| Objective:To compare the clinical anatomy of cervical pedicle measured by Iso-C arm and CT and evaluate the accuracy of the results. According to the results evaluate the safe angle range of pedicle screw. To compare the accuracy of cervical spine pedicle screw fixation assisted by Iso —C arm navigation system and X—ray fluoroscopy through imageology. Backgrounds:From 1990s ,because the computer technologies develops a lot and are widespreadly used,it is possible to combine the image taken by computer and spatial localization sensor with the focus of infection and constitute primary navigation system. The system not only help doctors make pre-operation plans and find the best approach of operation but also operate according to the indication of the computer which makes the operation more accurate and reliable. Iso—C arm navigation system have a lot of advantages such as using conveniently and less relative accuracy and are widely used recently, but its accuracy has not been reported. METHODS:First, we investigate some correlated subjects such as the working principle of navigator, the process of operation navigation, precision of operation navigation and advantage of operation navigation. To compare the length and width of the external and inner diameter of 120 cervical pedicle of 15 patients measured by Iso — C arm and CT, analyze the accuracy of Iso—C. According to the results evaluate the safe angle range of pedicle screw in simulation. 75 cervical pedicle screws were placed assisted by Iso—C arm navigation system and 76 cervical pedicle screws were placed assisted by X—ray fluoroscopy. Screw positions were evaluated by Iso-C arm 3-dimensional reconstruction. Results:1. In the measurement of Iso-c arm, The CEH become large gradually from C3 to C7,C3 is 6.57mm,C7 is 8.0mm;The CEW increase gradually too,C3 is 1.74mm,C7 is 3.48mm. The CIH increase gradually too,C3 is2.47mm,C7 is 3.63mm. The CIW increase gradually too,C3 isl.64mm,C7 is 3.51mm.The La(total length of pedicle) increase from C3 28.9mm to C7 33.4mm;The Lb(articular length of pedicle) increase from C3 14.9mm to C7 15.4mm.2. In the measurement of CT, The CEH increase gradually from C3 to C7,C3 is 6.62mm,C7 is 7.98mm;The CEW increase gradually from C3 to C7 too,C3 is 5.00mm,C7 is 6.88mm. The CIH increase gradually too,C3 is2.48mm,C7 is 3.64mm. The CIW increase gradually too,C3 isl.75mm,C7 is 3.70mm.The La(total length of pedicle) increase from C3 28.5mm to C7 33.6mm gradually;The Lb(articular length of pedicle) increase from C3 14.6mm to C7 15.6mm gradually.3. Compare the two measuring methods by t-test statistically, the results suggest two measuring methods have no obvious statistical difference (P>0.05).4. Evaluate the safe angle angle range of pedicle screw. when screws are not considered,from C3 to C7 the angle increase from 28.5°to 34.5°on sagittal plane, increase from 18.9°to 27.1°on transverse plane. when screws are considered, from C3 to C7 the angle increase from 16.5°to 23.1°on sagittal plane, increase from 7.1°to 15.3°on transverse plane. Compare the two groups statistically, the results suggest two groups have obvious statistical difference (P<0.05).5. In the computer-assisted group, 75(96.8% )screws were found completely within their pedicles compared with 76(89.7% )correctly placed screws in the X-ray assisted group(P<0. 05). The process of navigation investigated in fifteen patients showed that the mean time for Iso-C 3dimensional scanning registration,surface matching and Iso-C rescanning Was 13 (range from 10 to 16 minutes)minutes and the mean time for screw insertion Was 3 (range from 2 to 5.3 minutes) minutes with the mean position diviation0.75mm(0. 18～0. 96mm)per screw. No severe complications like neurovascular lision occurred in both groups. Conclusion:1. To compare the length and width of the external and inner diameter of 120 cervical pedicle of 15 patients measured by Iso—C arm and CT , the accuracy of Iso —C and CT have no obvious statistical diffierence. Iso—C arm can replace CT to measure and evaluate pre-operation and acquire 3D images for navigation system.2. To confirm the safe angle range of pedicle screws must consider the pedicle screws. The safe angle range in clinic is much less than the range in theory.3. Iso—C arm navigation system can increase the accuracy of cervical pedicle screw implantation significantly.
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