Pure Calcium Sulfate Research Articles

The Use of Dissolvable Synthetic Calcium Impregnated with Antibiotic in Osteoarticular Infection in Patients with Diabetes

The medical management of osteoarticular infections in patients with diabetes continues to be a considerable clinical dilemma because of inadequate blood supply and weakened immune systems. The objective of this study is to assess the effectiveness of dissolvable synthetic pure calcium sulfate beads with antibiotics in the treatment of osteoarticular infections in individuals diagnosed with diabetes mellitus. A retrospective analysis was conducted on 27 patients with diabetes (19 with type II diabetes and 8 with type I diabetes) who were diagnosed with osteoarticular infections and received treatment with locally delivered antibiotic-loaded calcium sulfate beads. The patients were monitored for a duration ranging from 6 months to 2 years, during which the clearance of infection, bone remodeling, and rates of recurrence were evaluated. The evaluation also included an assessment of glycemic control and its influence on infection treatment. The findings revealed a notable decrease in the recurrence of infections, as patients who were given combinations of two antibiotics showed better results in comparison to those who were exclusively treated with one antibiotic. A 92% eradication rate was achieved within the trial group, and patients who had dual-antibiotic treatment did not have any return of illness. Postoperative bone remodeling was shown to take place between 8 and 16 weeks, with faster recovery in individuals who maintained ideal glycemic control (HbA1c < 7%). Only one instance of soft tissue necrosis was documented, indicating minimal consequences. The results validate the use of dissolvable synthetic calcium sulfate as a secure and efficient local antibiotic administration method for controlling osteoarticular infections in patients with diabetes, providing improved infection management and facilitating bone regeneration.

Influence of magnesium and calcium sulfate whisker on crystallization characteristics of poly (butylene adipate-co-terephthalate) and Poly(butylene succinate)

Inorganic fillers of whisker-like morphology are considered promising materials, and they have gained significant attention in recent years as a substitute for glass fibers due to their fibrous surface characteristics and extremely low bulk density. This study selected magnesium sulfate whiskers (MSWs) containing crystal water and pure calcium sulfate whiskers (CSWs) as fillers. They were physically blended with biodegradable polymers PBAT and PBS in a range of 0.1 wt.% to 2 wt.% to form composite materials. The non-isothermal crystallization behavior of the composite materials was studied using differential scanning calorimetry (DSC). The data indicated that with an increase in whisker content, the crystallization temperature (Tc) of composites increased, and the addition of a small amount of whiskers led to a reduction in the half-crystallization time of the composite materials, indicating the crystallization capacity of the materials has been enhanced to varying degrees. Analysis via POM unveiled a consistent pattern of decreased spherulite size and heightened spherulite count with the introduction of whiskers. This phenomenon is ascribed to the whisker fillers’ function as nucleating agents within the polymer matrices, thereby stimulating the crystallization process. Interestingly, the findings suggest that CSWs exert a more significant influence on crystallization than MSWs, likely due to the distinct single fiber morphology of the former filler.

Synthesis and characterization of hydroxyapatite nanoparticles from calcium hydroxide fouled with gases evolved from smokestack of glass industry

In glass industry, the evolved gases and fumes from burning the gas fuel absorbed in calcium hydroxide to minimize the pollution of environment. After a period of time, the calcium hydroxide fouled with sulphate and carbonate as action of the absorbed SO3 and CO2 gases. Based on our interest to treatment the solid waste materials, this study intended to convert the obtained waste of calcium hydroxide fouled with gases to valuable products. Firstly, this waste was treated with water, caustic soda and acids. The results confirmed the conversion of waste to pure calcium sulfate by treatment with 6 v/v% sulfuric acid. Secondly, the obtained calcium sulfate was reacted with ammonium dihydrogen phosphate solution for preparation of calcium hydroxyapatite (HAp) nanoparticles. The produced HAp sample was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and scanning electron microscopy (SEM), thermal gravimetric analysis (TGA) and N2 adsorption measurements. The obtained findings confirmed that the HAp can be produced after calcination at 700 °C, nanorods-like of sizes ranged from 11 to 15 nm and with main surface functional groups of hydroxyapatite. TGA and DTA data indicated that HAp is thermally stable up to 700 °C. Also, the obtained HAp has Ca/P molar ratio of 1.60 and exhibited high total surface area of 146 m2/g with mesoporous structure which make this material can be used in medical and water purification applications.

The employing of pure calcium sulfate extracted from phosphogypsum for composing highly pure ammonium sulfate and calcium carbonate

ABSTRACT The phosphoric acid wet process waste stream provided the phosphogypsum (PG). Phosphogypsum waste is environmentally harmful and economically valuable. However, processing phosphogypsum to produce (NH4)2SO4 and CaCO3 can solve these environmental and economic issues. ICP-OES, XRD, SEM-EDS, FTIR, and TGA were used to characterize PG, purified CaSO4, (NH4)2SO4, and CaCO3. Herein, PG is treated with different HNO3 concentrations and 0.5M NH4NO3 to eliminate most impurities for gaining a highly purified CaSO4. The factors affecting CaSO4 purification were studied. These aspects include HNO3 and NH4NO3 concentration, the S/L ratio, time spent on treatment, temperature, and grain size. According to the findings, the ideal working conditions for extracting 98.71% of CaSO4 from PG are as follows: 149 µm grain size, 0.5M NH4NO3, 2M HNO3, 1/4 S/L, 30 minutes reaction time, 300 rpm, and 80°C. Using a pure CaSO4 suspension as the raw material, CO2, and a mechanical stirring method, the (NH4)2SO4 solutions crystallized by heating and CaCO3 precipitate were investigated through several trials. The preparation method was investigated by changing variables such as the NH4 +/Ca2+ molar ratio, reaction time, CO2 flow rate, and temperature. Finally, (NH4)2SO4 (98.25%) and CaCO3 (98.5%) are produced from the slurry of pure CaSO4.

Facilitating calcium sulfite oxidation during flue-gas desulfurization for efficient sulfur utilization using a robust MnTiO3 perovskite

Accelerating the oxidation of calcium sulfite is extremely crucial for the limestone/gypsum method of flue-gas desulfurization by enhancing the desulfurization efficiency, preventing subsequent SO2 release, and generating pure calcium sulfate as a value-added product for downstream utilization. In this work, MnTiO3 perovskite nanodisks with high crystallinity and good thermal stability were synthesized by a hydrothermal method. The highly stabled exposed 001 facets of the MnTiO3 catalyst give rise to its catalytic reactivity which promote the electron transfer in sulfite oxidation process thus effectively generated reactive oxygen species (O2−, OH, and SO4−) to accelerate the sulfite oxidation cycle. Compared with non-catalytic oxidation reactions, the calcium sulfite oxidation rate and calcium sulfate yield were increased by 4.3 times and 34.02% by using MnTiO3, respectively. After four cycles, the calcium sulfite oxidation rate was only 9.57% lower than that in the first cycle, and Mn leaching was minimal. To simulate actual usage scenarios, the extrusion method was employed to prepare a molded catalyst for facile separation from the desulfurization slurry, which revealed acceptable performance at a dosage of 10 g·L−1. The proposed MnTiO3 perovskite catalyst is non-toxic, cost-effective, convenient to synthesize, and recyclable, providing new possibilities for sulfur reclamation during flue-gas desulfurization.

Design and Manufacture of Bone Cements Based on Calcium Sulfate Hemihydrate and Mg, Sr-Doped Bioactive Glass.

In the present study, a novel composite bone cement based on calcium sulfate hemihydrate (CSH) and Mg, Sr-containing bioactive glass (BG) as solid phase, and solution of chitosan as liquid phase were developed. The phase composition, morphology, setting time, injectability, viscosity, and cellular responses of the composites with various contents of BG (0, 10, 20, and 30 wt.%) were investigated. The pure calcium sulfate cement was set at approximately 180 min, whereas the setting time was drastically decreased to 6 min by replacing 30 wt.% glass powder for CSH in the cement solid phase. BG changed the microscopic morphology of the set cement and decreased the size and compaction of the precipitated gypsum phase. Replacing the CSH phase with BG increased injection force of the produced cement; however, all the cements were injected at a nearly constant force, lower than 20 N. The viscosity measurements in oscillatory mode determined the shear-thinning behavior of the pastes. Although the viscosity of the pastes increased with increasing BG content, it was influenced by the frequency extent. Pure calcium sulfate cement exhibited some transient cytotoxicity on human-derived bone mesenchymal stem cells and it was compensated by introducing BG phase. Moreover, BG improved the cell proliferation and mineralization of extracellular matrix as shown by calcein measurements. The results indicate the injectable composite cement comprising 70 wt.% CSH and 30 wt.% Mg, Sr-doped BG has better setting, mechanical and cellular behaviors and hence, is a potential candidate for bone repair, however more animal and human clinical evaluations are essential.

Multistage modified Solvay process based on calcium oxide for carbon dioxide capture and reject brine desalination

Previous studies have investigated the overall performance of the modified Solvay process based on calcium oxide (CaO). In the modified process, calcium oxide (CaO) is reacted with brine salts and carbon dioxide. The results confirmed its effectiveness in capturing CO2 and managing reject brine in a single reaction. However, more attention is needed to overcome the low sodium (Na+) removal efficiency, which does not exceed 35 %. Therefore, the main objective of this research work to develop a novel technique where reject brine is passed through a total of seven stages. In each stage, a specific metal ion is recovered. In the first stage, a 100 % recovery of magnesium ions in the form of magnesium hydroxide solid was obtained by chemical reaction with ammonia (NH3) solution. Then, in the second stage, the ammoniated brine was treated based on the traditional Solvay process, where Na+ reduction, in the form of sodium bicarbonate (NaHCO3), and CO2 uptake reached almost 32.97 % and 37 g of CO2/1000 ml of treated brine, respectively. In the third stage, the electrocoagulation process (EC) was used to recover the sulfate ions (SO42-) in the form of pure calcium sulfate solid and also for the regeneration of NH3 as ammonium hydroxide leading to a total reduction of 96.5 % for SO42- ions. In the fourth stage, CaO was added to the treated brine according to the modified Solvay process. Reductions of 37.98 % and 27.97 % in Na+ and chloride (Cl−) ions were achieved, respectively. In stage 5, more recovery of NaHCO3 was attained by adding ammonium bicarbonate, while in stage 6, the treated brine mixture was passed through a second modified Solvay process. The CO2 uptake reached up to 60 g of CO2/1000 ml. In addition, Na+, Ca2+, K+, and Cl− removal was improved with 47.22 %, 56.33 %, 72.12 % and 34.41 %, respectively. In the last stage, the treated brine was inserted into the second EC process to recover CaCl2 solution and NH3 compounds. The overall reductions of for Na+, Ca2+, K+, and Cl− were 51 %, 93.59, 79 %, and 43.63 %, respectively. Moreover, solid products from each stage were characterized using SEM, XRD, FTIR, and Raman analyses. The products of each stage have diverse industrial applications.

Stability of oxide-sulfate mixtures and implications for deposit-induced degradation of advanced alloys and coatings

Turbine engines ingest atmospheric aerosols that include multi-cation oxide-sulfate mixtures, which deposit onto surfaces within the engine. These deposits are often implicated in hot corrosion of alloys and bond coats and can accelerate thermomechanical failure of ceramic coatings through reaction and infiltration mechanisms. Understanding the intrinsic stability of oxide-sulfate deposits, including the tendency for sulfate decomposition, is important to identify efficient testing protocols. This work addresses that need by integrating experiments and computational thermodynamics models to systematically analyze the effect of deposit composition and temperature on the sulfate decomposition and melting behavior of five model mixed-anion deposits. Mass loss analysis and energy dispersive x-ray spectroscopy show that sulfate decomposition occurs much faster in the mixtures compared to pure calcium sulfate. The thermodynamic computations show that reaction pathways forming ternary and quaternary silicates accelerate sulfate decomposition faster than those forming binary reaction products. The results also show that multi-cation mixtures can suppress the evaporation of sodium and potassium sulfates, retaining the sulfate-bearing liquid to higher temperatures. The results can be used to differentiate the behavior of sulfate-, sulfate-oxide-, and oxide-based deposits, and to guide the discovery of new high temperature alloys and coating materials.

Co-Deposition Mechanisms of Calcium Sulfate and Calcium Carbonate Scale in Produced Water

Co-precipitation of mineral-based salts during scaling remains poorly understood and thermodynamically undefined within the water industry. This study focuses on investigating calcium carbonate and calcium sulfate mixed precipitation in scaling. Scaling is often observed in the produced water supply as a result of treatment processes. Co-precipitation results were compared with experimental results of a single salt crystallization. Several parameters were carefully monitored, including the electrical conductivity, pH value, crystal morphology and crystal form. The existence of the calcium carbonate scale in the mixed system encourages the loose calcium sulfate scale to become more tightly packed. The mixed scale was firmly adhered to the beaker, and the adhesion of the co-deposition product was located between the pure calcium sulfate scale and the pure calcium carbonate scale. The crystalline form of calcium sulfate was gypsum in both pure material deposition and mixed deposition, while the calcium carbonate scale was stable in calcite form in the pure material deposition. In the co-deposition, apart from calcite form, some calcium carbonate scale crystals had metastable vaterite form. This indicated that the presence of SO42− ions reduced the energy barrier of the calcium carbonate scale and hindered its transformation from a vaterite form to a calcite one, and the increase in HCO3− content inhibited the formation of calcium sulfate scale.

A Novel One-Pot Synthesis and Characterization of Silk Fibroin/α-Calcium Sulfate Hemihydrate for Bone Regeneration

This study aims to fabricate silk fibroin/calcium sulfate (SF/CS) composites by one-pot synthesis for bone regeneration applications. The SF was harvested from degummed silkworm cocoons, dissolved in a solvent system comprising of calcium chloride:ethanol:water (1:2:8), and then mixed with a stoichiometric amount of sodium sulfate to prepare various SF/CS composites. The crystal pattern, glass transition temperature, and chemical composition of SF/CS samples were analyzed by XRD, DSC, and FTIR, respectively. These characterizations revealed the successful synthesis of pure calcium sulfate dihydrate (CSD) and calcium sulfate hemihydrate (CSH) when it was combined with SF. The thermal analysis through DSC indicated molecular-level interaction between the SF and CS. The FTIR deconvolution spectra demonstrated an increment in the β-sheet content by increasing CS content in the composites. The investigation into the morphology of the composites using SEM revealed the formation of plate-like dihydrate in the pure CS sample, while rod-like structures of α-CSH surrounded by SF in the composites were observed. The compressive strength of the hydrated 10 and 20% SF-incorporated CSH composites portrayed more than a twofold enhancement (statistically significant) in comparison to that of the pure CS samples. Reduced compressive strength was observed upon further increasing the SF content, possibly due to SF agglomeration that restricted its uniform distribution. Therefore, the one-pot synthesized SF/CS composites demonstrated suitable chemical, thermal, and morphological properties. However, additional biological analysis of its potential use as bone substitutes is required.

Physiochemical properties of copper doped calcium sulfate in vitro and angiogenesis in vivo

ABSTRACT Bone cements were prepared by mixing calcium sulfate and copper sulfate in various proportions. We examined physical and physicochemical properties of the copper doped calcium sulfates and the effects of the cements on angiogenesis in vivo. Rod shaped calcium sulfate crystals were visible by scanning electron microscopy in the cement that contained no copper sulfate, whereas plate-like crystals covered the surface of the cement with high copper content. After immersion of the cements in simulated body fluid (SBF) for 1 day, X-ray diffractometric analysis showed that gypsum precipitates had formed in the copper doped calcium sulfate. The compressive strength of the cements increased from 3.3 MPa for pure calcium sulfate to 6.4 MPa for samples with copper sulfate added. Calcium ion release was greatest from pure calcium sulfate, and the rate of copper ion release was higher for cements containing the most copper. We found that 6 weeks after implantation, more blood vessels had formed around the high copper cement than for the copper-free cement. Copper doped calcium sulfate appears to be useful for application to regenerative medicine including wound healing and bone tissue engineering.

Elution Profiles of Synthetic CaSO4 Hemihydrate Beads Loaded with Vancomycin and Tobramycin.

Backgrounds and ObjectivesThe use of local antibiotic delivery vehicles is common in the management of biofilm-related infections as they provide high concentrations of local antibiotics while simultaneously avoiding complications from systemic toxicity. We present a 100% pure synthetic calcium sulfate hemi-hydrate mixed with 240 mg tobramycin and 500 mg vancomycin per 10 cc mixture for use in revision surgeries of periprosthetic joint infections (PJIs). The purified carrier demonstrates bioabsorbablity, promotion of bone growth, a physiologically favorable pH, and hydrophilicity. These unique properties may alleviate persistent postoperative wound drainage seen in patients with PJI. Our questions consist of two parts: (1) does the novel calcium sulfate carrier provide therapeutic concentrations of antibiotic locally that can kill biofilm related infections? (2) Are serum concentrations of antibiotic significant to cause concern for systemic toxicity?MethodsTo address these questions, we assayed the elution of antibiotic concentrations obtained from surgical drains and serum among 50 patients in the first 5 postoperative days.ResultsThe elution of vancomycin and tobramycin was greatest on day 1 compared with those concentrations obtained on days 2, 3, 4, and 5; serum concentrations were largely undetectable. Our findings demonstrate that this calcium sulfate preparation provides therapeutic delivery of vancomycin and tobramycin locally at log 2–3 above the minimum inhibitory concentration (MIC), while avoiding toxic serum concentrations.ConclusionsWhen used in one-stage revision arthroplasties, the bioabsorbable, purified carrier delivers high concentrations of antibiotic while avoiding systemic toxicity.

Maximizing the strength of calcium sulfate for structural bone grafts.

Calcium sulfate (CS) combines remarkable properties of biodegradability, biocompatibility, and osteoconductivity but its low strength limits the range of its applications in orthopaedic surgery. In this study we have addressed this limitation by optimizing the fabrication process for pure CS, and by using mechanical testing procedures which are relevant for load carrying, or structural bone grafts (flexural tests in hydrated condition). By optimizing the processing parameters (pressure during setting, CS powder to water ratio, saturated solution) we produced CS samples with the highest flexural strength ever reported in hydrated conditions. Once these optimal conditions are used, the addition of "reinforcing" inclusions in the material decreased its strength because these inclusions actually act as defects instead of reinforcements. In addition, the CS can be formed in precise shapes while maintaining optimal processing conditions and provided a strength similar to that of bone with the same dimensions. Dense and porous materials can be combined to duplicate the trabecular and cortical architecture of long bones, with only a small loss of overall strength.

Characterization of Portuguese gypsums as raw materials for dermocosmetics

AbstractPortuguese gypsum deposits utilized by the cement industry were characterized mineralogically, chemically and technologically for possible application in dermocosmetics. The deposits studied (Loulé, Óbidos and Soure) correspond to small outcrops in diapiric anticline areas. In principle, they represent gypsites which are white, and generally of higher quality for traditional applications (e.g.white cement), or greyish, and generally not adequate for cements and mortars. The analytical methods used to characterize the materials were wet sieving and X-ray sedimentation, X-ray diffraction, X-ray fluorescence spectrometry and assessment of abrasiveness, plasticity, texturometrics (adhesivity and firmness), oil absorption and cooling rate. The Óbidos gypsum displayed greater mineralogical and chemical quality (almost pure calcium sulfate) and had a finer grain size (<63 μm), whereas Loulé and Soure gypsums contain mineralogical impurities (mainly quartz). The Óbidos gypsum shows good characteristics in general for application in dermocosmetics because of its absorption, plasticity, adhesivity, firmness and low abrasiveness.

Effect of temperature rising inhibitor on autogenous shrinkage of cement pastes

This study examines autogenous shrinkage behavior of cement pastes affected by temperature rising inhibitor (TRI). Dynamic elastic modulus, hydration kinetics, mineral phase compositions, pore solution and microstructure development were investigated by ultrasonic method, isothermal calorimetry, quantitative X-ray diffraction, inductively coupled plasma-optical spectroscopy and electrical resistivity, respectively. The results of the investigation indicate that reduction in surface tension of the pore solution is not due to the impact of TRI. Conversely, it is shown that growth process of ettringite crystals in pore solution the inhibition is delayed which results from the decreased growth rate of ettringite in pore solution and the slow dissolution rate of aluminum from clinkers affected by TRI. This is used to explain the derivation trend of mineral phases of clinkers, chemical compositions of pore solution, and decreases in the autogenous shrinkage of cement pastes. Experiments involving TRI and pure calcium sulfate aluminum clinker indicate expansion stress generation for a longer period when compared to that in the cement pastes only containing TRI, thereby confirming delayed ettringite growth mechanism.

Calcium sulphate crystallisation in the presence of mesoporous silica particles: Experiments and population balance modelling

A population balance model is used to investigate the effect of mesoporous silica particles on calcium sulphate crystallisation in a stirred batch crystalliser. The model accounts for nucleation, growth, agglomeration, breakage, and particle-assisted nucleation, and the model equations are solved numerically using the method of classes over a logarithmic, non-uniform mesh. The crystallisation process is characterized experimentally using electrical conductivity to track the ion concentration and laser diffraction to measure the steady-state crystal size distribution obtained at the end of the experiments. The experiments are carried out over a range of temperatures, initial supersaturations, particle pore diameters, and particle loadings. The model is first fitted to experimental data obtained in the absence of particles to determine kinetic parameters of the nucleation, growth, agglomeration, and breakage for pure calcium sulphate crystallisation. Varying pore diameter did not influence the catalytic effect of the particles, however, particle loading was found to significantly decrease the nucleation induction time. The model was extended to account for the presence of particles by fitting two additional mechanisms. The first proposed a particle-assisted nucleation where nuclei are produced via heterogeneous crystallisation, then detach by particle-particle collision that is second-order with respect to particle loading. The second proposed that the crystal breakage frequency increases linearly with particle loading. Good agreement with the experimental data is demonstrated over the range of conditions examined.

On the heat of formation of ye'elimite Ca4Al6O12.SO4 using density functional theory

The heat of formation of ye'elimite Ca4Al6O12.SO4 was calculated using density functional theory (DFT). The crystallographic ground state of ye'elimite is the orthorhombic Pcc2 modification in agreement with experimental information. Three different many-body interaction functionals were used for DFT calculations: the generalised gradient approximation (GGA), the Armiento/Mattsson 2005 functional (AM05) and the strongly conditioned and appropriately normed functional (Scan). The best results were obtained with the Scan functional and a heat of formation at 298 K of −35·5 kJ/mol referred to pure calcium oxide (CaO), aluminium oxide (Al2O3) and calcium sulfate (CaSO4) was found. All other reported modifications of ye'elimite (cubic, tetragonal, monoclinic) are unstable with endothermic heat of transformations ranging from +18 to +78 kJ/mol.

Treatment of chronic long-bone infections by dissolvable antibiotic beads (pure synthetic calcium sulfate impregnated with vancomycin and gentamicin)

Background This study reviews the clinical results using synthetic calcium sulfate impregnated with vancomycin and gentamicin dissolvable beads in 70 patients who suffered from chronic long-bone infection that was not responding to several trials of treatment. Patients and methods All patients prepared for surgical debridement and calcium sulfate impregnated with vancomycin and gentamicin beads were inserted into the wound. Results The main follow-up was 12 months; the mean age of the patients was 37.94. Staphylococcus aureus was the organism that had been reported in 45.71% of all swabs. In the final results 61 (87.14%) patients were completely healed while only nine (12.86%) patients still had infection. Complication Blood loss occurred in 15 (21.42%) patients and five (7.15%) patients developed deep venous thrombosis (DVT). Conclusion Dissolvable beads of calcium sulfate impregnated with vancomycin and gentamicin are an effective and safe tool for the treatment of chronic long-bone infections.

Careful interpretation of the wound status is needed with use of antibiotic impregnated biodegradable synthetic pure calcium sulfate beads: Series of 39 cases.

Introduction: The use of antibiotic impregnated biodegradable synthetic high purity calcium sulfate (SHPCS) beads is frequently reported as they offer increased concentration of antibiotics locally, without need for removal. However some wound discharge following their use has been noted. The purpose of this study was to determine any correlation between wound discharge and infection remission.Methodology: Retrospective study of 39 cases of Osteoarticular infections from April 2013 to November 2016 in whom SHPCS beads were used. All patients underwent the standard staged protocol of aggressive debridement, deep tissue biopsy, implant removal where indicated and early soft tissue cover. SHPCS beads were used locally in the second stage combined with appropriate antibiotics based on tissue culture. All patients received systemic antibiotics for a period of 6 weeks and followed up for a minimum period of six months. The study analysed the patient demographics, etiology, surgical procedures, culture patterns, local antibiotics used, radiological status of beads, incidence and characteristics of wound discharge and outcome.Results: There were 25 cases of chronic osteomyelitis, eight infected non unions, three peri prosthetic joint infections, two soft tissue infections and one case of acute osteomyelitis. 17 of these infections were following osteosynthesis. The cultures were negative on eight occasions in seven patients. A total of 40 organisms were isolated in the other patients; commonest being Staphylococcus aureus (n=16) and E coli (n=7). SHPCS beads were mixed with vancomycin in 17 cases, colistin in 11, vancomycin with colistin in eight and vancomycin with gentamicin in four. Voriconazole was used in one case with fungal infection.Eight cases (20.51 %) developed discharge from the wound at an average of 6 days after inserting the beads. The discharge was serous with no foul smell in six and purulent in two inflamed wounds. Four cases underwent re-debridement; two cases with purulent discharge and subsequent positive cultures; two with serous discharge early in the series and no evidence of infection on re-exploration with negative cultures. The remaining four patients with serous wound discharge were observed without any further surgical intervention, with the discharge stopping spontaneously between 15 to 36 days post operatively. There was no correlation between antibiotic used and wound discharge. Radiographic analysis showed dissolution of all the beads at an average of 36 days in the 39 cases. Heterotrophic ossification was not observed.Clinical and radiological remission of infection was observed in 37 cases (94.9%). Two patients died during the course of hospitalization, secondary to septicaemia and multi organ failure. Three patients had an infection recurrence within six months, managed successfully by re-debridement and appropriate antibiotics. Radiological union was achieved in seven of the eight infected non unions.Conclusions: With the encouraging rates of infection remission we have observed, we continue to use antibiotic loaded SHPCS as an alternative for local antibiotic delivery in the treatment of osteoarticular infections. However, wound discharge is a known potential observation following implantation of calcium sulfate beads, subsiding typically within four to six weeks.The appearance of wound discharge can vary, ranging from purulent discharges to non-purulent, serous/ sero sanguineous fluid wound discharges. The presence of a wound discharge alone does not necessarily imply a failure to treat the infection.It is important to be aware of this side effect and guard against unnecessary re- operations, by careful consideration and monitoring all of the available clinical signs of infection, in addition to blood test results and radiographic evidence. Further research is needed to determine the relationship between the implantation of antibiotic loaded calcium sulfates and the incidence and duration of drainage.

Local bio-absorbable antibiotic delivery in calcium sulfate beads in hip and knee arthroplasty

Antibiotic-impregnated calcium sulfate (AICS) beads have been used for prevention and treatment of periprosthetic joint infections. We evaluated post-operative complications following the use of AICS beads. 56 patients undergoing complex primary or revision hip or knee arthroplasty received antibiotic calcium sulfate beads. Primary outcomes were wound complication rates. Secondary outcomes included reoperation and reinfection rates. One case (1.7%) of persistent wound drainage occurred requiring surgical irrigation and a poly-exchange. No post-operative infections were seen. Use of 100% pure calcium sulfate AICS beads may help reduce post-operative wound complications. AICS appears to be a safe adjunct tool in local antibiotic delivery.