2.3. Clinical Handling Test
fracture
Eleven patients undergoing plate fixation osteosynthesis with PHILOS were enrolled in a focused registry at a single medical center (UZ Leuven, Leuven, Belgium). The clinical trial was approved by the local ethical committee and the Federal Agency for Medicines and Health Products Belgium (FAMHP, AFMPS/SE/80M0661) and was registered at clinicaltrials.gov (NCT03427112). Informed consent was obtained from all participants before surgery. The standard surgical protocol was maintained, except for attaching an Xin1 marker clip after plate prepositioning. The marker clip was manufactured from medical-grade stainless steel and PEEK (Polyetheretherketon) and was designed for reuse in a standard hospital surgical instruments workflow including autoclaving and cleaning. Intraoperative X-rays from two stages, before and after screw placement, were stored in a DICOM (Digital Imaging and Communications in Medicine) format and were retrospectively evaluated with the Xin1 software. No system feedback was provided to the surgeon during operation. Placed screw lengths during surgery were noted for all operations.Image pairs from both stages were formed from the available X-rays and processed with the Xin1 software. An image pair was found valid if the view angle between the images exceeded 15°. So that several valid pairs could be formed, the pair with the largest view angle was selected. Screw lengths and plate positions were computed from the selected pairs for both stages. The plate position is calculated in relation to the anatomy, defined as the offset of the calculated center of the humeral head from the central screw trajectory (screw 7, D-Level) in cranial–caudal and dorsal–ventral directions (To investigate the effect of potential head displacement during screw insertion in a real fracture situation, the differences in screw length before and after fixing the plate with screws (Statistically, correlation analysis was performed on the computed screw lengths before screw insertion and the actually placed screw lengths by pooling the patients and calculating Pearson’s correlation coefficient R. 