The overall objective of this study is to define a clinically relevant and applicable quantitative correlation between the change in spinopelvic parameters and change in functional anteversion between the standing and seated positions and challenge the historical safe zone paradigm. The central hypothesis is that the change spinopelvic mobility correlates with the change in functional anteversion. The investigators believe that this quantitative relationship will provide the clinician a tool to identify at-risk THA candidates and make appropriate patient-specific modifications to cup anteversion and post-operative rehabilitation.