Kinematic Analysis of Lumbar Spine Undergoing Extension and Dynamic Neural Foramina Cross Section Measurement
Yongjie Zhang; Boyle C. Cheng; Changho Oh; Jessica L. Spehar; and James Burgess

Source CMES: Computer Modeling in Engineering & Sciences, Vol. 29, No. 2, pp. 55-62, 2008
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Keywords Kinematic analysis, lumbar spine, interspinous process spacer device, image processing.
Abstract The spinal column plays a vital biomechanical role in the human body by providing structural support and facilitating motion. As degenerative changes occur in the spine, surgical treatment may be necessary in certain instances. Such treatments seek to address pain, frequently through the restriction of spinal motion. Traditional spinal implant devices are designed to restrict the motion of a functional spinal unit (FSU) but newer device designs allow for semi-constrained motion such as spinal arthroplasty devices. In this study, a sequence of fluoroscopic imaging data was recorded during the flexibility protocol with an interspinous process spacer device placed at$L$2-$L$3. We use image processing techniques to characterize the performance of interspinous spacers in addition to standard biomechanical methods of comparison such as range of motion (ROM). A fast marching method and the principal component analysis are developed and utilized for kinematics analysis of lumbar spine undergoing flexion extension bending and dynamic measurement of neural foramina cross section that ideally would be applicable to patient datasets. Flexion extension bending is related to the motion of leaning backward. The implanted level exhibits a major reduction in ROM (approximately 10.4{\%} compared to the intact state in flexion extension bending) but minor change in cross sectional foramina area (about 5.61{\%}). Effectiveness of such devices in extension bending is important from a translational medicine point of view and requires information beyond standard ROM measures alone.
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