Homologous Banked Bone Grafts for the Reconstruction of Large Cranial Defects in Pediatric Patients

Mastoid Obliteration With Freeze-Dried Bone Allograft in Canal Wall Down Tympanoplasty: Description of a Novel Technique and Case Report

Mastoid obliteration can be performed after canal wall down (CWD) mastoidectomy with various materials. Homologous bone tissue harvested from cadaver donor represents a feasible option with advantages. The purpose of the study is to describe the case of a patient diagnosed with middle ear cholesteatoma treated with mastoidectomy of the CWD and mastoid obliteration with homologous freeze-dried corticocancellous bone particulate in the Cittadella Hospital Ear, Nose, Throat (ENT) unit. The preoperative characteristics of the patients, the procurement and processing of bone allografts, the surgical technique, and postsurgical outcomes are described. No perioperative and postoperative complications were observed, and no rejection or foreign body reactions occurred. The patient then underwent a seriated follow-up. Audiometric tests showed an improvement in hearing levels. The volume of the neoexternal ear canal was 2.01 cm3. The case demonstrated clinical stability, substantial hearing recovery, and no need for specialist cleaning of the reformed external ear canal (EEC). The freeze-dried bone tissue allograft, in the technical way we used, appears to be a viable option in mastoid obliteration because homologous bone is not affected by material shortage, has fast assimilation, and ensures a useful radiological examination scan, at a low cost.

Dual-functional composite scaffolds for inhibiting infection and promoting bone regeneration

The treatment of infected bone defects is an intractable problem in orthopedics. It comprises two critical parts, namely that of infection control and bone defect repair. According to these two core tasks during treatment, the ideal approach of simultaneously controlling infection and repairing bone defects is promising treatment strategy. Several engineered biomaterials and drug delivery systems with dual functions of anti-bacterial action and ostogenesis-promotion have been developed and demonstrated excellent therapeutic effects. Compared with the conventional treatment method, the dual-functional composite scaffold can provide one-stage treatment avoiding multiple surgeries, thereby remarkably simplifying the treatment process and reducing the treatment time, overcoming the disadvantages of conventional bone transplantation. In this review, the impaired bone repair ability and its specific mechanisms in the microenvironment of pathogen infection and excessive inflammation were analyzed, providing a theoretical basis for the treatment of infectious bone defects. Furthermore, we discussed the composite dual-functional scaffold composed of a combination of antibacterial and osteogenic material. Finally, a series of advanced drug delivery systems with antibacterial and bone-promoting capabilities were summarized and discussed. This review provides a comprehensive understanding for the microenvironment of infectious bone defects and leading-edge design strategies for the antibacterial and bone-promoting dual-function scaffold, thus providing clinically significant treatment methods for infectious bone defects.

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Antibacterial and bone-promoting dual-function scaffolds are ideal strategies for treatment of infectious bone defects.

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The effect of infection on bone repair was summarized in detail from four important aspects.

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A variety of dual-function scaffolds based on antibacterial and osteogenic materials were discussed.

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Dual-function drug delivery systems promoting repair of infectious bone defects by locally releasing functional agents.

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Leading-edge design strategies, challenges and prospects for dual-functional biomaterials were provided.

Simvastatin-Incorporated Drug Delivery Systems for Bone Regeneration

Local drug delivery systems composed of biomaterials and osteogenic substances provide promising strategies for the reconstruction of large bone defects. In recent years, simvastatin has been studied extensively for its pleiotropic effects other than lowering of cholesterol, including its ability to induce osteogenesis and angiogenesis. Accordingly, several studies of simvastatin incorporated drug delivery systems have been performed to demonstrate the feasibility of such systems in enhancing bone regeneration. Therefore, this review explores the molecular mechanisms by which simvastatin affects bone metabolism and angiogenesis. The simvastatin concentrations that promote osteogenic differentiation are analyzed. Furthermore, we summarize and discuss a variety of simvastatin-loaded drug delivery systems that use different loading methods and materials. Finally, current shortcomings of and future development directions for simvastatin-loaded drug delivery systems are summarized. This review provides various advanced design strategies for simvastatin-incorporated drug delivery systems that can enhance bone regeneration.

Current concepts for tissue transplant services for developing countries

The transplantation of tissues can save lives and re-establish vital functions, where no alternatives of comparable effectiveness exist. This has led to establishment of tissue transplantation as a successful practice worldwide; however, a great variability between countries remains in terms of donation levels, safety, quality of grafts and their efficacy. Tissue transplantation requires coordination of different agencies involved in the implementation of procurement, processing, storage and distribution of tissues and cells from different hospital units that perform surgical procedures with graft-type input requirements. This biomaterial-like requirement has led to the constant development of the area and today these graft products of human origin can be the starting point for new and more advanced biotechnological products. For long-term sustainability and successful transplantation units, a process management comparable to the pharmaceutical industry in terms of quality management systems must be established to produce safe and high-quality human-derived products. This review aims to update the current concepts of tissue transplant services for its application for developing countries using the current Chilean scenario as a case study. We summarize our findings proposing a set of guidelines/actions that should be followed to ensure smooth tissue transplant services implementations with high efficiency and safe use.

Long-Term Characterization of Cranial Defects After Surgical Correction for Single-Suture Craniosynostosis

INTRODUCTION

Craniosynostosis is typically corrected surgically within the first year of life through cranial vault reconstruction. These procedures often leave open calvarial defects at the time of surgery, which are anticipated to close over time in a large proportion of cases. However, residual calvarial defects may result as long-term sequelae from cranial vault remodeling. When larger defects are present, they may necessitate further reconstruction for closure.Better understanding of the calvarial osseous healing process may help to identify which defects will resolve or shrink to acceptable size and which will require further surgery. Our study aims to assess the long-term changes in defect size after cranial vault reconstruction for craniosynostosis.

METHODS

One-year postoperative and long-term computed tomography scans were retrieved from the craniofacial anomalies archive. Analysis used custom software. All defects above the size of 1 cm were analyzed and tracked for calvarial location, surface area, and circularity. Monte Carlo simulation was performed to model the effect of initial defect size on the rate of defect closure.

RESULTS

We analyzed a total of 74 defects. The mean ± SD initial defect surface area was 3.27 ± 3.40 cm. The mean ± SD final defect surface area was 1.71 ± 2.54 cm. The mean ± SD percent decrease was 55.06% ± 28.99%. There was a significant difference in the percentage decrease of defects in the parietal and frontoparietal locations: 68.4% and 43.7%, respectively (P = 0.001). Monte Carlo simulation results suggest that less than 10% of defects above the size of 9 cm will close to the size of 2.5 cm or less.

CONCLUSIONS

We describe and make available a novel validated method of measuring cranial defects. We find that the large majority of initial defects greater than 9 cm remain at least 1 in in size (2.5 cm) 1 year postoperatively. In addition, there appear to be regional differences in closure rates across the cranium, with frontoparietal defects closing more slowly than those in the parietal region. This information will aid surgeons in the decision-making process regarding cranioplasty after craniosynostosis correction.

Transplant of Adult Bone for Reconstruction of a Large Post-Traumatic Cranial Defect in a Very Young Baby

Large cranial defects in very young patients are challenging. The ideal material for cranioplasty in this age group has not yet been identified. Cryopreserved autologous bone presents very high rates of failures, acrylic resins pose a number of compatibility problems, bioceramics may be contraindicated, and autografts may be not adequate for repair of large defects. We present an 18-month-old baby with a large post-traumatic cranial defect which was repaired by assembling a new bone flap on a sterile stereolithographic 3-D model. This customized newly assembled flap consisted of a scaffold of autologous bone (from vault duplication) sustaining 2 large grafts of homologous cadaveric bone. It was adequately modeled and contoured on the 3-D model using metallic plates and screws. Immediately after implantation on the skull, the metallic devices were progressively replaced by reabsorbable material, thus maintaining the previously obtained flap profile. In this paper we detail this original technique which was developed to manage this specific patient.