The Effect of Sacroiliac Fusion and Pelvic Fixation on Rod Strain in Thoracolumbar Fusion Constructs: A Biomechanical Investigation

Study Design.

In vitro biomechanical study.

Objective.

Investigate effects of sacroiliac joint (SIJ) fusion and iliac fixation on distal rod strain in thoracolumbar fusions.

Summary of Background Data.

Instrument failure is a multifactorial, challenging problem frequently encountered by spinal surgeons. Increased rod strain may lead to instrumentation failure and rod fracture.

Methods.

Seven fresh frozen human cadaveric specimens (T9–pelvis) used. Six operative constructs tested to investigate changes in rod strain at L5–S1 and S1–Ilium rods, posterior pedicle screws/rods from T10–S1 (PS), PS + bilateral iliac screw fixation, PS + unilateral iliac screw fixation (UIS), PS+UIS+3 unilateral SIJ screws, PS + 3 unilateral SIJ screws, and PS +6 bilateral SIJ screws. Uniaxial strain gauges were used to measure surface strain of rods during flexion-extension.

Results.

In flexion-extension, bilateral iliac screws added significant strain to L5–S1 compared with long fusion constructs ending at S1 (PS) (P 

Source: Spine - July 7, 2021 Category: Orthopaedics Tags: BIOMECHANICS Source Type: research