Fig. 1.

The true linear wear rate for the highly cross-linked polyethylene acetabular liner calculated using the 1-year film compared with the longest followup film available for each patient yielded a mean wear rate of 0.026 mm per year ± 0.135 mm per year with bedding-in included and 0.033 mm per year with bedding-in excluded. 2D = two-dimensional. The one outlier resulted from inadequate radiographic technique. The difference in radiographic projections of the two AP pelvis radiographs was greater than 25° rotation, the maximum rotation allowed by the software. For this reason, the radiographic software inappropriately assigned an abnormally high wear rate. This one outlier was removed from our final analysis of the wear but was included in the graphic analysis for completeness