Extrait

Background and study aims When hip replacements fail and have to be changed , there has usually been a significant amount of bone lost from around the implants. Often at the time of surgery, this lost bone is replaced with bone from a bone bank , where bone has been donated from patients who were undergoing hip replacement for the first time. Just like blood donation, the patients are screened for all known viral and prion (mad cow disease) infections before the bone is used. As with blood there remains a very small chance that new viruses or prions may be transmitted by the bone to patients. In order to increase the safety of the bone still further, a new means of sterilizing the bone to remove almost completely such a risk has been developed. The safety of the new bone and its mechanical properties in the laboratory has already been checked. As a final test, what happens to the bone in patients will be looked at using a special x-ray technique called radiostereometry. This technique of measuring whether the cup and bone graft move after they have been implanted can identify whether the bone is healthy and healing in place. Who can participate? Men and women aged between 50 and 80 who are having their hip replacements changed. What does the study involve? The two parts of the old hip replacement are removed. Bone is then be packed into the cup part (acetabulum) of the pelvis and a new cup cemented in place. The bone is chosen randomly immediately before the operation to be either the standard frozen bone or bone sterilized by the new method. The stem part of the hip replacement is then replaced and the hip put back into joint. During the operation, some tiny metal beads are placed into the two bones around the hip replacement. The beads are very small (less than 1mm across) and have been used to study joint replacements for almost 40 years. These beads allow medical staff to accurately identify the bone on radiostereometry radiographs. Radiostereometry radiographs are different from normal radiographs, in that two pictures are taken at the same time from different angles with a special cage holding the x-ray plates in position. Using special computer software, a three dimensional picture of the joint can be created with great accuracy. (This functions a bit like the 3D films seen in the cinema). The movement between the hip replacement and the beads in the bone are then measured, either when weight is put upon the leg or over time. The tiny movements seen can predict success or failure. What are the possible benefits and risks of participating? There is a slight increase in the amount of x-rays the patients receive. The study may benefit the patient were they to have any problems after surgery where the information collected would be given to the surgeon and might help in planning further treatment. Where is the study run from? Woodend Hospital, Aberdeen (UK) When is the study starting and how long is it expected to run for? September 2014 to October 2017 Who is funding the study? Chief Scientists Office (Scotland) Who is the main contact? Mr George P Ashcroft [email protected]

Critère d'inclusion

• Revision Hip replacement surgery

Liens

• ictrp
• isrctn