Percutaneous vertebroplasty: a new animal model.

Background Context Percutaneous vertebroplasty (PVP) is a minimally invasive surgical procedure and is frequently performed in humans who need surgical treatment of vertebral fractures. PVP involves cement injection into the vertebral body, thereby providing rapid and significant pain relief. Purpose The testing of novel biomaterials depends on suitable animal models. The aim of this study was to develop a reproducible and safe model of PVP in sheep. Study Design This study used ex vivo and in vivo large animal model study (Merino sheep). Methods Ex vivo vertebroplasty was performed through a bilateral modified parapedicular access in 24 ovine lumbar hemivertebrae, divided into four groups (n=6). Cerament (Bone Support, Lund, Sweden) was the control material. In the experimental group, a novel composite was tested—Spine-Ghost—which consisted of an alpha-calcium sulfate matrix enriched with micrometric particles of mesoporous bioactive glass. All vertebrae were assessed by micro-computed tomography (micro-CT) and underwent mechanical testing. For the in vivo study, 16 sheep were randomly allocated into control and experimental groups (n=8), and underwent PVP using the same bone cements. All vertebrae were assessed postmortem by micro-CT, histology, and reverse transcription-polymerase chain reaction (rt-PCR). This work has been supported by the European Commission under the 7th Framework Programme for collaborative projects (600,000–650,000 USD). Results In the ex vivo model, the average defect volume was 1,275.46±219.29 mm3. Adequate defect filling with cement was observed. No mechanical failure was observed under loads which were higher than physiological. In the in vivo study, cardiorespiratory distress was observed in two animals, and one sheep presented mild neurologic deficits in the hind limbs before recovering. Conclusions The model of PVP is considered suitable for preclinical in vivo studies, mimicking clinical application. All sheep recovered and completed a 6-month implantation period. There was no evidence of cement leakage into the vertebral foramen in the postmortem examination.

Mechanical properties of adobe blocks used in building construction in Huambo Province - Angola

Despite significant advances in building technologies with the use of conventional construction materials (as concrete and steel), which significantly have driven the construction industry, earth construction have demonstrated its importance and relevance, as well as it has matched in an efficient and eco-friendly manner the social housing concerns. The diversity of earth construction techniques allowed this material to adapt to different climatic, cultural and social contexts until the present time. However, in Angola, the construction with earth is still associated with population fringes of weak economic resources, for which, given the impossibility of being able to acquire modern construction materials (steel, cement, brick, among others), they resort to the use of available natural materials. Furthermore, the lack of scientific and technical knowledge justifies the negative appreciation of traditional building techniques, and the derogatory way how are considered the earth constructions in Angolan territory. Given the country's current development status, and taking into account the environmental requirements and the real socio-economic sustainability of Angola, it is considered that one of the viable and adequate options, could be the recovering and upgrading of the ancestral techniques of earth construction. The purpose of this research is to develop the technical and scientific knowledge in order to improve and optimize these construction solutions, responding to the real problems of housing quality as well as to the current social, economic and environmental sustainability requirements. In this paper, a description of the physical and mechanical characteristics of the adobes typically used in the construction of traditional houses in some localities of Huambo, province in Angola, is carried out. The methodology was based on mechanical in-situ testing in adobe blocks manufactured with traditional procedures: i) tensile strength evaluated with the bending test and compressive strength test on earth blocks specimens; and, ii) durability and erodibility test by Geelong method adopting the New Zealand standard (NZS) procedures (4297: 1998; 4297: 1998 and 4297: 1999). The results allow the characterization of the materials used in the construction of raw earth in the Huambo region, contributing to the development of knowledge of these sustainable and traditional housing constructive solutions with a strong presence in Angola [1, 2]. This study is part of a larger project in the area of Earth Construction [3], which aims to produce knowledge which can stimulate the use of environmental friendly construction materials and contribute to develop constructive solutions with improved performance, durability, comfort, safety and sustainability.