Pelvic Ring Fractures: A Biomechanical Comparison of Sacral and Lumbopelvic Fixation Techniques

Sudharshan Tripathi; Norihiro Nishida; Sophia Soehnlen; Amey Kelkar; Yogesh Kumaran; Toshihiro Seki; Takashi Sakai; Vijay K Goel

doi:10.3390/bioengineering11040348

Pelvic Ring Fractures: A Biomechanical Comparison of Sacral and Lumbopelvic Fixation Techniques

Bioengineering (Basel). 2024 Apr 2;11(4):348. doi: 10.3390/bioengineering11040348.

Authors

Sudharshan Tripathi¹, Norihiro Nishida², Sophia Soehnlen¹, Amey Kelkar¹, Yogesh Kumaran¹, Toshihiro Seki², Takashi Sakai², Vijay K Goel¹

Affiliations

¹ Engineering Center for Orthopedic Research (E-CORE), Department of Bioengineering and Orthopaedic Surgery, University of Toledo, Toledo, OH 43606, USA.
² Department of Orthopedic Surgery, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi, Ube 755-8505, Yamaguchi, Yamaguchi Prefecture, Japan.

Abstract

Background context: Pelvic ring fractures are becoming more common in the aging population and can prove to be fatal, having mortality rates between 10% and 16%. Stabilization of these fractures is challenging and often require immediate internal fixation. Therefore, it is necessary to have a biomechanical understanding of the different fixation techniques for pelvic ring fractures.

Methods: A previously validated three-dimensional finite element model of the lumbar spine, pelvis, and femur was used for this study. A unilateral pelvic ring fracture was simulated by resecting the left side of the sacrum and pelvis. Five different fixation techniques were used to stabilize the fracture. A compressive follower load and pure moment was applied to compare different biomechanical parameters including range of motion (contralateral sacroiliac joint, L1-S1 segment, L5-S1 segment), and stresses (L5-S1 nucleus stresses, instrument stresses) between different fixation techniques.

Results: Trans-iliac-trans-sacral screw fixation at S1 and S2 showed the highest stabilization for horizontal and vertical displacement at the sacral fracture site and reduction of contralateral sacroiliac joint for bending and flexion range of motion by 165% and 121%, respectively. DTSF (Double transiliac rod and screw fixation) model showed highest stabilization in horizontal displacement at the pubic rami fracture site, while the L5_PF_W_CC (L5-Ilium posterior screw fixation with cross connectors) and L5_PF_WO_CC (L5-Ilium posterior screw fixation without cross connectors) showed higher rod stresses, reduced L1-S1 (approximately 28%), and L5-S1 (approximately 90%) range of motion.

Conclusions: Longer sacral screw fixations were superior in stabilizing sacral and contralateral sacroiliac joint range of motion. Lumbopelvic fixations displayed a higher degree of stabilization in the horizontal displacement compared to vertical displacement of pubic rami fracture, while also indicating the highest rod stresses. When determining the surgical approach for pelvic ring fractures, patient-specific factors should be accounted for to weigh the advantages and disadvantages for each technique.

Keywords: finite element analysis; fixation techniques; fracture displacement; pelvic ring fractures; sacroiliac joint.

Grants and funding

The research was supported in part by NSF Industry/University Cooperative Research Center at The University of California at San Francisco, CA, The Ohio State University, Columbus, Ohio, The University of Toledo, Toledo, OH (www.nsfcdmi.org). Award number: 206965.