Abstract: Background Acetabular cementation during total hip arthroplasty is considered difficult mainly due to the appearance and anatomy of the acetabulum. Improved cementation technique has been shown to improve the longevity of acetabular components. Method We designed a ceramic model to investigate the effect of varying the initial cement pressurization and cup introduction times on the depth of cement penetration. 4 groups were prepared, 2 of which involved varying initial cement pressurization and cup introduction times. Group 3 involved initial cement pressurization with no cup introduction, while group 4 involved cup introduction with no prior cement pressurization. Results and interpretation Most cement penetration occurred in the early pressurization phase, and we conclude that a relatively early and longer cement pressurization time and late cup introduction are positive factors for increased cement penetration in the acetabulum model.

Abstract: Iodixanol (IDX) is a water soluble opacifier widely used in radiographical examinations of blood vessels and neural tissue, and it has been suggested as a potential contrast media in acrylic bone cement. The effect of the iodixanol particle size on the polymerisation process of the bone cement, the molecular weight, and the quasi-static mechanical properties have been investigated in this article. The investigation was performed using radiolucent Palacos powder mixed with 8 wt% of iodixanol with particle sizes ranging from 3 to 20 lm MMD, compared with commercial Palacos R (15 wt% ZrO2) as control. Tensile, compressive and flexural tests showed that smaller particles (groups with 3, 4, and 5 lm particles) resulted in significantly lower mechanical properties than the larger particles (groups with 15, 16, and 20 lm particles). There was no difference in molecular weight between the groups. The thermographical investigation showed that the IDX cements exhibit substantially lower maximum temperatures than Palacos R, with the 4 lm IDX group having the lowest maximum temperature. The isothermal and the constant rate differential scanning calorimetry (DSC) did not show any difference in polymerisation heat (DH) or glass transition temperature (Tg) between radiolucent cement, or cement containing either IDX, or ZrO2. The findings show that the particle size for a bone cement containing iodixanol should be above 8 lm MMD.

Abstract: Injectable bone substitutes (IBS) based on calcium phosphate (CaP) and/or calcium sulphate (CaS) are used as fillers in bone defects to stimulate bone integration and allow mechanical loading. Two types of IBS, IBS-1 is CaP+20%CaS and IBS-2 is CaS+40% hydroxyapatite, were investigated. The materials were injected into holes in the femur and tibia in rabbits. After 10 weeks the femora were subjected to indentation testing and tibiae were prepared for histology evaluation. IBS-1 lead to an higher indentation load compared to control, that is no material inserted, while IBS-2 showed no significant difference between material and control. Histology showed that with IBS-1, the bone penetrated into and integrated with the material in the defect. With IBS-2, new bone grew into the outer 0.5-1.0 mm. The materials could be used for different indications, such as to support fracture healing or in contained cavities.

Abstract: Radiopaque cement containing barium sulfate causes significantly more bone resorption in vivo and in vitro than radiolucent cement. The aim of this study was to investigate the osteolytic potential of an alternative radiopaque agent, triphenyl bismuth (TPB). Bone cement particles containing various concentration of TPB (15 and 25 wt %) prepared by two methods, blending and dissolution, were added to monocytes in a bone resorption assay and the extent of lacunar resorption on dentine slices was determined. The results clearly show that cement particles containing TPB cause less bone resorption than cement particles containing barium sulfate. In addition, our results suggest that TPB prepared by dissolution in bone cement induces less osteolytic response than TPB-cement prepared by blending. The osteolysis in response to bone cement wear particles may therefore be reduced with TPB prepared using the blending technique. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2005

Abstract: Self-curing acrylic bone cements are widely used in the � xation of prosthetic implants in orthopaedic surgery. Commercial bone cements are rendered radiopaque by the addition of heavy metal salts of barium and zirconia. The addition of barium sulphate adversely affects the mechanical strength and fracture toughness of bone cement and despite the fact that it has low solubility in water; its slow release and subsequent toxicity have caused concern. In an earlier study riphenyl bismuth (TPB) was found to be a viable alternative as a radiopaque agent in acrylic bone cements, which provided enhanced homogeneity. In this study we report the effect of the inclusion of TPB on the thermal properties of PMMA-based bone cements using both conventional DSC and Modulated Temperature DSC. Furthermore, analysis of the residual monomer contents is eported analysed by NMR spectroscopy in order to ascertain the in� uence of TPB on the polymerisation reaction. The glass transition temperature (Tg/ determined by DSC showed that the values decreased with the addition of increasing amounts of TPB through both blending and dissolution methods; however, the method of incorporatingTPB did not in� uence Tg. The magnitude of reduction was dependent of the amount of TPB and was greatest in the case of highest concentrationof TPB used. A TPB melting peak was observed in the 25 wt% TPBBC, suggesting a limit to the solubility of TPB. The residual monomer analysis showed that at 10 and 15% by weight of TPB in the cement caused no signi� cant changes in the residual monomer content but 25 wt% of TPB exhibited a signi� cantly higher residual monomer content.

Abstract: In a joint replacement surgery it is vital for bone cement to be radiologically detectable.Consequently, heavy metal salts of barium and zirconia are incorporated as a contrast medium for this purpose.The addition of such particulate additives, however, can be detrimental to some of the physical, mechanical and biological properties.The present study reports the feasibility of using an organo-bismuth compound, namely, triphenyl bismuth (TPB) as a radiopaque agent for orthopaedic bone cements.TPB was incorporated in the bone cement matrix by two methods, (i) blending: TPB was added to the polymer phase of the bone cement and (ii) dissolution: by dissolving TPB in the monomer phase methylmethacrylate.The results showed that the inclusion of TPB at concentrations of 15% and 25% by weight of the polymer, in the bone cement matrix did not affect the polymerisation exotherm temperature and setting time.Furthermore, the addition of TPB via the dissolution method provided a statistically significant increase in the strain to failure in comparison to commercial acrylic cements containing barium sulphate, thus reducing the brittleness of the cement.The detrimental effects on the mechanical properties post conditioning in water, was also much less pronounced in the homogeneous TPB cements in comparison to barium sulphate containing cements.These observations can be attributed to the formation of a homogeneous and continuous matrix of the resultant bone cement with a much lower porosity. r 2002 Elsevier Science Ltd.All rights reserved.