Three-dimensional Evaluations of Preoperative Planning Reproducibility for Osteosynthesis of Distal Humerus Fractures

Abstract Background: Three-dimensional preoperative planning has been applied to the osteosynthesis of distal humerus fractures. The present study investigated the reproducibility of 3D preoperative planning for the osteosynthesis of distal humerus fractures using 3D parameters. Methods: Twenty-four elbows of 24 distal humerus fracture patients who underwent osteosynthesis with three-dimensional preoperative planning were evaluated. 3D images of the distal humerus were created after taking preoperative CT scans of the injured elbow. Fracture reduction, implant selection, and placement simulations were performed based on 3D images. Postoperative CT images were taken onemonth after surgery. Reproducibility was evaluated with preoperative plans and postoperative 3D images. The longitudinal axis and coordinates of the humerus were defined on 3D images. The coronal angle (CA) was defined as the angle formed by the long axis and the line connecting the medial and lateral margins of the trochlea of the humerus on a coronal plane image. The sagittal angle (SA) was defined as the angle formed by the long axis and the line connecting the top of the lateral epicondyle and the center of the humeral capitellum on a sagittal plane image. The axial angle (AA) was defined as the angle between the sagittal plane and the line connecting the medial and lateral margins behind the trochlea of the humerus. Reproducibility was assessed by the intraclass correlation coefficient (ICC) of each measurement value on preoperative planning and postoperative images. Results: Preoperative planning and postoperative measurement values were CA: 85.5±6.0°/86.0±5.9°, SA: 141.3±8.3°/140.0±7.5°, and AA: 83.5±3.4°/82.5±5.0°, respectively. ICCs were CA: 0.75 (P<0.01), SA: 0.75 (P<0.01), and AA: 0.40 (P<0.05), respectively. Conclusions: The 3D preoperative planning of distal humeral fractures achieved the good reproducibility of coronal and sagittal angles, but the relatively poor reproducibility of the axial angle. This may be attributed to an inability to assess the rotation angle during surgery. We propose the measurement indices shown in the present study as a three-dimensional evaluation index for distal humerus fractures. Trial registration: Registered as NCT04349319 at ClinicalTrials.gov