Surgical Simplex Research Articles

Tibial Implant Fixation Behavior in Total Knee Arthroplasty: A Study With Five Different Bone Cements

BackgroundThe objectives of this study are to (1) evaluate if there is a potential difference in cemented implant fixation strength between tibial components made out of cobalt-chromium (CrCoMo) and of a ceramic zirconium nitride (ZrN) multilayer coating and to (2) test their behavior with 5 different bone cements in a standardized in vitro model for testing of the implant-cement-bone interface conditions. We also analyzed (3) whether initial fixation strength is a function of timing of the cement apposition and component implantation by an early, mid-term, and late usage within the cement-specific processing window. MethodsAn in vitro study using a synthetic polyurethane foam model was performed to investigate the implant fixation strength after cementation of tibial components by a push-out test. A total of 20 groups (n = 5 each) was used: Vega PS CrCoMo tibia and Vega PS ZrN tibia with the bone cements BonOs R, SmartSet HV, Cobalt HV, Palacos R, and Surgical Simplex P, respectively, using mid-term cement apposition. Three different cement apposition times—early, mid-term, and late usage—were tested with a total of 12 groups (n = 5 each) with the bone cements BonOs R and SmartSet HV. ResultsThere was no significant difference in implant-cement-bone fixation strength between CrCoMo and ZrN multilayer-coated Vega tibial trays tested with 5 different commonly used bone cements. ConclusionApposition of bone cements and tibial tray implantation in the early to mid of the cement-specific processing window is beneficial in regard to interface fixation in TKA.

NASAL BONE RECONSTRUCTION USING BONE CEMENT - “SURGICAL SIMPLEX P”

Surgical treatment of the defects and deformations in the facial area are still actual problems of reconstructive surgery. Medical and social aspects of the problem, pushes for intense search of the new materials for the reconstruction and improvement of surgical methods. The work presents an interesting clinical case description. The authors successfully used radiopaque medical cement “Surgical Simplex P” to fill in the deficit of the nasal bone and cartilage. It should be noted that the satisfactory effect was achieved in both functional and aesthetic point of view.

Comparative Study of Antibiotic Elution Profiles From Alternative Formulations of Polymethylmethacrylate Bone Cement

BackgroundPolymethylmethacrylate (PMMA) bone cement is commonly used in orthopedic surgery for implant fixation and local antibiotic delivery following surgical debridement. The incidence of nephrotoxicity necessitates the balance of antiinfective properties with the potential for toxicity. Thus, understanding antibiotic elution characteristics of different PMMA formulations is essential. We sought to address this by assessing elution of vancomycin, daptomycin, and tobramycin from Palacos LV (Palacos), Stryker Surgical Simplex P (Simplex), BIOMET Cobalt HV (Cobalt), and Zimmer Biomet Bone Cement R (Zimmer) radiopaque bone cements. MethodsAntibiotics were mixed with each cement formulation, and molds were used to produce beads of cement. Beads were incubated in phosphate-buffered saline at 37°C, and antibiotic elution was measured daily for 10 days with vancomycin and 5 days with daptomycin and tobramycin. Active antibiotic was quantified by serial dilution and comparison to the minimum inhibitory concentration. ResultsThe elution profiles of Simplex were significantly lower than all other cements with all antibiotics (P < .00093). Palacos exhibited a significantly higher vancomycin elution profile than all other cements (P < .00001). The difference in daptomycin elution profiles for Cobalt and Palacos was not significant (P > .43), but both were significantly higher than Zimmer (P < .0006). ConclusionOverall, Stryker Surgical Simplex P exhibits a significantly lower elution profile than all other cements tested. In general, Palacos LV exhibits an increased elution profile compared with other cements. This elution information may assist the surgeon in choosing different cement formulations for the local delivery of antibiotics.

Comparison of microleakage of root-end filling materials - An in vitro study

Objectives : The objective of the study was to evaluate the microleakage of various root end filling materials and to find the sealing ability of these materials. Methodology: Sixty (60) extracted single rooted anterior teeth were selected and divided into four groups of 15 samples each. Group A, B, C and D in which root-end filling was done with Surgical Simplex Bone Cement, Super EBA, Ketac Molar Glass Ionomer and Pro-root MTA respectively. The teeth were retrofilled and then the apical halves were submerged in 2% methylene blue dye. The depth of dye penetration and maximum value of leakage in each sample were recorded. Results: Group D had statistically significant difference from Group C (1.73±0.16 mm) as well as Group A (2.10±0.14 mm). Interpretation and Conclusion: Microleakage of group B was minimum. Thus concluding that Super EBA is a good root-end filling material.

Comparison of microleakage of root-end filling materials – In vitro study

ObjectivesThe objective of the study was to evaluate the microleakage of various root end filling materials and to find the sealing ability of these materials. MethodologySixty (60) extracted single rooted anterior teeth were selected and divided into four groups of 15 samples each. Group A, B, C and D in which root-end filling was done with Surgical Simplex Bone Cement, Super EBA, Ketac Molar Glass Ionomer and Pro-root MTA respectively. The teeth were retrofilled and then the apical halves were submerged in 2% methylene blue dye. The depth of dye penetration and maximum value of leakage in each sample were recorded. ResultsGroup D had statistically significant difference from Group C (1.73 ± 0.16 mm) as well as Group A (2.10 ± 0.14 mm). Interpretation and conclusionMicroleakage of Group B was minimum. Thus concluding that Super EBA is a good root-end filling material.

An autonomically-healed PMMA bone cement: influence of the crystal size of Grubbs' catalyst on fracture toughness and polymerisation rate

In this study, it was shown that the concept of autonomic healing of a neat polymeric material, which was introduced by White et al. (2001) could be applied to poly methyl methacrylate (PMMA) bone cement. The bone cement brand used – Surgical Simplex&#174P – is one that is widely used in cemented arthroplasties; the healing agent used was 2.0 wt.% dicyclopentadiene (DCPD), encapsulated in poly (urea-formaldehyde) microspheres (diameter = 226 ± 51 μm) and the catalyst used was 0.25 wt.% first-generation Grubbs' catalyst. The microspheres and the catalyst were blended with the cement's powder in a mortar bowl using a polymeric spatula and the blended powder mixture and the cement's liquid monomer were mixed under a partial vacuum. Autonomic healing of the cement was demonstrated through a comparison of the values of the plane-strain fracture toughness (KIC) of the control cement (no healing agent or catalyst included in the powder) and the cement in which the powder contained DCPD and Grubbs' catalyst. For the autonomically-healed cement, (KIC) was not significantly influenced by the size of the individual crystals of the Grubbs' catalyst (mean diameter, DG), but the estimated polymerisation rate of the curing cement at 37°C, increased significantly with decrease in DG.

Comparison of an experimental bone cement with surgical Simplex® P, Spineplex® and Cortoss®

Conventional polymethylmethacrylate (PMMA) cements and more recently Bisphenol-a-glycidyl dimethacrylate (BIS-GMA) composite cements are employed in procedures such as vertebroplasty. Unfortunately, such materials have inherent drawbacks including, a high curing exotherm, the incorporation of toxic components in their formulations, and critically, exhibit a modulus mismatch between cement and bone. The literature suggests that aluminium free, zinc based glass polyalkenoate cements (Zn-GPC) may be suitable alternative materials for consideration in such applications as vertebroplasty. This paper, examines one formulation of Zn-GPC and compares its strengths, modulus, and biocompatibility with three commercially available bone cements, Spineplex, Simplex P and Cortoss. The setting times indicate that the current formulation of Zn-GPC sets in a time unsuitable for clinical deployment. However during setting, the peak exotherm was recorded to be 33 degrees C, the lowest of all cements examined, and well below the threshold level for tissue necrosis to occur. The data obtained from mechanical testing shows the Zn-GPC has strengths of 63 MPa in compression and 30 MPa in biaxial flexure. Importantly these strengths remain stable with maturation; similar long term stability was exhibited by both Spineplex and Simplex P. Conversely, the strengths of Cortoss were observed to rapidly diminish with time, a cause for clinical concern. In addition to strengths, the modulus of each material was determined. Only the Zn-GPC exhibited a modulus similar to vertebral trabecular bone, with all commercial materials exhibiting excessively high moduli. Such data indicates that the use of Zn-GPC may reduce adjacent fractures. The final investigation used the well established simulated body fluid (SBF) method to examine the ability of each material to bond with bone. The results indicate that the Zn-GPC is capable of producing a bone like apatite layer at its surface within 24 h which increased in coverage and density up to 7 days. Conversely, Spineplex, and Simplex P exhibit no apatite layer formation, while Cortoss exhibits only minimal formation of an apatite layer after 7 days incubation in SBF. This paper shows that Zn-GPC, with optimised setting times, are suitable candidate materials for further development as bone cements.

Influence of strontia on various properties of Surgical Simplex ® P acrylic bone cement and experimental variants

The fact that the composition of acrylic bone cement, as used in cemented primary arthroplasties, is not optimal has been highlighted in the literature. For example: (i) deleterious effects of the radiopacifier (BaSO 4 or ZrO 2 particles in the powder) have been reported; (ii) there is an indication that pre-polymerized poly(methylmethacrylate) (PMMA) beads in the powder may be dispensed with; and (iii) there is a strong consensus that the accelerator commonly used, N, N-dimethyl- p-toluidine (DMPT), is toxic and has many other undesirable properties. At the same time, the effectiveness of drugs that contain a strontium compound in treating the effects of osteoporosis has been explained in terms of the role of strontium in bone formation and resorption. This indicates that strontium compounds may also have desirable effects on osseointegration of arthroplasties. The present study is a detailed evaluation of 24 acrylic bone cement formulations comprising different relative amounts of BaSO 4, strontia (as an alternative radiopacifier), pre-polymerized PMMA beads and DMPT. A large number of properties of the curing and cured cement were determined, including setting time, polymerization rate, fracture toughness and fatigue life. The focus was on the radiopacifier, with the finding being that many properties of formulations that contained strontia were about the same or better than those for cements that contained BaSO 4. Thus, further developmental work on strontia-containing acrylic bone cements is justified, with a view to making them candidates for use in cemented primary arthroplasties.

Influence of two changes in the composition of an acrylic bone cement on its handling, thermal, physical, and mechanical properties

This study is a contribution to the growing body of work on the influence of changes in the composition of an acrylic bone cement on various properties of the curing and cured material. The focus is on one commercially-available acrylic bone cement brand, Surgical Simplex P, and three variants of it and a series of properties, namely, setting time, maximum exotherm temperature, activation energy and frequency factor for the polymerization reaction, diffusion coefficient for the uptake of phosphate buffered saline, at 37 degrees C, ultimate compressive strength (UCS), plane-strain fracture toughness, fatigue life (under fully-reversed tension-compression stress), hardness (H) and elastic modulus (both determined using quasi-static nanoindentation), and the variation of the storage and loss moduli with frequency of the applied force in a dynamic nanoindentation test. It was found that (a) a 68% reduction in the volume of the activator, N,N dimethyl-4-toluidine, relative to the total volume of the liquid monomer (the amounts of all the constituents in the powder and of the hydroquinone in the liquid monomer remaining unchanged) led to, for example, a significant decrease in the rate of the polymerization reaction, at 37 degrees C (c') and a significant increase in H; and (b) the elimination of the pre-polymerized poly (methyl methacrylate) beads in the powder (the amounts of all the other powder constituents and those of the liquid monomer remaining unchanged) led to, for example, a significant drop in c' and a significant increase in UCS. Thus, these findings suggest a strategy for optimizing the composition of an acrylic bone cement.

The Influence of Antibiotics on the Fatigue Life of Acrylic Bone Cement

Aseptic loosening attributed to cement fracture and subsequent disruption of fixation interfaces remains a major long-term mode of failure of arthroplasties performed with cement1 (Fig. 1). The fracture strength of bone cement, especially in fatigue, is an important indicator of cement integrity and the potential for fixation failure. In current practice, orthopaedic surgeons may choose to utilize antibiotics in bone cement for prophylaxis or treatment of a known infection. However, the antibiotics, bone cement, and mixing method employed lead to variability in the quality of the end product2-5. To date, several United States orthopaedic manufacturers have received Food and Drug Administration (FDA) 510(k) clearance for use of their prepackaged antibiotic-loaded bone cement for the second stage of a two-stage revision after the initial infection has been eradicated. This availability provides a more uniform cement mix with known mechanical and elution characteristics at the level of 0.5 to 1.0 g of antibiotic per 40 g of polymer powder. In this study, we evaluated the influence of antibiotic inclusion on the porosity, strength, and fatigue life of six contemporary bone cements. Six surgical quality and commercially available surgical bone cements were evaluated: Endurance and Endurance Gentamicin (DePuy Orthopaedics, Warsaw, Indiana), Surgical Simplex P and Simplex P with Tobramycin (Stryker Orthopaedics, Mahwah, New Jersey), and VersaBond and VersaBond AB with Gentamicin (Smith and Nephew, Memphis, Tennessee). Ten 1.2-g doses of Tobramycin for Injection USP (United States Pharmacopeia) (Pharma-Tek, Huntington, New York), which is the base quantity supplied to the operating theater when antibiotics are hand-mixed with bone cement, were acquired. Three vacuum-mixing systems (Figs. 2-A, 2-B, and 2-C)—the Cemvac (DePuy Orthopaedics), the ACM (Advanced Cement Mixing System; Stryker), and the Vortex (Smith and Nephew)—were acquired directly from their manufacturers. Nine study samples were created: hand-mixed …

Influence of two changes in the composition of an acrylic bone cement on some of its properties: the case of Surgical Simplex® P

Influence of two changes in the composition of an acrylic bone cement on some of its properties: the case of Surgical Simplex® P

Preparation of Clay/PMMA Nanocomposites with Intercalated or Exfoliated Structure for Bone Cement Synthesis

AbstractSummary: Clay/PMMA nanocomposites were prepared by melt blending of an organically modified MMT with PMMA under various process conditions. The MMT clay was initially cation exchanged with octadecylammonium to enhance its hydrophobicity and to expand the interlamellar space of the silicate plates. PMMA was then inserted into the inter‐lamellar space of the modified clay by melt blending at an elevated temperature. The effects of blending temperature, blending time, and clay/PMMA compositions on the level of expansion and homogenization were investigated. Composites with intercalated and/or exfoliated clay structure were obtained depending upon the process conditions, as confirmed by XRD diffractometry. The thermal decomposition temperature (Td) and glass transition temperature (Tg) of the composites were determined, respectively, by TGA and DSC analyses. Marked improvements, up to 35 °C, of the thermal stability (Td) with respect to pure PMMA were achieved for many of the composite samples. The Tg of the composites, however, does not increase accordingly. Furthermore, a novel type of bone cement was synthesized by applying the clay/PMMA nanocomposites as a substitute for PMMA in a typical formulation. These bone cements demonstrated much higher impact strength and better cell compatibility than the surgical Simplex P cement. Therefore, the bone cements with clay/PMMA nanocomposites meet the requirement for the architectural design of orthopedic surgery.TEM images of an OA‐clay/PMMA composite.magnified imageTEM images of an OA‐clay/PMMA composite.

Effect of Pigmentation on the Mechanical and Polymerization Characteristics of Bone Cement

The impact on performance of additives to bone cement must be assessed before clinical use of the modified product. This study performed several standard acrylic bone cement tests on 3 commercially available products: Endurance, Surgical Simplex P, and Pigmented Endurance. The polymerization characteristics, consisting of doughing time, setting time, and maximum exothermic temperature, were found to be acceptable by the standards of the American Society for Testing and Materials/International Organization for Standards. For the mechanical characterization, analysis revealed statistical equivalence among all cement types, with the exception of compressive strength where Pigmented Endurance was stronger than Surgical Simplex P ( P < .02). In mechanical fatigue, there were no significant differences in the log cycles to failure among the cements; however, Weibull analysis predicted Surgical Simplex P to have a higher characteristic life than the other cements. In conclusion, differences do exist among cement types, but the addition of pigment to Endurance did not alter its performance.

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.

Factors affecting the cement penetration of a hip resurfacing implant: An in vitro study

An understanding of how the cementing technique influences cement penetration is important for surgeons to plan and conduct hip resurfacing procedures. Therefore the aim of this study is to determine the influence of the following parameters on cement penetration: use of pulse lavage, type of cement, and the standing period of the cement. Nine fresh frozen paired whole cadaver femora were used to investigate cement penetration. The femora were divided into three paired groups: (A) compared the use of pulse lavage to no pulse lavage, (B) compared two low viscosity bone cements SULCEM-3 (Zimmer GmbH, Switzerland) and Surgical Simplex (Stryker Orthopaedics, USA), and (C) compared bone cement viscosities using standing times of 1.5 min. and 3 min. The Durom Hip Resurfacing implant (Zimmer GmbH, Switzerland) was used in all groups. A single slice was taken out of the center of each head. Cement penetration ratio (penetration area divided by the bone area enclosed by implant) and mean cement penetration depth were measured. Cement penetration is increased using pulse lavage, and has the tendency to increase with increasing the cement standing time from 1.5 to 3 min. No difference in cement penetration was found when different cement brands of comparable viscosity were used.

Factors Affecting the Cement Penetration of a Hip Resurfacing Implant: An in Vitro Study

An understanding of how the cementing technique influences cement penetration is important for surgeons to plan and conduct hip resurfacing procedures. Therefore the aim of this study is to determine the influence of the following parameters on cement penetration: use of pulse lavage, type of cement, and the standing period of the cement. Nine fresh frozen paired whole cadaver femora were used to investigate cement penetration. The femora were divided into three paired groups: (A) compared the use of pulse lavage to no pulse lavage, (B) compared two low viscosity bone cements SULCEM-3 (Zimmer GmbH, Switzerland) and Surgical Simplex (Stryker Orthopaedics, USA), and (C) compared bone cement viscosities using standing times of 1.5 min. and 3 min. The Durom Hip Resurfacing implant (Zimmer GmbH, Switzerland) was used in all groups. A single slice was taken out of the center of each head. Cement penetration ratio (penetration area divided by the bone area enclosed by implant) and mean cement penetration depth were measured. Cement penetration is increased using pulse lavage, and has the tendency to increase with increasing the cement standing time from 1.5 to 3 min. No difference in cement penetration was found when different cement brands of comparable viscosity were used.

Depot local anesthetic in polymethylmethacrylate bone cement: a preliminary study.

Acrylic bone cement has been used successfully as a slow-release depot for antibiotics after orthopaedic surgery. The feasibility of administering local anesthetics in this way was examined in this preliminary in vitro study. Discs weighing approximately 4 g were prepared from five brands of acrylic cement (40 g) containing as much as 2 g of anesthetic base. Elution of the anesthetics into saline was measured during 72 hours. Prilocaine eluted the fastest and bupivacaine the slowest, with lidocaine between them. The elution rates were greatest in the first hour, declining thereafter. Rates also depended on the brand of cement with the quickest elution from CMW3 and the slowest from Surgical Simplex P. Using cement as a depot, therapeutic levels of a drug should be achievable in vivo at a negligible risk of toxicity. Before in vivo trials it is necessary to optimize elution of drugs in relation to the cement (brand, microstructure, method of preparation) and the concentration of a drug in the cement above which the cements' mechanical and adhesive properties are compromised.

Effect of choice of surgical gloves on dough time measurements of acrylic bone cement

In this study we investigated the effect of the brand of surgical gloves on the dough time determination for acrylic bone cements. Four different brands of powder-free latex surgical gloves were tested. Two commercial bone cements, Surgical Simplex ® P and Palacos ® R, were used for dough time measurement following standard test methods for acrylic bone cements (ASTM F-451 and ISO 5833). The results show that the measured dough time depended largely on the brand of gloves used, and could vary by nearly 250%. The surface morphological structures of gloves, determined by SEM, probably contribute to the differences in the measured dough time. This study provides experimental evidence that supports the need to describe the type of gloves used, in detail, when dough time is reported. It also illustrates the importance of the glove brand, when bone cement is to be handled as a dough in the clinical setting.

Heel pain in athletes

Objectives: To determine the maximum amount of a specific antibiotic added to 40 g acrylic bone cement in terms of the effect on mechanical properties of the bone cement on Day 0 and after antibiotic release on Day 15. Methods: In an experimental design, eight teicoplanin doses (0, 400 mg, 800 mg, 1200 mg, 1600 mg, 2000 mg, 3200 mg and 4000 mg) were added to bone cement (Surgical Simplex P). Specimens were prepared using the third generation cementing technique to determine the compressive strength and four-point bending strength according to ASTM and ISO standards, respectively. For each concentration, 10 samples were prepared for Day 0 and Day 15. Mechanical tests were performed on Day 0 and after antibiotic leaching in water at 37° C on Day 15. 0 mg specimens served as controls and mechanical strengths for each antibiotic concentration on Day 0 and Day 15 were compared. Results: In compression tests, Day 0 samples showed no significant differences, whereas Day 15 samples starting with 800 mg exhibited significant decreases in compressive strength. However, the compressive strengths were above the minimum standard of 70 MPa set by ASTM at all concentrations and in all groups. Four-point bending tests demonstrated significant decreases in strength starting with 1200 mg in Day 0 samples, and with 400 mg in Day 15 samples. Four-point bending strengths of 2000 mg, 3200 mg, and 4000 mg samples decreased below, or approximated closely the minimum standard of 50 MPa set by ISO on Day 15. Conclusion: Our results suggest that the maximum amount of teicoplanin dose to be safely added to 40 g of Surgical Simplex P is 1600 mg when third generation cement mixing and application techniques are employed.

The lithotriptor and its potential use in the revision of total hip arthroplasty.

The lithotriptor and its potential use in the revision of total hip arthroplasty.