Repeat validation of a method to measure in vivo three dimensional hip kinematics using computed tomography and fluoroscopy

Total hip arthroplasty or THA is a surgical procedure for the relief of significant disabling pain caused by osteoarthritis or hip fracture. Knowledge of the 3D kinematics of the hip during specific functional activities is important for THA component design. In this paper we compare kinematic measurements obtained by a new 2D-3D registration algorithm with measurements provided by the gold standard roentgen stereo analysis (RSA). The study validates a promising method for investigating the kinematics of some pathologies, which involves fitting three dimensional patient specific 3D CT scans to dynamic fluoroscopic images of the hip during functional activities. This is the first study in which single plane fluoroscopy has been used for kinematic measurements of natural hip bones. The main focus of the study is on the out-of-plane translation and rotation movements which are difficult to measure precisely using a single plane approach. From our experimental results we found that the precision of our proposed approach compares favourably with that of the most recent dual plane fluoroscopy approach.