Technological shocks mechanism on Macroeconomic Variables: A Dynamic Stochastic General Equilibrium (DSGE) approach.

As Ghana assumes a position of oil producer and middle-income country, it must learn to effectively deal with the related pressures from shocks. We analyze the effects of productivity shocks on Ghana’s total output using the multi-sector dynamic stochastic general equilibrium (DSGE) model. It was actualized that a productivity shock results in a temporary shrinkage in the final goods sectors due to the reallocation of labour from the final and intermediate goods sectors. We demonstrated that technological shock induces an initial fall in marginal cost of production but later rises to reach equilibrium

Treatment of infected tibial non-unions using a BMAC and S53P4 BAG combination for reconstruction of segmental bone defects: A clinical case series

Introduction: Treatment of infected non-unions of the tibia is a challenging problem. The cornerstones of optimal infected non-union treatment consist of extensive debridement, fracture fixation, antimicro-bial therapy and creation of an optimal local biological bone healing environment. The combination of S53P4 bioactive glass (BAG), as osteostimulative antibacterial bone graft substitute, and bone marrow as-pirate concentrate (BMAC) for the implantation of mesenchymal stem cells and growth factors might be a promising combination. In this paper, preliminary results of a new treatment algorithm for infected non-unions of the tibia is presented.Methods: In this retrospective case series patients with infected non-unions of the tibia are treated ac-cording to a new treatment algorithm. Patients are treated with extensive debridement surgery, replace-ment of the osteosynthesis and implantation of S53P4 BAG and BMAC in a one-stage or two-stage proce-dure based on non-union severity. Subsequently patients are treated with culture based antibiotic therapy and followed until union and infection eradication.Results: Five patients with an infected non-union were treated, mean age was 55, average NUSS-score was 44 and the average segmental bone defect was 4.6cm. One patient was treated in a one-stage pro-cedure and four patients in a two-stage induced membrane-, or "Masquelet"-procedure. On average, 23 ml S53P4 BAG and 6.2 ml BMAC was implanted. The mean follow-up period was 13.6 months and at the end of follow-up all patients had clinical consolidation with an average RUST-score of 7.8 and complete eradication of infection. Discussion: These early data on the combined implantation of S53P4 BAG and BMAC in treatment of infected non-unions shows promising results. These fracture healing results and eradication rates resulted in promising functional recovery of the patients. To substantiate these results, larger and higher quality studies should be performed.(c) 2021 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/

Antibiotic-loaded collagen sponges in clinical treatment of chronic osteomyelitis: a systematic review

Chronic osteomyelitis is caused by bacterial infection of the bone and is a major problem in orthopaedic surgery. Treatment of chronic osteomyelitis requires surgical debridement accompanied by local and systemic administration of antibiotics. A widely established biodegradable local antibiotic carrier is antibiotic-loaded collagen sponges (fleeces). These sponges are commonly used in the treatment of chronic osteomyelitis, but a systematic review of their clinical efficacy and assessment of the quality of evidence have not been conducted, to our knowledge.Methods:This systematic review, performed according to the PRISMA statement, examined the clinical efficacy of and quality of evidence regarding different antibiotic-loaded collagen sponges in the clinical treatment of chronic osteomyelitis. Clinical efficacy was defined as eradication of infection with bone and wound-healing. In addition, the in vivo pharmacokinetics of the various collagen sponges were evaluated. Quality was based on the Level of Evidence, methodological quality, and risks of bias.Results:A total of 813 articles were screened, and 10 were included. Gentamicin-sulfate sponges and gentamicin-sulfate/gentamicin-crobefate sponges were studied. A total of 413 patients were treated, with a success rate of 91%. Reported complications were fistulas, prolonged wound drainage, and wound-healing problems. In vivo pharmacokinetic profiles showed an average local antibiotic concentration that was above the minimum inhibitory concentration for only 5 days. The general quality of the included studies was low to moderate, and there was a moderate to high risk of bias.Conclusions:The evidence quality and Level of Evidence of the included studies were low, and the risk of bias in these studies was high. This makes the evidence regarding these sponges inconclusive, and no clinical decision-making can be based on these studies. Utilization of antibiotic-loaded collagen sponges in the treatment of chronic osteomyelitis should only be carried out with caution; studies with high-level evidence are needed.Level of Evidence:Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence

S53P4 bioactive glass

Bioactive glasses (BAGs) are synthetic bone graft substitutes that have been investigated by various orthopedic research groups in the past decades. These bone-bonding, osteoconductive materials can be used for various clinical applications. S53P4 is a specific composition of BAG, which is the main topic of this chapter, with the focus on granular S53P4. First, the working mechanism of S53P4 BAG is explained extensively on the basis of surface reactions, the bond to bone, osteostimulation, and bone proliferation around the material. S53P4 BAG has an antibacterial effect that is unique among bone graft materials, which makes the material useful in (suspected) septic bone defects. This antibacterial effect is discussed in detail. Additionally, its degradation and effect on angiogenesis are addressed. The chapter concludes with the current clinical applications of the material that are known in the literature

Bioactive glass can potentially reinforce large bone defects

Introduction: Bioactive glass (BAG) has been studied widely and seems to be a very promising biomaterial in regeneration of large bone defects and osteomyelitis treatment, because of its bone bonding and antibacterial properties[1]-[5]. Potentially, it could also mechanically reinforce large defects, thus making it suitable for load-bearing applications. However, the mechanical properties of the reconstructive layer and its dependence on BAG:bone allograft mixture composition are unknown. In this study, we measured the mechanical properties of different impacted BAG/bone graft mixtures. Then these properties were used in micro-Finite Element (FE) patient-specific models to investigate whether these mixtures could restore mechanical properties of large bone defects. Materials and Methods: Five different S53P4 BAG/bone graft mixtures were impacted in a cylindrical holder, mechanically tested in confined compression and scanned with micro-CT. From these images, the mixture was identified by its three phases: bone, glass or interface region. Micro-Finite-Element (FE) models of the composites were made using a Young’s modulus of 2.5 GPa for bone and 35 GPa for BAG. The Young’s modulus for the interface region was determined by fitting experimental and micro-FE results for the same specimens. High-Resolution peripheral quantitative CT scans of a 9 mm region of the distal tibia of seven subjects were used for studying the reinforcement potential. Micro-FE models of this region were made to determine its stiffness in the original state, with a simulated cortical defect, and after that a mixture of BAG/bone or BAG alone was simulated in the defect. Results: The confined compression tests showed a strong dependence of the Young’s modulus of the BAG/bone composite on the amount of BAG, ranging from 116.7±18.2 to 654.2±35.2 MPa. The micro-FE results could fairly reproduce these measured moduli, when using a stiffness of 25 MPa for the interface layer (R2=0.678, see Figure 1)

Mechanical properties of bioactive glass putty formulations

Introduction: Bioactive glass (BAG) has been studied widely and seems to be a very promising biomaterial in regeneration of large bone defects and osteomyelitis treatment, because of its bone bonding and antibacterial properties[1]-[5]. Its high stiffness could potentially also enable mechanical reinforcement of large defects. The loose-granular nature of this material, however, makes it difficult to handle by the surgeon. Moreover, in previous research we found only sub-optimal mechanical properties for pure BAG fillings[6]. Recently a BAG putty was developed that is easier to handle. The aim of the current study is to determine the mechanical properties of this putty and its dependence on composition. Materials and Methods: Five different compositions of S53P4 putty were tested in mechanical confined compression tests, after impaction of the samples (n=5 per group). The putty materials all consist of a synthetic binder (matrix: 20 wt% PEG 400, 40 wt% PEG 1500, 15 wt% PEG 3000 and 25 wt% glycerol), BAG granules (2.0-3.15 mm) and BAG powder (300-500 µm). Impaction was performed with the use of a custom-made impaction device (providing clinical relevant strains)[7]. After the samples were equally confined in PMMA chambers, they were subjected to 900 cycles of loading (40 – 850 N) followed by 300 s of rest. From the recorded displacement – time curves, the Young’s Modulus (elastic behaviour), plastic strains (permanent deformations) and creep strains (viscous behaviour) were determined and compared for the five compositions[7],[8]. Results and discussion: The results for impactability (measure for the height difference before and after impaction), Young’s Moduli, creep and plastic strain are shown in Figure 2. Significant differences between the putty compositions were found only for impactability and plastic strain. With an increasing amount of matrix the impactability decreases significantly. It has to be noted that the overall impactability is low, compared to graft materials such as morsellized cancellous bone or porous titanium[6],[7]. However, these materials are much less mouldable than the putty materials. The Young’s moduli of all putty compositions were found to be in range of the modulus of cancellous bone (100-500 MPa), which is the desired range[9]. Furthermore, creep strains were low, which indicate that viscous behaviour will not likely affect the graft layer stability. The plastic strain increases with larger matrix content. Such plastic strain can threaten the graft stability in load-bearing applications and thus should be kept low. Conclusion: For load bearing sites where the putty can be well confined in the defect, putty compositions with the low amount of matrix could be beneficial since their plastic strains are lowest. In other situations, the compositions with more matrix would be preferred because they are easier to handle