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Updated: Aug 17, 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
A biomechanical study of posterior spinal instrumentation using pedicle screws with and without cross-links
M Umar Burney1, Debi P Mukherjee, Alan L Ogden
1Department of Orthopaedic Surgery, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
Objective:
It is not clear from the studies reported in the literature whether the addition of cross-links to bilateral pedicle screws increases the stiffness of the construct significantly to fix multilevel vertebral bodies. The current study addresses the question of how cross-links change the rotational stiffness of constructs with 6, 12, and 20 pedicle screws.
Methods:
Seven thoracolumbar 10-level spine segments (T4-L1), from individuals of average age 72 years (range 46-83 years), were instrumented with pedicle screws (6, 12, and 20) and tested in torsion with and without cross-links. As the cadaver specimens had signs of osteopenia, constructs consisting of 10 wood blocks 35 x 35 x 78 mm (weight x height x length) were also tested following an identical protocol as in the cadavers to prove the concept.
Results:
For both wood blocks and cadavers, the rotational stiffness increased linearly with number of screws with and without cross-links. Two cross-links increased rotational stiffness significantly for both 12 and 20 screws (nonsignificant for 6 screws) for wood block constructs. However, the rotational stiffness values of the cadaver constructs with or without cross-links failed to show any significant differences.
Conclusions:
This work has raised the need for developing a suitable animal model for the study of multilevel vertebral bodies to simulate the fixation of scoliosis corrections.
