MEASUREMENT ACCURACY IN ACETABULAR CUP WEAR - 3 RETROSPECTIVE METHODSCOMPARED WITH ROENTGEN STEREOPHOTOGRAMMETRY

The accuracy of three methods (the simple and noncomputerized Scheier- Sandel and Charnley-Duo methods and the computerized fin Bild Roentgen Analyse [EBRA] method) for retrospective wear measurements of the ace tabular cup from standard pelvis radiographs was studied. Measurements on 13 hip prostheses were compared with those obtained by roentgen st ereophotogrammetry analysis. The Scheier-Sandel method had the lowest accuracy and the EBRA method had the best accuracy. The Charnley-Duo m ethod was almost as good when starting analysis 3 months after surgery and is easier to use. The EBRA method is useful for accurate measurem ents on a small number of patients; the Charnley-Duo method is recomme nded for clinical wear studies on a larger number of patients.