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PubMed1983

A comparison of the mechanical properties of Simplex, Zimmer, and Zimmer low viscosity bone cements.

Many different methods have been used to compare polymethylmethacrylate bone cements. In this paper the three currently available cements were compared in regard to dough and set times, heat of polymerization, compressive, tensile, 3 and 4 point bending strengths, fracture toughness, flexural modulus, void density distribution, and viscosity. Methods used were ASTM designated for bone cement or plastics in general whenever possible. Significant differences in set and dough times and heat of polymerization were noted. All cements were equal in compressive, tensile, and fracture toughness testing; Zimmer Regular Cement was significantly weaker (p less than 0.001) in flexural testing and had a significantly (p less than 0.001) decreased modulus of elasticity when compared to LVC and Simplex Cements. Void density distributions were not significantly different. Viscosity was shown to vary between these cements as well. This data was analysed both to determine differences between various brands of cement and to assess the relevance to clinical use and failure modes in vivo of these different means of testing.

Bone Cements↗
PubMed1987

Presence of macrophages at the bone-cement interface of stable hip arthroplasty components.

The bone cement interface of four clinically stable hip-joint prosthetic components was examined histologically for the presence of macrophages using routine staining and a histochemical technique for acid phosphatase. Macrophages were found in the absence of wear debris in all four cases. Because these cells are capable of bone resorption, their presence at a well-fixed interface must give cause for concern.

Acid Phosphatase↗
PubMed1995

Infection adjacent to titanium and bone cement implants: an experimental study in rabbits.

A pure titanium cylinder or a piece of bone cement was implanted in each upper tibial metaphysis of 20 rabbits. After 4 months radiograms were taken and 10(4), 10(6), or 10(8) Staphylococcus aureus were injected into each leg through central holes in the implants in three groups of animals. Four weeks later new radiograms, bacteriological and histological biopsies were obtained. Three animals died before the end of the experiment. In animals which received 10(6) or 10(8) S. aureus radiographic signs of infection were found in 11/22 legs with both titanium and bone cement implants. No radiolucent zones developed around the implants. Bacteriological cultures from bone close to the implants were negative in all legs with titanium implants and positive in four legs with cement implants. Seven cultures were negative in spite of radiographic changes. It is concluded that after a proper time for wound healing the bone around unloaded implants of both titanium and bone cement is fairly resistant to infection. In some cases, healing of an infection in the surrounding bone seems possible.

Animals↗
PubMed2000

Fracture and fatigue properties of acrylic bone cement: the effects of mixing method, sterilization treatment, and molecular weight.

The purpose of this study was to characterize the relative and combined effects of sterilization, molecular weight, and mixing method on the fracture and fatigue performance of acrylic bone cement. Palacos R brand bone cement powder was sterilized using ethylene oxide gas (EtO) or gamma irradiation. Nonsterile material was used as a control. Molecular weights of the bone-cement powders and cured cements were measured using gel permeation chromatography. Hand and vacuum mixing were employed to mold single edge-notched bend specimens for fracture toughness testing. Molded dog-bone specimens were used for fatigue tests. Electron microscopy was used to study fracture mechanisms. Analysis of variance and Student t-tests were used to compare fracture and fatigue performance between sterilization and mixing groups. Our results indicate that vacuum mixing improved significantly the fracture and fatigue resistance (P<.05, P<.07) over hand mixing in radiation-sterilized and EtO-sterilized groups. In vacuum-mixed cement, the degradation in molecular weight resulting from gamma irradiation decreased fracture resistance significantly when compared with EtO sterilization and control (P<.05). A corresponding decrease in fatigue resistance was observed in the cement that was degraded severely by a radiation dose of 10 MRad (P<.05). In contrast, EtO sterilization did not result in a significantly different fracture resistance when compared with unsterilized controls for vacuum-mixed cement (P>.1). For hand-mixed cement, fracture and fatigue resistance appeared to be independent of sterilization method. This independence is believed to be the result of higher porosity that compromised the mechanical properties and obscures any effect of sterilization. Our results indicate that a combination of nonionizing sterilization and vacuum mixing resulted in the best mechanical performance and is most likely to contribute to enhanced longevity in vivo.

Animals↗
PubMed1998

Acrylic bone cements incorporating polymeric active components derived from salicylic acid: curing parameters and properties.

A methacrylic monomer derived from salicylic acid, 5-hydroxy-2-methacrylamido benzoic acid, 5-HMA, was incorporated with 2-hydroxyethyl methacrylate, (HEMA), in different proportions to the liquid phase of classical bone cement formulations. The monomer 5-HMA shows the ability to form molecular complexes with calcium atoms in order to improve osteointegration in the application of bone cement formulations used for the fixation of joint prostheses such as knee and hip. Kinetic parameters, peak temperature and setting time of the bone cement formulations prepared were determined, obtaining lower peak temperature values when 5-HMA was incorporated, with respect to classical acrylic bone cements based on PMMA. Mechanical and thermal properties as well as surface energy values, have been determined for all cured bone cement formulations.

Journal Article↗
PubMed1988

In vitro characterization and biomechanical optimization of a biodegradable particulate composite bone cement.

We have developed a biodegradable particulate composite bone cement and used in vitro and in vivo methods for studying its suitability for orthopaedic applications. The composite matrix consists of gelatin, water, and sodium salicylate. The particulate phase is made up of powdered and particulate (355-600 microns diameter) tricalcium phosphate. Paraformaldehyde (0.1% to 0.5% by weight) is used as a matrix cross-linking agent. The effects of incubation time, particulate volume fraction, density of the individual particles, water content, concentration of crosslinking agent, and freeze-drying on the unconfined compressive strength and modulus of the particulate composite were measured. Compressive strengths of 7 MPa and moduli of 65 MPa could be achieved. Mechanical properties depended critically upon the water content of the particulate composite, with values of strength and modulus decreasing rapidly outside a range of 10-14% of specimen dry weight. High-density tricalcium phosphate particulate produced cement with twice the strength found with porous particulate. In a companion study we document in vivo performance of this particulate composite in an animal model system.

Biocompatible Materials↗
PubMed2000

Osteoconductivity of an injectable and bioresorbable poly(propylene glycol-co-fumaric acid) bone cement.

We have investigated an injectable form of a resorbable bone cement based on in situ crosslinking of the unsaturated polyester, poly(propylene glycol-co-fumaric acid) (PPF). This material, filled with calcium gluconate/hydroxyapatite (CG/HA), cures to a hard cement degradable by hydrolysis. The purpose of this study was to evaluate the osteoconductive properties of this injectable cement. The cement was used as an adjunct to fixation with an intramedullary rod in the rat femoral osteotomy model. Ingrowth of new bone into the cement was examined in vivo. Negative and positive controls with rigid and loose internal fixation were included for comparison. Animals were evaluated histologically and histomorphometrically at 4 weeks postoperatively. Results of this study showed osteoblastic activity and new bone formation at the interface between the femoral bone and the cement in the experimental group. However, there was little bone remodeling at the endosteal surface in positive and negative controls. Histologic evaluation of the cement revealed the formation of cavitations, which likely resulted from leaching of the highly soluble calcium gluconate portion of the filler from the cement. These cavitations were sites of ingrowth of vascular and bony tissues. Intimate contact between the bone cement and the endosteal surface of the cortex was found. Quantitative histomorphometric analysis corroborated these observations. Findings of this study demonstrated the osteoconductivity of this type of injectable PPF-based bone cement.

Animals↗
PubMed2005

Nano-mechanics of bone and bioactive bone cement interfaces in a load-bearing model.

Many bioactive bone cements were developed for total hip replacement and found to bond with bone directly. However, the mechanical properties at the bone/bone cement interface under load bearing are not fully understood. In this study, a bioactive bone cement, which consists of strontium-containing hydroxyapatite (Sr-HA) powder and bisphenol-alpha-glycidyl dimethacrylate (Bis-GMA)-based resin, was evaluated in rabbit hip replacement for 6 months, and the mechanical properties of interfaces of cancellous bone/Sr-HA cement and cortical bone/Sr-HA cement were investigated by nanoindentation. The results showed that Young's modulus (17.6+/-4.2 GPa) and hardness (987.6+/-329.2 MPa) at interface between cancellous bone and Sr-HA cement were significantly higher than those at the cancellous bone (12.7+/-1.7 GPa; 632.7+/-108.4 MPa) and Sr-HA cement (5.2+/-0.5 GPa; 265.5+/-39.2 MPa); whereas Young's modulus (6.3+/-2.8 GPa) and hardness (417.4+/-164.5 MPa) at interface between cortical bone and Sr-HA cement were significantly lower than those at cortical bone (12.9+/-2.2 GPa; 887.9+/-162.0 MPa), but significantly higher than Sr-HA cement (3.6+/-0.3 GPa; 239.1+/-30.4 MPa). The results of the mechanical properties of the interfaces were supported by the histological observation and chemical composition. Osseointegration of Sr-HA cement with cancellous bone was observed. An apatite layer with high content of calcium and phosphorus was found between cancellous bone and Sr-HA cement. However, no such apatite layer was observed at the interface between cortical bone and Sr-HA cement. And the contents of calcium and phosphorus of the interface were lower than those of cortical bone. The mechanical properties indicated that these two interfaces were diffused interfaces, and cancellous bone or cortical bone was grown into Sr-HA cement 6 months after the implantation.

Animals↗
PubMedDate not supplied

Tensile properties of a bone cement containing non-ionic contrast media.

The addition of contrast media such as BaSO4 or ZrO2 to bone cement has adverse effects in joint replacements, including third body wear and particle-induced bone resorption. Ground PMMA containing particles of the non-ionic water-soluble iodine-based X-ray contrast media, iohexol (IHX) and iodixanol (IDX), has, in bone tissue culture, shown less bone resorption than commercial cements. These water-soluble non-ceramic contrast media may change the mechanical properties of acrylic bone cement. The static mechanical properties of bone cement containing either IHX or IDX have been investigated. There was no significant difference in ultimate stress between Palacos R (with 15.0 wt % of ZrO2) and plain cement with 8.0 wt % of IHX or IDX with mass median diameter (MMD) of 15.0 or 16.0 microm, while strain to failure was higher for the latter (p < 0.02). The larger particles (15.0 or 16.0 microm) gave significantly higher (p < 0.001) ultimate tensile strengths and strains to failure than smaller sizes (2.4 or 3.6 microm). Decreasing the amount of IHX from 10.0 wt % to 6.0 wt % gave a higher ultimate tensile strength (p < 0.001) and strain to failure (p < 0.02). Scanning electron microscopy (SEM) showed the smaller contrast media particles attached to the surface of the polymer beads, which may prevent areas of the acrylate bead surface from participating in the polymerization. In conclusion, the mechanical properties of bone cement were influenced by the size and amount of contrast medium particles. By choosing the appropriate amount and size of particles of water-soluble non-ionic contrast media the mechanical properties of the new radio-opaque bone cement can be optimized, thus reaching and surpassing given regulatory standards.

Journal Article↗
PubMed2004

Ossicular reconstruction using bone cement.

OBJECTIVE: The objective of this study was to describe our results of ossicular reconstruction using bone cement. STUDY DESIGN: We conducted a retrospective review of 264 patients with chronic suppurative otitis media operated on since 1999. SETTING: Academic tertiary referral center. PATIENTS: : Two hundred sixty-four patients with chronic suppurative otitis media underwent mastoidectomy with tympanoplasty. Eighty patients had incudostapedial disarticulation secondary to infection and or cholesteatoma and were reconstructed using an incus interposition graft (n = 31), a partial ossicular prosthesis (POP; n = 31), or more recently, bone source (n = 18). This study evaluates the results of the ossiculoplasties using bone source. INTERVENTION: Ossicular discontinuity was repaired using bone cement. MAIN OUTCOME MEASURE: Audiometric studies pre- and postintervention were compared. One to 3 years of follow up are provided. RESULTS: Preoperative air-bone gaps ranged from 18 dB to 60 dB and averaged 33 dB. Postoperative air-bone gaps ranged from 1 to 24 dB and averaged 10 dB. No patients have experienced any increase in their persistent conductive hearing loss. The pre-/postoperative hearing loss comparisons showed statistically significant hearing improvement. There were no complications. CONCLUSION: The use of POPs and incus interposition grafts is fraught with the possibility of migration and resultant recurrent conductive hearing loss. Using bone cement to reconstruct the ossicular chain restores the integrity of the ossicular chain in the most natural of ways. This reconstruction technique provides an excellent alternative to currently accepted methods and should be considered for incus-stapes disarticulation. There has been no dissolution of the bone source and the results have persisted thus far.

Adolescent↗
PubMed2000

Evaluation of calcium phosphates and experimental calcium phosphate bone cements using osteogenic cultures.

In this study, rat bone marrow cells (RBM) were used to evaluate two biodegradable calcium phosphate bone cements and bioactive calcium phosphate ceramics. The substances investigated were: two novel calcium phosphate cements, Biocement F and Biocement H, tricalcium phosphate (TCP), surface-modified alpha-tricalcium phosphate [TCP (s)] and a rapid resorbable calcium phosphate ceramic consisting of CaKPO(4) (sample code R5). RBM cells were cultured on disc-shaped test substrates for 14 days. The culture medium was changed daily and also examined for calcium, phosphate, and potassium concentrations. Specimens were evaluated using light microscopy, and morphometry of the cell-covered substrate surface, scanning electron microscopy, and energy dispersive X-ray analysis and morphometry of the cell-covered substrate surface. Areas of mineralization were identified by tetracyline labeling. Except for R 5, rat bone-marrow cells attached and grew on all substrate surfaces. Of the different calcium phosphate materials tested, TCP and TCP (s) facilitated osteoblast growth and extracellular matrix elaboration to the highest degree, followed by Biocements H and F. The inhibition of cell growth encountered with R 5 seems to be related to its high phosphate and potassium ion release.

Absorbable Implants↗
PubMed1999

Modified acrylic bone cement with high amounts of ethoxytriethyleneglycol methacrylate.

One cause of arthroplasty failure is the brittle mechanical behavior of bone cements. However, the improvement of cement formulations must also be accompanied by the maintenance of a wide variety of characteristics. New bone cements were obtained by the substitution of high percentages, up to 60% (v/v), of methyl methacrylate (MMA) by a higher molecular weight and more hydrophilic monomer, ethoxytriethyleneglycol methacrylate (TEG). The essential advantages of these materials were the decrease of maximum temperature together with a decrease in the residual monomer content with respect to conventional cement formulations. The water absorption process obeyed diffusion laws and the equilibrium water content increased by the introduction of higher percentages of the hydrophilic component. This characteristic had an appreciable effect on the viscoelastic behavior analyzed by DMTA. These modified bone cements had reduced polymerization shrinkage and similar levels of porosity. Tensile test revealed that the introduction of TEGMA gave rise to an important modification of the mechanical behavior, with a noticeable increase in the fracture strain. This fact was also confirmed by means of the analysis of the fracture surfaces by SEM.

Absorption↗
PubMed2002

Fixation of the tibial component using CMW-1 or Palacos bone cement with gentamicin: similar outcome in a randomized radiostereometric study of 51 total knee arthroplasties.

We studied CMW-1 bone cement with gentamicin in the laboratory and in a randomized clinical study. Palacos bone cement containing gentamicin was used as the control. In the preclinical evaluation, the CMW cement had slightly less mechanical strength. In the clinical study, 51 patients (51 knees) operated on with total knee arthroplasty were studied for 2 years. We used radiostereometric analysis to measure migration of the tibial components, randomized to fixation with either of the two types of cement. The extent and pattern of migration were similar in both groups, and we found no differences in the number, size and extent of radiolucent lines or clinical outcome. No complications occurred. Our findings suggest a need for more studies of CMW-1 bone cement containing gentamicin in a larger cohort of patients.

Aged↗
PubMed1992

The effect of the addition of methylene blue on the fatigue strength of Simplex P bone-cement.

To aid in cement removal during revision arthroplasty, it has been proposed to add methylene blue to bone cement to provide contrast between the cement and bone. However, it is essential that the fatigue strength of the cement not be reduced by the addition of the methylene blue. The effect of adding 1 mL of an aqueous 1% solution of methylene blue to one pack of Simplex P prepared in the standard fashion (uncentrifuged) was studied. We also measured the fatigue properties of centrifuged Simplex P with three different methylene blue preparations. We studied adding 1 mL of an aqueous 1% solution of methylene blue, 0.5 g of methylene blue powder, and 0.1 mL of a 10% solution of methylene blue per pack of Simplex P bone cement. Adding 1 mL of a 1% methylene blue solution to 40 g of Simplex P without centrifuging the cement after mixing produced a cement with a mean fatigue life comparable to the uncentrifuged Simplex P without the methylene blue. However, the fatigue data scatter was higher for the uncentrifuged methylene blue preparation. The optimum methylene blue impregnated cement preparation was produced by adding 1 mL of a 1% methylene blue solution to 40 g of Simplex P powder, mixing with chilled monomer, and centrifuging for 60 s. Sterile 1 mL vials of 1% methylene blue solution are available in the operating room.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone Cements↗
PubMed1987

Optimum pore size for bone cement fixation.

The interface shear properties of porous coated Ti-6Al-4V alloy embedded in bone cement were examined as a function of pore size. Cylindric Ti-6Al-4V alloy push-out specimens were coated with two layers of spheric powders having particle size ranges of 297-420 microns, 420-500 microns, 595-707 microns, and 850-1400 microns. Sintering resulted in mean pore sizes of 165, 285, 345, and 550 microns, respectively, and porosities in the range of 40%-44%. There was a statistically significant difference between the mean pore sizes obtained from the four particle size ranges. There were no differences between the mean porosities. The porous-coated specimens were embedded in bone cement and mechanical push-out testing was performed. Non-coated specimens having a satin surface finish were also embedded in bone cement and tested. The noncoated metal specimens displayed an interface shear strength of 4.2 +/- 0.4 MPa, whereas the shear strengths for the porous-coated specimens were significantly higher and increased as pore size increased. The mean interface shear strengths determined were 17.0 +/- 2.1 MPa (165 microns pore size), 18.1 +/- 2.3 MPa (285 micron pore size), 23.6 +/- 1.7 MPa (345 microns pore size), and 25.4 +/- 3.4 MPa (550 microns pore size). Significant differences in shear strength for the porous-coated specimens were found between the two smaller particle sizes and the two larger particle sizes. As pore size increased from 285 microns to 345 microns, a statistically significant increase in shear strength from 18.1 MPa to 23.6 MPa was observed.

Alloys↗
PubMed1990

The influence of bone and bone cement debris on counterface roughness in sliding wear tests of ultra-high molecular weight polyethylene on stainless steel.

Studies of explanted hip prostheses have shown high wear rates of ultra-high molecular weight polyethylene (UHMWPE) acetabular cups and roughening of the surface of the metallic femoral head. Bone and bone cement particles have also been found in the articulating surfaces of some joints. It has been proposed that bone or bone cement particles may cause scratching and deterioration in the surface finish of metallic femoral heads, thus producing increased wear rates and excessive amounts of wear debris. Sliding wear tests of UHMWPE pins on stainless steel have been performed with particles of different types of bone and bone cement added. Damage to the stainless steel counterface and the motion of particles through the interface have been studied. Particles of bone cement with zirconium and barium sulphate additives and particles of cortical bone scratched the stainless steel counterface. The cement particles with zirconium additive produced significantly greater surface damage. The number of particles entering the contact and embedding in the UHMWPE pin was dependent on particle size and geometry, surface roughness and contact stress. Particles are likely to cause surface roughening and increased wear rates in artificial joints.

Bone Cements↗
PubMed2005

Microtomography assessment of failure in acrylic bone cement.

Micromechanical studies of fatigue and fracture processes in acrylic bone cement have been limited to surface examination techniques and indirect signal analysis. Observations may then be mechanically unrepresentative and/or affected by the presence of the free surface. To overcome such limiting factors the present study has utilised synchrotron X-ray microtomography for the observation of internal defects and failure processes that occurred within a commercial bone cement during loading. The high resolution and the edge detection capability (via phase contrast imaging) have enabled clear microstructural imaging of both strongly and weakly absorbing features, with an effective isotropic voxel size of 0.7 microm. Detailed assessment of fatigue damage processes in in vitro fatigue test specimens is also achieved. Present observations confirm a link with macroscopic failure and the presence of larger voids, at which crack initiation may be linked to the mechanical stress concentration set up by adjacent beads at pore surfaces. This study does not particularly support the suggested propensity for failure to occur via the inter-bead matrix; however crack deflections at matrix/bead interfaces and the incidence of crack arrest within beads do imply locally increased resistance to failure and potential improvements in global crack growth resistance via crack tip shielding.

Biocompatible Materials↗
PubMed1976

[Biological effect of bariumsulfate as contrast material in bone cement. An animal study on rabbit femora (author's transl)].

The investigations presented in this paper concern the question of toxicity of Bariumsulfate as an ingredient of bone-cement. In 6 rabbits the medullary cavity of the right femur was filled with bone-cement which contained Bariumsulfate as X-ray contrast ingredient and the left one with BaSO4-free bone-cement. 4 1/2 months post operationem the femura were investigated by histological and microradiographic methods. The status of both sides was compared. On the BaSO4-containing side regularly necrotic lamellar bone structures in the zones of osteogenesis and single disseminated necroses are found which are not caused by the primary lesion occuring during the implantation procedure. Additionally the zone of primary lesions which is found on both sides was more extensive at the BaSO4-containing side.

Animals↗