The current gold standard surgical intervention for spinal deformity correction and for discogenic axial back pain with or without concomitant radiculopathy is a segmental spinal fusion. Currently, over 250,000 spine fusions are performed yearly in the US. However, current fusion approaches suffer from significant drawbacks including subsidence, stress shielding, and the inability to direct delivery of bone morphogenic protein (BMP) for bone regeneration. We propose to develop degradable polymeric fusion cages that are designed to have sufficient mechanical integrity for withstanding surgical implantation and spinal loads, while at the same time providing directed delivery of BMP for bone fusion. Specifically, we will create and test prototype interbody degradable spinal fusion cages to meet these load bearing and biofactor delivery requirements by computationally optimizing device design for both load carrying and directed permeability requirements, fabricating the cages from degradable polymer using Solid Free-Form Fabrication (SFF) techniques, and testing these in vivo in a Yucatan minipig spine fusion model. We hypothesize that optimizing degradable spine interbody fusion cages to meet both the initial and the intermediate- term load carry as well as directed biofactor delivery requirements will provide superior arthrodesis compared to current degradable cages fabricated from designs previously used for titanium cages. This global design hypothesis will be tested through the following 3 specific aims:
Specific Aim 1 : Computational Optimization of Spinal Fusion Cages.
Specific Aim 2 : Device Fabrication and In Vitro Evaluation.
Specific Aim 3 : Test Fusion Performance in an In Vivo Yucatan minipig Model. The end result will verify if the designed degradable fusion device provides superior fusion results compared to conventional designs, and more broadly, whether the optimization approach could be utilized to improve performance of other skeletal reconstruction devices. ? ? ?
| Kang, Heesuk; Hollister, Scott J; La Marca, Frank et al. (2013) Porous biodegradable lumbar interbody fusion cage design and fabrication using integrated global-local topology optimization with laser sintering. J Biomech Eng 135:101013-8 |
