Kinematic Accuracy in Tracking Total Wrist Arthroplasty with Biplane Videoradiography using a CT-generated Model.

Total Wrist Arthroplasty (TWA) for improving the functionality of severe wrist joint pathology has not had the same success, in parameters such as motion restoration and implant survival, as hip, knee, and shoulder arthroplasty. These other arthroplasties have been studied extensively, including the use of biplane videoradiography (BVR) that has allowed investigators to study the in-vivo motion of the total joint replacement during dynamic activities. The wrist has not been a previous focus, and utilization of BVR for wrist arthroplasty presents unique challenges due to the design characteristics of TWAs. Accordingly, the aims of this study were 1) to develop a methodology for generating TWA component models for use in BVR, and 2) to evaluate the accuracy of model-image registration in a single cadaveric model. A model of the carpal component was constructed from a CT scan, and a model of the radial component was generated from a surface scanner. BVR was acquired for three anatomical tasks from a cadaver specimen. Optical motion capture was used as the gold standard. BVR's bias in flexion/extension, radial/ulnar deviation, and pronosupination was less than 0.3°, 0.5°, and 0.6°. Translation bias was less than 0.2 mm with a standard deviation of less than 0.4 mm. This BVR technique achieved a kinematic accuracy comparable to previous studies on other total joint replacements. BVR's application to the study of TWA function in patients could advance the understanding of TWA and thus the implant's success.