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PubMedDate not supplied

[Tissue burden with exogenous trace elements caused by roentgen contrast media in bone cements].

In 44 patients undergoing a change of total hip prosthesis, made of Co-Cr alloy and at one point with a Refobacin-Palacos chain we analyzed samples of the hip joint capsule and fascia lata. Using Instrumental Neutron Activation Analysis (INAA) up to 18 elements were analyzed. The findings demonstrate that the tissues in the surroundings as well as in direct contact with the total hip prosthesis are burdened by corrosion products of the alloy and by decomposition of the bone cement. The decomposition of bone cement can be shown in the extraordinary high concentration of Barium, Zirconium and Hafnium which are added to Bone Cements as X-ray contrast. Microscopic findings at the same time complete and confirm the trace element analyses.

Adult↗
PubMed2004

Efficacy of vacuum bone cement mixing systems in reducing methylmethacrylate fume exposure: comparison of 7 different mixing devices and handmixing.

BACKGROUND: Polymethylmethacrylate (PMMA) bone cements are mainly used for implant fixation in joint replacement surgery. During cement preparation for application, all staff in the operating theatre are exposed to methylmethacrylate (MMA) fumes, which are known to have toxic side effects. METHODS AND RESULTS: In this study we found that vacuum mixing of bone cement with 7 commercially available mixing devices significantly reduced the emission of MMA vapors in the breathing zone when compared with classic hand mixing in an open bowl. Gas chromatography appears to be more sensitive for detection of MMA fumes than Photo Inonization Detection. INTERPRETATION: According to present knowledge, even repeated mixing of PMMA bone cement during a normal working day does not seem to constitute an increased health risk, particularly if vacuum mixing is implemented.

Air Pollution, Indoor↗
PubMed2000

Bioactive polymethyl methacrylate-based bone cement: comparison of glass beads, apatite- and wollastonite-containing glass-ceramic, and hydroxyapatite fillers on mechanical and biological properties.

A new bioactive bone cement (designated GBC) consisting of polymethyl methacrylate (PMMA) as an organic matrix and bioactive glass beads as an inorganic filler has been developed. The bioactive beads, consisting of MgO-CaO-SiO(2)-P(2)O(5)-CaF(2) glass, have been newly designed, and a novel PMMA powder was selected. The purpose of the present study was to compare this new bone cement GBC's mechanical properties in vitro and its osteoconductivity in vivo with cements consisting of the same matrix as GBC and either apatite- and wollastonite-containing glass-ceramic (AW-GC) powder (designated AWC) or sintered hydroxyapatite (HA) powder (HAC). Each filler added to the cements amounted to 70 wt %. The bending strength of GBC was significantly higher than that of AWC and HAC (p < 0.0001). Cements were packed into intramedullar canals of rat tibiae in order to evaluate osteoconductivity as determined by an affinity index. Rats were sacrificed at 2, 4, and 8 weeks after operation. An affinity index, which equaled the length of bone in direct contact with the cement expressed as a percentage of the total length of the cement surface, was calculated for each cement. At each time interval studied, GBC showed a significantly higher affinity index than AWC or HAC up to 8 weeks after implantation (p < 0.03). The value for GBC increased significantly with time up to 8 weeks (p < 0.006). The handling property of GBC was comparable with that of PMMA bone cement. Our study revealed that the higher osteoconductivity of GBC was due to the higher bioactivity of the bioactive glass beads at the cement surface and the lower solubility of the new PMMA powder to MMA monomer. In addition, it was found that the smaller spherical shape and glassy phase of the glass beads gave GBC strong enough mechanical properties to be useful under weight-bearing conditions. GBC shows promise as an alternative with improved properties to the conventionally used PMMA bone cement.

Animals↗
PubMed2000

Relative roles of cement molecular weight and mixing method on the fatigue performance of acrylic bone cement: Simplex P versus Osteopal.

The weight-average molecular weight (MW(w)) of a cement and the method used to mix its powder and liquid monomer constituents have been identified in the literature as key variables that affect mechanical properties of the fully polymerized cement that are relevant to its performance as a grouting agent in cemented arthroplasties. The goal of the present work was to identify which of these two variables exerts the greater effect in the case of fully reversed tension-compression fatigue performance. A judicious choice of cement brands, Surgical Simplex P and Osteopal, and the use of hand versus vacuum mixing, permitted this identification to be achieved. Three key observations were made in this work. First, for a given cement, the fatigue performance of vacuum-mixed specimens is far superior to that of hand-mixed ones, which may be a consequence of the substantially lower percentage areal porosity of the former specimens. Second, regardless of the mixing method, the fatigue performance of Osteopal outstrips that of Simplex P, a result that is attributed to the much higher MW(w) of the former cement. Third, hand-mixed Osteopal outperforms vacuum-mixed Simplex P (especially at low alternating stress levels), indicating that MW(w) of a bone cement is more influential than mixing method on its fatigue performance.

Arthroplasty, Replacement↗
PubMed1992

[Influence of vacuum mixing on mechanical properties of homemade bone cement].

Porosity, density and rotating bar bending fatigue life of homemade bone cement are analyzed with scanning electron microscopy for two different mixing techniques: manually vacuum mixing and manually non-vacuum mixing. By vacuum mixing the rotating bar bending fatigue life is increased from 0.98 x 10(4) +/- 0.31 x 10(4) to 1.33 x 10(4) +/- 0.17 x 10(4) (P < 0.05), density increased from 1.0638 +/- 0.0005g/cm3 to 1.1024 +/- 0.0068g/cm3 (P < 0.05), porosity reduced from 10.35% +/- 2.33% to 5.83% +/- 1.74% (P < 0.05), and incidence rate of big air inclusion reduced from 5.93% to 0.9%. We believe, vacuum mixing technique of bone cement should be recommended as a routine procedure to prevent aseptic loosening of prosthesis after total joint arthroplasty.

Bone Cements↗
PubMed1995

Bioactive bone cement: the effect of amounts of glass powder and histologic changes with time.

A study was conducted to examine the influence of the amount of glass powder added to a bioactive bone cement of our formula on its mechanical and biologic properties. Serial changes in the cement with time were also examined. The bioactive bone cement consisted of CaO-SiO2-P2O5-CaF2 glass powder and bisphenol-a-glycidyl methacrylate resin. Glass powder was added to the cement in 30, 50, 70, and 80% weight ratios. The compressive strengths of the resulting cements (171-239 MPa) were more than double that of polymethylmethacrylate cement (68 MPa). Histologic examination of rat tibiae bearing artificial defects packed with each bioactive cement showed direct bone contact 4 weeks after surgery. The cement with a higher percentage of glass powder showed better direct formation of bone around its periphery with a thicker reactive layer. Under scanning electron microscopic observation, the reactive layer showed increased levels of calcium and phosphorus. Examination of histologic changes up to 26 weeks showed progressive bone formation around the cement and no sign of biodegradation.

Animals↗
PubMed1998

Development of bioactive bone cement and its clinical applications.

This paper is a summary of already published papers on the bioactive bone cement (BA cement) which consists of CaO-SiO2-P2O5-MgO-CaF2 (AW glass-ceramic) powder and bisphenol-a-glycidyl methacrylate (Bis-GMA) resin. Two types of BA cement, dough and injection type, were prepared by changing their chemical compositions slightly. They harden in a few minutes exhibiting much lower curing temperature than PMMA cement. They have significantly higher compressive, bending, and tensile strengths than PMMA cement and have a character of bonding directly with bone in 4-8 weeks in vivo. Intercalary prosthetic replacement of the femur and total prosthetic replacement of the hip were performed in dogs using either PMMA cement or BA cement. Mechanical tests demonstrated that fixation strengths of these prostheses with BA cement increased with time and were significantly greater than those with PMMA cement tested at any time. Results of histological examinations showed direct bonding between BA cement and bone, and that the bone trabeculae around BA cement mantle grew with time, while with PMMA cement an intervening soft tissue layer was always observed at the cement-bone interface. BA cement was used in a few aged patients to install a hip prosthesis either in cases of revision or femoral neck fracture. The longest follow-up period of the patient is 4 yrs. The patients have been doing well with no adverse effect of the cement to date.

Animals↗
PubMed2003

Comparison of the response of human peripheral blood mononuclear cells to challenge with particles of three bone cements in vitro.

This study compared the effects of different sizes of three clinically relevant endotoxin free bone cement particles on primary human macrophage TNF-alpha production in vitro. The bone cements used were CMW original, CMW1RO and Palacos R. The cement wear debris was generated aseptically and then sequentially filtered to produce the size ranges 0.1-1 microm, 0.1-10 microm, 1-10 microm and >10 microm. The debris was cultured with human peripheral blood mononuclear cells at particle volume (microm(3)) per cell ratios of 100:1, 10:1 and 1:1. TNF-alpha production was determined by ELISA and cell viability by MTT conversion. CMW1RO particles induced increased TNF-alpha production by PBMNCs when tested in the size range 0.1-1 microm, and also to a lesser degree in the sizes 0.1-10 microm and 1-10 microm at the particle volume (microm(3)) to cell number ratios of 100:1 and 10:1. The increase in TNF-alpha production induced by Palacos R debris was only observed with the particle size ranges less than 10 microm at the ratio of 100:1. This study demonstrated that bone cement particles are capable of inducing raised TNF-alpha production in vitro. This is dependent upon cement particle size, volume and cement particle type, with cement particles containing radio-opaque additives being the most active.

Cell Adhesion↗
PubMed2005

Acrylic bone cements: composition and properties.

Cementing endoprostheses is one of the most frequently performed orthopedic procedures in the world today. The bone cements that are currently available commercially are all based on the chemical substance methylmethacrylate. Although all of them have the same chemical basis, acrylic bone cements are not all alike. This article discusses the composition of acrylic bone cements and the influence of the composition on the properties of the material.

Anti-Bacterial Agents↗
PubMed2004

The effect of bone cement particles on the friction of polyethylene and polyurethane knee bearings.

Compliant layer knee joints have been considered for use in an attempt to increase the serviceable life of artificial joints. If designed correctly, these joints should operate within the full-fluid film lubrication regime. However, adverse tribological conditions, such as the presence of bone and bone cement particles, may breach the fluid film and cause surface wear. The frictional behaviour of both polyurethane (PU) and conventional polyethylene (PE) tibial components against a metallic femoral component was therefore assessed when bone cement particles were introduced into the lubricant. The bone cement particles caused a large increase in the frictional torque of both the PE and PU bearings; however, the friction produced by the PU bearings was still considerably lower than that produced by the PE bearings. The volume of bone cement particles between each of the bearings and the resultant frictional torque both decreased over time. This occurred more quickly with the PE bearings but greater damage was caused to the surface of the PE bearings than the PU components.

Biocompatible Materials↗
PubMed1993

Biological evaluation of an ionomeric bone cement by osteoblast cell culture methods.

Periosteal derived bovine osteoblast-like cells migrated in culture onto an ionomeric cement. Cell cultures were maintained for 4 weeks and used to study the in vitro behaviour of cells on the ionomeric bone cement (IC). The cells produced bone matrix proteins (osteocalcin, bone sialoprotein II) and were osteoblast-like. The osteoblast-like cells colonized the substrate in monolayers and produced an extracellular matrix as seen by light and scanning electron microscopy. Morphological comparison between cells growing on the ionomeric bone cement and cortical bone revealed no significant difference in phenotypic expression. Staining for aluminium in osteoblasts growing on the IC showed an uptake and storage of aluminium in the cells. Energy dispersive X-ray microanalysis revealed high concentrations of aluminium and silicon in the periosteal tissue. Despite the known toxic effect of aluminium in vivo and in vitro on osteoblasts, no signs of toxicity were apparent on light and scanning electron microscopy analysis.

Aluminum Oxide↗
PubMed2001

Effect of biofluid environment on the dissolution and flexural strength of calcium phosphate bone cements.

This study investigates the dissolution of calcium (Ca2+), phosphorus (P5+), and the transverse strength of commercially available calcium phosphate (CaP) bone cements after immersion in fetal bovine serum and a tissue fluid substitute. It was observed that although a continual increase in Ca2+ and P5+ dissolution was detected in all three test media throughout the 21-day period, no statistical difference existed in the overall Ca2+ release after incubating the cements in the three different media. However, P5+ release after immersion in Tris solution (0.37 +/- 0.02 microgram/mm2) and fetal bovine serum solution (0.347 +/- 0.06 microgram/mm2) was significantly higher when compared with P5+ released (0.03 +/- 0.002 microgram/mm2) in tissue fluid substitute. In addition, no significant difference in transverse strength was observed for samples immersed in the three solutions during the 21-day period. However, the transverse strength for immersed CaP cement bars at 37 degrees C was statistically greater than non-immersed bars set aside at room temperature for the 21-day period (7.78 +/- 1.82 N and 3.19 +/- 0.93 N, respectively). It was concluded from this study that the transverse strength of the CaP bone cements was not significantly affected by the dissolution process but by the temperature at which the bone cement was exposed.

Animals↗
PubMed1976

[Antibiotica release from bone cement in animal experiment].

The release of antibiotics from bone cement palacos into cortical bone after experimental ostemyelitis in sheep was demonstrated by our experiments. High carbenicillin and cephalothin concentration levels were present for 2 weeks, but after 3 weeks were no longer evident. Lincomycin and gentamicin in the first days showed high tissue levels, then decreased and increased again after the 2nd week. Gentamicin was examined over 10 months, producing high levels after this time also.

Animals↗
PubMedDate not supplied

Penetration and flow of acrylic bone cement.

Fixation of prosthetic joint components into bone is influenced by the degree of mechanical interdigitation of the acrylic into cancellous interstices. The rheology of polymerizing polymethylmethacrylate was studied by pressurizing acrylic bone cement with a piston apparatus to produce flow into cylindrical cavities one to 3 mm in diameter. The acrylic penetration per unit of applied pressure increased with increasing cavity diameter. This suggests that greater penetration should occur in cancellous bone containing larger interstitial cavities. More than one-half (64 %) of the filling observed in our experiments took place within the first second of pressure application. Short duration, high level pressure pulses are the most effective means to achieve maximum penetration. Clinically, this is accomplished by vigorous finger packing. The cement should be pressurized as early as possible within the rasped cavity (immediately after dough stage if possible). The depth of penetration for 4-minute pressurization averaged three times that for 6 1/2-minute pressurization for the range of hole sizes and pressure levels tested.

Bone Cements↗
PubMed2005

Effects of nano HAP on biological and structural properties of glass bone cement.

A novel type of glass-based nanoscale hydroxyapatite (HAP) bioactive bone cement (designed as GBNHAPC) was synthesized by adding nanoscale hydroxyapatite crystalline (20-40 nm), into the self-setting glass-based bone cement (GBC). The inhibition rate of nanoscale HAP and micron HAP on osteosarcoma U2-OS cells was examined. The effects of nanoscale HAP on the crystal phase, microstructure and compressive strength of GBNHAPC were studied, respectively. It was concluded that nanoscale HAP could inhibit the cell proliferation, whereas micron HAP could not, and that nanoscale HAP could be dispersed in the cement evenly and the morphology did not change significantly after a longer immersion time. XRD and FTIR results show nanoscale HAP did not affect the setting reaction of the cement. Furthermore, GBNHAPC had a higher compressive strength (92.6 +/- 3.8 MPa) than GBC (80.1 +/- 3.0 MPa). It was believed that GBNHAPC might be a desirable biomaterial that could not only fill bone defects but also inhibit cancer cell growth.

Bone Cements↗
PubMed2006

Surface characterisation of various bone cements prepared with functionalised methacrylates/bioactive ceramics in relation to HOB behaviour.

This study reports the relationship between the biocompatibility and surface properties of experimental bone cements. The effect of hydroxyapatite (HA) or alpha-tri-calcium phosphate (alpha-TCP) incorporated into bone cements prepared with methyl methacrylate as base monomer and either methacrylic acid or diethyl amino ethyl methacrylate (DEAEMA) as comonomers was investigated. The in vitro biocompatibility of these composite cements was assessed in terms of the interaction of primary human osteoblasts grown on the materials over a period of 5 days and compared with a control surface. These results were related to the surface properties investigated through a number of techniques, namely Fourier transform infrared, contact angle measurements, X-ray photoelectron spectroscopy and energy dispersive analysis of X-rays. Complementary techniques of thermal analysis and ion chromatography were also performed. Biocompatibility results showed that the addition of alpha-TCP improves biocompatibility regardless of comonomer type. This is in contrast to HA-based cements where cell proliferation was significantly lower. Surface characterisations showed that structural integrity of the materials was maintained in the presence of the acid and base comonomers, and water contact angles were reduced particularly in DEAEMA containing materials. Furthermore, ion chromatography confirmed higher Ca2+ and PO4(3-) ion release by both types of ceramics, particularly for those containing DEAEMA. In conclusion, the incorporation of acidic and basic comonomers to either HA or alpha-TCP ceramics containing bone cements can have differential effects upon the attachment and proliferation of bone cells in vitro. Moreover, those cements consisting of alpha-TCP and containing DEAEMA comonomer indicated the most favourable biocompatibility.

Biocompatible Materials↗
PubMed1998

Bone cement reconstruction of the ossicular chain: a preliminary report.

OBJECTIVE: To determine the feasibility and efficacy of using a bone cement, Oto-Cem, to reconstruct the ossicular chain. STUDY DESIGN: Prospective clinical trial on nine consecutively chosen adult patients with ossicular chain defects. PATIENTS AND SETTING: Nine patients with ossicular chain defects involving the long process of the incus were treated at the Carolina Ear and Hearing Clinic. The ossicular chain was reconstructed using bone cement by itself or in conjunction with a stapes prosthesis. MAIN OUTCOME MEASURES: Preoperative audiograms were compared with audiograms 3, 6, and 12 months after reconstruction. RESULTS: There was a mean pure-tone average (PTA) improvement of 15 dB in patients undergoing incus to stapes suprastructure reconstruction with the bone cement. The incus to mobile footplate reconstruction (using a stapes prosthesis attached to the newly reconstructed incus) resulted in a 34-dB PTA postoperative improvement. Two of the three patients with incus to oval window repairs experienced a 10-dB improvement in PTA. One of the three patients experienced a loss in speech discrimination and a 2-dB loss in PTA. CONCLUSIONS: Despite the limited number of patients, this preliminary study demonstrates the effectiveness of Oto-Cem in reconstructing a foreshortened incus. There was a substantial hearing improvement in all but one patient in the incus to stapes or the incus to footplate categories.

Auditory Threshold↗
PubMed2002

Theoretical prediction and experimental determination of the effect of mold characteristics on temperature and monomer conversion fraction profiles during polymerization of a PMMA-based bone cement.

The present work is concerned with applications of a kinetic model for free-radical polymerization of a polymethylmethacrylate-based bone cement. Autocatalytic behavior at the first part of the reaction as well as a diffusion control phenomenon near vitrification are described by the model. Comparison of theoretical computations with experimental measurements for the temperature evolution during batch casting demonstrated the capacity of the proposed model to represent the kinetic behavior of the polymerization reaction. Temperature evolution and monomer conversion were simulated for the cure of the cement in molds made of different materials. The maximum monomer conversion fraction was markedly influenced by the physical properties of the mold material. The unreacted monomer acts as a plasticizer that influences the mechanical behavior of the cement. Hence, the same cement formulation cured in molds of different materials may result in different mechanical response because of the differences in the amounts of residual monomer. Standardization of the mold type to prepare specimens for the mechanical characterization of bone cements is recommended. Theoretical prediction of temperature evolution during hip replacement indicated that for cement thickness lower than 6 mm the peak temperature at the bone-cement interface was below the limit stated for thermal injury (50 degrees C for more than 1 min). The use of thin cement layers is recommended to diminish the risk of thermal injury; however, it is accompanied by an increase in the amount of unreacted monomer present in the cured material.

Arthroplasty, Replacement, Hip↗