The relationship between microstructure of vertebral cancellous bone and fixation strength of pedicle screws
- VernacularTitle:椎体骨微结构参数与椎弓根螺钉固定强度的相关性
- Author:
Xu-sheng LI
1
;
Ming-xuan GAO
1
;
Xiao-yan LIANG
1
;
Sheng-gui LI
1
;
Hong-bin SHAO
1
;
Shi-cheng YANG
1
Author Information
1. Department of Orthopedics, the General Hospital of Lanzhou Military Command
- Publication Type:Journal Article
- Keywords:
Osteoporosis;
Pedicle screw;
Bone mineral density;
Bone micro-architecture
- From:
Journal of Medical Biomechanics
2014;29(3):E260-E265
- CountryChina
- Language:Chinese
-
Abstract:
Objective By measuring the microstructure parameters of cancellous bone in vertebral bodies with different bone mineral density (BMD) levels, to study the correlation between such parameters and the corresponding maximum pullout strength (MPS) when fixed by pedicle screws, so as to understand if the microstructure parameters are related with screw stability and further to reveal the cause of screw loosening. Methods Based on the BMD detection results, fresh human cadaver spines were stratified into four levels: normal, osteopenia, osteoporosis and severe osteoporosis, according to diagnosis criteria in clinic. The corresponding vertebral specimens were then instrumented with pedicle screws, and screw pullout tests were conducted to measure the MPS of such screws. All the vertebral specimens were collected subsequently, and the cancellous bone cylinders were drilled from the center of each vertebra for micro CT scanning. Microstructure parameters of the vertebral trabecular bone at different BMD levels were obtained to investigate the interrelationships in between, and the relationships between the microstruture parameters and corresponding MPS of pedicle screws with osteoporosis severity were then compared. Results With the decline of BMD from normal to severe osteoporosis level, the corresponding MPS of pedicle screws was significantly declined. With the severity of osteoporosis increasing, the progressive bone volume loss, mechanical incompetence and microstructure deterioration also appeared evidently. Significant differences were found in microstructure parameters at different BMD levels. Strong correlations were extensively observed among BMD, microstructure parameters and MPS of screws. The MPS of pedicle screws was highly correlated with bone volume over total volume (BV/TV), trabecular thickness (Tb.Th) and trabecular separation (Tb.Sp) from micro-CT scanning. Conclusions Significant deterioration would occur in bone tissues with the decline of BMD level, and the MPS of pedicle screws was highly correlated with some microstructure parameters.
