Biomechanical Comparison of the Luque-Galveston and Colorado II Methods for Sacropelvic Fixation

· (a – Medtronic Sofamor Danek)

This study compared the new Colorado II method of sacropelvic fixation (plate + 1 iliac and 2 sacral screws) to the standard Galveston method. Eight human cadavers were dissected from L1 to the sacrum leaving the discs and both longitudinal ligaments intact. 18 gauge sub-laminar wires were passed at L2, L3, L4 and L5 and secured to 5.5mm lordotic rods. The proximal spine was attached via a cantilever apparatus for bending moments or an axially aligned fixture for torsional testing (MTS 858 machine). Sequential testing of Galveston and Colorado II systems was performed with torsion at 1º per second between + 2Nm and flexion/extension for 20 cycles between + 5Nm. Data for construct stiffness was analyzed using a one-way ANOVA (p<0.05). Although the Coloraodo II method does not provide a continuous connection of the rod to the ilium, the initial construct stability in flexion-extension and torsional loading appears similar to the Galveston method. The multiple points of fixation of the Colorado II construct may protect against rod pullout in the osteoporotic bone of neuromuscular spinal deformity patients.

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