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DETC 2003 - Design of an Interbody Fusion Implant 1/23
Optimum Topology and Shape Design of an Interbody Fusion Implant for Lumbar Spine Fixation
Andrés Tovar, Shawn E. Gano, John E. Renaud and James J. Mason
University of Notre DameDepartment of Aerospace and Mechanical Engineering
29th Design Automation Conference – International 2003 DETC September 2-6, 2003 – Chicago, IL
DETC 2003 - Design of an Interbody Fusion Implant 2/23
Content
• Lumbar Spine Fixation
• Topology Optimization
• Shape Optimization
• Results and Conclusions
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The Spinal Column
[http://www.spineuniverse.com]
DETC 2003 - Design of an Interbody Fusion Implant 4/23
Disc Problems
[http://www.spineuniverse.com]
DETC 2003 - Design of an Interbody Fusion Implant 5/23
PLIF – Posterior Lumbar Interbody Fusion
Fusion with spinal instrumentation
[Virginia Spine Institute]
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ALIF – Anterior Lumbar Interbody Fusion
[http://www.spineuniverse.com]
Interbody cage fusion
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New fusion procedure
ImplantBone Graft
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Design procedure
•Topology optimization
•Shape optimization
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Topology optimization
ImplantBone Graft
2064 design variables
[FEBM / GENESIS]
Design Domain
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Vertebra model
Cortical boneCancellous bone
Cartilage
Design domain
[Goel and Weinstein, 2000]
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Load conditions
[Rohlmann et al, 2001]
• Flexion 15.0 Nm• Extension 5.0 Nm• Lateral bending 7.5 Nm• Compressive preload 400 N
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Lateral bending
+
+
Left & rightlateral bending
7.5 Nm
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Flexion and extension
+
+
Flexion15.0 Nm
Extension5.0 Nm
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The topology optimization problem
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The topology optimization problem
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Optimum topologies
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Spline approximation
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Domains and perturbation vectors
18 domains 18 design variables
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The shape optimization problem
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Shape optimization
Flexion
Extension
Left lateral bending
Right lateral bending
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Shape optimization
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Results
Stress analysis Designs
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Summary and Conclusions
• An optimum geometry for a new interbody fusion implant is obtained using topology and shape optimization.
• The topology optimization minimizes strain energy subject to a mass fraction constraint.
• The shape optimization minimizes mass subject to a maximum von Mises stress constraint (maximizes volume available for bone graft material).
• A total volume fraction of 66% is available for the bone graft.
Thank you
DETC 2003 - Design of an Interbody Fusion Implant 25/23
Shape optimization
Flexion Extension Lateral bending
