Biomaterials have had an increasingly important role in recent decades, in biomedical device design and the development of tissue engineering solutions for cell delivery, drug delivery, device integration, tissue replacement, and more. There is an increasing trend in tissue engineering to use natural substrates, such as macromolecules native to plants and animals to improve the biocompatibility and biodegradability of delivered materials. At the same time, these materials have favourable mechanical properties and often considered to be biologically inert. More importantly, these macromolecules possess innate functions and properties due to their unique chemical composition and structure, which increase their bioactivity and therapeutic potential in a wide range of applications. While much focus has been on integrating these materials into these devices via a spectrum of cross-linking mechanisms, little attention is drawn to residual bioactivity that is often hampered during isolation, purification, and production processes. Herein, we discuss methods of initial material characterisation to determine innate bioactivity, means of material processing including cross-linking, decellularisation, and purification techniques and finally, a biological assessment of retained bioactivity of a final product. This review aims to address considerations for biomaterials design from natural polymers, through the optimisation and preservation of bioactive components that maximise the inherent bioactive potency of the substrate to promote tissue regeneration.

The Durometer hardness test is one of the most commonly used measurements to qualitatively assess and compare the mechanical behavior of elastomeric and elastomeric-like materials. This paper presents nonlinear finite element simulations of hardness tests which act to provide a mapping of measured Durometer Shore A and D values to the stress-strain behavior of elastomers. In the simulations, the nonlinear stress-strain behavior of the elastomers is first represented using the Gaussian (neo-Hookean) constitutive model. The predictive capability of the simulations is verified by comparison of calculated conversions of Shore A to Shore D values with the guideline conversion chart in ASTM D2240. The simulation results are then used to determine the relationship between the neo-Hookean elastic modulus and Shore A and Shore D values. The simulation results show the elastomer to undergo locally large deformations during hardness testing. In order to assess the potential role of the limiting extensibility of the elastomer on the hardness measurement, simulations are conducted where the elastomer is represented by the non-Gaussian Arruda-Boyce constitutive model. The limiting extensibility is found to predict a higher hardness value for a material with a given initial modulus. This effect is pronounced as the limiting extensibility decreases to less than 5 and eliminates the one-to-one mapping of hardness to modulus. However, the durometer hardness test still can be used as a reasonable approximation of the initial neo-Hookean modulus unless the limiting extensibility is known to be small as is the case in many materials, such as some elastomers and most soft biological tissues.

This review aims to identify the role of augmented, virtual or mixed reality (AR, VR or MR) technologies in setting of spinal surgery. The authors address the challenges surrounding the implementation of this technology in the operating room. A technical standpoint addresses the efficacy of these imaging modalities based on the current literature in the field. Ultimately, these technologies must be cost-effective to ensure widespread adoption. This may be achieved through reduced surgical times and decreased incidence of post-operative complications and revisions while maintaining equivalent safety profile to alternative surgical approaches. While current studies focus mainly on the successful placement of pedicle screws via AR-guided instrumentation, a wider scope of procedures may be assisted using AR, VR or MR technology once efficacy and safety have been validated. These emerging technologies offer a significant advantage in the guidance of complex procedures that require high precision and accuracy using minimally invasive interventions.

BackgroundThe plastic surgery literature is vast, consisting of a plethora of diverse articles written by a myriad of illustrious authors. Despite this considerable archive of published material, it remains nebulous as to which precise papers have had the greatest impact on our specialty. The aim of this study was to identify the most cited papers in the plastic surgery literature and perform a citation analysis paying particular attention to the evidence levels of the clinical studies.MethodsWe identified the 50 most cited papers published in the 20 highest impact plastic surgery journals through the Web of Science. The articles were ranked in order of number of citations acquired and level of evidence assessed.ResultsThe top 50 cited papers were published in six different journals between the years 1957 and 2007. Forty-two of the papers in the top 50 were considered as level IV or V evidence. No level I or II evidence was present in the top 50 list. The average level of evidence of the top 50 papers was 4.28.ConclusionsIn the plastic surgery literature, no positive correlation exists between a high number of citations and a high level of evidence. Anatomical reconstructive challenges tend to be the main focus of plastic surgery rather than pathologic diseases and consequently, papers with lower levels of evidence are relatively more valuable in plastic surgery than many other specialties.

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