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PubMed2002

[Technical principles for removal of femoral bone cements in hip prosthesis implant revision].

As the removal of femoral bone cement is one of the most challenging tasks in cemented total Hip Revision, a lot of different technical devices have been developed to aid the surgeon. All of their pros and cons are partly consequences of the specific system-design but mainly arise from the basic physical principles used. The known methods and devices as well as their data-handling have therefore been analysed, reduced to their principles according to the criteria of systematic engineering design and systematized in order to provide a better comparability and starting point for the development of new devices.

Arthroplasty, Replacement, Hip↗
PubMed1975

[Working time of bone cements].

The period of applicability during polymerisation of four well introduced bone cements (Sulfix-6, CMW, Simplex, Palacos) was measured by a subjective method in function of room respectively conditioning temperature. Simultaneously temperature in the cement and mechanical admittance (transfer of oscillation of 750 Hz) were registered. The duration of working-up period and plymerisation period depends considerably from the room temperature. An increase of 10 degree C accelerates polymerisation by a factor of 1.5 to 2.0. The working time of the products differs widely. Increased room temperature means also increasing maximum polymerisation temperature. Mechanical admittance is an interesting measure for the objectivation of the working period. Discussing new ISO standards a proposal is made for more accurate determination of the end of the working-up period (set time).

Bone Cements↗
PubMed2006

Preparation of acrylic bone cements for vertebroplasty with bismuth salicylate as radiopaque agent.

One of the problems of percutaneous vertebroplasty attributed to the use of acrylic cements is related to the radiopacity of the formulation. The use of bismuth salicylate as the radiopaque agent is proposed in this work, taking into account the high radiopacity of organobismuth compounds used in dental applications and the possible analgesic effect of salicylic acid. Various cements formulated with this compound (some of them modified with polyethylene oxide) were examined. Setting parameters, mechanical properties, rheological behaviour, injectability, radiopacity and biocompatibility were studied for a variety of formulations, showing that the cement formulations containing bismuth salicylate have a higher radiopacity and better injection properties than commercial bone cement preparations and present good mechanical properties.

Biocompatible Materials↗
PubMed1976

Antibiotic-impregnated acrylic bone cement.

In vitro and in vivo experiments were performed to study the antibacterial and mechanical properties of Simplex and Palacos acrylic bone cements utilized for the production of acrylic cement-antibiotic composites. Acrylic cement without antibiotic had no bacteriostatic effect on Staphylococcus aureus, Escherichia coli, and Pseudomonas. Oxacillin, cefazolin, and gentamicin are stable in acrylic cement and are released in a microbiologically active form. The three antibiotics diffused from the Palacos in larger amounts daily and for a significantly longer time than from the Simplex. Mechanical tests demonstrated that admixture of antibiotics and acrylic cement had no influence on the compressive and diametral tension strengths of the cement. Bacteriostatic concentrations of oxacillin in wound hematomas were measured for fourteen days after implantation of an oxacillin-Simplex composite in dogs. High bactericidal concentrations of the antibiotic were measured in the surrounding bone for twenty-one days after implantation.

Animals↗
PubMedDate not supplied

Effects of stem design and pre-cooling prostheses on the heat generated by bone cement in an in vitro model.

The necrotizing effects of the heat, particularly at more than 50 degrees C, produced by the exothermic polymerization process associated with the acrylic implant cement polymethylmethacrylate (PMMA) are well documented. The temperature changes that occur are dependent on the thickness of the PMMA. The current study investigates the hypothesis that the heat produced by the bone cement may be reduced by the choice of stem design and by pre-cooling the hip prosthesis. The thermal alterations at the bone-cement interface were measured in an in vitro model. The results indicated that a temperature decrease of approximately 7 degrees C could be achieved by pre-cooling the prosthesis, and by changing the shape of the prosthesis stem from flat and wide to round.

Bone Cements↗
PubMedDate not supplied

[Acrylic bone cement use for internal spondylodesis in neurosurgical operations].

Vertebral column stabilization relying on performing of surgical internal spondylodesis with acrylic bone cement (methylmethacrylate, MMA) was carried out in 27 cases treated surgically in Department and Clinic of Neurosurgery in Poznań from 1996 to 1999. The age of patients was 16-69 (mean age 50.29 +/- 15.29) years. Male patients predominated (2:1). The vertebral lesion was caused by neoplasm (55% of cases), degenerative disease (26%), trauma (19%). Pathological changes were found in cervical region in 16 (59%), in thoracic region in 6 (22%) and in lumbar region in 5 (19%) patients. The anterior surgical approach to vertebral column was chosen in 17 (63%), posterolateral approach in 8 (30%) and posterior approach in 2 (7%) patients. Bone acrylic cement was used for reconstruction of vertebral body damaged by neoplasm or trauma, whereas it substituted the removed intervertebral disc or vertebral body in degenerative diseases. The acrylic cement graft in all cases maintained the proper anterior and medial vertebral column alignment. Semiliquid acrylic cement was used for filling of defects after tumour removal in thoracic and lumbar vertebral bodies. Acrylic cement graft was properly prepared in cuboid form and was inserted into the intervertebral spaces in patients with trauma or degenerative diseases. In all cases involving bone acrylic cement, stabilization of the vertebral segment was completed by metallic implants (cervical plates, "Z" plates, intrapedicular screws and rods). No postoperative complications (wound infections or implant dislocation) were observed. Postoperative, neurological signs were intensified in 3 cases (12%) and were regressive. Mortality rate was 4%. This type of internal spondylodesis makes possible to restore the anterior and medial columns and immobilisation of the proper vertebral segments.

Adolescent↗
PubMed1991

Bone cement and wound healing. An experimental study in the rat.

The local effect of methyl methacrylate on wound healing was studied in rats using viscose cellulose sponges. A 7 mm diameter cylindrical section was removed from the sponges, filled with freshly prepared bone cement or left empty in controls. Two sponges were implanted subcutaneously into each rat. The concentrations of DNA, RNA-ribose, nitrogen, hydroxyproline, uronic acids and hexosamines of the sponges were determined 5, 10 and 21 days postoperatively. The concentrations of collagen and glycosaminoglycans were similar in experimental and control samples and only small differences were detected in the amounts of DNA. It was concluded that methyl methacrylate bone cement did not have any practical harmful effects on wound healing.

Animals↗
PubMed1983

Tobramycin in bone cement. An in-depth analysis of wound, serum, and urine concentrations in patients undergoing total hip revision arthroplasty.

In this prospective clinical study, ten patients were treated by revision of total hip arthroplasties utilizing tobramycin-impregnated bone cement. After the operation, serum, urine, and wound suction drainage concentrations of tobramycin were determined serially by radioimmunoassay. Although high local wound concentrations, 5.7 micrograms/ml, were maintained for as long as 48 hours, serum concentration never reached even normal therapeutic ranges (greater than 2.0 micrograms/ml). There were no immediate postoperative infections; all patients are pain-free and ambulate without external support two years after surgery. One patient who had had a preoperative infection was successfully treated for late manifestation of infection 24 months after revision. Based on the evidence obtained in this study, tobramycin in bone cement is currently acceptable for clinical use.

Adult↗
PubMed1976

Polyacrylic bone cement containing erythromycin and colistin. I. In vitro bacteriological activity and diffusion properties of erythromycin, colistin and erythromycin/colistin comibination.

Erythromycin and colistin demonstrate a non-antagonistic ability to inhibit the growth of a wide variety of aerobic and anaerobic bacterial isolates. When incorporated in Surgical Simplex P Radiopaque Bone Cement, fabricated cement pellets were effective in inhibiting 98% of all anaerobic and aerobic test isolates. Separate experiments indicate that each antibiotic can diffuse from polymerized cement, and that the concentration of each antibiotic is consistently above the minimum inhibitory concentration of 96% of the isolates. We conclude that erythromycin/colistin Surgical Simplex P radiopaque Bone Cement is a worthy candidate for clinical investigation.

Bone Cements↗
PubMed1993

Polyisobutylene-toughened poly(methyl methacrylate): III. PMMA-l-PIB networks as bone cements.

A series of novel polyisobutylene (PIB)-toughened poly(methyl methacrylate) (PMMA) networks consist of rubbery PIB domains covalently bonded to a glassy PMMA matrix. Materials containing 8.5-17 wt.% PIB (Mn = 18,000 g/mol) in a PMMA matrix (PIB/PMMA) were evaluated to assess their feasibility as the powder component along with methyl methacrylate (MMA) as the liquid component in a standard powder/liquid bone cement formulation. A standard ISO four-point bend test, commonly used for testing bone cements, was employed to investigate flexural properties. The mixing time and powder/liquid (P/L) ratio were studied to formulate novel PIB/PMMA cements for optimum toughness. Appropriate formulations led to improved toughness while adequate flexural strength and modulus were maintained. An experimental PIB/PMMA-system exhibited approximately 57 MPa flexural strength and approximately 2000 MPa flexural modulus.

Biocompatible Materials↗
PubMed2003

Effect of test specimen cross-sectional shape on the in vitro fatigue life of acrylic bone cement.

Constant-amplitude uniaxial tension-compression fatigue tests were conducted on specimens fabricated from 12 sets of acrylic bone cements, covering cement formulations with three different viscosities (so-called "high-", "medium-" and "low-viscosity" varieties), two different methods of mixing the cement constituents (so-called "hand-" and "vacuum-mixed" methods) and two test specimen shapes (rectangular-cross-sectioned or "flat" and circular-cross-sectioned or "round"). The test results-namely, the number of fatigue stress cycles, N(f)-were analyzed using the linearized transformation of the three-parameter Weibull relationship, allowing the values of the Weibull mean, N(WM), to be determined for each set. Values ranged from 14,300 to 1,284,331 for the round specimen sets and from 2898 to 72,960 for the flat specimen sets. Statistical analysis of the ln N(f) data, together with an examination of the N(WM) values, showed that, for any combination of cement formulation and mixing method, round specimens had significantly longer fatigue lives compared to flat ones. These results are explained in terms of two factors. The first is the smaller surface area of the waisted zone in the round specimens compared to that in the flat specimens (nominal value of 157mm(2) versus nominal value of 185mm(2)), leading to the possibility of fewer crack initiation sites on the round specimens compared to the flat ones. Secondly, it is postulated that the crystallinity of the round specimens was higher than that of the flat ones, a consequence of the significantly lower measured residual liquid monomer contents of the former compared to the latter (3.40+/-1.28wt%/wt compared to 3.81+/-1.48wt%/wt). The significance of the present finding is that it indicates that, for a set of bone cement formulation and experimental conditions, discriminating fatigue test results are more likely to be obtained if flat, rather than round, test specimens are used.

Acrylic Resins↗
PubMed2000

Treatment of fractures of the distal radius with a remodellable bone cement: a prospective, randomised study using Norian SRS.

We performed a prospective, randomised study on 110 patients more than 50 years old with fractures of the distal radius to compare the outcome of conservative treatment with that using remodellable bone cement (Norian skeletal repair system, SRS) and immobilisation in a cast for two weeks. Patients treated with SRS had less pain and earlier restoration of movement and grip strength. The results at one year were satisfactory in 81.54% of the SRS patients and 55.55% of the control group. The rates of malunion were 18.2% and 41.8%, respectively. There was a significant relationship between the functional and radiological results. Soft-tissue extrusion was present initially in 69.1% of the SRS patients; most deposits disappeared progressively, but persisted in 32.73% at one year. We conclude that the injection of a remodellable bone cement into the trabecular defect of fractures of the distal radius provides a better clinical and radiological result than conventional treatment.

Age Factors↗
PubMed1993

The bone-cement interface: histological observations on the interface of cemented arthroplasties within the immediate and late phases.

Undecalcified specimens of cemented arthroplasties obtained during the early and late phases were studied. On the tenth postoperative day, there was excellent interlocking of the cement with the soft and hard tissues of the bone: there was no necrosis of the bed of the implant: a neutrophilic and macrophagic inflammatory response, where present, was mild and focal. Samples of the bone-cement interface of well fixed components obtained (at autopsy or by biopsy) many years after implantation revealed a thin and quiescent fibrous interfacial membrane alternating with bone and osteoid (that is, segmental osseointegration) or a cartilaginous layer abutting on the cement. It is concluded that, firstly, modern cementation techniques are not associated with extensive necrosis of the underlying bone in the immediate postoperative period; secondly, monomeric and polymeric methylmethacrylate as such is not toxic to the tissues; and, thirdly, acrylic cement is osseointegrated when motion at the interface is at its minimum.

Aged↗
PubMed1989

Air inclusion in bone cement. Importance of the mixing technique.

The amount of air inclusion in bone cement (Simplex P) expressed as density and porosity was analyzed for five different mixing conditions: manual, mechanical, centrifuged manual, centrifuged mechanical, and mechanical in combination with vacuum. Mechanical mixing resulted in a cement of less porosity and increased density. Centrifugation did not further improve the cement. Mechanical mixing in combination with vacuum was superior to the other techniques in density and porosity.

Air↗
PubMed2005

The contradictory effects of pores on fatigue cracking of bone cement.

The beneficial effect of porosity reduction on the fatigue life of bone cement has been demonstrated in numerous experimental studies. Clinically, however, it seems that the beneficial effect of porosity reduction of cement around total hip replacement components can only be found in large follow-up studies. Little is known about the actual mechanical effect of a pore on fatigue crack formation in cement mantles. We studied the effect of pores on the crack formation process in a finite element model of a transverse slice of a total hip reconstruction. We created models with a single large pore and models with multiple pores at levels of 2, 4, and 9%. The models were cyclically torque-loaded, causing macrocracks to appear in the cement mantle. In all models, we found that pores acted as microcrack initiators. However, pores could have both a detrimental and a beneficial effect on the macrocrack propagation in the cement mantle. Both effects were seen in the models with a single large pore and in the models with multiple pores. Pores would either accelerate, deviate, or decelerate the macrocrack propagation in the cement mantle. The effect of the pores depended on the location of the pores with respect to the stress intensities in the model, but was independent of the pore size or the level of porosity. The results may explain why the beneficial effect of vacuum mixing is difficult to demonstrate clinically. Stress intensities that are present in a cement mantle in an in vivo situation may overshadow the detrimental effect of a pore, while the beneficial effect may become more pronounced.

Bone Cements↗
PubMed1975

Slow crack growth in acrylic bone cement.

Slow crack growth in Perspex acrylic sheet (PMMA) and Simplex acrylic bone cement in air and water has been studied from a fracture mechanics viewpoint. It has been found that the crack velocity, V, for each material depends upon the intensification of stress at the tip of the crack. Experimental measurements have been made of V as a function of the stress intensity factor, K, at the crack tip, and a derived V, K relationship has been used to predict the times-to-failure of components made from PMMA and Simplex cement. Direct measurements of time-to-failure for PMMA have shown that the predicted values give a conservative estimate of the structural lifetime of the material.

Bone Cements↗
PubMedDate not supplied

[The role of a bone cement filling in intralesional tumor treatment].

The article reports on the results of treatment of cystic and juxta-articular benign primary bone tumors and tumor-like lesions with a temporary bone cement plug. The mean implantation time of the cement plug was 18 months, following which the cement plug was replaced with an autologous spongiosa filling. Cases were followed up for an average of 58 months. In the patient group as a whole, a relapse rate of 5.8% was recorded (0% for Giant Cell Tumors alone). It was possible to describe the clinically functional results as "good" and "very good" in 95% of the cases. It is clear from these results that temporary plugging of large juxta-articular bone lesions is an excellent treatment method. The article goes on to describe complications in detail. Results are given in detailed tables.

Adolescent↗
PubMed2001

Effective bactericidal activity of tobramycin and vancomycin eluted from acrylic bone cement.

We studied the bioactivity of vancomycin and tobramycin eluted from methylmethacrylate bone cement. Aliquots of the drainage were obtained at 1, 6, 12 and 24 hours following total hip prosthetic implantation with vancomycin-tobramycin-loaded cement in 3 patients. The samples were analyzed with fluorescence polarization immunoassay and bioassay, using group B streptococcus for vancomycin and Escherichia coli for tobramycin. These bacteria were selected due to the effectiveness of vancomycin and poor effectiveness of tobramycin against group B streptococcus and conversely with E. coli. The immunodetection of vancomycin averaged 14 (1 hour), 9 (6 hours), 10 (12 hours) and 11 microg/mL (24 hours). The bioassay averaged 47, 36, 79 and 41 microg/mL (p = 0.03). The immunodetection of tobramycin averaged 43, 21, 18 and 14 microg/mL; and bioassay 30, 15, 15 and 12 microg/mL (p = 0.1). Both antibiotics eluted with a highly effective bactericidal activity. Our findings indicate that the presence of tobramycin has a synergistic-like effect on the bactericidal activity of vancomycin, which has not been previously reported. We recommend a combination of vancomycin and tobramycin with cement for the treatment of orthopedic infections caused by gram-positive organisms.

Aged↗