Can simple radiographs be predictive of total hip dislocation?

The usefulness of angles measured on standardized radiographs to determine acetabular position and predict dislocation after primary total hip arthroplasty (THA) was reviewed retrospectively. Seventy-four patients (97 primary THAs) were reviewed. All patients underwent a standardized protocol of postoperative radiographs which included an anteroposterior view of the pelvis and a cross-table lateral radiograph of the hip. Two angles were measured to define acetabular position: the abduction angle was measured on the anteroposterior radiograph and the version angle was measured on the cross-table lateral radiograph. The values for these angles were compared in a group of known dislocating THAs (7 hips) and a control group of stable THAs (90 hips). These radiographic measurements were also assessed for their reproducibility. The values for the abduction and version angles were not significantly different between the two groups. The values for abduction and version angles for a given hip, from one examination to another, were reproducible. Neither the abduction nor the version angle was a predictor of dislocation.