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PubMed1996

Effect of BaSO4 on the fatigue crack propagation rate of PMMA bone cement.

To determine the effect of BaSO4 on the fatigue crack growth rate, da/dN = C(delta K)n, of poly(methyl methacrylate) (PMMA) bone cement, radiopaque bone cement, radiolucent bone cement, and commercial PMMA (Plexiglas) were tested using a methodology based on ASTM E647. The crack growth rate of radiopaque bone cement was one order of magnitude less than that of radiolucent. Fractographic analysis showed that the regions of rapid catastrophic fracture were smooth for all materials tested. The radiopaque fatigue surface was rough and characterized by ragged-edged stacked plateaus, a morphology consistent with the model of crack propagation through the interbead matrix. Voids were visible in the interbead matrix on the order of the size of BaSO4 particles. The fatigue surface of radiolucent bone cement was relatively smooth, a morphology consistent with crack propagation through both the PMMA beads and interbead matrix. Fatigue striations were visible, and their spacing correlated well with crack propagation rates. The striations indicated an increased crack growth rate through the PMMA beads.

Barium Sulfate↗
PubMed1995

Innovations in acrylic bone cement and application equipment.

A new bone cement was developed with the purpose of reducing the adverse biological effects during cementation of implants. This bone cement is characterized by lower exotherm, low release of monomer, low residual content of monomer, and retained physical properties. The essential innovation was substitution of half of the methylmethacrylate (MMA) in the monomer with long chain, high molecular weight, less volatile, and less soluble methacrylates (n-decylmethacrylate, isobornyl-methacrylate), as well as alteration of the accelerator system to a mix of dihydroxypropyl-p-toluidine and N,N-dimethyl-p-toluidine. The powder contains butylmethacrylate-MMA copolymers. These measures lower the glass-transition temperature, and permit more complete mixing in an integrated package, mixing, and delivery system consisting of a vacuum packed, double chamber pouch. The porosity was reduced to about 2% and the largest voids measured 0.1 mm. The polymerization exotherm was reduced to 58 degrees C. The compressive strength was 82 MPa, the four-point bending strength 55 MPa, the flexural modulus 2.24 GPa, the tensile strength 32 MPa, and the shear strength 36 MPa. The fracture toughness was 0.89 MPa square root of cm. These mechanical properties together with the fatigue life were on level with manually mixed, conventional PMMA bone cements.

Biocompatible Materials↗
PubMed1986

Variations in the density of bone cement after centrifugation.

Barium sulfate added to bone cement to provide radiopacity has a density about four times greater than that of polymerized radiolucent bone cement. Because centrifugation might make a clinically significant change in the distribution of barium sulfate, this process was studied. Radiolucent and radiopaque Simplex-P bone cement (Howmedica, Inc., Rutherford, New Jersey) were mixed with and without cooling and centrifuged for two or four minutes at 2,000 g or 1,000 g (gravity acceleration). The density of sections of the hardened bone cement was measured using the Archimedes principle. Erythromycin and colistin were added to cement batches to test whether or not centrifugation affected the distribution of antibiotics. Direct and radiographic observation and density measurements (cooled specimens, 2,000 g, p less than 0.01) verified that barium sulfate does accumulate at the bottom of the centrifugation tubes. Thin sections of the bone cement revealed that only larger particles (20-100 micron) of barium sulfate were deposited at the bottom. No evidence of redistribution of antibiotics after centrifugation was seen. It is recommended that Simplex-P bone cement be reformulated to eliminate concern about inhomogeneities that arise from centrifugation. Further, it is recommended that cooled, centrifuged antibiotic cement be used for long-stem revision hip surgery, where longer setting times are necessary, and room temperature cement for "fresh" hip surgery. A total centrifuge time of two minutes with a 2,000 g maximum force is recommended.

Anti-Bacterial Agents↗
PubMed1980

Alumina as a filler for bone cement: a feasibility study.

A composite bone cement of Alcoa A-10 Alumina and very finely ground poly(methyl methacrylate) beads (PMMA) was fabricated. It was tested in an attempt to improve on the conventionally used pure PMMA bone cement. By knowing the densities of the powders and their volumes, the mass of each was calculated for the most efficient packing of PMMA and Al2O3 powders and a 65% PMMA: 35% Al2O3 ratio by weight composition was determined. This was tested, as well as the pure cement so comparisons could be made. Cylinders for the strength tests were also made of silane treated Al2O3. The compositions were tested for compressive and tensile strengths. The pure PMMA, composite and silane treated composite had compressive strengths of 79.64 +/- 13.0, 83.17 +/- 4.8, and 71.52 +/- 8.6 MPa and the tensile strengths were 6.69 +/- 0.6, 5.12 +/- 0.3, and 7.12 +/- 0.5 MPa respectively. Also the 65%-35% PMMA-Al2O3 composite required 64% less monomer for mixing than did the pure cement which is thought to be better for tissue healing. The maximum temperature attained from room temperature was 110 degrees-115 degrees C for both cements. The composite took 6.5 min longer to reach its peak temperature than did the pure cement. The bone cements were implanted for one week in a rabbit and both compositions seemed acceptable by the tissue.

Aluminum↗
PubMed2002

Creep behavior comparison of CMW1 and palacos R-40 clinical bone cements.

The restrained dynamic creep behaviors of two clinical bone cements, Palacos R-40 and CMW1 have been investigated at room temperature and body temperature. It was found that the two cements demonstrated significantly different creep deformations, with Palacos R-40 bone cement demonstrating higher creep strain than CMW1 bone cement at each loading cycle. For both cements, two stages of creep were identified with a higher creep rate during early cycling followed by a steady-state creep rate. The test temperature had a strong effect on the creep performance of the bone cements with higher creep rate observed at body temperature. The relationship between creep deformation and loading cycles can be expressed by single logarithmic model. The SEM examinations revealed that CMW1 bone cement is more sensitive to defects within the specimen especially to the defects at the edges of the specimen than Palacos R-40 bone cement. However, in the absence of micro-cracks or defects within the inner surface layer, the dynamic loading (at less than 10.6 MPa) is unlikely to produce micro-cracks in the CMW1 bone cement. The different behaviors between the two bone cements may be attributed to differences in chemical compositions and molecular weight distributions.

Journal Article↗
PubMed1992

The fracture toughness of titanium-fiber-reinforced bone cement.

Fracture of the poly(methyl methacrylate) bone cement mantle can lead to the loosening and ultimate failure of cemented total joint prostheses. The addition of fibers to the bone cement increases fracture resistance and may reduce, if not eliminate, in vivo fracturing. This study discusses the effect of incorporating titanium (Ti) fibers on fracture toughness. Essential characteristics of the composite bone cement included a homogeneous and uniform fiber distribution, and a minimal increase in apparent viscosity of the polymerizing cement. Ti fiber contents of 1%, 2%, and 5% by volume increased the fracture toughness over non-reinforced bone cement by up to 56%. Bone cements of two different viscosities were used as matrix material, but when reinforced with the same fiber type and content, they showed no difference in fracture toughness. Four different fiber aspect ratios (68, 125, 227, 417) were tested. At 5% fiber content, there was no statistically significant dependence of fracture toughness on fiber aspect ratio. Scanning electron microscopy revealed important toughening mechanisms such as fiber/matrix debonding, local fracture path alteration, and ductile fiber deformation and fracture. Fiber fracture was evidence that the critical fiber length was exceeded. The surfaces of the Ti fibers were rough and irregular, indicating that a high degree of mechanical interlock between matrix and fiber was likely. The energy absorption contribution of plastic deformation and ductile fracture is absent in brittle fibers, like carbon, but is a distinction of the Ti fibers used in this study.

Biocompatible Materials↗
PubMed1998

Flow intrusion characteristics and fracture properties of titanium-fibre-reinforced bone cement.

Two clinically relevant considerations for a new bone cement are its fracture properties and flow intrusion characteristics. We present data for a titanium-fibre-reinforced poly(methyl methacrylate) (Ti-PMMA). The fracture properties presented are a concise review of previously published material, while the flow intrusion observations are new. We performed fracture toughness and fatigue fracture experiments. Two types of fatigue specimens were designed and tested. A 'smooth' specimen represented the extreme case of minimum surface flaws. The lifetime of a 'smooth' specimen incorporates fatigue crack initiation (FCI) and fatigue crack propagation (FCP). 'Notched' specimens were created by machining a sharp notch into cylindrical specimens. The sharp notch effectively eliminated FCI from a random surface flaw and thus we made the assumption that the lifetime of the notched specimen was a function of FCP only. Fatigue testing was performed on rotating-bending fatigue machines until failure. Fibre addition resulted in a significant increase in fracture toughness over the control bone cement. Fibre addition and the combination of fibre addition and centrifugation increased the fatigue crack initiation and propagation resistance of the bone cement. For the intrusion studies, eight femurs were obtained from four dogs. The femurs were prepared following a procedure similar to that in human hip replacement surgery. One of the pair of femurs from each dog was filled with non-reinforced bone cement and the other was filled with Ti-PMMA. A stainless-steel rod was inserted into the cement to simulate the insertion of a prosthesis stem. The cemented bones were sectioned and then stained with Alizarin Red S to distinguish the bone from the PMMA or Ti-PMMA. Because of the irregular bone morphology, it was not practical to quantify intrusion depth, but instead to make general observations on the intrusion characteristics. The Ti fibres did not generally flow into the small openings; however, fibre addition did not hinder the bone cement's ability to penetrate into bone interstices.

Animals↗
PubMed1991

[Histamine release and cardiovascular reactions to implantation of bone cement during total hip replacement].

Cardiovascular reactions to acrylic bone cement in patients with total hip replacement are a common complication. Hypotension and arrhythmias are the most frequently observed symptoms. Elderly patients with fractures of the femoral neck constitute a special risk group. In some patients these reactions can be fatal. The mechanisms suggested to explain these reactions are embolism of air, polymer or fat, reaction to the heat, and toxic or vasodilating effects of the acrylic monomer. In a pilot study and in a case report a significant rise of the plasma histamine was described following cementation of the femur. We therefore performed an investigation to find whether application of bone cement to the femur caused histamine release in elective hip surgery, and, independently of this, also investigated whether premedication with H1- + H2-antagonists had any effect on the cardiovascular reactions due to bone cement implantation into the femoral shaft in elderly patients with hip fracture. METHODS. Part I. In all, 40 patients, scheduled for elective surgical hip replacement were anesthetized by general or epidural anesthesia. Patients were continuously monitored by ECG. Blood pressure was recorded noninvasively at 2-min intervals during the study. Blood samples for the determination of the plasma histamine were taken immediately before implantation of the bone cement into the femur, and 2, 5, and 10 min after. Part II. A further group of 20 patients aged greater than or equal to 70 years with fractures of the femoral neck and in whom total hip replacement was planned were included in the study. In this group, 10 patients were randomly assigned to receive 4 mg clemastine + 400 mg cimetidine i.v. about 15 min before implantation of the bone cement. All patients were operated on under general anesthesia. ECG was monitored continuously and blood pressure was monitored at 2-min intervals during the study. Changes of the blood pressure and heart rate and therapeutic interventions following the implantation of the bone cement were documented. RESULTS. Part I. In 11 of the 40 patients (27.5%) plasma histamine increased by greater than 0.5 ng/ml (9 patients greater than 1 ng/ml). In comparable groups (patients with a control systolic blood pressure less than or equal to 130 mmHg) the histamine responders showed a significantly greater reduction in systolic blood pressure (-5.7 +/- 14.7 vs -17.7 +/- 8.6 mmHg). Part II. In the control group we observed a significantly greater fall in systolic blood pressure than in premedicated patients (41.5 +/- 25.4 vs 11.0 +/- 13.4 mmHg). In the control group 7 of the 10 patients required therapeutic interventions, while in the premedicated group only one therapeutic intervention was necessary (P less than 0.05). DISCUSSION. We have demonstrated that the implantation of acrylic bone cement into the femur may increase plasma histamine by greater than 1 ng/ml. In elderly patients with preexisting cardiac diseases or/and hypovolemia even moderate histamine release can cause serious, sometimes potentially fatal, cardiovascular complications. In this special risk group with hip fractures we found a significant reduction in the frequency of cardiovascular reactions to bone cement implantation in patients premedicated with H1 + H2 antagonists. Because we also observed significant falls in systolic blood pressure in premedicated patients, we assume that the pathogenesis of cardiovascular reactions to bone cement implantation is multifactorial. It may be that potentially lethal complications only occur if two or more of the predisposing factors (hypovolemia, myocardial insufficiency, arrhythmia, embolism, histamine release) are present simultaneously. Pre- and intraoperative measures therefore have to be instituted to eliminate all possible risk factors.

Aged↗
PubMed2000

Radiopacity and fatigue characterization of a novel acrylic bone cement with sodium fluoride.

Acrylic bone cement must provide good radiographic visibility and good long-term mechanical resistance in joint replacements. A new formulation of cement with 6% barium sulfate and 6% sodium fluoride was developed (Fluoride Bone Cement). Barium sulfate is a necessary addition to allow radiographic visibility although it reduces the mechanical strength of the material. Sodium fluoride promotes bone formation. However, its effect on the mechanical behavior is currently unknown while its influence on radiopacity can only be roughly estimated. The aim of this investigation was to establish if the new formulation would be suitable for clinical trials. In this respect, a mechanical (fatigue test) and radiographic (optical density measurements on x-ray films) characterization was performed on a typical commercially available cement with barium sulfate added and on the Fluoride Bone Cement. It was demonstrated that the fluoride cement has a (marginally) superior fatigue strength and comparable radiopacity to commercial radiopaque cements.

Arthroplasty, Replacement↗
PubMed2004

The development of theoretical relationships between some handling parameters (setting time and setting temperature), composition (relative amounts of initiator and activator) and ambient temperature for acrylic bone cement.

Commercially available acrylic bone cements are two-component systems based on the polymerization of methyl methacrylate around poly(methyl methacrylate) particles. When benzoyl peroxide (BPO), which is the initiator, in the powder component meets accelerator (N,N-dimethyl-p-toluidine (DMpT)) in the liquid component, radicals are produced, initiating the polymerization. This solidifies the cement. In this work, kinetic expressions have been developed that describe the relationship between bone cement setting time on the one hand, and BPO and DMpT concentrations on the other. Changes in setting time with ambient temperature follow a complex relationship, because both the polymerization process (initiation, propagation, and termination) and the swelling and dissolution of the polymer particles contribute to setting. The contribution of polymer swelling and dissolution to the setting process was determined by developing a relationship between the doughing time, which is substantially independent of DMpT or BPO concentrations, and ambient temperature. A value of 64 kJ mol(-1) was found for the activation energy for this process. An activation energy for the overall setting process of 68 kJ mol(-1) was determined from setting-time measurements over several ambient temperatures. This indicates that the sensitivity of setting time to temperature depends more on swelling and dissolution than on the polymerization process.

Benzoyl Peroxide↗
PubMed1996

Calorimetric characterization of the formation of acrylic type bone cements.

The formation of acrylic bone cements upon heating was investigated by differential scanning calorimetry (DSC). The effects of the contents of initiators, accelerator, biocompatibilizer, and crosslinking agents on the rate and the heat of polymerization during DSC heating were studied. The rate and the heat of polymerization (delta H) were characterized by the peak temperature and the area of the DSC exotherm, respectively. It was found that both the rate and heat of polymerization decreased with increasing heating rate. The delta H was increased considerably with increasing benzoyl peroxide (BPO) initiator concentration from 1 to 10% (w/v), whereas the rate of polymerization was reduced significantly. An increase in azobisisobutyronitrile (AIBN) initiator concentration also induced an increase in delta H, but the rate of reaction was not affected considerably. The addition of accelerator promoted the rate of reaction but resulted in a drop in delta H. The rate of polymerization for the system containing BPO initiator was increased quite significantly with the addition of hydroxyethyl methacrylate (HEMA) biocompatibilizer, while the delta H was slightly increased. For the system using AIBN as the initiator, the rate of polymerization was decreased slightly and the delta H dropped significantly with the addition of HEMA. The effect of ethylene glycol dimethacrylate (EGDMA) crosslinking agent was also examined. Polymerization became more rapid with the addition of EGDMA in the bone cement using BPO initiator, while it remained approximately constant for the system using AIBN as the initiator. No systematic change in delta H was observed with the addition of EGDMA in both systems. This study demonstrated that DSC is a potential tool to measure the amount of heat released and also the rate of polymerization for bone cements.

Acrylates↗
PubMed1989

Elastic constants of composites formed from PMMA bone cement and anisotropic bovine tibial cancellous bone.

An ultrasonic pulse-transit time technique is used to determine the nine orthotropic engineering constants of 32 cement-cancellous bone composites as a function of volume fractions of bone ranging from 0.0 to 0.4. The composites are manufactured using well-aligned bovine cancellous bone from the proximal end of the tibia and low viscosity bone cement. Selected composites are also subjected to mechanical compression tests to compare with the ultrasonic results. There is excellent correlation between the dynamic or ultrasonically determined moduli and the static or mechanically determined moduli; the dynamic moduli are approximately twice the static moduli and this difference is thought to be due to the effect of strain rate. An orthotropic model is assumed requiring nine independent elastic constants to be determined. The dynamic Young's modulus in the direction of major trabecular alignment, E1, increases linearly from 4.9 to 10.4 GPa as bone volume fraction increases from 0 to 0.4; dynamic E2 and E3 values increase from 4.9 to 7 GPa as bone volume fractions increase from 0 to 0.4, with E2 being slightly higher than E3. The dynamic shear modulus, G12, increases from 1.8 to 3.0 GPa, and G31 and G23 increase slightly from 1.8 to 2.2 GPa as bone volume fractions increase from 0 to 0.4. The Poisson's ratios are more sensitive than the Young's moduli and shear moduli to experimental error in the velocity measurements. The mechanically tested modulus (static modulus) in the direction of major trabecular alignment, E1, increases with volume fraction of bone from 2.4 to 4.4 GPa as the bone volume fraction increases from 0 to 0.25; static E2 and E3 values are either equal to or lower than that of pure PMMA.

Animals↗
PubMed1988

The effect of centrifugation on the fatigue life of bone cement in the presence of surface irregularities.

Reduction of the porosity of bone cement by centrifugation significantly improves the fatigue life of the cement when smooth, waisted specimens are tested. However, bone cement in vivo has surface irregularities at the interdigitation of the cement with the trabecular bone. The effect of centrifugation on the fatigue life of Simplex P in specimens containing surface irregularities was investigated by examining both composite specimens of trabecular bone and bone cement and specimens containing a sharp, circumferential notch. For the specimens with the sharp notch, the bone cement that had been centrifuged lasted significantly longer in fatigue (47,039 +/- 40,277 cycles) than the uncentrifuged specimens (3103 +/- 1950 cycles). Eleven of 15 uncentrifuged specimens broke at the location of a void, rather than the notch. In contrast, when the porosity was reduced by centrifugation, 13 of the 15 specimens broke at the notch. For the specimens that were a composite of bone cement and trabecular bone, the centrifuged specimens had a significant increase in fatigue life compared to the uncentrifuged specimens when tested at both 7 MPA (641,056 +/- 444,131 cycles vs. 237,969 +/- 124,153 cycles) and 15 MPA (8800 +/- 4673 cycles vs. 1534 +/- 719 cycles). Reduction of porosity in bone cement by centrifugation significantly extends its fatigue life even in the presence of trabecular bone or sharp surface notches as used in total joint replacements. These data support the concept that reduction of porosity of bone cement by centrifugation may extend the duration of fixation of the components in cemented total joint arthroplasties.

Animals↗
PubMed2001

Cemented total hip arthroplasty with Boneloc bone cement.

Boneloc cement (WK-345, Biomet Inc, Warsaw, Ind) attempted to improve cement characteristics by reducing exotherm during polymerization, lowering residual monomer and solubility, raising molecular weight, and lowering airborne monomer and aromatic amines. To study the efficacy of this cement, a selected group of 20 patients were prospectively enrolled and followed up after hip arthroplasty. All components were cemented. During the enrollment period, approximately 70 other hip arthroplasties were performed. Clinical evaluation was based on the Harris hip score. Radiographic evaluation was based on assessment of position of the components, subsidence, and/or presence of radiolucencies. Patients had follow-up for an average of 42 months (11 to 58 months); 1 was lost to follow-up. Of these, 7 (35%) had failure at last follow-up. Despite its initial promise, Boneloc cement had an unacceptably high failure rate over a relatively short follow-up period and is not recommended for use. Despite the longevity and odor toxicity problems with conventional bone cement, new cement technologies must be approached with caution.

Adult↗
PubMed1991

A new bioactive bone cement: its histological and mechanical characterization.

We have developed a bioactive bone cement using CaO-SiO 2-P 2O 5-CaF 2 glass powders and ammonium phosphate solution, and investigated its histological and mechanical characteristics in vivo. A bone defect was drilled in proximal metaphysis of the rat tibia and filled with the bioactive bone cement in paste form or polymethylmethacrylate (PMMA) bone cement in the dough state. The cements were allowed to harden in situ. Histological examination demonstrated direct bonding between the new cement and bone by 4 weeks. The bioactive bone cement did not degrade up to 24 weeks postimplantation. The inflammatory reaction to the bioactive bone cement was less intense than the reaction induced by PMMA. Changes in the mechanical properties of the cement in vivo were studied by implanting hardened cylindrical specimens of both types of cement into the hindlimb muscles of rats for 12 weeks. The compressive strength of the bioactive cement increased significantly after implantation, and reached 68 MPa in 1 week and 73 MPa in 4 weeks. These values were comparable to those of PMMA, and were maintained up to 12 weeks after implantation. This bioactive bone cement hardens in situ within a few minutes with negligible rise of temperature and can be easily handled as a paste for filling bone cavities of different shapes. In addition, this cement has good osteoconductive and bone bonding potential and fairly high mechanical strength. Therefore, this new cement could be used both as a bioactive bone cement and bone defect filler.

Animals↗
PubMed1997

Properties of acrylic bone cement: state of the art review.

Acrylic bone cement occupies a distinctive place in the hierarchy of synthetic biomaterials, because it is the only material currently used for anchoring the prosthesis to the contiguous bone in a cemented arthroplasty. However, the cement is not without its drawbacks. The main one is the role that it has been postulated to play in the aseptic loosening and, hence, clinical life of the arthroplasty. In turn, this role is directly related to the mechanical properties of the cement, especially the resistance to fracture of the cement in the mantle at the cement-prosthesis interface or the cement-bone interface. The present work is a detailed critical review of the recent literature on the properties of bone cement that are considered germane to its use in the stated application. The relevant properties are identified and a case is made for including each of them. Compilations of the values of these properties, obtained under clearly identified conditions, are presented for the six commercial formulations of bone cement in current popular orthopedic use. The gaps and unresolved questions in the current data base, efforts that should be made to address these issues, and research directions are covered.

Acrylates↗
PubMed2005

Influence of the radiopacifier in an acrylic bone cement on its mechanical, thermal, and physical properties: barium sulfate-containing cement versus iodine-containing cement.

In all acrylic bone cement formulations in clinical use today, radiopacity is provided by micron-sized particles (typical mean diameter of between about 1 and 2 microm) of either BaSO(4) or ZrO(2). However, a number of research reports have highlighted the fact that these particles have deleterious effects on various properties of the cured cement. Thus, there is interest in alternative radiopacifiers. The present study focuses on one such alternative. Specifically, a cement that contains covalently bound iodine in the powder (herein designated the I-cement) was compared with a commercially available cement of comparable composition (C-ment3), in which radiopacity is provided by BaSO(4) particles (this cement is herein designated the B-cement), on the basis of the strength (sigma(b)), modulus (E(b)), and work-to-fracture (U(b)), under four-point bending, plane-strain fracture toughness (K(IC)), Weibull mean fatigue life, N(WM) (fatigue conditions: +/-15 MPa; 2 Hz), activation energy (Q), and frequency factor (ln Z) for the cement polymerization process (both determined by using differential scanning calorimetry at heating rates of 5, 10, 15, and 20 K min(-1)), and the diffusion coefficient for the absorption of phosphate-buffered saline at 37 degrees C (D). For the B-cement, the values of sigma(b), E(b), U(b), K(IC), N(WM), Q, ln Z, and D were 53 +/- 3 MPa, 3000 +/- 120 MPa, 108 +/- 15 kJ m(-3), 1.67 +/- 0.02 MPa check mark m, 7197 cycles, 243 +/- 17 kJ mol(-1), 87 +/- 6, and (3.15 +/- 0.94) x 10(-12) m(2) s(-1), respectively. For the I-cement, the corresponding values were 58 +/- 5 MPa, 2790 +/- 140 MPa, 118 +/- 45 kJ m(-3), 1.73 +/- 0.11 MPa check mark m, 5520 cycles, 267 +/- 19 kJ mol(-1), 95 +/- 9, and (3.83 +/- 0.25) x 10(-12) m(2) s(-1). For each of the properties of the fully cured cement, except for the rate constant of the polymerization reaction, at 37 degrees C (k'), as estimated from the Q and ln Z results, there is no statistically significant difference between the two cements. k' for the I-cement was about a third that for the B-cement, suggesting that the former cement has a higher thermal stability. The influence of various characteristics of the starting powder (mean particle size, particle size distribution, and morphology) on the properties of the cured cements appears to be complex. When all the present results are considered, there is a clear indication that the I-cement is a viable candidate cement for use in cemented arthroplasties in place of the B-cement.

Arthroplasty↗
PubMed2000

PMMA-based composite materials with reactive ceramic fillers: part III: radiopacifying particle-reinforced bone cements.

New acrylic bone cements were prepared from alumina particles previously treated by 3-(trimethoxysilyl)propylmethacrylate (gamma-MPS), able to act both as radiopacifying and reinforcing agents. The present study deals with the handling characteristics and the compressive behavior of such cements. The influence of the particles morphology, their surface-modification by gamma-MPS bonding agent, their concentration in the cement, the powder-to-liquid ratio and the benzoyl peroxide concentration are reported. The role of grafted gamma-MPS molecules as coupling agent was confirmed. For several formulations, compressive strength and modulus reached 150 MPa and 3400 MPa respectively. Limitations in the use of such formulations are also comprehensively discussed.

Journal Article↗