The aim of the project is to develop a more biocompatible bone cement for increased joint prosthetic survival and to enclose the bone cement in a prepacking system which allows closed mixing in the operating theatre giving a better cement quality and improved environmental control.

The aim of the project is to develop a more biocompatible bone cement for increased joint prosthetic survival and to enclose the bone cement in a repacking system which allows closed mixing in the operating theatre giving abetter cement quality and improved environmental control. One million joint implants were inserted around the world in 1994 with 300.000 in Europe. Polymethyl methacrylate bone cement has been used as a filling material for joint implants since 1958. Improvements in the operative and cementingte chnique during the 70's and bone cement properties in the 80's, have led to a substantial improvement in prosthetic longevity from 70-80% to 90-95% 10year-survival in cemented implants. However, prosthetic loosening is still a problem. The use of hydroxyapatite (HA) has been shown to increase bone in growth in the early postoperative period when used as a coating material, thus giving a more stable and possibly longer lasting implant. A patent application for new bone cement with HA as an additive and with a different antibiotic mixture and a new radiographic marker has been sent in 1994. A further patent application has been filed in 1994 concerning a closed prepacking system, which permits packing of cement under sterilised condition and cement mixing in the operating theatre under closed conditions. The patents are owned by the contributing companies who are part of the current project.

The project consists of an industrial, a preclinical and a clinical part. The industrial partners will produce the polymers, additives and the mixing system. The preclinical part will focus on the bone interface reaction to the new HA bone cement. This will be tested in loaded and unloaded conditions in solid and particulate material. Antibiotic pharmacokinetics will be studied in vivo and in vitro. The mechanical properties and performance will be tested in joint simulators and by finite element modelling. The effect of third body wears of particulate Hatchment will be analysed using a simulator. The efficiency of the mixing prepacking system will be also tested concerning cement properties. The clinical part will be carried out using joint implants marked with tantalum beads and radio stereometry where prosthetic motion can be measured precisely. This allows for early prediction of later loosening and failure.

The clinical data and the bone reaction using dual energy X-ray absorptiometry will be followed. The project will run for three years. It is well grounded in both the scientific and industrial communities with highly competent participants with complementarities of skills. In order to succeed in the development of the new bone cement and delivery system this European collaboration is necessary. The humanitarian and economic benefits of this project could be very significant both in reducing the need of replacement operations and reduction of costs (estimated 30 M ECU in Europe). The project will also enable Europe to remain in the forefront in biomaterial area as well as providing better economic opportunities (including providing increased employment) for the industrial SME participants involved in the project.