RT Journal Article SR Electronic T1 Relative position of the supra-acetabular bone to the crestal plane: a radiological analysis JF BMJ Military Health JO BMJ Mil Health FD British Medical Journal Publishing Group SP 89 OP 92 DO 10.1136/jramc-2019-001251 VO 167 IS 2 A1 George Dehn A1 N Hammer A1 M C Wyatt A1 S J Soltani A1 D C Kieser YR 2021 UL http://militaryhealth.bmj.com/content/167/2/89.abstract AB Introduction Displaced unstable pelvic injuries are life threatening and require rapid reduction and stabilisation, typically achieved with an external fixator. Recently, the benefits of supra-acetabular pins have been proven; however, these are usually inserted under fluoroscopic guidance. In austere environments and in extremis, this facility is limited and fixation using anatomical landmarks is required. Thus, the aim of this study is to determine the relative position of the supra-acetabular bone to the crestal plane and examine its consistency in military-aged European personnel.Methods A radiological review of 50 randomised pelvic CT scans in European patients aged 18–30 years from a Level 1 trauma centre was performed. The CT scans were analysed using 3D rendering software. The relative position of the supra-acetabular bone to the crestal plane was determined.Results The supra-acetabular bone relative to the crestal plane was approximately 28° caudal and 24° medial to the crestal plane. The mean minimum distance from the pin’s entry point to the sciatic notch was approximately 73 mm. There were no differences noted between genders or hemipelvic side.Conclusions The supra-acetabular bone maintains a consistent relative position to the crestal plane. Thus, with the surgeon’s thumb on the anterior superior iliac spine (ASIS) and index finger on the iliac tubercle, defining the crestal plane, a supra-acetabular pin can be inserted into the anterior inferior iliac spine, which lies 3 cm inferior and 2 cm medial to the ASIS, and advanced along the supra-acetabular bone by angling the pin 30° caudal and 25° medial to the crestal plane.