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An Anesthesia, Surgery, and Harvest Method for the Evaluation of Transpedicular Screws Using an In Vivo Porcine Lumbar Spine Model
Published on: May 31, 2017
Expandable pedicle screw trajectory in cadaveric lumbar vertebra: an evaluation using microcomputed tomography
Shi-Yong Wan1, Zi-xiang Wu, Wei Zhang
1Department of Orthopaedics, Xijing Hospital, Fourth Military Medical University, Xi'an, Shaanxi, China.
Journal of Spinal Disorders & Techniques
|October 27, 2010
Summary
Expandable pedicle screws (EPSs) can be safely removed from human vertebrae after 6 months. Screw removal did not fracture the pedicle, and bone density influenced expansion and fracture risk.
Area of Science:
- Spine surgery
- Orthopedic biomechanics
- Surgical device evaluation
Background:
- Transpedicular fixation is standard for posterior spinal fixation.
- Osteoporotic patients face high risks of internal fixation failure.
- Expandable pedicle screws (EPSs) enhance fixation in osteoporotic spines, but their expansion in vertebral bodies and removal safety are understudied.
Purpose of the Study:
- To evaluate the safety of removing expandable pedicle screws (EPSs) from human vertebral bodies after a 6-month insertion period.
- To assess the degree of screw tip expansion within vertebral bodies.
- To determine the risk of pedicle fracture during EPS removal.
Main Methods:
- In vitro study using cadaveric lumbar vertebrae.
- Microcomputed tomography (micro-CT) imaging and 3D reconstruction were employed.
- Measurements included screw expansion diameter, trajectory diameter, and bone volume fraction (BV/TV) in pedicle and vertebral body regions.
Main Results:
- EPSs expanded by 17.38% in vertebral bodies and trajectories increased by 16.31% (pedicle) and 9.08% (pedicle trajectory).
- Statistically significant differences were observed (P < 0.05).
- Negative correlations were found between trajectory diameter and BV/TV in both pedicle (r = -0.88) and vertebral body (r = -0.85) regions.
Conclusions:
- Expandable pedicle screws can be removed reliably without causing pedicle fracture.
- Bone volume fraction (BV/TV) significantly impacts EPS expansion and the occurrence of pedicle fracture.
