Depth of pedicle screw into the vertebral body and its stability：a biomechanical analysis
10.3969/j.issn.2095-4344.2016.09.011
- VernacularTitle:椎弓根螺钉置入椎体深度与其稳定性的生物力学分析
- Author:
Wei DU
;
Mingquan QIAN
- Publication Type:Journal Article
- From:
Chinese Journal of Tissue Engineering Research
2016;20(9):1289-1294
- CountryChina
- Language:Chinese
-
Abstract:
BACKGROUND:Effects of pedicle screw placement on fracture reduction or stability of mechanics are influenced by various factors. Pedicle screw fixation failure is mainly due to fracture, loosening and fatigue. The main influential factors for biomechanical stability of pedicle screw are length and diameter. The research on the depth is less. OBJECTIVE:To analyze the relationship between pedicle screw placement depth of vertebral body and the fixed stability based on the biomechanics. METHODS: A model of single vertebral compression fractures was made in 15 pigs aged 5 months on L2 vertebral specimen. According to the length of anteroposterior diameter, vertebral pedicle screws were inserted in different depths (80%, 90% and 100% of anteroposterior diameter). After fixation, specimens were loaded 10 000 times at the frequency of 0.5 Hz (340±125) N on a WDT-10KN type universal material testing machine. Ranges of motion at anteflexion, backward extension, left bending and right bending and the maximum axial pulout force were measured in each group, and the difference of intergroup data was compared. RESULTS AND CONCLUSION:(1) Ranges of motion at anteflexion, backward extension, left bending and right bending in each group were significantly smaler in the 100% and 90% groups than in the 80% group (P < 0.05), and above parameters were smaler in the 100% group than in the 90% group (P< 0.05). (2) After fatigue test, the maximum axial pulout force was significantly larger in the 100% and 90% groups than in the 80% group (P< 0.05), and above data were significantly larger in the 100% group than in the 90% group (P < 0.05). (3) Results indicate that the depth into the vertebral body was significantly associated with its fixed stability. The deeper the depth into the vertebral body, the stronger the vertebral stability was: 100% group > 90% group > 80% group.
