RESUMEN
BACKGROUND:Anterior cervical discectomy and bone graft fusion are effective method to treat cervical spondylosis. This method can provide firm fixation and the fusion rate is high. However, for cervical vertebra involved in more than two segments, the stability of fixator and bone graft is poor due to big bone graft span, which may easily cause fusion failure and pseudarthrosis, and impact curative effects. OBJECTIVE:To investigate biomechanical stability of anterior cervical pedicle screw implantation for osteoporosis in the vertebra. METHODS:A total of 12 human cervical vertebrae were col ected, including 6 vertebrae with normal bone density and 6 vertebrae with osteoporosis. Data of 60 vertebra specimens were analyzed. 30 osteoporotic specimens implanted in anterior cervical pedicle screw were set as anterior cervical pedicle screw group. 30 normal specimens implanted in anterior cervical pedicle screw were set as anterior vertebral screw group. According to bone density, 40 vertebrae were col ected in above two groups, and were considered as normal bone mineral density group, instant osteoporosis group, fatigue normal bone mineral density group, and fatigue osteoporosis group (n=10). Bone mineral density of each vertebra was detected using dual-energy X-ray absorptiometry. Biomechanical index of two kinds of screws was detected using ElectroForce 3510 material testing machine. RESULTS AND CONCLUSION:Bone mineral content, vertebral screw pul-out strength, vertebral screw pul-out stiffness, pedicle screw pul-out strength, and pedicle screw pul-out stiffness were significantly higher in the anterior cervical pedicle screw group than in the anterior vertebral screw group (P<0.05). The maximum axial pul-out strength of normal bone mineral density group, instant osteoporosis group, fatigue normal bone mineral density group, and fatigue osteoporosis group was significantly higher than in the anterior vertebral screw group (P<0.05). The results confirmed that osteoporotic vertebral biomechanical performance is more stable in anterior pedicle screws compared with the anterior vertebral screw.