BACKGROUND: The biomechanical mechanism of spinal three-column after interspinous process fusion remains unclear. The goal of this study is to assess the biomechanics and clinical effects of facet joint plus interspinous process graft fusion on preventing postoperative correction loss in thoracolumbar fractures with disc damage treated with posterior approach. METHODS: By simulating internal fixation device removal postoperatively, two surgical finite element models of the L1-L2 segments for facet joint plus interspinous process fusion (treatment group model) and single-level facet joint fusion (control group model) were established and compression, flexion and extension were modeled on the basis of spinal three-column theory. The radiologic follow-up of a small prospective randomized controlled trial for the treatment group and control group was done to detect the clinical effects of these two surgical models. RESULTS: The disc compressive displacement and strain of the treatment group model were significantly reduced as compared to those of the control group model, the stress level on facet joint bone graft was also decreased. The posterior tension band of the treatment model was stronger and more stable than that of the control model. Accordingly, clinical trial results at postoperative late stage of the treatment group were significantly better than those of the control group, which had statistically significant difference (P<0.05). INTERPRETATION: Facet joint plus interspinous process fusion is able to model the three-dimensional spinal stability more effectively than single-level facet joint fusion and is superior in bony fusion to prevent postoperative late correction loss in thoracolumbar fracture surgery.
BACKGROUND: The biomechanical mechanism of spinal three-column after interspinous process fusion remains unclear. The goal of this study is to assess the biomechanics and clinical effects of facet joint plus interspinous process graft fusion on preventing postoperative correction loss in thoracolumbar fractures with disc damage treated with posterior approach. METHODS: By simulating internal fixation device removal postoperatively, two surgical finite element models of the L1-L2 segments for facet joint plus interspinous process fusion (treatment group model) and single-level facet joint fusion (control group model) were established and compression, flexion and extension were modeled on the basis of spinal three-column theory. The radiologic follow-up of a small prospective randomized controlled trial for the treatment group and control group was done to detect the clinical effects of these two surgical models. RESULTS: The disc compressive displacement and strain of the treatment group model were significantly reduced as compared to those of the control group model, the stress level on facet joint bone graft was also decreased. The posterior tension band of the treatment model was stronger and more stable than that of the control model. Accordingly, clinical trial results at postoperative late stage of the treatment group were significantly better than those of the control group, which had statistically significant difference (P<0.05). INTERPRETATION: Facet joint plus interspinous process fusion is able to model the three-dimensional spinal stability more effectively than single-level facet joint fusion and is superior in bony fusion to prevent postoperative late correction loss in thoracolumbar fracture surgery.