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Updated: Jul 9, 2026
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
[Micro-CT evaluation and histological analysis of screw-bone interface of expansile pedicle screw in osteoporotic
Shi-yong Wan1, Wei Lei, Zi-xiang Wu
1Institute of Orthopaedics and Traumatology of People's Liberation Army, Xijing Hospital, Fourth Military Medical University, Xi'an 710033, China.
Objective:
To investigate the properties of screw-bone interface of expansive pedicle screw (EPS) in osteoporotic sheep using micro-CT and histology.
Methods:
Six female sheep with bilateral ovariectomy-induced osteoporosis were employed in this experiment and were randomly assigned into 2 groups: A and B. After EPS insertion in each femoral condyles, sheep in group A were bred for 3 months, while those in group B 6 months. Femoral condyles with EPS were 3D-imaged and reconstructed by micro-CT. Histology was evaluated thereafter.
Results:
The trabecular microstructure was denser at the screw-bone interface than in the distant parts in expansive section, especially within spiral marking. In the non-expansive section, however, there was no significant difference between the interface and the distant parts. The regions of interest (ROI) adjacent to EPS were reconstructed and analyzed by micro-CT using the same thresholds. The 3D-parameters generated, including tissue mineral density (TMD), bone volume fraction (BVF, BV/TV), bone surface/bone volume (BS/BV) ratio, trabecular thickness (Tb.Th), and trabecular separation (Tb.Sp), were significantly better in expansive than in non-expansive sections (P < 0.05). Histologically, newly formed bone trabeculae crawled along the expansive fissures and into the center of EPS. The newly formed bones, as well as the bone at the bone-screw interface, closely contacted the EPS and constructed four compartments.
Conclusions:
Based on micro-CT and histological evaluation, the study suggest that EPS can significantly provide stabilization in osteoporotic cancellous bone.
