| ObjectiveThere are numerous posterior fixation technique for lower cervical instability. Lateral mass screw-plate offered a good biomechanical stability, provided a high fusion rates. However, they are expensive and technically demanding. Damage to neurovascular structures, especially with the Magerl technique, has been reported. Recently, transarticular screws have been safely used in the cervical spine. However, few anatomic studies concerning this technique are available. This study is designed to:1.Measurements are taken to obtain the parameters of the lower cervical facet joints relatived to the transarticular screw placement.2. Evaluate the distance from the point of screw piercing out to the upper and lower nerve roots3.Evaluate the feasibility of the transarticular screw placement techniques on the lower cervical spine fixation by anatomic measurements on dry specimens of the lower cervical spine. Hoping that it can be helped to reduce the relative complications in clinical treatment.Method14matched human cervical spines from C3to C7were directly evaluated. Anatomic evaluation of the cervical superior and inferior facets included the facet height, width. The projection of the inferior facet on the posterior aspect of the lateral mass was measured, with an electronic vernier caliper (Guang Lu; accuracy of0.1mm).The data is relatived to screw placement technique. Take digital photographs of these speciments with a camera (Sony).The pictures entered into the computer were processed with Photoshop softwara to evaluate the argue of surface.All of the parameters can be used to understand the factors which can effect the correctly placement of the screw insertion.In five patients with lower cervical spine instability, using this techniqu.3.5mm unicortical transaticular screws were used.The screws were assessed on postoperative radiographs and CT scans, to test and verify the reliability of present screw placement technique.ResultThe average width of the articular surface of C3-C7is10.113.4mm, a length of8.110.8mm. Under the joint height h gradually increases in C3-C7:9.5-11.7mm.46.8°-52.0°。α range46.8°-52.0°approximatel。Articular surface and the horizontal angle on the lateral mass of C3C5closer to the mean range of48.4°-54.2°。C6, C7, and the horizontal angle (R), mean70.0°about C6is less than the C7.10.3～16.7mm。The height of the lateral mass of the lower cervical spine tended to increase the scope of the C3-C7:10.316.7mm.Operative in accordance with the measurement results and other reports of lower cervical facet joint screw technique, and postoperative patients with cervical shooting X-ray and CT screw channel scan, the results of facet joint screw placement accurate. screws across the facet joints in complex fixed, four-layer cortex does not appear to damage the blood vessels, nerves.ConclusionObservation and measurement of specimens show that transfacet screw fixtion on lower cervical spine is feasibility. Damaging blood vessels or nerves don’t occur. The lower cervical spine by the facet joints fixation technique in clinical has a2. The center of the articular surface of the lateral mass of the center of the bottom of about2mm, the joint complex for the screw fixation provides sufficient cortical bone. C3～C7The C3-the C7under the cervical spine by the joint screw fixed a security, a stable screw range:entrance point to the lateral mass of the center of a bit more, screw in the sagittal nail’s angle tends to40°, the other safety angle is in the region of10°-AngleA. |
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