Effect of Fatigue Loading on The Static and Dynamic Response of Spinal Column Post Vertebroplasty
Date Issued
2009
Date
2009
Author(s)
Liao, Cheng-Fu
Abstract
Objective: To investigate the effect of fatigue loading on the biomechanical responses of spinal column post vertebroplasty.ummary of Background Data: Fatigue loading is one of the risk factors for vertebral compression fracture. Vertebroplasty is a minimal invasive surgery for spinal compression fracture. It is believed that the fatigue loading is also an important factor for the vertebrale-fracture post vertebroplasty. We hope we can explore the mechanical response of augmented vertebra secondary to the fatigue loading. The results may help to predict or prevent the vertebral refracture.ethods: Ten human thoracic motion segments (T4-T7, T5-T8, T9-T12) were used and set up accelerometer on 1st and 2nd level. Specimens were applied with impulse testing to measure the stiffness and acceleration after fractured, augmented, and fatigue loading. The fatigue loadingsere 650N, 950N, and 1150N at 5Hz for 1, 2, 3, 4, and 5 hours (18,000, 36,000, 54,000, 72,000, and 90,000 cycles), and 12-hours rest was applied between different loadings. The paired-t test was respectively performed to evaluate the variations of stiffness and acceleration after a seriesf fatigue loading. The independent t-test was performed to evaluate the variation of acceleration on 1st and 2nd level.esults: After fractured, the stiffness decreased 13.5% (P = 0.14), and acceleration of level 2 increased 25.8% (P = 0.00). The variations of these properties were recovered after cement injection. After 5-hours fatigue loading, the stiffness increased 26% (P = 0.00) but acceleration ofevel 1 decreased 14% (P = 0.00), and both recovered after 12-hours rest. Under high loading condition, the changing rates of acceleration and stiffness is higher, especially in the first hour.onclusion: Spinal stability was decreased after vertebral compression fracture, and recovered post vertebroplasty. The stiffness increased but acceleration decreased after fatigue loadings, and rest could restore these mechanical properties. The results of numerical model indicated thenternal force of spinal column increased 1.46% after 5-hours fatigue loading. The internal force of spinal column increased rapidly under high loading condition. Therefore, a long-term activity is a risk factor for vertebral refracture.
Subjects
fatigue
impulse test
acceleration
Type
thesis
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