Research Article Biomechanical Comparison of Different External Fixation Configurations for Posttraumatic Pelvic Ring Instability Simon Tiziani, 1 Georg Osterhoff, 1 Stephen J. Ferguson, 2 Gregor Spreiter, 2 Max J. Scheyerer, 1 Gian-Leza Spinas, 1 Guido A. Wanner, 1 Hans-Peter Simmen, 1 and Clément M. L. Werner 1 1 Department of Surgery, Division of Trauma Surgery, University Hospital Zurich, Raemistrasse 100, 8091 Zurich, Switzerland 2 Institute for Biomechanics, ETH Zurich, HCI-E355.2 Wolfgang-Pauli-Strasse 10, 8093 Zurich, Switzerland Correspondence should be addressed to Simon Tiziani; simon.tiziani@uzh.ch Received 10 September 2013; Accepted 13 November 2013; Published 2 February 2014 Academic Editor: J¨ orn Kircher Copyright © 2014 Simon Tiziani et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Background. External ixation is useful in the primary treatment of pelvic ring injuries. he present study compared the biomechanical stability of ive diferent conigurations of an external pelvic ring ixation system. Methods. Five conigurations of an anterior external pelvic ring ixation system were tested using a universal testing machine. One single connecting rod was used in group “SINGLE,” two parallel connecting rods in group “DOUBLE,” two and four rods, respectively, in a tent-like coniguration in groups “SINGLE TENT” and “DOUBLE TENT,” and a rhomboid-like coniguration in group “RHOMBOID.” Each specimen was subjected to a total of 2000 consecutive cyclic loadings at 1 Hz lateral compression/distraction (±50 N) and torque (±0.5 Nm) loading alternating every 200 cycles. Translational and rotational stifness were determined at 100, 300, 500, 700, and 900 cycles. Results. he “SINGLE TENT” and “RHOMBOID” conigurations already failed with a preloading of 50 N compression force. he “DOUBLE” coniguration had around twice the translational stability compared with the “SINGLE” and “DOUBLE TENT” conigurations. Rotational stifness observed for the “DOUBLE” and “DOUBLE TENT” conigurations was about 50% higher compared to the SINGLE coniguration. Conclusion. Using two parallel connecting rods provides the highest translational and rotational stability. 1. Background Although unstable pelvic ring injuries are relatively rare [1], patients sufering from such injuries oten show extensive haemorrhage [2]. Blood loss can occur from osseous struc- tures at the fracture site, venous bleeding from the sacral plexus, or arterial bleeding [3]. Pelvic volume increases with pelvic ring disruption, which further hinders haemostasis. he primary objective in such situations is to reestablish pelvic ring integrity and stability, reducing pelvic volume in the process [3, 4]. Together with pelvic packing and clamping, external pelvic ixation has become an established adjunct for stabilizing unstable fractures and increasing chances of haemostasis [5–10]. External ixation may assist haemostasis in diferent ways, reducing fracture surfaces, ensuring blood clot stability, stopping venous bleeding, and achieving some tamponade by reducing pelvic volume [11, 12], though it has been shown that it may not induce pressure-induced tampon- ade [6]. here are numerous diferent external ixator con- structs with each making diferent conigurations possible. Furthermore there are diferent locations for pin anchoring in the pelvis. A supra-acetabular placement of the external ixa- tor pins has been shown to be superior in stability compared to pins placed in the iliac crest [13, 14]. Continuing stability of the external ixation is crucial in ensuring optimal chance for haemostasis. Patients rarely present with isolated injuries to the pelvis. Concomitant abdominal injuries are frequent, making, for example, further abdominal surgery necessary [15]. his and the fact that some patients are obese, have made it necessary to come up with diferent conigurations of the external ixation construct to it the respective situations. he following conigurations, tested in this study, were in use at Hindawi Publishing Corporation Advances in Orthopedic Surgery Volume 2014, Article ID 360165, 5 pages http://dx.doi.org/10.1155/2014/360165