Introduction Acetabular cup version is crucial for successful total hip arthroplasty (THA). Many methods have been described
for measurement of cup version angle. The aim of this study is to assess the accuracy of five commonly used methods for
measurement of acetabular cup version in plain antero-posterior views of the pelvis and hip.
Material and methods Sixty primary THA cases were subjected postoperatively to plain A-P of the pelvis (AP-P), A-P view of the
hip (AP-H), and computed tomography (CT) imaging. The acetabular cup version wasmeasured in AP-P and AP-H by fivemethods
(Lewinnek, Widmer, Hassan et al., Ackland et al., and Liaw et al.). These measurements were compared to the CT measurement.
Results All plain X-ray methods showed no significant differences from the CT, except those of Hassan et al. in AP-H, and
Widmer and Ackland et al. in AP-P.
Conclusions and recommendations For measurement of acetabular cup version angle, we recommend the use of Lewinnek and
Liaw et al. methods both in AP-P and in AP-H, while Hassan et al.’s method is recommended in AP-P only, and Widmer and
Ackland et al.’s methods in AP-H only.