• Kees-Jan Ponsen, Pieter Joosse, Gilbert A Hoek Van Dijke, and Chris J Snijders.
• Trauma Unit, Department of Surgery, Academic Medical Centre, University of Amsterdam, Amsterdam. K.J.Ponsen@amc.uva.nl
• Acta Orthop. 2007 Oct 1; 78 (5): 648-53.

BackgroundThe mechanical properties of current external fixator systems for unstable (type C) pelvic ring fractures are inferior to internal fixation, and are not optimal for definitive treatment. We explored methods to increase stability of external fixator constructs.MethodsAn experimental model was used for load tests. The same pelvic fixator was used while different pin diameters, pin positions, and modes of pubic symphysis fixation were tested.ResultsChanging of the pin diameter of the unthreaded part from 6 to 8 mm resulted in an increase in stiffness of 20%. An increase in stiffness by a factor of 1.9 was found by placing a pin on the iliac crest and one supra-acetabular. An additional increase by a factor of 3.6 was obtained by adding pubic symphysis plate fixation. Parasymphyseal pin fixation instead reduced stiffness, but not so much as when parasymphyseal pins were connected to the external fixator of the pelvic ring. The final configuration was at least 6 times stiffer than the initial configuration.InterpretationThe new concept of parasymphyseal pin fixation connected to an external fixator of the pelvic ring produces a considerable increase in stability for the treatment of type C pelvic ring injuries, as does an increase in pin diameter and alternative pin positioning.

13 keywords...

hide…