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PubMed1979

[Reaction of articular cartilage to subchondral defect filling with autologous cancelous bone, Kiel's bone chips and bone cement].

Equally sized subchondral osseous defects were produced in 30 adult rabbits. The defects were filled with autologous cancellous bone, bone cement, or macerated heterologous cancellous bone. Twelve weeks later those filled with autologous cancellous bone showed consolidation with preservation of the subchondral border line. There were no degenerative changes of the joint's cartilage. Filling with bone cement or heterologous cancellous bone, on the other hand, led to destruction of the joint's cartilage. The defects treated with heterologous cancellous bone had not reached osseous consolidation at that time. These results suggest that effective treatment of subchondral osseous defects can only be achieved by filling with autologous cancellous bone.

Animals↗

PubMed1991

Compressive behavior of human bone-cement composites.

Current surgical practice in the implantation of cemented total joint arthroplasties generally creates a zone of variable thickness in which polymethylmethacrylate (PMMA) is intermixed with trabecular bone. The authors' objectives in these experiments were to characterize the compressive mechanical properties of this bone-cement composite material. They found that the mechanical properties of bone-cement composite specimens, fabricated under in vitro conditions that would promote nearly complete cement filling, are closer to the properties of trabecular bone than to those of cement. For both low-viscosity cement (LVC) and PMMA specimens, with the cement introduced by either hand-packing or pressurized injection at periods of 2 and 7 minutes, the compressive strengths ranged from 29 MPa to 50 MPa and the compressive moduli from 539 MPa to 1,210 MPa. Cement volume fractions achieved using different filling methods ranged from 76% to 87%. In contrast to previous studies of bone-cement composites using high-density bovine bone, neither mechanical properties nor filling parameters correlated significantly with bone porosity measured prior to filling. The authors expect that the mechanical properties of bone-cement regions created at surgery under less than these ideal in vitro filling conditions will only approach their values as an upper limit. Thus, bone-cement composites created in situ at surgery will also exhibit mechanical properties well below previously assumed values.

Aged↗

PubMed2002

[Stabilizing effect and sintering tendency of 3 different cages and bone cement for fusion of cervical vertebrae segments].

Important requirement for spinal fusion devices for segment are that they provide sufficient stability and guarantee a low subsidence risk. An important requirement for spinal fusion devices for segments are that they provide sufficient stability and guarantee a low subsidence risk. Therefore, in the following in vitro study, the stabilizing effect and subsidence tendency of cervical fusion cages and bone cement were investigated during cyclic loading. The WING cages (Medinorm AG) and BAK cages (Spinetec) made of titanium, the carbon fiber reinforced PEEK cage from Acromed (DePuy Acromed), and bone cement (PMMA, Sulzer) were tested. Twenty-four human cervical spine specimens were first tested intact with a standardized flexibility test (+/- 2.5 Nm). Then the implants were inserted and the primary stability determined. For the simulation of the postoperative loading of the cervical spine a cyclic loading protocol with 700 loading cycles was performed. In this test pure moments +/- 2.0 Nm in 9 different loading directions in randomized order were applied together with a 50 N preload to simulate the weight of the head. The subsidence and "long term stability" was measured after 50, 100, 200, 300, 500, and 700 cycles. All implants had a stabilizing effect in all directions most obviously in lateral bending. Here the range of motion was between 20.9% (AcroMed Cage), and 62% (BAK Cage) with respect to the intact specimen (100%). In laterial bending, flexion, and axial rotation the AcroMed cage stabilized the most followed by the bone cement, WING and BAK Cage. In extension the specimens treated with bone cement were the most stable. After 700 loading cycles the specimens with the BAK cage lost 1.6 mm in height, with the WING Cage 0.8 mm, with the Acromed 0.7 mm, and with the bone cement 0.5 mm. Two Acromed Cages dislocated during the long term testing. Cages have the potential to stabilize as effectively as bone cement. A smaller contact area, however, causes a higher subsidence risk compared to bone cement but increases the fusion area, thus increasing the chance of obtaining bony fusion.

Biomechanical Phenomena↗

PubMed1990

Use of antibiotic-loaded bone cement in the management of common infections of the foot and ankle.

Antibiotic-loaded bone cement is a useful adjunct in the management of chronic osteomyelitis and in the prevention of recurrent osteomyelitis after an initial attack. Additionally, antibiotic-loaded bone cement stimulated the formation of granulation tissue in excess of that which would normally be expected. Our experience has been consistent with others' experience, which suggests that the use of antibiotic-loaded bone cement is an effective means of reducing the length of hospitalization and the cost usually associated with traditional methods in the management of bone and soft-tissue infections.

Adolescent↗

PubMed2001

Bioactive bone cement: effect of filler size on mechanical properties and osteoconductivity.

A bioactive bone cement (designated GBC), consisting of bioactive glass beads as an inorganic filler and poly(methyl methacrylate) (PMMA) as an organic matrix, has been developed. The purpose of the present study was to examine the effect of the size of the glass beads added as a filler to GBC on its mechanical properties and osteoconductivity. Serial changes in GBC with time were also examined. Four different sizes of beads (mean diameters 4, 5, 9, and 13 microm) consisting of MgO-CaO-SiO(2)-P(2)O(5)-CaF(2) glass were added to four GBC mixes in a proportion of 70 wt %. The bending strength of GBC increased as the mean size of the glass beads decreased. The four GBC mixes were packed into the intramedullary canals of rat tibiae to evaluate osteoconductivity, as determined by an affinity index. Rats were sacrificed at 4 and 8 weeks after surgery. The affinity index, which equaled the length of bone in direct contact with the cement surface expressed as a percentage of the total length of the cement surface, was calculated for each cement at each interval. Histologically, new bone had formed along the surface of all types of GBC within 4 weeks. At each time interval, there was a trend for the affinity index of GBC to increase as the mean glass bead size decreased. The affinity indices for all types of GBC increased significantly with time up to 8 weeks. The handling properties of GBC were comparable to those of conventional PMMA bone cement. We concluded that, considering both mechanical properties and osteoconductivity, GBC made with smaller sized glass beads as filler was the most suitable cement. GBC shows promise as an alternative bone cement with improved properties compared to conventional PMMA bone cement.

Animals↗

PubMed2004

[The comparison of in vivo and in vitro elution of gentamycin from bone cement].

INTRODUCTION: The authors report their in vivo and in vitro results of the elution characteristics of gentamycin sulfate from bone cement, which is the most commonly used way of local antibiotic prophylaxis in Europe in the field of orthopedic surgery. AIM: The aim of this study was to investigate the elution of the gentamycin sulfate from bone cement, describe the dynamics of the emission in time and evaluate the relationship between the minimal inhibitory concentration (MIC) and the eluted concentration of the antibiotic. METHODS: The in vivo investigation samples were taken from 9 patient from drain fluids to evaluate the eluted antibiotic concentration by fluorescent polarisation immunoassay method (FPI). The in vitro emission-dynamics of two different bone cement-Gentamycin sulphate complex were analysed by plate diffusion method during one-year period after mixing. RESULTS: Their results showed that 24 hours after the operation the gentamycin concentrations in the drain fluid taken from around the endoprosthesis implanted with Palacos-R bone cement diminished, yet remained above the MIC level. High but rapidly decreasing antibiotic level was detected by the in vitro method within the first week, reading an almost steadily low concentration by the end of the first month. Surprisingly, after one year it was still possible to demonstrate the inhibitory effect of the drug from both tested types of cements. CONCLUSIONS: It is concluded that the gentamycin is able to elute from the bone cement in useful concentration after the implantation of endoprosthesis. However, this in vitro method is a useful and reproducible technique for the measurement of the efficacy of antibiotic emission from bone cement, the conversation of the results to the in vivo remains to be obscured. Nevertheless, the usage of local antibiotic prophylaxis seems to be useful during orthopaedic major intervention.

Aged↗

PubMed2001

Benign calcaneal bone cyst and pathologic fracture--surgical treatment with injectable calcium-phosphate bone cement (Norian): a case report.

Solitary calcaneal bone cysts are uncommon. Usually they measure 1/3 to 1/2 of the calcaneal length. Symptomatic calcaneal bone cysts are generally treated with open debridement and autologous bone grafting. We report a case of a patient with a displaced intra-articular calcaneal fracture who presents with a large benign calcaneal bone cyst. This patient was treated with debridement and filling of defect with injectable calcium-phosphate bone cement (Norian) and open reduction and internal fixation of the calcaneal fracture.

Adult↗

PubMed1977

Antibacterial activity of antibiotics in acrylic bone cement.

The release of various penicillins and other antibiotics from two brands of polymerised bone cement has been studied in vitro and in vivo in mice. Bone cement plugs containing antibiotics demonstrated antibacterial activity as a result of diffusion of antibiotic from the plugs into the surrounding medium. With all antibiotics tested, from 2-5 to 10 per cent of the antibiotic in the cement was released in vitro in active form within twenty-four hours. Most of the activity appeared within three hours of the start of the test, but in some cases low levels of activity were detected after four days. Antibiotic cement plugs implanted in mice and rats produced low concentrations of antibiotic in the blood up to two hours after implantation, but activity was seldom detected subsequently. In general, penicillins and non-penicillin antibiotics showed similar diffusion characteristics, and the pattern of release in vitro and in vivo was consistent with the leaching of antibiotic from, or near, the surface of the bone cement.

Acrylic Resins↗

PubMed2005

Antibacterial and mechanical properties of bone cement impregnated with chitosan nanoparticles.

Although total joint replacement has become commonplace in recent years, bacterial infection remains a significant complication following this procedure. One approach to reduce the incidence of joint replacement infection is to add antimicrobial agents to the bone cement used to fix the implant. In this in vitro study, we investigated the use of chitosan nanoparticles (CS NP) and quaternary ammonium chitosan derivative nanoparticles (QCS NP) as bactericidal agents in poly(methyl methacrylate) (PMMA) bone cement with and without gentamicin. The antibacterial activity was tested against Staphylococcus aureus (S. aureus) and Staphylococcus epidermidis (S. epidermidis). A 10(3)-fold reduction in the number of viable bacterial cells upon contact with the surface was achievable using QCS NP at a nanoparticle/bone cement weight ratio of 15%. The inhibition of S. aureus and S. epidermidis growth on the surface of the CS NP and QCS NP-loaded bone cements was clearly shown using the LIVE/DEAD Baclight bacterial viability kits and fluorescence microscopy. The CS NP and QCS NP also provided a significant additional bactericidal effect to gentamicin-loaded bone cement. The antibacterial effectiveness remained high even after the modified bone cements had been immersed for 3 weeks in an aqueous medium. No cytotoxic effect of the CS NP- and QCS NP-loaded cements was shown in a mouse fibroblast MTT cytotoxicity assay. Mechanical tests indicated that the addition of the CS and QCS in nanoparticulate form allowed the retention of a significant degree of the bone cement's strength. These results indicate a new promising strategy for combating joint implant infection.

3T3 Cells↗

PubMed2004

The chemistry of acrylic bone cements and implications for clinical use in image-guided therapy.

Advances in image-guided therapy for vertebral fractures and other bone-related disorders have made acrylic bone cement an integral part of the interventional armamentarium. Unfortunately, information on the properties and chemistry of these compounds is mostly published in the biomaterial sciences literature, a source with which the interventional community is generally unfamiliar. This review focuses on the chemistry of bone cement polymerization and the properties of components in polymethylmethacrylate (PMMA)-based polymers, the most commonly used bone cements in interventional procedures such as percutaneous vertebroplasty. The effects of altering the concentration of components such as methylmethacrylate monomers, PMMA beads, benzoyl peroxide activator, N,N-dimethyl-p-toluidine (DMPT) initiator, and radiopacifiers on the setting time, polymerization temperature, and compressive strength of the cement are also considered. This information will allow interventional radiologists to manipulate bone cement characteristics for specific applications and maximize the clinical potential of image-guided interventions.

Bone Cements↗

PubMed1996

Mechanical and biological properties of two types of bioactive bone cements containing MgO-CaO-SiO2-P2O5-CaF2 glass and glass-ceramic powder.

In this study two types of bioactive bone cement containing either MgO-CaO-SiO2-P2O5-CaF2 glass (type A) or glass-ceramic powder (type B) were made to evaluate the effect of the crystalline phases on their mechanical and biological properties. Type A bone cement was produced from glass powder and bisphenol-a-glycidyl methacrylate (BIS-GMA) resin, and type B from glass-ceramic powder containing apatite and wollastonite crystals and BIS-GMA resin. Glass or glass-ceramic powder (30, 50, 70, and 80 by wt %) was added to the cement. The compressive strength of type A (153-180 MPa) and B (167-194 MPa) cement were more than twice that of conventional polymethylmethacrylate (PMMA) cement (68 MPa). Histological examination of rat tibiae showed that all the bioactive cements formed direct contact with the bone. A reactive layer was seen at the bone-cement interface. In specimens with type A cement the reactive layer consisted of two layers, a radiopaque outer layer (Ca-P-rich layer) and a relatively radiolucent inner layer (low-calcium-level layer). With type B cement, although the Ca-P-rich layer was seen, the radiolucent inner layer was absent. Up to 26 weeks there was progressive bone formation around each cement (70 wt %) and no evidence of biodegradation. The mechanical and biological properties of the cements were compared with those of a previously reported bone cement containing MgO-free CaO-SiO2-P2O5-CaF2 glass powder (designated type C).

Animals↗

PubMed2005

[In vitro elution and mechanical properties of antibiotic-loaded SmartSet HV and Palacos R acrylic bone cements].

BACKGROUND: The continuing emergence of new bone cements with additional antibiotics makes it important to establish which one will provide the most favourable antibiotic elution. An in vitro antibiotic elution and mechanical study was therefore carried out to compare a newer bone cement, SmartSet, with the established Palacos R cement. METHODS: Samples were prepared with each cement adding 1 g gentamicin, 1 g of vancomycin, or 1 g of gentamicin and vancomycin. The samples were analysed using fluorescence polarisation immunoassay. Mechanical tests were performed to determine whether any significant degradation in the cement strength occurred following addition of the antibiotic. RESULTS: With regards to gentamicin release Palacos R eluted significantly more antibiotic over the study period than SmartSet (p<0.001). Both cements eluted significantly more gentamicin when two antibiotics were added. With respect to vancomycin release there was no significant difference. Palacos R was significantly stronger than SmartSet in the 4-point bending test when the gentamicin + vancomycin antibiotic groups were compared (p=0.01). Palacos R also demonstrated a higher elastic modulus than SmartSet when the gentamicin and gentamicin + vancomycin groups were compared (p=0.03, p=0.005). CONCLUSIONS: Gentamcin shows better release characteristics from Palacos R. Both cements exhibited synergistic release of combined antibiotics.

Adhesiveness↗

PubMed1985

Leaching of tobramycin from PMMA bone cement beads.

The in vitro leaching characteristics of tobramycin from acrylic resin (PMMA) bone cement beads have been determined by a radioimmune assay. Tobramycin was incorporated at two concentrations into bone cement beads fabricated from three commercial brands of acrylic resin. Antibiotic leaching followed a curvilinear relationship of the form X . Y = A . X + B . Y. All beads showed similar tobramycin leaching rates over time but the initial amount of leached material differed with the amount of tobramycin incorporated in the bead and the source of the PMMA bone cement. The data indicate that tobramycin-impregnated PMMA beads permit antibiotic leaching at a controlled rate compatible with possible clinical application.

Bone Cements↗

PubMed2002

New partially degradable and bioactive acrylic bone cements based on starch blends and ceramic fillers.

This work reports the development of new partially biodegradable acrylic bone cements based on corn starch/cellulose acetate blends (SCA), prepared by the free radical polymerization of methyl methacrylate and acrylic acid at low temperature. Amounts of biocompatible, osteoconductive and osteophilic mineral component such as hydroxylapatite (sintered and non-sintered), were incorporated in different percentages to confer a bone-bonding character to the bone cements in this type of applications. All cement formulations were characterized by 1H NMR spectroscopy. Curing parameters and mechanical properties were determined finding formulations which complete the ASTM legislation. Hydration degree, degradation studies, as well as bioactivity tests were performed in all prepared formulations. The developed systems show a range of properties that might allow for their application as self-curing bone cements, exhibiting several advantages with respect to other commercially available bone cements.

Bone Cements↗

PubMed1996

Intercalary replacement of canine femora using a new bioactive bone cement.

We have developed a bioactive bone cement (BA cement) consisting of Bis-GMA resin and bioactive glass powder. It has high compressive and tensile strengths, a low curing temperature and its bioactivity allows it to bond directly with bone. We operated on the 18 femora of nine mongrel dogs for intercalary replacement of part of the bone by a metal prosthesis using either PMMA cement or BA cement for fixation. Three dogs were killed at each of 4, 12 and 26 weeks after surgery for the evaluation of fixation strength by a push-out test and for histological examination by Giemsa surface staining and SEM. Fixation strengths with PMMA cement at 4, 12 and 26 weeks after surgery were 46.8 +/- 18.9, 50.0 +/- 24.7, and 58.2 +/- 28.9 kgf (mean +/-sD), respectively. Those with BA cement were 56.8 +/- 26.1, 67.2 +/- 19.2, and 72.8 +/- 22.2 kgf, respectively. Fibrous tissue intervened between bone and PMMA cement but BA cement had bonded directly to bone at 12 and 26 weeks. This suggests that BA cement will be useful in providing long-lasting fixation of implants to bone under weight-bearing conditions.

Animals↗

PubMed1990

A reduced-modulus acrylic bone cement: preliminary results.

Excessive local contact stress is implicated as an important factor in the initiation of the loosening process after total joint arthroplasties. A reduced-modulus acrylic bone cement, which decreases the bone-cement interface stresses, was developed to test this hypothesis. The formulation consists of butylmethacrylate beads, having a glass transition temperature of 27 degrees C, in a methylmethacrylate matrix. This cement, polybutylmethylmethacrylate (PBMMA), has an elastic modulus one-eighth that of standard PMMA bone cement, 0.27 vs. 2.1 GPa, at body temperature. In vivo use in a pilot study using the sheep total hip arthroplasty model shows a reduction in the rate of loosening of femoral components when compared both radiographically and mechanically with PMMA controls.

Acrylic Resins↗

PubMed1996

Is there any difference between vacuum mixing systems in reducing bone cement porosity?

Six vacuum mixing systems, Cemvac, Merck, Mitvac, Optivac, Osteobond, and Stryker, were tested using prechilled Palacos R bone cement to investigate the reduction of porosity compared to mixing at atmospheric pressure. In addition the Optivac, Osteobond, and Stryker were tested using Simplex P bone cement to find out if they were effective in reducing the porosity of a middle viscosity bone cement. All vacuum mixing systems reduced the number of macropores (> 1 mm) and micropores (0.1 mm < voids < 1 mm) and increased the density of both Palacos R and Simplex P. But only the Optivac, Stryker, and Merck systems reduced the area percentage of macropores with more than 50% compared to the control. When using Simplex P bone cement, all three mixing systems tested reduced the numbers and the area percentage of macropores compared to the control. The results show that vacuum mixing is effective in reducing the porosity in both a high viscosity cement such as Palacos R and a middle viscosity cement such as Simplex P. Not all systems tested were effective in reducing the number and size of large voids.

Absorptiometry, Photon↗

PubMedDate not supplied

The effect of bone cement used for endoprosthesis stabilization on the activity of lysosomal enzymes in peripheral blood granulocytes.

The effect of bone cement used for stabilization of hip joint endoprosthesis on the activity of lysosomal enzymes in peripheral blood granulocytes was studied. The operations were carried out under balanced, non-toxic, endotracheal anaesthesia using muscle relaxants. The blood for tests was obtained from an antecubital vein before and during anaesthesia, before application of bone cement, and 10 min., 1 hour and 24, 48 and 72 hours after endoprosthesis implantation using bone cement. The activity of acid phosphatase, acid protease and neutral protease was determined by calculating it in relation to protein level in the studied fractions. During anaesthesia as well as during the operation when bone cement was applied no statistically significant differences were found in the activity of lysosomal enzymes. On the other hand, after the operation statistically significant changes were found in the activity of lysosomal marker enzymes. Lability of lysosomal membranes appeared with permeation of hydrolases into supernatant. These results confirmed the importance of lysosomal proteins in the processes of wound healing and general postoperative course.

Acid Phosphatase↗