Topology Optimization Of Spinal Interbody Cage For Reducing Stress Shielding Effect
| dc.contributor.author | Chuah, Hun Guan | |
| dc.date.accessioned | 2016-10-17T06:30:50Z | |
| dc.date.available | 2016-10-17T06:30:50Z | |
| dc.date.issued | 2009-04 | |
| dc.description.abstract | Intervertebral disc degeneration or damage resulting from acute and chronic spinal injury induces the spine structure instability. The spinal structure instability can be resolved by surgical treatment, spinal fusion where the defected disc column is inserted with spinal cage implant to provoke the bony growth and thus, form the bridging vertebrae. Subsequently, the adjacent vertebrae fused configuration successfully stabilizes the structure of functional spine unit. The bony growth progress is strongly base on the stress magnitude formed on the bone. Therefore, the partial load retained by the implant should be minimized and thus reduces the stress shielding effect to bone. By manipulating the composite theory, the factor of volume and Young Modulus of implant were encountered have influence to the stress shielding effect to the bone. For investigating the influence of the factors to stress shielding effect, a half two identical vertebrae segment model instrumented with a block shaped implant was developed. By reducing the implant volume, the stress of the superior and inferior vertebrae increased corresponding to the reducing segment stiffuess under 301 MPa compression force. In contrast, the change of material (Young Modulus) produced the similar stress shielding effect. A L4-L5 intact segment was developed and validated by comparing to the published result (Shirazi, 1994, Panjabi, 1977). The validated segment was instrumented with a pair of cage implant and it was imposed with five pairs of spinal muscles force. The topology optimization method was employed to optimize the cage for reducing the stress shielding effect. The optimization objective was to maximize the implant stiffuess while constraining the volume reduction from 30% to 80% from the initial implant volume. The new design base on 70% volume reduction solution has reduced the stress shielding effect by generating . minimum 17.10%, 18.11% and 18.43% higher stress value in vertebrae body compared to Saber cage model in flexion-extension, lateral bending and axial rotation respectively. Three identical geometry new designs with PEEK, Titanium and cortical materials produced the similar stress magnitude in vertebrae in three phases of trunk movements even the Young Modulus of Titanium (1l0000 MPa) is larger than PEEK (20000 MPa) and cortical (17000 MPa). The optimized design with less volume compared with initial design showed the potential to reduce the stress shielding effect | en_US |
| dc.identifier.uri | http://hdl.handle.net/123456789/2754 | |
| dc.subject | The spinal structure instability | en_US |
| dc.subject | can be resolved by surgical treatment | en_US |
| dc.title | Topology Optimization Of Spinal Interbody Cage For Reducing Stress Shielding Effect | en_US |
| dc.type | Thesis | en_US |
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