It is concluded that the TiZr1317 implant with a hydrophilic sandblasted and acid-etched surface showed similar or even stronger bone tissue responses than the Ti control implant.

It is important to compare different contrast media used in bone cement according to their ability to attenuate X-rays and thereby produce image contrast between bone cement and its surroundings in clinical applications. The radiopacity of bone cement is often evaluated by making radiographs of cement in air at an X-ray tube voltage of 40 kV. We have developed a method for ranking contrast media in bone cement simulating the clinical situation, by (1) choosing the same X-ray tube voltage as used in clinical work, and (2) using a water phantom to imitate the effects of the patients' soft tissue on the X-ray photons. In clinical work it is desirable to have low radiation dose, but high image contrast. The voltage chosen is a compromise, because both dose and image contrast decrease with higher voltage. Three contrast media (ZrO 2 , BaSO 4 , and Iodixanol) have been compared for degree of "image contrast." Comparing 10 wt % contrast media samples at an X-ray tube voltage of 40 kV, ZrO 2 produced higher image contrast than the other media. However, at 80 kV, using a water phantom, the results were reversed, ZrO 2 produced lower image contrast than both BaSO 4 and Iodixanol. We conclude that evaluations of contrast media should be made with voltages and phantoms imitating the clinical application.

Iodixanol (IDX) and iohexol (IHX) have been investigated as possible radiopacification agents for polymethylmethacrylate (PMMA) bone cement, to replace the currently used barium sulphate and zirconia. IDX and IHX are both water-soluble iodine-based contrast media and for the last 20 years have been used extensively in clinical diagnostic procedures such as contrast media enhanced computed tomography, angiography and urography. One of the major reasons to remove the current radiopacifying agents is their well-documented cytotoxicity and their potential to increase bone resorption.Using in vitro bone resorption assays, the effect of PMMA particles plus IDX or IHX to induce osteoclast formation and lacunar resorption on dentine slices has been investigated. These responses have been compared with the in vitro response to PMMA particles containing the conventional radiopacifying agents, that is, barium sulphate and zirconia. In parallel, the in vivo reaction, in terms of new bone formation, to particles of these materials has been tested using a bone harvest chamber in rabbit tibiae.In vitro cell culture showed that PMMA containing IHX resulted in significantly less bone resorption than PMMA containing the conventional opacifiers. In vivo testing, however, showed no significant differences between the amounts of new bone formed around cement samples containing the two iodine-based opacifying agents in particulate form, although both led to fewer inflammatory cells than particles of PMMA containing zirconia. Our results suggest that a non-ionic radiopacifier could be considered as an alternative to the conventional radiopacifying agents used in biomaterials in orthopaedic surgery.

Two different methods have been used to fatigue test four bone cements. Each method has been used previously, but the results have not been compared. One method tests at least 10 samples over a single stress range in tension only and uses Weibull analysis to calculate the median number of cycles to failure and the Weibull modulus. The second test regime uses fewer specimens at various stress levels tested in fully reversed tension-compression, and generates a stress versus number of cycles to failure (S-N) or Wöhler curve. Data from specimens where the fracture surface contains pores greater than 1mm across is rejected. The single stress level test is quicker to perform however, provides only tensile fatigue data, but the material tested includes pores, thus more physiological cement is tested. The multiple stress level testing regime uses combined tension and compression loading and multiple stress levels, thus more physiological loading, but excludes specimens where the defects are greater than 1mm across, so is less representative of cement in vivo. The fatigue lives between the cements were up to a factor 15 different for the single stress level tension only tests, while they were only a factor of 2 different in the fully reversed tension-compression testing. The single stress level results are more effected by surface flaws, thus the differences found using the multiple stress levels are more indicative of differences in the fatigue lives of the cements. However, the single stress level tests are quicker, so are useful for initial screening.

Water uptake and release characteristics of PMMA cement containing the water-soluble contrast media iohexol or iodixanol have been investigated. The water uptake study revealed that iohexol had the highest uptake of water (3.7%) and that iodixanol had an uptake close to that of Palacos R (2.3% and 1.9%). The curves obtained showed the materials to follow classic diffusion theory, with an initial linearity with respect to t(1/2) making it possible to calculate the diffusion coefficients. This showed iohexol to have the lowest diffusion coefficient, Palacos R the highest, and iodixanol close to that of Palacos R. The release study showed that more iohexol than iodixanol was released from the bone cement; the long-term release was above 25 microg/mL for iohexol compared to slightly above 10 microg/mL for iodixanol. A microCT investigation showed that the risk of developing an observable radiolucent zone is negligible.