Biomechanical Comparison of Nucleotomy with Lumbar Spine Fusion versus Nucleotomy Alone: Vibration Analysis of the Adjacent Spinal Segments

This study aimed to investigate the effect of transforaminal lumbar interbody fusion (TLIF) with bilateral pedicle screw fixation (BPSF) on dynamic responses of the adjacent spinal segments to whole body vibration (WBV) after nucleotomy. A previously validated finite element model of an intact L1-sacrum lumbar spine was modified to simulate nucleotomy with and without TLIF and BPSF at L4–L5. Transit dynamic analyses were conducted on the nucleotomy alone and the fusion models under a vertical vibration load. The computed dynamic responses for the two models at adjacent levels were recorded and compared. The results showed that at level (L5–S1) below the denucleated disc, maximum response values of the disc bulge, annulus stress and intradiscal pressure decreased due to the fusion by 5.6%, 5.2% and 7.2%, and their vibration amplitudes decreased by 30.5%, 25.7% and 24.3%. At levels (L1–L2, L2–L3 and L3–L4) above the denucleated disc, maximum response values and vibration amplitudes of the strains and stresses also produced 5.2–8.9% and 25.9–29.7% deceases due to the fusion. It implies that after nucleotomy, application of the TLIF with BPSF might be helpful to prevent negative effects of the vertical WBV on adjacent disc levels.