Tsuang FY, et al. - Five finite element models were created for analysis in order to investigate the biomechanical features of a single fusion model (posterior lumbar interbody fusion with internal fixation) with various lordosis angles prior to and following removal of the internal fixation device. In the non-lordotic intervertebral cage at the L4-L5 (FUS-f-0c) model, the range of motion (ROM) of adjacent segments was discovered to be greater than in the lordotic intervertebral cage at the L4-L5 model. Following removing the fixator, the adjacent segments in the lumbar spine following removal of the spinal fixator and FUS-f-0c model models had a ROM that was comparable to the intact spine under all loading conditions. Eliminating the fixator also decreased the contact forces on adjacent facet joints and diminished the peak stresses on the discs at adjacent levels. In the FUS-f-0c model (at both L2/L3 and L3/L4), the greatest rise in stress on the discs was discovered, with intervertebral stress at L3/L4 rising by 83% when put in the flexion. Hence, this study showed how removing the spinal fixation construct following bone fusion could decrease intradiscal pressure and facet contact forces at adjacent segments while maintaining a proper level of lumbar lordosis.