Optimum design of an interbody implant for lumbar spine fixation

A new minimally invasive surgical technique for lumbar spine fixation is currently in development. The procedure makes use of an interbody implant that is inserted between two vertebral bodies. The implant is packed with bone graft material that fuses the motion segment. The implant must be capable of retaining bone graft material and supporting spinal loads while fusion occurs. The different load conditions analyzed include: compression, flexion, extension, and lateral bending. The goal of this research is to obtain an optimum design of this interbody implant. Finite element-based optimization techniques are used to drive the design. The multiobjective optimization process is performed in two stages: topology optimization followed by shape optimization. As a result, the final design maximizes the volume allocated for the bone graft material and maintains von Mises stress levels in the implant below the stress limit. The finite element-based optimization software GENESIS is used in the design process. (c) 2005 Elsevier Ltd. All rights reserved.