Abstract
Aim: Investigate the influence of end-plate preparation in a model of corporectomy to evaluate the best biomechanical configuration.
Methods: A non-linear 3D finite element model of a lumbar spine L3–L5 was used as a physiologic model (Noailly, 2003). The model was modified with the insertion of a transpedicular instrumentation (Surgival SA, Spain) and the removal of the L4 vertebral body and two adjacent discs. A femur allograft was inserted anteriorly. Four configurations were investigated: with allograft supported on the entire end-plate, with allograft supported on the half of cartilage endplate thickness, with allograft supported on the subcondral cortical shell and, finally, with allograft supported on the trabecular bone. Four types of loadings were applied: compression (1000N), flexion, extension, and rotation (15Nm). Strain and stresses were calculated in large displacement (MARC, MSC Software).
Results: Results indicate that the preparation of the end-plates has a minor influence on the strain and stresses within the adjacent vertebrae when rigid transpedicular instrumentation was placed. The use of a fixator to create fusion of the two vertebras makes the lumbar spine much stiffer. The resection of the cartilage and support the allograft in the cortical shell changes most the maximal principal strains in the remaining end-plate, and creates a peak stress in the contact area. On the other hand, complete resection of cartilage and subcondral cortical end-plate is the configuration that changes least the maximal principal strains within the adjacent vertebrae.
Conclusion: Preservation of the cortical end-plate may not offer a significant biomechanical advantage in reconstructing the anterior column when rigid transpedicular instrumentation was used.
Theses abstracts were prepared by Professor Roger Lemaire. Correspondence should be addressed to EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
