Three-dimensionally-navigated cross-cannulated screw fixation for traumatic pubic symphysis diastasis: an anatomical study

Abstract

Objective: The aim of this study was to design and optimize the secure corridor of cross-cannulated screw implantation in pubic symphysis through Orbic 3D (Siemens Medical Solutions, Erlangen, Germany) computerized navigation and to provide an anatomic basis through the study of regional anatomy. Methods: Fifteen embalmed adult cadavers (8 males, 7 females) were used in this study. All pelvic specimens were placed in the supine position on a radiolucent carbon fiber table. The ideal angle of screw placement, appropriate screw diameter, and perfect attachment point were determined by the computerized navigation system. According to the above data, cross-cannulated screws 6.5 mm in diameter were implanted by the guide pins. Based on detailed local dissection, the entry-exit points of double screws were exposed in the pelvis. The distances were measured between the entry-exit points and the major structures. Radiographs and computed tomography (CT) scans of the pelvis were performed to reassess the position of screws. Results: The trajectory of the first screw originated from the trailing edge of the pubic tubercula to the anterior-lower corner of the contralateral pubic tubercula. The second screw was directed from the base of the pubic tubercula to the junctional zone between the pubic tubercula and inferior ramus of the pubis of the opposite side of the body. Both screws maintained a safe distance from the surrounding major structures. All screw corridors were found intact without any damage under X-ray and CT images. Conclusion: The Orbic 3D computer navigation system is a reliable and new method of achieving a secure corridor for screw implantation in the pubic symphysis.