the influence of α-tricalcium phosphate powder preparation methods on properties of cement are examined: milling, thermal treatment at temperatures up to 600°C and treatment with deionized water. The properties of cements based on prepared powders evaluated are: setting time, injectability and cohesion. The compressive strength of selected cement samples was determined. Thermal treatment improves injectability, but significantly prolongs setting time and reduces cohesiveness. Treatment of powder particles with deionized water increases setting time, but also significantly reduces injectability. It was not possible to significantly increase powder liquid ratio (from 1.75 to 2.00), if thermally treated powders were used. It was found that reduction of particle size, under certain conditions, can increase the injectability of cements. Powder preparation methods do not significantly affect the compression strength of cement, but fast setting upon the contact water based fluids is necessary to obtain cohesive cements.

Abstract: Calcium silicate (CS) is a main component of Portland cement and is responsible for the strength development. Recent research has shown that dicalcium silicate cement (CSC) is bioactive and is a potential candidate for bone replacement. Traditionally, dicalcium silicate powder is synthesized by a solid state reaction or a sol-gel method. The solid-state reaction, however, usually needs a higher temperature and a longer calcination time. Furthermore, the dicalcium silicate powder made by the sol-gel method is not pure, and contains a significant quantity of CaO which is harmful to the strength and biological properties of the CSC. The Pechini technique is an alternative, low temperature polymeric precursor route for synthesis of high purity powders. In this study, purer CS powder was synthesized via the Pechini method by calcination at 800°C for 3h. DSC-TGA, XRD, SEM were used for characterization of CS powder and the hydrated cement. The DSC-TGA curves showed that the main exothermic peak was at 479°C and the total mass loss was 79.2%. The XRD patterns of CSC after hydration for 7, 14, and 35 days illustrated that dicalcium silicate hydrate (Ca_1.5SiO_3.5·xH₂O, C-S-H) was formed in the hardened CS paste. The XRD peaks on the diffraction pattern of the C-S-H of the day 35 sample were of greater intensity than those at day 7 and day 14. This demonstrates that the hydration speed was slow and complete hydration could take more than one month. Flake-like crystals were observed on scanning electron micrographs following hardening. The degradation study result showed that there was no mass loss of CSC after the samples were soaked into phosphate buffered saline (PBS) for 40 days. The silicon assay revealed that orthosilicic acid could be released from CSC after the samples were soaked in simulated body fluid (SBF). Silicon is known to be critical to skeletal mineralization. The existence of silicon may stimulate the proliferation of bone and activate cells to produce bone. Investigation of cell attachment confirmed that the MC-3T3 cells attached well to the surfaces of CSC after seeding.