Papers by Keyword: Hydroxyapatite Ceramic

Abstract: Bioactivity of biomaterials is recognized to be of importance and the behavior of nanosized HA and β-TCP particles is described and compared. The study focuses on the influence of the phase transformation and grain size on the reprecipitation of calcium phosphate and the effect of immersion time in SBF on the surface characteristics of the samples. The HA and β-TCP samples were fabricated by mixing the powders in a ball mill, drying, uniaxial pressing and sintering at 1150oC for 240 minute using fixed heating and cooling rates. The densified samples were then immersed in a simulated body fluid (SBF) for controlled periods of time in order to investigate their bioactivities. Changes in the surface structure were examined to investigate and characterize phase formation and the chemical functionality of the samples.

Abstract: Uncemented hip arthroplasty is gaining interest. However, it is alleged that uncemented hip implants fail in osteoporotic bone because of early loosening and a higher incidence of periprosthetic fractures. Will Hydroxyapatite Ceramic Coated Hips (HAC) bond on to the osteoporotic bone and continue to function well in this vulnerable group of patients Post-menopausal women are prone to develop osteoporosis. They are seen too frequently with wrist, hip and spinal crush fractures following minor low impact injuries. These ladies also contribute to the cohort of patents requiring hip arthroplasty for all the usual diagnoses including sub capital fractures. This is a study of HAC hip arthroplasty in female patients over the age of sixty which includes women with osteoporosis.

Abstract: To reduce osteolysis and loosening, alumina bearings in hip arthroplasty have been used in Sunderland since 1991. This consecutive series demonstrates the results which have been most rewarding. However, ceramic implant fractures have been encountered but these probably represent less than meticulous operative technique. The results are published and the complications discussed together with advice to reduce the incidence of implant failure.

Abstract: Traditionally implants for hip arthroplasty are secured with bone cement. Problems have been encountered with cement fixation with loosening and osteolysis attributed to the reaction to particulate cement material and also polyethylene debris from wear. Cementing techniques have been improved and the Swedish Hip Register [1] demonstrates that the revision rates have been reduced with improved cementing techniques. However, uncemented hip arthroplasty is now having a revival. In particular, bioactive materials are being used and this paper presents the results of a consecutive series of hip arthroplasties carried out over a total period of just 16 years. All the patients are included, including primary and revision hip arthroplasty. Patients are assessed using the Harris Hip Score [2]. 13% of the hips scored less than 80 on the Harris Hip Score but only 9.4% scored poor pain scores. These represent the results of poor hip arthroplasty, of which an even smaller percentage are related to failed HA hip arthroplasty.

Abstract: Various recombinant growth factors have been used for promoting osteoblastic differentiation cascade. To compare the growth/differentiation factor-5 (GDF-5) and bone morphogenetic protein-2 (BMP-2) in the in vivo osteogenic potential of bone marrow mesenchymal stem cells (MSCs), the bone formation was assessed by rat subcutaneous implantation of 5 kinds of hydroxyapatite (HA) implants; namely GDF/HA composites, BMP/HA composites, MSCs/HA composites and the MSCs/HA composites supplemented with recombinant mouse GDF-5 (GDF/MSCs/HA) or recombinant human BMP-2 (BMP/MSCs/HA). Neither the GDF/HA nor the BMP/HA composites exhibited any bone formation at any time after implantation. At both 2 and 4 weeks after implantation, obvious de novo bone formation together with active osteoblasts was seen histologically in many pores of the GDF/MSCs/HA and BMP/MSCs/HA composites. The GDF/MSCs/HA and BMP/MSCs/HA composites also showed high alkaline phosphatase (ALP) and osteocalcin expression determined at both the protein and gene levels. Compared with GDF/MSCs/HA, the BMP/MSCs/HA composites exhibited excellent osteogenesis with relatively early osteoblastic phenotype expression. These findings indicate that the two growth factors synergistically enhance de novo bone formation capability of MSCs/HA composites and the importance of ceramic surface to retain and to deliver the molecules of growth factors for the cell differentiation and maturation.