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At least 991 records · Page 55Linked to original sources
PubMed2001

Setting characteristics and mechanical behaviour of a calcium phosphate bone cement containing tetracycline.

Calcium phosphate cements are used for bone defect filling and they may also be used as delivery systems for active agents. The physicochemical behaviour of an ionic cement, with a final composition of hydroxyapatite, containing tetracycline hydrochloride was investigated. Chemical characterisation, X-ray diffraction analysis, compressive strength and tensile strength were performed. It is known that the antibiotic can be adsorbed on calcium phosphate compounds and the presence of chloride ions can strongly influence the behaviour of the cement. Adding more than 1% (w/w) of 95% pure tetracycline hydrochloride in the solid phase led to a cement with poor mechanical properties, but which, in addition to hydroxyapatite, contained residual starting reagents. For this reason, experiments were also performed with tetracycline previously treated with a calcium sulphate solution. Using a treated tetracycline, it was possible to introduce at least 7% (w/w) of active ingredient whilst still allowing the reaction to proceed to completion i.e. the formation of hydroxyapatite with good mechanical properties. Therefore, treating the tetracycline HCI with calcium sulphate solution prior to reaction conserved the activity of the antibiotic, limited the influence of the antibiotic on the cement evolution and retained the physical properties of the cement.

Bone Cements↗
PubMed2001

Primary arthroplasty of infected hips and knees in special cases using antibiotic-loaded bone-cement for fixation.

As a consequence of successful 1-stage exchange of infected joint prostheses, we decided to treat bacterial infection of the hip or knee by joint resection, synovectomy, and primary implantation of a hip or stabilized knee prosthesis. Since 1984, we have performed this procedure on 51 hips and 32 knees. All operations were preceded by identification of the causative organism and choice of appropriate antibiotics for addition to the bone-cement. The long-term rate of success corresponds to that of 1-stage exchange of infected prostheses. The different anatomic conditions at the hip and knee have to be taken into consideration. This treatment is restricted to special cases and should be performed only in specialized clinics with competent assistance from a bacteriologist.

Aged↗
PubMed2005

Subsidence of titanium straight stems in combination with highly viscous bone cement.

Varying results and a high rate of subsidence have been reported for the straight femoral stem (M.E. Muller) made of titanium alloy. We examined subsidence in 135 titanium-alloy straight stems implanted with high viscosity cement after 68.8+/-11.5 months using a digital high-precision method (EBRA-FCA). One revised implant showed a subsidence of 14.6 mm and another 2.5 mm over 5 years. A third implant without migration was found to be loose. The 122 implants without loosening showed a mean subsidence of 0.1+/-0.1 mm, and focal osteolysis was seen in two. Altogether, we found subsidence of the titanium stems very small. The small subsidence may be related to the use of high viscosity bone cement.

Aged↗
PubMed2000

Rapid chondrolysis after an intra-articular leak of bone cement in treatment of a benign acetabular subchondral cyst: an unusual complication of percutaneous injection of acrylic cement.

Percutaneous injection of methylmethacrylate is now increasingly employed to treat bone lesions, both malignant and benign. However, the risks of this procedure are still to be fully established. In this report, we describe a case of rapid chondrolysis appearing after the intra-articular leakage of cement during injection of an acetabular subchondral cyst, resulting in hip replacement. Although the mechanism of such chondrolysis is unknown, this event suggests a chondrolytic effect of the acrylic cement. Thus, it is essential to systematically search for the presence of an intra-articular passage before injecting bone cement into a peri-articular cyst. This unusual complication highlights the need for rigorous evaluation of the benefits and risks of percutaneous injection of acrylic cement in the treatment of benign lesions, especially close to an articulation.

Acetabulum↗
PubMed1977

[Pharmacokinetics of methylmethacrylate monomer of bone cements: method for qualitative and quantitative monomer determination in respiratory air].

The methylmethacrylate-monomer deported into circulation from bone cement implantation during endoprothetic operation is subject to unaltered exhalation. Qualitative evidence of monomer excretion in the exhaled air is established in animal experiment. The quantitative determination of monomer in the exhaled air in man undergoing hip-joint replacement are stated and the method is demonstrated. Pharmacocinetically exhalation has priority over metabolisation.

Acetabulum↗
PubMed1991

[Removal of bone cement with laser].

In operations requiring replacement of cemented endoprothesis, the removal of both the prosthesis and the cement is often difficult as the cement adheres strongly to the bone. Mechanical removal frequently results in fenestration or traumatisation of the bone. The aim of non-contact removal of polymethylmethacrylate (PMMA) with the laser, is to access normally inaccessible regions while inflicting a minimum amount of damage to the bone substance. The much cited cw or superpulsed CO2-laser cannot be used clinically, due to the thermal stressing of the bone. The paper shows spectra of PMMA with and without dopants, e.g. Tinuvin as UV absorber, optical staining with a high-pressure mercury lamp at lambda = 275 +/- 25 nm, lambda = 350 +/- 25 nm and various radiation times, as well as with an excimer laser lambda = 248 nm, FWHM 20 ns, and ablation measurements were made with the following lasers: excimer laser, Lambda Physics, EMG 102, FWHM 25 ns, lambda = 351 nm, excimer laser, Technolas, MAX 10, FWHM 60 ns, lambda = 308 nm, and a pulsed CO2 laser from PSI, lambda = 9.2 and 10.6 microns, FWHM 130 and 65 microseconds, pulse peak power 3.8 and 7.7 kW. The excimer laser, pulse length less than 100 ns, is unsuitable for clinical use because the required removal rate cannot be achieved either with doped PMMA or with pure PMMA. More promising results have been obtained with the pulsed (microseconds range) CO2 laser which has a removal rate of up to 30 times that of the above-mentioned excimer laser, with significantly lower thermal stressing of the bone than with the cw or super pulsed CO2 laser.

Bone Cements↗
PubMed1988

Fatigue properties of acrylic bone cement: S-N, P-N, and P-S-N data.

The determination of the fatigue properties of a material is a fundamental criteria in the engineering design process. The fatigue properties are governed by a number of factors, one of which is the inherent scatter in the data. In order to take into account this scatter in the results, the concept of the probability of failure (P) is introduced and interconnected with the well known stress (S) versus number of cycles to failure (N) data. This report determines the S-N curve, P-N curve, and P-S-N contour for the three leading acrylic bone cements: Surgical Simplex P, Zimmer LVC, and Zimmer Regular. Tensile specimens were fabricated according to ASTM D638 specifications and tested in uniaxial, zero-tension fatigue. The resulting stress versus number of cycles to failure data was subjected to a nonlinear least-squares analysis to determine the mathematical expression of the fatigue curve. Statistical analysis showed excellent fit of the data to the predicted curve for estimation of the endurance limit of each cement. The results indicated that Zimmer LVC had the highest endurance limit while the limit of Simplex-P and Zimmer Regular were significantly lower. No significant difference was noted in the endurance limit between Simplex-P and Zimmer Regular. The probability of failure at each stress level was determined with respect to fatigue distribution functions. Using the normal distribution function and previous S-N data, the P-S-N contour was generated for each cement. The P-S-N contour fully describes the fatigue characteristics of the material.

Acrylates↗
PubMed2002

Lysineurethanedimethacrylate--a novel generation of amino acid based monomers for bone cements and tissue repair.

A novel amino acid based dimethacrylate monomer (lysineurethanedimethacrylate, LUDM) was prepared by the addition of hydroxyethylmethacrylate (HEMA) to lysinediisocyanate (LDI). The structure was confirmed by FT-IR and 1H and 13C NMR spectroscopy as well as FAB-MS. Photopolymerized LUDM exhibited low volume shrinkage upon polymerization, good mechanical properties (Young's modulus: 3740 MPa) and high thermal stability. Osteoblast adhesion and growth on polymerized LUDM samples evidenced the biocompatibility. Further improvement of the mechanical properties was obtained by using Ca-hydroxyapatite as inorganic filler varying between 10 and 30 wt%. The Young's and flexural moduli increased with increasing filler content ranging from 3740 to 5250 MPa and from 2020 to 3690 MPa, respectively. The mechanical properties and the good biocompatibility of the lysine-based methacrylate networks make them interesting materials for medical applications, e.g. bone cements, and tissue engineering.

Biocompatible Materials↗
PubMedDate not supplied

Six years of continuous intrathecal infusion of opioid and bupivacaine in the treatment of refractory pain due to intrapelvic extrusion of bone cement after total hip arthroplasty.

BACKGROUND AND OBJECTIVES: There is at present no reliable method for long-term treatment of severe pain following complications of total hip arthroplasty. We explored the long-term use of continuous intrathecal opioid/bupivacaine analgesia in a case not amendable to corrective surgery. METHODS: A 77-year-old woman, having a total hip arthroplasty, developed refractory nociceptive-neuropathic pain located at the ventral and dorsal aspects of the left hip. Radiographs showed a mandarine-sized intrapelvic mass of bone cement adhering to the roof of the acetabular cup. Further surgery had been declined by the surgeon and by the patient. An 18-gauge Portex intrathecal catheter was inserted, and an intrathecal infusion of 4.75 mg/mL bupivacaine and 0.015 mg/mL buprenorphine was started from a portable Pharmacia-Deltec (St. Paul, Minnesota) pump. RESULTS: The mean daily doses during the treatment period (more than 6 years up to now) were 37 mg for bupivacaine and 0.114 mg for buprenorphine. The intrathecal treatment gave the patient 85-100% pain relief. The patient could transport herself in a wheelchair, was able to perform her own hygiene, receive visits, read, watch television, and also shop and visit restaurants. There has been no need to replace the intrathecal catheter. CONCLUSION: Intrathecal infusion of opioid/bupivacaine can provide satisfactory long-term analgesia in patients with refractory pain from the hip joint.

Aged↗
PubMed1999

Temperature elevation caused by bone cement polymerization during vertebroplasty.

Percutaneous vertebroplasty (PVP), whereby polymethylmethacrylate cement is injected into the vertebral body (VB), has been used to successfully treat various spinal lesions. The mechanism responsible for the palliative effect of PVP is unknown, but it may be the result of neural damage caused by heat liberated during polymerization of the polymethylmethacrylate. The purpose of the current study was to measure in vitro temperature histories at three key locations (anterior cortex, center, spinal canal) in VBs injected with one of two different bone cements (Simplex P and Orthocomp) to determine the role temperature plays in PVP. Twelve VBs (T11-L2) from three elderly female spines were instrumented with thermocouples and injected with 10 cc of one of the two cements. Temperatures were measured with the VBs in a bath (37 degrees C) for 15 min after injection. A Student's paired t-test was used to determine differences in peak temperature and time above 50 degrees C between the two cement groups. Peak temperatures and temperatures above 50 degrees C were significantly higher and longer, respectively, at the center of VBs injected with Simplex P (61.8 +/- 12.7 degrees C; 3.6 +/- 2.1 min) than those injected with Orthocomp (51.2 +/- 6.2 degrees C; 1.3 +/- 1.4 min). There was no significant difference in peak temperature between cements at the spinal canal location; temperature there did not rise above 41 degrees C. Although thermal damage to intraosseous neural tissue caused by cement polymerization cannot be ruled out as a potential mechanism for pain relief experienced by patients subsequent to PVP, it seems unlikely based on the worst-case conditions tested in the current study.

Aged↗
PubMed2003

A radiopaque polymeric matrix for acrylic bone cements.

As part of the search for an alternative to inorganic radiopaque agents, this work studies the possibility of modifying bone cement formulations by incorporating a radiopaque monomer, that is, 4-iodophenol methacrylate (IPMA), in the liquid phase. The monomer was synthesized in the laboratory, and cements were prepared by the standard method. The influence on the different cement characteristics of various monomer concentrations was studied. It was seen that the setting time decreased as the percentage of monomer increased. The radiopacity attained in the 15 vol.% IPMA formulations was about the same as that for a cement containing 10 wt.% barium sulphate. Dynamic and static mechanical properties were measured. The materials did not show significant differences in the glass transition temperature. However, static mechanical properties showed enhanced compressive strength, tensile strength, and elastic modulus with respect to conventional cements formulated with barium sulphate. Histological studies showed a good response of muscular tissue to implanted specimens.

Barium Sulfate↗
PubMed1997

Analysis of the leaching and toxicity of new amine activators for the curing of acrylic bone cements and composites.

The comparative reactivity of new tertiary amine activators with the basic chemical structure of N,N-dimethyl-4-toluidine, but reduced toxicity, is analysed. The leaching of the amine compounds from cured cements was studied by analysis of the concentration of the corresponding amine in a physiological saline solution after 3 months of immersion, giving lower values for the new amine compounds as compared to N,N-dimethyl-4-toluidine. The acute toxicity was determined by intravenous injection of saline solutions of the corresponding chlorhydrates in mice and the cytotoxicity by the evolution of specific culture media. The results obtained demonstrate a lower acute toxicity and cytotoxicity of the new activators, even with a noticeable antiseptic action, which makes these materials very interesting from a practical point of view as activators of the curing process of acrylic bone cements for orthopaedic surgery and dentistry.

Acrylic Resins↗
PubMed2000

The effect of a silane coupling agent on the bond strength of bone cement and cobalt-chrome alloy.

Debonding of the cement-implant interface has been hypothesized to be the leading initial indicator of failed total hip prostheses. Many attempts have been made to increase the bond strength of this interface by precoating the implant, increasing the implant's surface roughness, and creating macro-grooves or channels on the implant. However, each of these approaches introduces new complications. This study introduces a unique silane coupling agent used to chemically bond the bone cement to the implant. Cylindrical cobalt-chrome samples were treated with the silane coupling agent, bonded to polymethylmethacrylate, and pushed out to failure. The mean shear strengths were compared to the failure strengths of untreated samples. Half of the specimens were tested immediately following cement curing, and the other half were tested after immersion in saline solution for 60 days. The mean shear strength of the silane-coated samples ranged from 18.2 to 24.1 MPa, and the mean shear strength of the uncoated samples ranged from 7.6 to 15.0 MPa. The increase in strength following silane coating noted in this study may increase the longevity of the implant by decreasing debonding at the interface and, therefore, subsequent failure due to loosening.

Bone Cements↗
PubMed2005

In vitro testing of gentamicin-vancomycin loaded bone cement to prevent prosthetic joint infection.

Sepsis is a greatly feared complication of total joint arthroplasty. One key question is how to prevent perioperative bacterial adherence, and therefore the potential for infectious complications. The objective of our study was to appraise the emerging capacity of staphylococcal survival on prosthetic materials and to analyze the in vitro effects of gentamicin and vancomycin loaded polymethylmethacrylate (PMMA) cement on bacterial adherence and growth. Hospital acquired staphylococcal strains were systematically inoculated on four orthopedic materials (ultrahigh molecular weight polyethylene, PMMA without antibiotic, commercially produced PMMA loaded with gentamicin, and manually mixed PMMA loaded with gentamicin and vancomycin). Staphylococci were identified using culture and biochemical tests. The inoculated material was allowed to incubate in a liquid broth growth media and subsequently prepared for scanning electron microscopy and bacterial growth quantification. Materials without antibiotics showed evidence of staphylococcal growth. PMMA loaded with only gentamicin grew methicillin-resistant Staphylococcus aureus. Gentamicin-vancomycin loaded PMMA completely inhibited any bacterial growth. Low-dose gentamicin-vancomycin loaded PMMA prevents staphylococcal colonization better than commercially manufactured PMMA loaded with gentamicin. We recommend this combination in high-risk procedures and revision surgeries requiring bone cement.

Anti-Bacterial Agents↗
PubMed1998

Assessment of acrylic bone cement as a local delivery vehicle for the application of non-steroidal anti-inflammatory drugs.

Non-steroidal anti-inflammatory drugs (NSAIDs) have been widely used to reduce the inflammation and pain in patients suffering from arthritis. There is a possible use for these drugs in the treatment of inflammation associated with periodontitis. However, the propensity of NSAIDs to cause serious side effects, including gastrointestinal bleeding, has reduced their usefulness. The local application of NSAIDs can avoid these side effects by delivering low doses of drug directly to the affected site. Three NSAIDs (indomethacin, tolmetin and mefenamic acid) were incorporated into polymethylmethacrylate bone cement (PM MA) strips in a range of concentrations and their cytotoxicity, pattern of drug release and ability to suppress elevated levels of prostaglandin E2 (PGE2) in cultured human periodontal ligament fibroblasts (HPLF) assessed. The strips released between 10 and 30% of the total incorporated drug over 7 days, with the highest levels released by strips containing 20% w/w of drug. Strips containing 20% indomethacin and mefenamic acid released in excess of toxic levels in the first 24 h. Strips containing 20, 10 and 5% w/w NSAID significantly (P < 0.05) reduced the level of PGE2 expression by E. coli lipopolysaccharide (LPS) challenged cells, with only the 20% mefenamic acid strip performing significantly better than the other drugs. We conclude that local delivery of NSAIDs using PMMA as a sustained release vehicle is a possible additional tool in the treatment of periodontitis.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1999

Crosslinking characteristics of an injectable poly(propylene fumarate)/beta-tricalcium phosphate paste and mechanical properties of the crosslinked composite for use as a biodegradable bone cement.

We investigated the crosslinking characteristics of an injectable composite paste of poly(propylene fumarate) (PPF), N-vinyl pyrrolidinone (N-VP), benzoyl peroxide (BP), sodium chloride (NaCl), and beta-tricalcium phosphate (beta-TCP). We examined the effects of PPF molecular weight, N-VP/PPF ratio, BP/PPF ratio, and NaCl weight percent on the crosslinking temperature, heat release upon crosslinking, gel point, and the composite compressive strength and modulus. The maximum crosslinking temperature did not vary widely among formulations, with the absolute values falling between 38 degrees and 48 degrees C, which was much lower than that of 94 degrees C for poly(methyl methacrylate) bone cement controls tested under the same conditions. The total heat released upon crosslinking was decreased by an increase in PPF molecular weight and a decrease in N-VP/PPF ratio. The gel point was affected strongly by the PPF molecular weight, with a decrease in PPF molecular weight more rapidly leading to a gel point. An increase in initiator concentration had the same effect to a lesser degree. The time frame for curing was varied from 1-121 min, allowing the composite to be tailored to specific applications. The compressive strength and compressive modulus values increased with decreasing N-VP/PPF, increasing NaCl content, and increasing BP/PPF ratio. For all formulations, the compressive strength values fell between 1 and 12 MPa, and the compressive modulus values fell between 23 and 265 MPa. These data suggest that injectable PPF/beta-TCP pastes can be prepared with handling characteristics appropriate for clinical orthopedic applications and that the mechanical properties of the cured composites are suitable for trabecular bone replacement.

Biodegradation, Environmental↗