Definition of endoprosthetic loosening. Comparison of arthrography, scintigraphy and roentgen stereophotogrammetry in prosthetic hips.

Contrast arthrography, radionuclide arthrography, scintigraphy and roentgen stereophotogrammetric analysis (RSA) were used to detect mechanical loosening in 14 painful total hip replacements. All prosthetic components unstable by RSA, or with abnormal arthrogram, or with increased scintigraphic activity, or loose at revision were migrating, but no non-migrating components demonstrated any of these signs of loosening. Our findings indicate that mechanical loosening should be defined as migration.