Effect of Off-Axis Fluoroscopy Imaging on Two-Dimensional Kinematics in the Lumbar Spine: A Dynamic In Vitro...

Area of Science:

• Biomechanics
• Medical Imaging
• Spine Surgery

Background:

• Spine intersegmental motion analysis aids in biomechanical classification of low back pain (LBP).
• Two-dimensional (2D) fluoroscopy offers a cost-effective tool for evaluating spinal motion.
• Validation of 2D fluoroscopy for quantifying lumbar intervertebral motion is essential.

Purpose of the Study:

• To compare 2D fluoroscopic and optoelectronic measures of intervertebral rotations during dynamic lumbar spine flexion-extension in vitro.
• To evaluate the impact of C-arm rotation (simulating off-axis patient alignment) on intervertebral kinematics measured by fluoroscopy.

Main Methods:

• Six cadaveric lumbar-sacrum specimens were used.
• Active marker optoelectronic sensors and 2D fluoroscopy were employed simultaneously.
• Image receptor rotation simulated off-axis alignment, with quantitative motion analysis software used to determine intersegmental rotations.

Main Results:

• Mean absolute differences between optoelectronic and fluoroscopic rotation measures were under 0.5 degrees.
• No significant differences (P > 0.05) in rotation measures were found at various off-axis fluoroscopic angles.
• Small spine misalignments did not increase measurement variation compared to perfect alignment.

Conclusions:

• 2D fluoroscopic measurement of lumbar spine intersegmental rotation during flexion-extension is robust.
• The technique is reliable even with imperfect patient alignment, supporting its clinical application for LBP assessment.