Detection of articular perforations of the proximal humerus fracture using a mobile 3D image intensifier - a cadaver study.

Background: The purpose of this study was to investigate the accuracy of perforation detection with multiplanar reconstructions using a mobile 3D image intensifier.

Methods: In 12 paired human humeri, K-wires perforating the subchondral bone and placed just below the cartilage level were directed toward five specific regions in the humeral head. Image acquisition was initiated by a fluoroscopy scan. Within a range of 90°, 45° external rotation (ER) and 45° internal rotation (IR). The number and percentage of detected perforating screws were grouped and analyzed. Furthermore, the fluoroscopic images were converted into multiplanar CT-like reconstructions. Each K-wire perforation was characterized as "detected" or "not detected".

Results: In the series of fluoroscopy images in the standard neutral position at 30° internal rotation, and 30° external rotation, the perforations of all K-wires (n = 56) were detected. Twenty-nine (51.8%) of them were detected in one AP view, 22 (39.3%) in two AP views, and five (8.9%) in three AP views. All K-wire perforations (100%, n = 56) were detected in multiplanar reconstructions.

Conclusion: In order to reveal all of the intraoperative and postoperative screw perforations in a "five screw configuration", conventional AP images should be established in both the neutral positions (0°), at 30° internal rotation and 30° external rotation. Alternatively, the intraoperative 3D scan with multiplanar reconstructions enables a 100% rate of detection of the screw perforations.