Arthrography in loosened hip prostheses. Assessment of possibilities for intra-articular therapy.

BACKGROUND Loosening is a major complication in prosthesis surgery. Less invasive alternatives to revision surgery are required to prevent and treat prosthesis loosening. Some experimental therapies investigating alternative treatments exploit the intra-articular space as a route of administration. For efficient, local delivery of therapeutic agents a contained joint space is required. Furthermore, the volume of the joint space determines the concentration of the therapeutic ingredient in the joint. METHODS A retrospective analysis of 221 hip arthrograms performed between 1994 and 2004 for diagnosis of prosthesis loosening was performed. All arthrograms were studied for leakage of contrast medium and the volume of injected contrast medium. RESULTS There was a contained joint in 164 arthrograms (74%). The volume in these hips was 31+/-12.7 ml. Male patients had a larger joint volume than female patients (P=0.019). There was no difference in containment and joint volume between hips with a primary and with a revised prosthesis. CONCLUSIONS For successful intra-articular therapy it is necessary that the injected agent remains in the jointspace. As leakage of contrast medium was shown in about a quarter of hips, this study shows that an arthrogram may be useful in the inclusion procedure for intra-articular studies to determine containment of the joint and also the volume that can be injected.