Biomechanical analysis of a new minimally invasive system for osteosynthesis of pubis symphysis disruption

Introduction: We analysed the effectiveness of a new percutaneous osteosynthesis system for the treatment of pelvis fractures with rotational instability. Methods: A pre-clinical cross-sectional experimental study wherein Tile type B1 injuries (open-book fractures) were produced in 10 specimens of fresh human cadavers, including the L4-5 vertebrae, pelvic ring, and proximal third of the femur, keeping intact the capsular and ligamentous structures, is presented in this paper. The physiological mobility of the intact pelvis in a standing position post-injury was compared to that following the performance of a minimally invasive osteosynthesis of the symphysis with two cannulated screws. A specially designed test rig capable of applying loads simulating different weights, coupled with a photogrammetry system, was employed to determine the 3D displacements and rotations in three test cases: intact, injured and fixed. Results: After applying an axial load of 300 N, no differences were observed in the average displacement (mm) of the facet joints of the intact pubic symphysis in comparison to those treated with screws (p > 0.7). A statistical difference was observed between the average displacements of the sacroiliac facet joints and pelvises with symphyseal fractures treated with screws after the application of a load (p < 0.05). Conclusion: The symphyseal setting with two crossed screws appears to be an effective alternative to osteosynthesis in pelvic fractures with rotational instability. (C) 2012 Elsevier Ltd. All rights reserved.