QUANTIFICATION OF THE PERFORMANCE OF MONO- AND BI-PLANAR 3D FLUOROSCOPY COMPARED TO MARKER-BASED RSA

Accurate knowledge of joint kinematics is fundamental for research and clinical purposes. Radiologic based joint kinematic estimation technique have been recently used to study intact joint in-vivo kinematics. Bi-planar methods are more accurate but expensive and invasive, while mono-planar ones are less reliable but more suitable for the clinical practice. The present work is a comparison of mono- and bi-planar fluoroscopic methods using the marker based Roentgen stereophotogrammetric analysis as gold-standard. Five repetitions of a simulated walking task with bone phantoms were analyzed. The dominant source of error for the bi-planar method was the longitudinal symmetry of the bones. The mono-planar technique was limited in the estimation of the out-of-plane pose parameters, but as good as bi-planar for the in-plane pose parameters. With error of the order of the millimeter and the degree, mono-planar fluoroscopy could be sufficient for clinical analysis, provided that it relies upon the most reliable information and avoiding the out-of-plane transaltion.