Biomechanical Analysis for Enhanced Expulsion-Proof Intervertebral Fusion Device

This study aimed to compare the sinking and shifting characteristics of an enhanced expulsion-proof intervertebral fusion device (EEIFD) with a traditional transforaminal lumbar interbody fusion device (TTLIFD). Five specimens of each device were selected for analysis. Four mechanical tests-compression, subsidence, expulsion, and torque-were conducted for each cage. Additionally, a blade-cutting torque test was performed on the EEIFD, with load-displacement curves and mechanical values recorded. In static axial compression, static subsidence, and dynamic subsidence tests, the EEIFD demonstrated performance comparable to the TTLIFD. In expulsion testing, the maximum expulsion force for the EEIFD when the blade was rotated out (534.02 ± 21.24 N) was significantly higher than when the blade was not rotated out (476.97 ± 24.45 N) (P = 6.81 × 10-4). Moreover, the maximum expulsion force for the EEIFD with blade rotation (534.02 ± 21.24 N) was significantly higher than that of the TTLIFD (444.01 ± 12.42 N) (P = 9.82 × 10-5). These findings indicated that the EEIFD effectively enhanced expulsion prevention and antisubsidence performance.