We compared the accuracy, operating time and radiation exposure
of the introduction of iliosacral screws using O-arm/Stealth Navigation
and standard fluoroscopy. Iliosacral screws were introduced percutaneously into the first
sacral body (S1) of ten human cadavers, four men and six women.
The mean age was 77 years (58 to 85). Screws were introduced using
a standard technique into the left side of S1 using C-Arm fluoroscopy
and then into the right side using O-Arm/Stealth Navigation. The
radiation was measured on the surgeon by dosimeters placed under
a lead thyroid shield and apron, on a finger, a hat and on the cadavers.Aims
Materials and Methods
We created virtual three-dimensional reconstruction models from computed tomography scans obtained from patients with acetabular fractures. Virtual cylindrical implants were placed intraosseously in the anterior column, the posterior column and across the dome of the acetabulum. The maximum diameter which was entirely contained within the bone was determined for each position of the screw. In the same model, the cross-sectional diameters of the columns were measured and compared to the maximum diameter of the corresponding virtual implant. We found that the mean maximum diameter of virtual implant accommodated by the anterior columns was 6.4 mm and that the smallest diameter of the columns was larger than the maximum diameter of the equivalent virtual implant. This study suggests that the size of the screw used for percutaneous fixation of acetabular fractures should not be based solely on the measurement of cross-sectional diameter and that virtual three-dimensional reconstructions might be useful in pre-operative planning.
