Accuracy of a Fluoroscopy Technique for Assessing Patellar Tracking

Accuracy of a novel fluoroscopy-based method of assessing patellar tracking was determined by comparing the pattern of patellar motion with respect to orientation (flexion, internal rotation, and lateral tilt) and translation (lateral, proximal, and anterior) with the pattern of patellar motion measured using Roentgen Stereophotogrammetric Analysis (RSA) in one cadaver knee specimen. Each pose in the patellar motion could be obtained from a single as well as multiple calibrated fluoroscopic images. The mean error (SD) varies from 0.73 (0.44) to 1.60 (0.48) degrees for patellar orientation and from 0.48 (0.37) to 1.20 (0.57) mm for patellar translation. These errors appear to be sufficiently low to identify clinically significant differences in patellar kinematics.