• Xiaolong Shui, Xiaozhou Ying, Jianzhong Kong, Yongzeng Feng, Wei Hu, Xiaoshan Guo, and Gang Wang.
• Department of Orthopaedic Surgery, The Second Affiliated Hospital of Wenzhou Medical University, 109 Xue yuan xi Road, Wenzhou, 325000, China.
• Arch Orthop Trauma Surg. 2015 Aug 1;135(8):1093-9.

PurposesOur objective was to measure the sagittal plane rotational (flexion and extension) displacement of hemipelvis radiologically and analyze the ratio of flexion and extension displacement of unstable pelvic fractures.MethodsWe used 8 cadaveric models to study the radiographic evidence of pelvic fractures in the sagittal plane. We performed pelvic osteotomy on 8 cadavers to simulate anterior and posterior pelvic ring injury. Radiological data were measured in the flexion and extension group under different angles (5°, 10°, 15°, 20°, and 25°). We retrospectively reviewed 164 patients who were diagnosed with a unilateral fracture of the pelvis. Pelvic ring displacement was identified and recorded radiographically in cadaveric models.ResultsThe flexion and extension displacement of pelvic fractures was measured in terms of the vertical distance of fracture from the top of iliac crest to the pubic tubercle (CD) or from the top of iliac crest to the lowest point of ischial tuberosity (AB). Fifty-seven pelves showed flexion displacement and 15 showed extension displacement. Closed reduction including internal fixation and external fixation was successfully used in 141 cases (86.0 %). The success rates of closed reduction in flexion and extension displacement groups were 77 and 73 %, respectively, which were lower than in unstable pelvic ring fractures.ConclusionsThe sagittal plane rotation (flexion and extension) displacement of pelvic fractures could be measured by special points and lines on the radiographs. Minimally invasive reduction should be based on clearly identified differences between the sagittal plane rotation and the vertical displacement of pelvic fractures.

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