Reason for performing studyBiplane high-speed fluoroscopy is a new method for gait analysis of the equine distal extremity. This is the first study validating the noninvasive tracking possibilities (Autoscoping and Scientific Rotoscoping) taking equine anatomy into account. ObjectivesTo determine the resolution with which Autoscoping and Scientific Rotoscoping depict motion of the equine phalanges in comparison to the invasive gold standard marker-based registration. Study designComparative exvivo study. MethodsIn 5 distal extremities of slaughtered ponies, 3 or 4 tantalum beads with 1mm diameter were implanted in each of the proximal, middle and distal phalangeal bones. Three-dimensional models of the bones were reconstructed using computed tomographic data (120kV, 50mA, slice thickness 1mm, increment 0.5). The beads were digitally removed from the bone models. Biplane fluoroscopic videos were taken at 69.53.5kV, 102.522.5mA, 500frames/s and 0.5ms shutter speed. The 5 specimens were moved in the trial field of the biplane fluoroscopic setup in a step-like motion (simulation of landing, main stance phase, lift-off). Marker-based registration, Autoscoping and Scientific Rotoscoping were carried out. For statistical analysis agreement was computed as percentiles, mean and s.d. ResultsThe medians of Scientific Rotoscoping ranged from 0.16 to 0.66mm in translations and 0.43 to 2.78 degrees in rotations, while values for Autoscoping were 0.13-0.70mm and 0.28-2.39 degrees respectively. With 2 exceptions, all differences between methods were statistically significant. Scientific Rotoscoping is more time efficient than Autoscoping and results in smaller maximum errors. Main limitationsThe experimental set-up was specifically designed to accommodate invivo requirements. Autoscoping was not manually corrected but rather expected to work automatically. ConclusionsIt is possible to noninvasively apply both Autoscoping and Scientific Rotoscoping for gait analysis of the equine phalanges with high precision. The summary is available in Chinese - see supporting information.
