A study on the use of the Osstell apparatus to evaluate pedicle screw stability: An in-vitro study using micro-CT
Fig 2
Micro-CT images and image analysis.
(a) The bone mineral density phantom made from aluminum alloy and hydroxyapatites. The values indicate the original bone mineral density values. (b) Sagittal image of the screw insertion area after screw removal. (c) Axial images of the screw insertion area. (d) Red areas represent the areas with values lower than −325.0 a.u. (i.e., “air”). The yellow circles represent the 5.5-mm outer diameter of the screw. We defined the location of air surrounded by the yellow circle as the screw insertion area. (e) Actual measurement area. (f) Histogram of the calibrated values. (g) Example of the screw insertion area after first screw insertion and removal. The red line is the average screw insertion area.