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The dynamic response of L(2)/L(3) motion segment in cyclic axial compressive loading.
J-L Wang1, M Parnianpour, A Shirazi-Adl
1Department of Orthopaedics, The National Taiwan University Hospital, Taiwan, ROC.
Clinical Biomechanics (Bristol, Avon)
|June 30, 2001
Summary
Repetitive spinal loading alters motion segment mechanics. Cyclic loading decreases stiffness and increases strain in outer anulus fibers, highlighting changes in load sharing within the spine.
Area of Science:
- Biomechanics
- Spinal Mechanics
- Finite Element Analysis
Background:
- Repetitive spinal loading is a risk factor for low back disorders.
- Quantitative understanding of spinal injury mechanisms and internal load sharing is limited.
Purpose of the Study:
- Investigate the dynamic response and load sharing of passive elements in the L2-L3 motion segment.
- Analyze stress and strain distribution during axial compressive cyclic loading.
Main Methods:
- Utilized a validated viscoelastic nonlinear finite element model of the L2-L3 motion segment.
- Applied cyclic axial compressive loading (600-1000 N at 0.5 Hz for 15 cycles).
- Quantified stress, strain, and strain energy density of various spinal elements.
Main Results:
- Decreased axial stiffness of the motion segment observed.
- Increased intradiscal pressure and strain in outermost anulus fibers.
- Reduced axial stresses in outer anulus lamellae, with increased strain at the endplate.
Conclusions:
- Load sharing among passive spinal elements changes with cyclic loading.
- Spinal response to axial load is history-dependent.
- Loss of disc height and increased disc bulge elevate strain in outer anulus fibers, indicating potential failure risk.