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PubMedDate not supplied

Does keel size, the use of screws, and the use of bone cement affect fixation of a metal glenoid implant?

The objective of this study was to determine the effect of screws and keel size on the fixation of an all-metal glenoid component. A prototype stainless-steel glenoid component was designed and implanted in 10 cadaveric scapulae. A testing apparatus capable of producing a loading vector at various angles, magnitudes, and directions was used. The independent variables included six directions and three angles of joint load, and five fixation modalities-three different-sized cross-keels (small, medium, and large), screws, and bone cement. Implant micromotion relative to bone was measured by four displacement transducers at the superior, inferior, anterior, and posterior sites. The components displayed a consistent response to loading of ipsilateral compression and contralateral distraction. Use of progressively larger keels did not significantly improve implant stability. Stability decreased as the angle of load application increased (P <.05). Screw and cement fixation resulted in the most stable fixation (P <.05).

Arthroplasty↗
PubMed2005

Osteolytic potential of triphenyl bismuth as an alternative contrast medium in acrylic bone cement.

Radiopaque cement containing barium sulfate causes significantly more bone resorption in vivo and in vitro than radiolucent cement. The aim of this study was to investigate the osteolytic potential of an alternative radiopaque agent, triphenyl bismuth (TPB). Bone cement particles containing various concentration of TPB (15 and 25 wt %) prepared by two methods, blending and dissolution, were added to monocytes in a bone resorption assay and the extent of lacunar resorption on dentine slices was determined. The results clearly show that cement particles containing TPB cause less bone resorption than cement particles containing barium sulfate. In addition, our results suggest that TPB prepared by dissolution in bone cement induces less osteolytic response than TPB-cement prepared by blending. The osteolysis in response to bone cement wear particles may therefore be reduced with TPB prepared using the blending technique.

Animals↗
PubMed1992

Inhibition of bacterial adhesion by tobramycin-impregnated PMMA bone cement.

We investigated the effect of tobramycin-impregnated polymethylmethacrylate (PMMA) bone cement on the adhesion and colonization of Staphylococcus epidermidis. The pattern of colonization was quantitated using plate count techniques and electron microscopy. Colonization of the tobramycin-impregnated disc surface by adhesive bacteria was demonstrated but it was less than in the control disc. This finding suggests that tobramycin may reduce bacterial adherence and proliferation on the PMMA surface.

Bacterial Adhesion↗
PubMed1977

Analysis of the ingredients and determination of the residual components of acrylic bone cements.

Rapid and reliable methods for the characterization and quantitative determination of ingredients usually present in self-curing methacrylate bone cements were developed using spectrophotometric, gas chromatographic (GC), and coventional gravimetric procedures. These procedures are applicable to non-crosslinked methacrylate resins. In the presence of some copolymers, polymer blends or crosslinking agents, or other ingredients which will result in the formation of insoluble methacrylate resins, some modification of the identification procedures and quantitative estimation of the resin components will be required. Molecular weight and molecular weight distribution of the powder and cured cement were obtained from viscosity and gel-permeation measurements. Residual low molecular weight materials in the cured cement were determined for various storage times. Residual and water-leachable monomer and residual dimethyl-p-toluidine (DMPT) were measured by GC. In air, The monomer content of the cured resin decreased from 3.3% after 1 hr to 2.4% after 215 days. When stored in water at 37 degrees C, over 65% of the extractable monomer is leached out within 10 min. After 6 hr, the rate of diffusion of monomer into the aqueous phase is low. The cured cement contains as much as 0.6% DMPT, which does not leach out. Residual peroxide, estimated spectrophotometrically, amounts to 0.8%, but decreases to 0.14% after 15 months in water at 37 degrees C. A semiquantitative colorimetric test indicated that the hydroquinone content of specimens analyzed within 24 hr after curing amounted to 9 ppm.

Benzoyl Peroxide↗
PubMed1999

Effect of two variables on the fatigue performance of acrylic bone cement: mixing method and viscosity.

The goal of the present work was to establish the relative influence of one exogenous variable versus one endogenous variable on the fully-reversed tension-compression fatigue performance of bone cement. The method used to mix the cement constituents was the exogenous variable, while the viscosity of the mixed cement dough was the endogenous variable. Two commercial cement formulations (Palacos R and Osteopal) and two cement mixing methods (hand mixing and vacuum mixing) were used. It was found that for a given mixing method, cement viscosity exerts a marginal influence on fatigue performance. On the other hand, for a given cement formulation, vacuum mixing led to a statistically significant improvement in fatigue performance. The present results demonstrate the superior influence of mixing method over cement viscosity.

Acrylates↗
PubMed2000

[Water jet cutting for bones and bone cement--parameter study of possibilities and limits of a new method].

Water jet techniques have been used in industrial cutting, drilling and cleaning applications for more than 30 years. Plain water is typically used for the cutting of non-metallic materials. The addition of abrasive substances to the stream allows almost any material to be cut. The first medical applications were reported in the early 1980s, when the water jet was used to cut organs. The present study investigates the use of water jet cutting technology for endoprosthesis revision surgery. Bone and PMMA (polymethylmethacrylate) samples were cut at different pressures using an industrial water jet cutting device. Using plain water at 400 bar, PMMA was cut selectively without damaging the bone; above 400 bar, bone was also cut, but the cutting depths in PMMA were significantly greater (p < 0.05). Adding a water-soluble abrasive disaccharide to the water results in a significantly higher removal rate for both materials (p < 0.05), but selectivity is lost, although the differences in cutting depth between the two materials was significant (p < 0.05). With an abrasive, the quality of the cut was better for both materials. The water jet technology--in particular the abrasive technique--can be used to cut biomaterials such as bone and bone cement. The diameter of the jet is a great advantage when working in the confined area at the prosthesis interface. The cutting process is essentially cold, thus eliminating a thermal effect, and the jet reaction forces are relatively low. Accurate manipulation of the hydro jet nozzle is possible both manually and by robot. The results obtained show that it is possible to remove prostheses with this cutting technique, rapidly and with little damage to the surrounding tissue. Problem areas are the development of sterile pumps and the "depth control" of the jet.

Animals↗
PubMedDate not supplied

Molecular and mechanical property changes during aging of bone cement in vitro and in vivo.

The changes in mechanical properties and free radical concentration of curing Simplex P Radiopaque Bone Cement in vivo and in vitro conditions were studied. Samples were prepared so that each in vivo sample that cured and aged in the canine femoral intramedullary cavities had an in vitro counterpart that was cured and aged in a constant-temperature saline bath at 37 degrees C. An electron paramagnetic resonance (EPR) spectrometer was used to measure the growth and decay (curing) of polymerization radicals. The results of EPR measurements showed that the curing (disappearance of free radicals) of in vivo samples takes a much longer time (more than 4 weeks) than in vitro curing (less than 2 weeks). The mechanical tests indicate that, whether aged in vivo or in vitro, the strength increased rapidly for the first 1-2 weeks and then slight increases were seen for up to 6 months.

Animals↗
PubMed2006

Optimisation of the composition of an acrylic bone cement: application to relative amounts of the initiator and the activator/co-initiator in Surgical Simplex P.

In cemented arthroplasties, the two-part self-curing acrylic bone cement is currently the only material used for anchoring the total joint replacement to the contiguous bone. In virtually all commercially available formulations of this cement, the agents used for the initiation and activation/co-initiation of the radical polymerisation reaction are benzoyl peroxide (BPO) and N, N dimethyl-para-toluidine (DMPT), respectively. There are no reports in the open literature on the rationale for the amounts of these and other constituents in the formulations of the cement. Given the concerns that have been raised in the literature regarding the effect of residual DMPT on the body, it is important to keep the starting amounts of BPO and DMPT as high and as low, respectively, as possible. In the present work, the focus is on the relative amounts of these two agents in the case of one widely used commercial formulation, Surgical Simplex(R) P. Thirty variants of this cement were formulated, covering three concentrations of the co-polymer/BPO (75%, 80%, and 85% of the mass of the powder) and DMPT amounts (ranging from 0.8 %v/v to 2.4% v/v.) The setting time (t(set)), the peak temperature reached during the cement polymerisation process (T(max)), and the ultimate compressive strength (UCS) of each of the formulations were determined in accordance with procedures specified in ISO 5833. A critical examination of all the results indicated that the optimum ratio of the concentration of the initiator (BPO embedded in the PMMA-sytrene co-polymer) to that of the activator/co-initiator (DMPT) in Surgical Simplex(R) P is 57.14 (80%w/w co-polymer + BPO per 1.4%v/v DMPT). The mean values of t(set), T(max), and UCS of this optimum formulation were determined to be 12.30 min, 68 degrees C, and 101 MPa, respectively, all of which are within the limits specified in ISO 5833. The commercially available formulation of this cement contains 2.5%v/v DMPT, while the optimum formulation, as found in the present work, has 44% less DMPT, which may translate to a smaller amount of residual DMPT that is available for elution into the periprosthetic tissue in a cemented arthroplasty, over the in vivo life of the joint replacement.

Adhesiveness↗
PubMedDate not supplied

Structural weakening of layered acrylic bone cement.

Occasionally during arthroplasty procedures, additional cement is required to supplement an initial polymerizing mass. In vitro studies demonstrate that this practice significantly weakens the integrity of the added cement, as determined in mechanical shear. This is accompanied by a marked increase in cement porosity, with the voids acting as sites of stress concentration. This caveat has important consequences in clinical use of acrylic bone cement.

Bone Cements↗
PubMed1984

Late complications of total hip replacement from bone cement within the pelvis. A review of the literature and a case report involving dyspareunia.

It is not uncommon to observe bone cement in the pelvis on radiographs after total hip replacement, a finding which is generally considered to be benign. This paper reviews some catastrophic late complications from intrapelvic methylmethacrylate. We also describe a case of progressive, unbearable dyspareunia beginning three years after total hip replacement. A possible explanation of the pathophysiology is suggested. Recommendations for prevention, diagnosis, and treatment of these late complications are offered.

Adult↗
PubMed1981

Systemic antibiotics and gentamicin-containing bone cement in the prophylaxis of postoperative infections in total hip arthroplasty.

In a prospective controlled multicenter study, the prophylactic effect of gentamicin-containing bone cement on postoperative infections in total hip arthroplasties was compared with that of systemically given antibiotics; 812 arthroplasties were randomly assigned to an antibiotic and 821 to a gentamicin-cement group. When the patients had been followed for a period of one to two years, 13 deep infections were diagnosed in the antibiotic group and three in the gentamicin-cement group. The difference was statistically significant.

Anti-Bacterial Agents↗
PubMed1989

Fatigue properties of bone cement. Comparison of mixing techniques.

A four-point bending test was made on 54 specimens of CMW, Simplex P, and Zimmer LVC bone cements. The samples were cyclically loaded at a stress level of 20 MPa at a frequency of 4 Hz. The different cements were mixed either by hand or mechanically with or without a 0.15-bar vacuum. Mechanical mixing in a vacuum improved all three cements, and was the best of all the tested mixing techniques. Simplex P showed the best fatigue properties regardless of mixing technique.

Bone Cements↗
PubMed1999

Calcium phosphate bone cements for clinical applications. Part II: precipitate formation during setting reactions.

Calcium phosphate bone cements (CPBC) have been of great interest in medicine and dentistry due to their excellent biocompatibility and bone-repair properties. In this article, a review is presented of the scientific literature concerning precipitate formation during setting reactions of CPBCs. Firstly, the available information has been classified according to the intended final product or calcium phosphate formed during setting reactions. Taking the final product into account, a second classification has been made according to the calcium phosphates present in the original powder mixture. This is the most natural classification procedure because it is based on thermodynamic reasons supported by solubility diagrams for the calcium phosphate salts. By understanding the thermodynamics of calcium phosphate salts in an aqueous solution at room or body temperature it is possible to optimize the manufacturing technology involved in the production of CPBCs. Knowledge of the limitations of this thermodynamic approach opens up new possibilities in the search for CPBCs with better in vitro and in vivo properties for clinical applications.

Journal Article↗
PubMed2004

Comparison of various vacuum mixing systems and bone cements as regards reliability, porosity and bending strength.

BACKGROUND: There are several vacuum mixing systems on the market which are arbitrarily used with various bone cements in clinical work. Hardly any studies have been done on the performance and handling of these systems in combination with different cement brands. MATERIAL AND METHODS: We therefore tested 6 vacuum mixing systems (Palamix, Summit, Cemvac, Optivac, Vacumix, MixOR) in combination with 6 cement brands (Palacos R, Simplex P, CWM 1, CWM 2000, Palamed G, VersaBond) concerning their reliability, user-friendliness, porosity and bending strength. RESULTS: Our study indicated that each system has weak points. The preparation of the mixed cement for gun injection can present problems. If cement collection under vacuum fails, porosity is increased. Manual collection without a vacuum carries the risk of intermixing air. For comfortable and effective retrograde cement application, cement guns should have a stable connection with the cartridge and a high piston stroke. There are marked differences between the systems as regards overall porosity when all tested cements are considered (range 2-18%), and between the cements when all tested systems are considered (range 2-17%). All test samples exceeded the required bending strength of 50 MPa, according to ISO 5833. Palaces specimens showed excessive plastic deformation in the bending test. INTERPRETATION: There are better and worse mixing system/cement combinations for a given system and a given cement. Systems with cement collection under vacuum reduce porosity best.

Bone Cements↗
PubMed2005

Development of a strontium-containing hydroxyapatite bone cement.

A new route was developed to synthesis a new type of strontium-containing hydroxyapatite (Sr-HAP) bone cement with precursors of tetracalcium phosphate (TTCP), strontium hydrogen phosphate (DSPA), dicalcium phosphate (DCPA), phosphate acid and water. The processing parameters and fundamental properties including pH value, setting time, compressive strength of final hardened body and the cytotoxicity for serial extracts of each cements were investigated. The result shows that the final product of the cement after setting for 24h is nonstoichiometic Sr-containing hydroxyapatite (Ca(10-m-x)Sr(x) square(m)(HPO4)y(PO4)6-y(OH)2-2m square2m, 0<x<1, nSr-HAP) and no other harmful impurities were detected. The pH value of Sr-containing cement pastes approaches to 7.0-7.6 when they are mixed with a ratio of 1:1 of powder to liquid (P/L) in weight. The setting time of the cement pastes is 4-11 min for the initial one and 10-17 min for the final one when the concentration of diluted phosphate is in a range of 0.5-1.0 mol/l. The compressive strengths of the hardened cements with different molar ratios of Sr/(Sr+Ca) after subjected an immersion in simulated body fluid (SBF) increase uniformly from 1 day to 5 days, where they get maximum values, respectively, but then decrease till to 2 weeks. Especially for the CPC-1, with a Sr/(Sr+Ca) molar ratios of 5% in cement powder composition, the largest compressive strength gained at 5 days is 66.57 MPa and the lowest one gained at 2 weeks is 44.75 MPa, which matches the value of human bones and can be expected to use in clinic application in repairing the nonloading sites on account of the positive result of cytotoxicity test of the extracts of Sr-containing calcium phosphate cement (Sr-CPC).

Animals↗
PubMed2001

Bone cement with reduced proportion of monomer in total hip arthroplasty: preclinical evaluation and randomized study of 47 cases with 5 years' follow-up.

Bone cement with reduced amount of monomer and low curing temperature may improve implant fixation due to reduced toxicity. We analyzed the mechanical, chemical and thermal properties of such a cement (Cemex Rx) using Palacos R as control. The in vivo performance of the 2 cements was also evaluated in a prospective randomized study of 47 hips, where either of the cement types was used to fixate Lubinus SP2 prostheses with the stem made of titanium alloy. Cemex Rx had a reduced tensile strength, probably because this cement was manually mixed, as recommended by the manufacturer. A standardized labor tory test showed lower curing temperature for Cemex, but measurements at 37 degrees and with prechilled Palacos R and Cemex Rx, as in clinical work, showed no difference. In the clinical study radiostereometric measurements of cup and stem migration showed similar values in the 2 groups up to 5 years after the operation. The cement mantle was stable in both groups, but the stems migrated similarly inside the cement mantle regardless of the type of cement used. Proximal wear was low (0.04-0.05 mm/year) and tended to be lower in the Cemex group (p = 0.02). Aluminum and vanadium levels in serum increased 5 years after the operation, but no difference was noted between the 2 groups. Collagen markers (PICP, ICTP) showed similar increases in bone turnover 6 weeks and 6 months after operation in both groups.

Aged↗
PubMed1982

[Bone cement as replacement material of cervical disks].

Experimental and thermographic investigations, clinical and radiological long-term studies proved that the replacement of herniated cervical discs by bone cement has to be regarded as an operative procedure equivalent to other techniques using auto- or homogenous bone-graft. Tissue reactions on the allograft were studied. There is no risk of thermonecrosis at the adjacent neurogenic structures by polymerization heat. Clinical late results correspond with those of other operative techniques, the morbidity rates are about the same. Cervical anterior interbody fusion using PMMA is an alternative technique in the treatment of ruptured cervical discs.

Animals↗
PubMedDate not supplied

Free radical decay kinetics in PMMA bone cement.

Electron-spin resonance has been used to measure the decay of the concentration of polymerization radicals in polymethyl methacrylate (PMMA) bone cement and the kinetics of the decay determined. Thermal annealing at various temperatures has shown that the logarithm of the concentration of radicals varies linearly with time, but with a nonzero intercept. These results have been analyzed by including both first- and second-order decay processes. The first-order process has an activation energy of 39 +/- 2 kcal/mol and is probably due to a diffusion-limited termination. The second-order process has an activation energy of 36 +/- 5 kcal/mol and is probably due to bimolecular termination.

Bone Cements↗