Navigation of the cup in total hip arthroplasty is well analyzed and shows accurate results, reducing cup outliers of Lewinnek's "safe zone/' With regard to the combined anteversion of cup and stem, however, a ''new" safe zone with a range of 25deg to 50deg has been published. The aim of this study was to analyze total anteversion (cup and stem) by postoperative 3D computed tomography in isolated cup navigation cases. In 46 patients, the mean combined anteversion was 34.4deg (range, 16.3deg-573deg, SD+-9.3deg) with 10 outliers. The mean cup anteversion was 19.5deg (range, 11deg-27deg, SD+-3.7deg). Regarding Lewinnek's "safe zone" (cup only), we observed 5 outliers. An improvement of technique of stem implantation or navigation may reduce outliers of combined anteversion. The correct positioning of the ac-etabular and femoral components during implantation of a total hip arthroplasty (THA) minimizes the risk of impingement and thus any potential complications such as accelerated polyethylene wear, osteolysis, and premature loosening of the implant. Previous studies examined the optimum position of the cup, where positioning in the "safe zone" according Lewinnek et al, with an abduction of 40deg (+- 10deg) and an anteversion of 15deg (+-10deg), was desired. If positioning of the acetabular cup occurs within this zone, then the risk of dislocation could be reduced.
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