Analysis of current literature highlights a wide variation in reported infection risk for different materials in cranial repair. The purpose of these composite materials are to mimic natural bone and assist in restoring function (structurally and aesthetically) to the human skull. This review aims to examine the meta-data in order to provide an amalgamated overview of potential trends between implant material, manufacturing method and infection risk, in order to provide a core reference point for future studies surrounding emerging biomedical materials in the fields of cranioplasty by providing base point for understanding the capabilities and limitations of current technologies. Methods: A search for articles was conducted, with the following criteria seen as fundamental in providing an accurate picture of the current landscape: publication in the last decade, provision of a numerical value for both number of implants and infection cases, patient sample of 10+, adult patients, and cranioplasty/cranial repair. Results: A total of 41 articles were seen to meet the author’s inclusion criteria. Average infection rates per material ranged between 2.04% and 10.98%. The results indicate that there is variation between materials in regards to total infection risk, however, depending on the materials compared, this value may be insignificant. Alternative risk factors associated with infection, including surgical time, revisions and previous infection, have a greater impact on infection potential than material variation. Comparison of fabrication methods did highlight a notable effect on average infection rate. Trends can be observed showing that materials with greater levels of surface interaction and active support of tissue ingrowth presented greater infection resistance. Such characteristics are due to the physical structures of the implants. Conclusions: It can be said that the manufacturing methods can influence biomedical materials to assist in minimizing implant infection risk.

Zirconia-toughened alumina (ZTA) using yttria-stabilised zirconia is a good option for ceramic-ceramic bearing couples for hip joint replacement. Gelcasting is a colloidal processing technique capable of producing complex products with a range of dimensions and materials by a relatively low-cost production process. Using gelcasting, ZTA samples were prepared, optimising the stages of fabrication, including slurry preparation with varying solid loadings, moulding and de-moulding, drying and sintering. Density, hardness, fracture toughness, flexural strength and grain size were observed relative to slurry solid loadings between 58 and 62 vol. %, as well as sintering temperatures of 1550 °C and 1650 °C. Optimal conditions found were plastic mould, 4000 g/mol PEG with 30 vol. % concentration, 61% solid loading and T_s = 1550 °C. ZTA samples of high density (maximum 99.1%), high hardness (maximum 1902 HV), high fracture toughness (maximum 5.43 MPa m^1/2) and high flexural strength (maximum 618 MPa) were successfully prepared by gelcasting and pressureless sintering.

The selection of biomaterials as biomedical implants is a significant challenge. Ultra-high molecular weight polyethylene (UHMWPE) and composites of such kind have been extensively used in medical implants, notably in the bearings of the hip, knee, and other joint prostheses, owing to its biocompatibility and high wear resistance. For the Anterior Cruciate Ligament (ACL) graft, synthetic UHMWPE is an ideal candidate due to its biocompatibility and extremely high tensile strength. However, significant problems are observed in UHMWPE based implants, such as wear debris and oxidative degradation. To resolve the issue of wear and to enhance the life of UHMWPE as an implant, in recent years, this field has witnessed numerous innovative methodologies such as biofunctionalization or high temperature melting of UHMWPE to enhance its toughness and strength. The surface functionalization/modification/treatment of UHMWPE is very challenging as it requires optimizing many variables, such as surface tension and wettability, active functional groups on the surface, irradiation, and protein immobilization to successfully improve the mechanical properties of UHMWPE and reduce or eliminate the wear or osteolysis of the UHMWPE implant. Despite these difficulties, several surface roughening, functionalization, and irradiation processing technologies have been developed and applied in the recent past. The basic research and direct industrial applications of such material improvement technology are very significant, as evidenced by the significant number of published papers and patents. However, the available literature on research methodology and techniques related to material property enhancement and protection from wear of UHMWPE is disseminated, and there is a lack of a comprehensive source for the research community to access information on the subject matter. Here we provide an overview of recent developments and core challenges in the surface modification/functionalization/irradiation of UHMWPE and apply these findings to the case study of UHMWPE for ACL repair.

Electrospun fibres have gained broad interest in biomedical applications, including tissue engineering scaffolds, due to their potential in mimicking extracellular matrix and producing structures favourable for cell and tissue growth. The development of scaffolds often involves multivariate production parameters and multiple output characteristics to define product quality. In this study on electrospinning of polycaprolactone (PCL), response surface methodology (RSM) was applied to investigate the determining parameters and find optimal settings to achieve the desired properties of fibrous scaffold for acetabular labrum implant. The results showed that solution concentration influenced fibre diameter, while elastic modulus was determined by solution concentration, flow rate, temperature, collector rotation speed, and interaction between concentration and temperature. Relationships between these variables and outputs were modelled, followed by an optimization procedure. Using the optimized setting (solution concentration of 10% w/v, flow rate of 4.5 mL/h, temperature of 45 °C, and collector rotation speed of 1500 RPM), a target elastic modulus of 25 MPa could be achieved at a minimum possible fibre diameter (1.39 ± 0.20 µm). This work demonstrated that multivariate factors of production parameters and multiple responses can be investigated, modelled, and optimized using RSM.

This review of literature focuses on the multiple uses of Functional Electrical Stimulation (FES) and how this modality may be a valuable home-based therapy. Papers pertaining to home FES exercise were collected using the Web of Science, Google Scholar databases and collegial hints. In our opinion, the following statements summarize the results. FES may be used to induce health benefits in populations with paralysis, and in persons with musculoskeletal, cardiorespiratory and renal pathology. The EU Project Rise showed how FES could have a variety of encouraging outcomes for patients with denervated muscles following traumatic injuries. As suggested by recent literature, FES has proven to be a viable form of exercise for elderly individuals. Thus, Home FES may be an option for patients looking for an additional form of muscle and cardiopulmonary physical therapy.

In this study porous alumina samples were prepared and then coated using the biomimetic coating technique using a five times Simulated Body Fluid (5.0SBF) as the growth solution. A coating was achieved after pre-treatment with concentrated acid. From elemental analysis, the coating contained calcium and phosphorous, but also sodium and chlorine. Halite was identified by XRD, a sodium chloride phase. Sintering was done to remove the halite phase. Once halite was burnt off, the calcium phosphate crystals were not covered with halite and, therefore, the apatite phases can be clearly observed. Cell culturing showed sufficient cell attachment to the less porous alumina, Sample B, that has more calcium phosphate growth, while the porous alumina, Sample A, with minimal calcium phosphate growth attained very little cell attachment. This is likely due to the contribution that calcium phosphate plays in the attachment of bone-like cells to a bioinert ceramic such as alumina. These results were repeated on both SEM and confocal microscopy analysis. Confocal microscopy was a novel characterisation approach which gave useful information and was a visual aid.