| Objective:According to use Resnick technique to place atlas pedicle screws and measure its related trails by anatomic and CT scans, then analysis and compare the two results,and evaluate the consistency of anatomy and Imaging studies, then to provide the theoretical support and references in placing atlas pedicle screws among chinese by Renick Technique.Methods:Ningxia Medical University of Anatomy provided 20 specimens of adult head and neck(excluding atlas deformed specimens, regardless of sex, height, weight and age) for experiment.Take 20 atlantoaxial complexes from them after anatomy of the specimen.Use Resnick Technique to place pedicle screws. The entrance point(A) should be the midpoint of top and lower edge of atlas posterior arch anatomically, which is over the center of dentate isthmus.,then make vertical coronal plane and sagittal plane form an angle(α) of 10° and make it and horizontal plane form an angle(β) of 50.Choose screws in a diameter of 3.5mm. The intersection of pedicle screw and atlas anterior arch cortex is B. The process of measurement should be three steps: The first step:Before placing pedicle screws: use a digimatic caliper to measure the thinnest height(h) of bottom of posterior arch of atlas, the maximum width(w) of posterior arch,and the distance(d) between entrance point and the vertical line of tuberculum posterius atlantista. The second step:The measurement of imaging: use a protractor to measure the oblique angle(β) after atlas pedicle in specimens.then give them a CT scan,so that we can measure vertical coronal plane and sagittal plane form an angle(α),and use a digimatic caliper to measure the thinnest height(h) of bottom of posterior arch of atlas, the maximum width(w) of posterior arch, the total length(AB) of screw channel, the screw is considered as the safe distance of spinal cord(the interior safe distance S1), the shortest distance between transverse foramen and the screw is the safe distance of vessel(The lateral safe distance S2), the distance(d) between entrance point and the vertical line of tuberculum posterius atlantista.The third step: cut atlas with a saw blade,then measure vertical coronal plane and sagittal plane form an angle(α), the total length(AB) of screw channel,the safe distance of spinal cord(S1), the safe distance of vessel(S2).When finishing measuring,collection all the date we measurement,then making Statistical analysis with a Statistical software of SPSS19.0.Result:The result of anatomic measurement(1) the thinnest height(h) of bottom of posterior arch of atlas is 5.02±0.28 mm from left and 5.42±0.54 mm from right; the width(w). 9.71±1.04 mm is on the left, 8.51±1.13 mm is on the right.(2) The distance(d) between entrance point and the vertical line of tuberculum posterius atlantista is 19.01±1.92 mm from left and 18.9±2.06 mm from right.(3)the total length(AB) of atlas screw channel is 25.00±2.92 mm from left and 24.21±2.70 mm from right.(4) the safe distance of spinal cord(S1) is 2.11± 0.31 mm from left and 2.63±0.72 mm from righ; the safe distance of vessel(S2) is 3.24±0.88 mm from left and 3.73±0.53 mm from right;(5)the screw tilt angle(α) is 8.1°±2.0 o from left and 9.6°±2.0 o from right; the oblique angle(β) is 5.2 o±1.1 o from left and 4.8°±1.3 o from right.The result of imaging measurement(1) the thinnest height(h) of bottom of posterior arch of atlas is 5.35±0.49 mm from left and 5.73±0.68 mm from right; the width(w).10.14± 1.57 mm is on the left,9.73±1.33 mm is on the right.(2) The distance(d) between entrance point and the vertical line of tuberculum posterius atlantista is 18.10±2.93 mm from left and 18.82±2.12 mm from right.(3)the total length(AB) of atlas screw channel is 26.60±1.89 mm from left and 25.11±2.52 mm from right.(4) the safe distance of spinal cord(S1) is 2.42±0.55 mm from left and 2.74±0.82 mm from righ; the safe distance of vessel(S2) is 3.64±0.78 mm from left and 3.99±0.70 mm from right;(5)the screw tilt angle(α) is 8.7°±2.5 o from left and 10.2°±2.7 o from right; the oblique angle(β) is 5.6 o±1.6o from left and 5.1°±1.4 o from right.Conclusion:In anatomical theory, placing pedicle screws into atlas by Resnick Technique among Chinese is feasible and safe and is Consistent with the result of CT measurement,and the entrance point should be over the center of dentata isthmus anatomically, and the midpoint of top and lower edge of atlas posterior arch, and it is safe to keep vertical coronal plane with sagittal plane of a 10° angle and with horizontal plane an angle of 5o when placing. |
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