A novel internal fixation system for sacral fractures: a finite element biomechanical study

Area of Science:

• Orthopedic surgery
• Biomechanical engineering
• Trauma management

Background:

• Sacroiliac joint screw (SIJS) fixation is standard for posterior pelvic ring injuries but poses risks like neurovascular damage and has a steep learning curve.
• Denis zone I sacral fractures require stable fixation to prevent complications.

Purpose of the Study:

• Introduce and evaluate the biomechanical performance of a novel Posterior Internal Fixation (P-INFIX) system.
• Compare P-INFIX to SIJS for treating Denis zone I sacral fractures using finite element analysis.

Main Methods:

• A 3D pelvic model was created from CT data.
• Denis zone I sacral fracture simulated and stabilized with P-INFIX or SIJS.
• Finite element analysis conducted under sitting, supine, and lateral decubitus positions.

Main Results:

• P-INFIX demonstrated fracture stability comparable to SIJS.
• SIJS showed a slight advantage in limiting lateral displacement, but all displacements were clinically insignificant.
• P-INFIX peak stress was higher than SIJS but within safe limits for titanium alloy.

Conclusions:

• The P-INFIX system offers comparable biomechanical stability to SIJS for Denis zone I sacral fractures.
• P-INFIX presents a promising, potentially safer, and more accessible alternative fixation technique.