Improved intra-operative reduction control using a three-dimensional mobile image intensifier - a proximal tibia cadaver study.

This study aimed to analyse whether the precision of a three-dimensional mobile image intensifier (ISO-C 3D) differs from conventional two-dimensional fluoroscopy and high resolution CT scan in a fracture model of the proximal tibia. A depression fracture of the medial plateau (AO/OTA 41-B2.3) was created in 12 formalin-fixed, human cadaver knees. The cartilage of the depression could be positioned above (+1mm, +2mm), below (-1mm, -2mm), or in line with the joint surface. Fluoroscopy, computed tomography (CT) scans, and ISO-C 3D scans (four different protocols: 100 images, 66 images, 50 images, and 33 images) were done for each fracture level. Three independent observers assessed each imaging set. The difference between the estimated reduction and the real reduction was used for statistical analysis. Our hypothesis was that no differences in the precision exist between the imaging techniques (p<0.05). The conventional image intensifier group (0.7 mm+/-0.67) showed significantly higher deviations than the CT group (0.3 mm+/-0.43; p<0.001) and significantly higher deviations than all ISO-C 3D groups (0.4-0.5 mm; p<0.001). Of the ISO-C 3D groups, only the scan protocol with the lowest number of images (0.5 mm+/-0.51) showed significantly lower precision than the CT group (p<0.001). It was concluded that the three-dimensional mobile image intensifier showed higher precision in reduction assessment in a fracture model of the tibial plateau compared to fluoroscopy. High resolution CT scans should remain the standard for post-operative assessment of reduction outside the operating theatre.