Effect of titanium cage implantation with different lengths on vertebral fusion in goat model

English Keywords:Titanium cage bone graft  Vertebral fusion  Biomechanics  Goat

English Abstract:

  【Abstract】 Objectives: To study the effect of implantation of different lengths of titanium cage on the bone graft fusion of vertebral body, and to construct the lumbar vertebra resection model by removing the different length of goat vertebra. Methods: A total of 15 goats were randomly divided into 3 groups, 5 goats in each group, an animal model was constructed by means of anterior extraperitoneal approach. According to the length of the resected vertebral body, the goats were divided into group A(removal of 0.5 vertebral body), group B(removal of 1 vertebral body) and group C(removal of 1.5 vertebral bodies). The venous blood samples were taken at fourteenth days to detect the levels of BGP, BALP, BMP-2, TGF-β and VEGF. The goats were sacrificed 4 months after the artificial feeding. The bone healing in different lengths of titanium cage was analyzed by imaging, and the growth of trabecular bone in different length position from the titanium cage and bone contact surface was observed by tissue dying. The deformation and displacement of vertebral body under different motion conditions such as flexion, extension, lateral bending and torsion were detected by mechanical testing instrument. The data provided by three-dimensional CT scanning were used for finite element analysis. Results: At the fourteenth day, the expression levels of BGP, BALP, BMP-2, TGF-β and VEGF in group A(the OD values were 0.271±0.032, 0.522±0.060, 0.306±0.046, 0.314±0.055 and 0.364±0.033) were significantly lower than those in group B(the OD values were 0.657±0.085, 1.360±0.145, 0.775±0.065, 0.767±0.068 and 1.037±0.039) and group C(the OD values were 0.664±0.041, 1.348±0.113, 0.741±0.066, 1.038±0.079和1.280±0.067)(P＜0.05). The CT values in the contact surface of titanium cage and bone trabecular of A, B, C groups were 0.82±0.13, 0.75±0.12 and 0.40±0.06, respectively. However, the distance of bone contact surface was 10mm, CT values decreased to 0.42±0.07, 0.28±0.08, 0.14±0.03, compared with the 0mm point, there were significant differences in three groups(P＜0.05). Imaging results showed that the trabecular bone in titanium cage was less than the trabecular bone in interface, and the longer the titanium cage was, the worse the trabecular growth was. The biomechanical test and finite element analysis showed that the longer the fixed section was, the smaller the mobility was, the worse the deformation resistance was. Histological analysis showed that the farther the distance from titanium cage interface, the worse the bone trabecula growth, and as the titanium cage longer, the growth of bone trabecula in titanium cage became worse, indicating that titanium cage was longer, the bone trabecular density of same length position from titanium cage and bone contact surface was small. Conclusions: The shorter the length of the titanium cage bone, the better the bone growth, the lower the expression of inflammatory factors, the better the vertebral mobility.