Effect of Elastic Modulus on Biomechanical Properties of Lumbar Interbody Fusion Cage

This work focuses on the influence of elastic modulus on biomechanical properties of lumbar interbody fusion cages by selecting two titanium alloys with different elastic modulus. They were made by a new β type alloy with chemical composition of Ti-24Nb-4Zr-7.6Sn having low Young0s modulus ~50 GPa and by a conventional biomedical alloy Ti-6Al-4V having Young0s modulus »110 GPa. The results showed that the designed cages with low modulus (LMC) and high modulus (HMC) can keep identical compression load ~9.8 kN and endure fatigue cycles higher than 5×10⁶ without functional or mechanical failure under 2.0 kN axial compression. The anti-subsidence ability of both group cages were examined by axial compression of thoracic spine specimens (T₉~T₁₀) dissected freshly from the calf with averaged age of 6 months. The results showed that the LMC has better anti-subsidence ability than the HMC (p<0.05). The above results suggest that the cage with low elastic modulus has great potential for clinical applications.