Papers by Keyword: Orthopaedic

Abstract: This paper focused on lateral trochanteric wall stress which is a contributing factor for the success of complex trochanteric fracture management with loss of medical bone support. Its aim was to assess performance of augmented fixations to Dynamic Hip Screw (DHS). The analysis was performed using Finite Element (FE) method, where the femoral bone and fixations were developed from reverse engineering technique. The boundary conditions were physiological loads with constraints at distal condyle. It was revealed that lateral augmented fixation i.e. trochanteric stabilization plate raised the trochanteric lateral wall stress that could be at risk of bone breakage.

Abstract: This work aims to review current trends in research within the field of iron-based scaffolds for orthopaedic applications. Current research is trapped in a ‘see-saw’ type problem where an increase in corrosion rate of the base metal is required to accelerate the degradation process making the resorption time compatible with the healing time. This is done via several methods including porosity control, cathodic element addition and/or patterning and alloying. In turn, this increase in corrosion rate causes the local concentration of metallic ions to increase beyond the toxicity limit for osteoblast type cells, thus negatively effecting cytocompatibility. This is most pronounced when considering the orthopaedic environment, in which static conditions provide for increased local ion concentrations, resulting in local toxicity. However, research from the medical field of Thalassemia may help solve this dilemma by providing chelation medicine for patients undergoing implantation of resorbable orthopaedic scaffolds, throughout the resorption period. Excretion of iron would then be provided mainly through bowel movement and urination.

Abstract: Two methods of loading bisphosphonate (BP) into hydroxylapatite (HA) coatings on crystalline TiO2 surfaces were investigated to improve bone ingrowth to implant surfaces. In the study the BP pamidronate was used. Ti-plates coated with crystalline TiO2 were soaked in phosphate buffer saline (PBS) for 7 days at 40° C and thereafter soaked in solutions of BP, 0.5 mg/ml for 15 or 60 minutes (fast loading method). In the second method BP was dissolved into PBS in different concentrations before immersion of the discs for 7 days (co-precipitation method). Surface and bulk were analysed using electron spectroscopy for chemical analysis, scanning electron microscope and x-ray diffraction. Release of BP was studied using alternating ionic current method. It was shown that fast loading by soaking in a BP solution for 15 minutes was sufficient to load BP into a HA coating. Co-precipitation showed that a thin layer of calcium phosphate crystals containing BP can be deposited directly onto a crystalline TiO2 surface.

Abstract: Different types of bone grafts are available in Brazil due to the increase of use of biomaterials for hard tissue replacement. This study was designed to evaluate the scientific production of Brazilian research groups on safety and efficacy of calcium phosphate bone grafts of commercial use in Brazil. The calcium phosphate bone grafts approved for commercial use in Brazil were searched at the National Health Regulatory Agency’s database (ANVISA). The main leaders’ names of the Brazilian Research Groups on these health technologies were obtained by applying the search strategies to the National Council of Technological and Scientific Development’s database (CNPq). Afterwards, it was performed a systematic search of studies conducted by these leaders on calcium phosphate bone grafts and published from 2000 to May 2008 at the following databases: Medline, Lilacs and Scielo. Twenty-nine bone grafts composed by calcium phosphates were registered at Anvisa in May 2008. From those products, 17 and 12 were from imported and national origin respectively. There were twenty-four Brazilian research groups on calcium phosphate bone grafts whose scientific production consisted of 5 studies on bone grafts registered at Anvisa: 3 experiments conducted in animals on the Brazilian bovine bone graft Gen-Ox®, one prospective comparative study and one case report both evaluating the clinical performance of a national biomaterial composed by BMP, demineralized bovine bone, inorganic bovine bone and bovine collagen with the commercial name Gen-Tech® for dentistry applications and 6 months of follow-up. However, all the included studies had poor methodological quality and could not be used for further recommendations despite their good results. The scientific evidence produced by the Brazilian research groups on safety and efficacy of calcium phosphate bone grafts of commercial use in Brazil is still scant. Additional studies are necessary to evaluate these technologies.

Abstract: Ceramics have been increasingly used in orthopaedics during the last 30 years. Their biological inertness, high hardness and good mechanical strength make them excellent candidates for components such as femoral heads and acetabular cup in Total Hip Replacement prostheses. Currently used bio-inert ceramics – alumina and zirconia – give good clinical results, especially compared to metal – polymer couplings. However, they are subjected to severe biological, tribological and mechanical solicitations during more than fifteen years for the most successful prostheses. They answer these solicitations by presenting specific degradation mechanisms. We will thus examine the phenomena that can account for the long-term behaviour of zirconia components (heads and cups) in THR prostheses.