A computer aided measurement method for unstable pelvic fractures based on standardized radiographsReport as inadecuate

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BMC Medical Imaging

, 15:41

First Online: 30 September 2015Received: 23 May 2015Accepted: 21 September 2015


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.

KeywordsUnstable pelvic fractures Radiographic assessment Software-based measurement Reliability study AbbreviationsAPAnterior-posterior



ICCIntraclass correlation coefficient



ASISAnterior superior iliac spine

Jing-xin Zhao and Zhe Zhao contributed equally to this work.

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Author: Jing-xin Zhao - Zhe Zhao - Li-cheng Zhang - Xiu-yun Su - Hai-long Du - Li-ning Zhang - Li-hai Zhang - Pei-fu Tang

Source: https://link.springer.com/


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