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PubMed1987

The microscopic anatomy of the bone-cement interface in failed total hip arthroplasties.

Thirty specimens were removed from the bone-cement interface in 25 hips revised for aseptic loosening of total hip arthroplasty. Histologic examination of the membranous tissues revealed that histiocytosis, fibrosis, and necrosis were present in every specimen. Other prominent features included particles of acrylic cement, polyethylene debris, and fragments of necrotic bone. Mechanical failure was characterized by cement fractures, and microfracture of bone. The presence of cement debris and bone detritus in the membranes, and smooth appearance of the removed cement mantles substantiated the presence of mechanical failure. The process of loosening was characterized by the recruitment of histiocytes into the interface and the subsequent resorption of bone around the prosthesis. This may be a manifestation of the rate of cement wear and tear, particle size, and the immunologic predispositions of the host. These observations on interfaces of loosened prostheses are reexamined and reinterpreted in the light of radiologic observations on interface radiolucent zones and well-functioning prostheses.

Acetabulum↗
PubMed1994

In vitro micronucleus induction by polymethyl methacrylate bone cement in cultured human lymphocytes.

Human lymphocytes cultured in vitro were used to assess the ability of polymethyl methacrylate (PMMA), currently used in orthopaedic surgery as bone cement, to induce micronuclei in binucleated cells. The results of the study show a significant increase in the micronucleus frequency in treated cultures and therefore the genotoxic effect of PMMA bone cement or its ingredients (methyl methacrylate, dimethyl para-toluidine and hydroquinone) usually present in self-curing methacrylate bone cement and released in small quantities after polymerisation. This effect is evident during the stage immediately after the polymerisation process, and after a certain period of time (5 days in our experimental model).

Adult↗
PubMed1980

The effect of posterior spinal fixation with bone cement upon vertebral growth in dogs. An experimental study.

In an experimental study the authors tried to clarify the effect on vertebral growth and spinal curvature in dogs following fixation of the posterior elements of the spine at different levels using bone cement. In three separate experimental groups a segment of the dorsal spine, the dorso-lumbar spine or the lumbar spine was securely fixed with bone cement incorporating a radio-opaque wire marker. Growth of the spine was observed with renal X-rays over a six-month period and the following results obtained: 1. Growth in height of the vertebra was not affected by the fixation; 2. The intervertebral disc spaces widened anteriorly and narrowed posteriorly even when fracture of the bone cement occurred; 3. Increasing lordosis developed in all three experimental groups even when a physiological kyphosis was normally present. The greatest increase occurred in the lumbar spine; 4. Fracture of the cement occurred consistently when attempting to secure the dorso-lumbar junction.

Animals↗
PubMedDate not supplied

The acetabular cement-bone interface in experimental arthroplasties in dogs.

Increased clinical loosening of total hip arthroplasty acetabular components has been noted in patients with long follow-up and in young active individuals. Evaluation of the acetabular cement-bone interface has been limited to a few human cadaveric specimens and to canine studies in which the data are difficult to interpret. The effects of cement fixation of the acetabular component were investigated in serial observations in 21 dogs with hip surface replacements. The postoperative survival time before evaluation was from two to 46 weeks. Twenty animals were clinically normal before autopsy. Analytic techniques used to examine acetabular fixation included the use of epoxy-embedded specimens to preserve the cement-bone interface and conventional histologic sections. After two weeks, no direct contact between the cement and bone was seen. A correlation between the adequacy of cement fixation and interface membrane thickness was found. Poor acrylic fixation resulted in thick membranes up to 2 mm thick and horizontal trabeculation of the interface woven bone. Good cement intrusion led to a thinner, almost minimal membrane two to three cells in thickness.

Acetabulum↗
PubMed2004

In vivo aging test for a bioactive bone cement consisting of glass bead filler and PMMA matrix.

The degradation of a new bioactive bone cement (GBC), comprised of an inorganic filler (bioactive MgO-CaO-SiO(2)-P(2)O(5)-CaF(2) glass beads) and an organic matrix [high-molecular-weight polymethyl methacrylate (PMMA)], was evaluated in an in vivo aging test. Hardened rectangular specimens (20 x 4 x 3 mm) were prepared from two GBC formulations (containing 50% w/w [GBC50] or 60% w/w [GBC60] bioactive beads) and a conventional PMMA bone cement control (CMW-1). Initial bending strengths were measured with the use of the three-point bending method. Specimens of all three cements were then implanted into the dorsal subcutaneous tissue of rats, removed after 3, 6, or 12 months, and tested for bending strength. The bending strengths (MPa) of GBC50 at baseline (0 months), 3, 6, and 12 months were 136 +/- 1, 119 +/- 3, 106 +/- 5 and 104 +/- 5, respectively. Corresponding values were 138 +/- 3, 120 +/- 3, 110 +/- 2 and 109 +/- 5 for GBC60, and 106 +/- 5, 97 +/- 5, 92 +/- 4 and 88 +/- 4 for CMW-1. Although the bending strengths of all three cements decreased significantly from 0 to 6 months, those of GBC50 and GBC60 did not change significantly thereafter, whereas that of CMW-1 declined significantly between 6 and 12 months. Thus, degradation of GBC50 and GBC60 does not appear to continue after 6 months, whereas CMW-1 degrades progressively over 12 months. Moreover, the bending strengths of GBC50 and GBC60 (especially GBC60) were significantly higher than that of CMW-1 throughout. It is believed that GBC60 is strong enough for use under weight-bearing conditions and that its mechanical strength is retained in vivo; however, its dynamic fatigue behavior will need assessment before application in the clinical setting.

Animals↗
PubMed1998

Effect of polymerization reaction inhibitor on mechanical properties and surface reactivity of bioactive bone cement.

We introduced an inhibitor to the polymerization reaction of bioactive bone cement (AWC) consisting of MgO-CaO-SiO2-P2O5-CaF2 apatite and wollastonite containing glass-ceramic powder and bisphenol-alpha-glycidyl methacrylate based resin, together with an increased amount of accelerator but without any prolongation of its setting time in order to improve the degree of polymerization and decrease the amount of incompletely polymerized monomers on the cement surface. A comparison was made between the AWC containing the inhibitor [AWC(I+)] and the AWC without it [AWC(I-)] with regard to setting parameters, mechanical properties, and surface reactivity in vitro and in vivo. The proportion of glass-ceramic powder added to the AWC was 70% (w/w). The total amount of heat generation and the peak temperature of the AWC(I+) during polymerization were slightly greater than those of the AWC(I-). The mechanical strength of AWC(I+) was higher than that of the AWC(I-) under wet conditions. In simulated body fluid, the width of the Ca-P rich layer on the surface of the AWC(I+) was less than that on the AWC(I-) after 28 days of immersion, although the rate of apatite formation on the top surface of the AWC(I+) was almost identical to that on the AWC(I-) surface. Histological examination using rat tibiae up to 26 weeks revealed that the bioactivity of the AWC(I+) was equivalent to that of the AWC(I-). Scanning electron microscopy and energy-dispersive X-ray microanalysis demonstrated that the Ca-P rich layer in the AWC(I+) was significantly narrower than that in the AWC(I-) at the same time points. These results indicate that introduction of the inhibitor improved the mechanical properties of the AWC and made the Ca-P rich layer narrower, but it had no adverse effect on bioactivity.

Animals↗
PubMed2004

Intramedullary bone cementing for the treatment of Colles fracture in elderly patients.

Eighteen patients with Colles fractures, mean age 70 years (range 55-91), were treated by intramedullary bone cementing. The best indication for this technique was an unstable extra-articular Colles fracture with osteoporosis. Bone cement was packed into the canal that was made by curettage of intramedullary cancellous bone from the dorsal fracture site. Intramedullary cementing caused little bleeding from the medullary canal and no irritation of the extensor tendons. Because of rigid fixation, patients could use the affected hand for light activities without any external orthosis the day after surgery. Cortical healing was seen in all cases within three months and there was no cement loosening or other complications during the mean 28 month (range 6-43) follow up period. Intramedullary bone cementing is one of the optimal treatments for Colles fractures in elderly patients.

Age Factors↗
PubMed1977

Temperature control of a bone cement by addition of a crystalline monomer.

The peak temperature reached during the polymerization of a bone cement was reduced by addition of solid N-vinylcarboazole to the powder component. It was also necessary to saturate the liquid component with N-vinylcarbazole to prevent dissolution from the modified powder component on mixing. It is believed that this technique is generally applicable and opens up the possibility of achieving temperature control of bone cements with choice from a range of crystalline monomers.

Bone Cements↗
PubMed2004

The influence of the viscosity classification of an acrylic bone cement on its in vitro fatigue performance.

The goal of the present work was to investigate the influence of the viscosity classification of an acrylic bone cement on its in vitro fatigue performance, as determined in fully-reversed tension-compression (+/-15 MPa) fatigue tests. The test matrix comprised six commercially available bone cements [Orthoset1, (OS1), Orthoset(R)3 (OS3), CemexRX (CRX), Cemex XL (CXL), Palacos R (PR) and Osteopal (OP)], two methods of mixing the cement constituents (hand-mixing and vacuum-mixing), two methods of fabricating the test specimens (direct molding and molding followed by machining), two specimen cross-sectional shapes (rectangular or "flat" and circular or "round"), and four test frequencies (1, 2, 5, and 10 Hz). In total, 185 specimens, distributed among 20 sets, were tested. The test results (number of fatigue stress cycles, N_f) were processed using the linearized transformation of the three-parameter Weibull distribution, whence estimates of the Weibull mean, N_[WM], were obtained. Statistical analysis of the ln N_f results (Mann-Whitney test; alpha<0.05) and a comparison of the N_[WM] estimates for specimen sets in which the formulations have essentially the same composition but different viscosity classification (namely, OS1 versus OS3, CRX versus CXL, and PR versus OP) showed that, in the majority of the comparisons carried out, the viscosity classification of a bone cement does not exert a significant influence on its in vitro fatigue performance.

Adult↗
PubMed1991

The effect of the extracorporeal shock wave lithotriptor on bone cement.

For the purpose of studying its applicability for acrylic cement removal during total hip revision surgery, experiments with an extracorporeal shock wave lithotriptor were carried out. High-energy shock waves (HESW) were focussed on discs of polymethylmethacrylate bone cement. The average discharge was 18.1 kV; the number of shock waves 0, 100, 250, 500, 1000, and 2000; the application rate was 85 shocks/min. Macroscopic or radiographic effects were not in evidence. Microscopically, typical lesions in a small concentric focal area with a diameter of 8.5 (+/- 2.5) mm were found. The individual lesions were smaller than 0.1 mm, and displayed characteristic shapes. The area porosity increased with the number of shocks. The maximal area porosity caused by the HESW, measured by quantitative microscopy, was 4% after 2000 shock waves. The lesions were also studied by scanning electron microscopy. It can be concluded that HESW causes only microscopic lesions on the frontal surface of discs of bone cement, and that these lesions are small compared to the pores normally present in bone cement, when applied clinically.

Bone Cements↗
PubMed1997

Effect of calcium carbonate on clinical compliance of apatitic calcium phosphate bone cement.

Clinical requirements for calcium phosphate bone cements were formulated in terms of the initial setting time, the final setting time, the cohesion time, and the ultimate compressive strength. Two cement formulations were tested. Biocement F was made of a powder containing alpha-tertiary calcium phosphate, precipitated hydroxyapatite, and monetite. Biocement D powder also contained CaCO3. The liquid/powder (L/P) ratio of the cement paste and the accelerator concentrations (% Na2HPO4) in the cement liquid were varied. For Biocement F there was a small area of combinations of L/P ratio and percent Na2HPO4 for which all clinical requirements were satisfied. This area covered only pastes that could be applied as doughs. However, Biocement D showed a much larger area of full compliance and it covered both doughlike and injectable pastes.

Apatites↗
PubMed1977

[Tissue compatibility of bone cement with and without barium sulfate (author's transl)].

Cylindrical plugs of polymerized Simplex-P bone cement with and without barium sulfate were implanted in the rabbit tibial metaphysis. Titanium was used as control material. The animals were observed for 4--4.5 months. Histological analysis showed that all titanium implants were healed into the bone with a direct bone-implant contact, which was also true for about 60% of the cement implants. The remaining cement implants were encapsulated by connective tissue, probably due to biomechanical factors. It was not possible in this study to show a difference in the tissue reaction to bone cement containing barium sulfate and bone cement free from barium sulfate.

Animals↗
PubMed2006

The mechanical properties of recovered PMMA bone cement: a preliminary study.

Samples of polymethylmethacrylate (PMMA) bone cement, used in the fixation of hip prostheses, have been recovered from 11 patients after in service life spans of between 15 and 24 years. Eighteen samples in total have been recovered from the acetabular and/or femoral cement. Samples were subjected to three point bending tests, their density, porosity and microhardness determined and all specimens were examined using EDX and X-ray techniques. Since the porosity of many of the samples is very high, the continuous matrix properties are inferred from the performance of individual specimens. No evidence has been found to suggest that the PMMA has deteriorated whilst in-vivo and the mechanical properties of the cement matrices appear to be comparable to freshly made PMMA.

Arthroplasty, Replacement, Hip↗
PubMed1998

Study of polymerization of acrylic bone cement: effect of HEMA and EGDMA.

The polymerization reaction of standard surgical Simplex-P radiopaque bone cement was investigated by differential scanning calorimetry to determine the influence of hydroxyethyl methacrylate (HEMA) and ethylene glycol dimethacrylate (EGDMA) on the polymerization reaction. From the kinetic analysis, the polymerization reaction of the modified acrylic bone cement was found to be approximately a first-order reaction. The reaction rate constants (k) were determined. It was found that the effects of HEMA and EGDMA contents on the rate and the heat of polymerization can be explained by the frequency factor and the activation energy. An increase in HEMA content tends to result in an increase in the values of both frequency factor and activation energy, whereas an increase in EGDMA content tends to induce a decrease in the frequency factor and activation energy.

Bone Cements↗
PubMed1982

The effect of initial temperature on free radical decay in PMMA bone cement.

The effect of varying the initial temperature of the components of poly(methyl methacrylate) (PMMA) bone cement has been investigated. Electron paramagnetic resonance (EPR) spectroscopy was used to monitor free radical decay during the curing of the cement. Samples cured in saline at 37 degrees C were found to exhibit first-order decay kinetics for the polymerization radicals for approximately one week after mixing. This indicates that the decay did not take place by combination or disproportionation and was probably due to a transfer process. Decreasing the temperature of the bone cement components prior to mixing resulted in smaller decay rates, but still with first-order kinetics. This decrease in decay rate with lower initial temperature may be due to decreased porosity of the cement, possibly due to decreased monomer evaporation. SEM micrographs of the samples were consistent with this change in porosity.

Bone Cements↗
PubMed1997

[The plain-film radiological changes in the cervical spine following a ventral fusion operation with bone cement].

PURPOSE: The usual treatment in cervical nerve root compression syndrome is the ventral fusion with bone cement. We examined the influence of this interponate on the postoperative changes of the cervical spine. MATERIALS AND METHODS: 33 patients were followed-up postoperatively over 6 months, who were treated with 39 ventral fusions because of cervical myelopathy. The lateral view of the cervical spine was used to measure the size of the bone cement interponate, the height of the intervertebral body space and the angle of both vertebral bodies. RESULTS: There was no change on the size of the interponate. Postoperatively there was a slight enlargement of the intervertebral body space. During further follow-up examinations there was a decrease to the preoperative size because of the destruction of the endplates. Similar to this observation, there was a change of the angle in the operated segment. First there was a decrease of the angle, later an increase. 6 months postoperatively the preoperatively status was re-attained. Clinical examination of the patients revealed new neurologic deficits in 10% of the cases. CONCLUSION: We conclude that the postoperative deficits can be only partially explained because the structural changes occur with both the uncomplicated postoperative courses and in patients with postoperative deficits.

Adult↗
PubMed1997

Effect of crosslinking agents on acrylic bone cements based on poly(methylmethacrylate).

Three different crosslinking agents were added to the monomer content of the bone cement formulation based on poly(methylmethacrylate), PMMA, in various concentrations, and their effects on the curing parameters and mechanical properties were determined. The different crosslinking agents were dimethacrylates containing a range of chain lengths and degrees of flexibility. For the parent formulation of the bone cement, PMMA powder was used, and the properties and kinetics of curing were compared for the same system with and without crosslinking agents. It was found that at low concentrations of crosslinking agents, the mechanical properties were superior but steadily decreased with increasing concentrations. Poly(ethyleneglycoldimethacrylate), EGDMA(400), even when used at very low concentrations, produced a steady improvement in the mechanical properties and could be used in cement formulations with a view to reducing creep and improving mechanical properties.

Acrylates↗
PubMed1981

The depot administration of penicillin G and gentamicin in acrylic bone cement.

The in vitro elution of penicillin and gentamicin from polymethylmethacrylate was studied qualitatively and quantitatively. Penicillin eluted poorly from Simplex P. Higher levels of penicillin eluted in sustained fashion from Palacos; concentrations of one microgram or more per gram of cement were recorded during the thirteen weeks of observation. Although the in vitro leaching of gentamicin from Palacos cement was similar to that of penicillin, there were two important differences: (1) most of the gentamicin leaching from the Palacos did so within the first twenty-four hours, and (2) the concentrations decreased to less than one microgram per gram of cement after the sixth week of observation. The in vivo elutions of penicillin and gentamicin from Palacos were studied in canine femora. The concentrations of penicillin and gentamicin in the endosteal bone at the bone-cement interface exceeded the concentrations found after intravenous administration of either agent. Bactericidal concentrations of gentamicin in osseous tissue persisted for seven months after implantation. Peak concentrations in serum following the depot administration of either penicillin or gentamicin occurred within thirty minutes of implantation. Concentrations of gentamicin in serum did not approach toxic levels. These data suggest that a high concentration of either penicillin or gentamicin can be obtained at the bone-cement interface--one of the vulnerable sites in total joint arthroplasty--for a prolonged period with the depot administration of these agents in acrylic bone cement. These osseous concentrations can be achieved without exposing the patient to elevated levels in serum and their potential toxic side effects.

Animals↗