The objective of this study is to analyze subjects having a normal hip and compare the in vivo kinematics to subjects requiring a total hip arthroplasty (THA) due to having a diseased hip and then later post-operative to their implanted hip. Ten subjects will have a normal hip, ten hips will be diseased, requiring a THA and then those ten diseased hips will be re-analyzed at six months post-operative after implantation of a THA.