Construct Rigidity after Fatigue Loading in Pedicle Subtraction Osteotomy with or without Adjacent Interbody...

Area of Science:

• Spine surgery
• Orthopedic biomechanics
• Spinal fusion techniques

Background:

• Rod fracture is a concern in pedicle subtraction osteotomy (PSO) when adjacent disc spaces are preserved.
• The biomechanical impact of interbody support on PSO constructs requires further investigation.

Purpose of the Study:

• To compare the multidirectional bending rigidity and fatigue life of PSO segments with and without interbody support.
• To evaluate the stabilizing effect of interbody cages in PSO procedures.

Main Methods:

• Twelve spinal specimens underwent posterior fixation and L3 PSO.
• Six specimens received additional extreme lateral interbody fusion (XLIF) cages (L2-L3, L3-L4); six did not.
• Multidirectional bending and fatigue testing were performed to measure motion and stiffness.

Main Results:

• The addition of XLIF cages significantly reduced axial rotation (AR) range of motion across the L2-L4 segment by 25.7%.
• The PSO + XLIF group showed a trend towards greater dynamic stiffness (22.2% increase) during fatigue testing compared to PSO alone.

Conclusions:

• Interbody cage placement in PSO settings offers a potential acute stabilizing effect.
• A staged approach with cage insertion may be clinically beneficial, warranting further investigation.