Abstract
BackgroundTo set up a method for measuring radiographic displacement of unstable pelvic ring fractures based on standardized X-ray images and then test its reliability and validity using a software-based measurement technique.MethodsTwenty-five patients that were diagnosed as AO/OTA type B or C pelvic fractures with unilateral pelvis fractured and dislocated were eligible for inclusion by a review of medical records in our clinical centre. Based on the input pelvic preoperative CT data, the standardized X-ray images, including inlet, outlet, and anterior-posterior (AP) radiographs, were simulated using Armira software (Visage Imaging GmbH, Berlin, Germany). After representative anatomic landmarks were marked on the standardized X-ray images, the 2-dimensional (2D) coordinates of these points could be revealed in Digimizer software (Model: Mitutoyo Corp., Tokyo, Japan). Subsequently, we developed a formula that indicated the translational and rotational displacement patterns of the injured hemipelvis. Five separate observers calculated the displacement outcomes using the established formula and determined the rotational patterns using a 3D-CT model based on their overall impression. We performed 3D reconstruction of all the fractured pelvises using Mimics (Materialise, Haasrode, Belgium) and determined the translational and rotational displacement using 3-matic suite. The interobserver reliability of the new method was assessed by comparing the continuous measure and categorical outcomes using intraclass correlation coefficient (ICC) and kappa statistic, respectively.ResultThe interobserver reliability of the new method for translational and rotational measurement was high, with both ICCs above 0.9. Rotational outcome assessed by the new method was the same as that concluded by 3-matic software. The agreement for rotational outcome among orthopaedic surgeons based on overall impression was poor (kappa statistic, 0.250 to 0.426). Compared with the 3D reconstruction outcome, the interobserver reliability of the formula method for translational and rotational measures was perfect with both ICCs more than 0.9.ConclusionsThe new method for measuring displacement using a formula was reliable, and could minimise the measurement errors and maximise the precision of pelvic fracture description. Furthermore, this study was useful for standardising the operative plan and establishing a theoretical basis for robot-assisted pelvic fracture surgery based on 2-D radiographs.
Highlights
To set up a method for measuring radiographic displacement of unstable pelvic ring fractures based on standardized X-ray images and test its reliability and validity using a software-based measurement technique
This study was useful for standardising the operative plan and establishing a theoretical basis for robot-assisted pelvic fracture surgery based on 2-D radiographs
The most severe injury observed in an orthopaedic trauma centre are disruptions of the pelvic ring, especially unstable pelvic ring fractures, which are characterized as a posterior pelvic ring fracture with the partial or total displacement of unilateral or bilateral pelvis
Summary
To set up a method for measuring radiographic displacement of unstable pelvic ring fractures based on standardized X-ray images and test its reliability and validity using a software-based measurement technique. The fracture displacement is assessed using radiological tools, including roentgenography and CT scans. As radiographic assessment remains the standard for preoperative assessment, the first step of management is rapid and precise measurement and the determination of the displacement of the injured pelvis. CT based measurements method of pelvic displacements was considered as the “gold standard” [1, 2]. Regarding the higher cost and patients’ radiation exposure of CT scan, the imaging examinations based on the radiographs were still the most available and convenient tools in most clinical settings
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