Anatomic Study Of The Pedicle Screw Placement Technique On Sacrum 2

Under the current treatment of spondylolisthesis, lumbosacral tumor, trauma and other causes of the majority of lumbosacral instability surgery to sacral 1 pedicle fixed in the sacral wing or sacral cape ahead of the medial. Through observation, such fixed in the following Shortcomings: The first reason is the vertebrae of sacral 1 that making a variation in the sacral vertebrae, one does not have sufficient space to implant a screw or sacral vertebrae exists lesion, such as a sacral inflammation, cancer, tuberculosis, etc. Secondly, if the severe spondylolisthesis or lumbosacral too large relative angle, sacral 1 and screw 4, 5 connecting over a difficult angle, and nails near the tail, shorter arm to the stability of internal fixation have affected [1]. Third is lumbar 5 vertebral spondylolisthesis is, if we use two pairs of pedicle screw fixation is prone to "parallelogram effect" not conducive to fixed, if we use three pairs of screw fixation in the lumbar sacral 3,4 and 1, will be too much damage lumbar activities segment, but there is also a "top-heavy". Finally, when patients are getting on in age, sacral vertebrae of osteoporosis or a single screw placement sacral a lack of intensity. From the four, pedicle screw placement technique on sacrum 2 related very in-depth study of the need and value.Objctive: It provide the sacrum pedicle screw fixation anatomical data, accurate studies sacral 2 screw nails, nail into the plane, nails into point of view and depth, understanding sacral 2 parameters and the surrounding anatomy, sacrococcygeal adjacent about the blood vessels and nerves. provide the basis for clinical application.Methods: Selected 15 cases of dry specimens that measuring sacrum, for the sacral 2 and related structures for observation. In 10 adult cadavers observed on blood vessels and nerves take shape, and in the sacral region simulation sacral 2 pedicle enter points x.y on the sacrum (After the first sacral hole edge of the horizon and sacral ipsilateral lateral ridge, Middle Ridge intersection), The sacral 2 pedicle fixed to the anterolateral to the sacrum (sacrum and the ear-shaped face of geopolitical hole between presacral). Two screws into the same angle F, and sacrum cape are parallel planar. X entrance point is the minimum angle of the E (22.13±1.98) degrees, is the largest (43.77±1.33) degrees. In 10 adult cadavers sacral two sides on the pedicle screw into the sacrum. Two observations on the placement of sacral canal, the sacral foramina, presacral adjacent to blood vessels and nerves and the degree of risk, lumbar screws and screw insertion connected difficulty level.Results:⑴.Presacral-sacral and the corresponding aperture hole after getting presacral no significant lateral hole lateral notch, presacral hole edge of the plane after the hole in the corresponding lower edge of the top side of the plane, sacral Hole after hole to the presacral Traveling field forward direction is upward, sacral 2 medial and lateral mass-sacral 2, linked to the lateral margin of backward integration with the pedicle, almost all of the components of bone. Sacrum "pedicle" front end associated with vertebral bone quality of a vertebral thick, and the lateral side block linked to a quality of bone are, could play the role of stable fixed. Even the back-end laminectomy, flat top, but there are not obvious trace all, the stress is concentrated, is the most solid part of vertebral body. And cervical, thoracic, lumbar pedicle different from the sacrum "pedicle" both sides did not intervertebral foramen. Scral 2 has sufficient space structure capacity home screws, as vertebral body in front of veassels and nerves running around presacral hole with lateral mass screws penetration of the cortex before sacrum, screw front of the medial near iliac vein, it should be in screw placement in strict accordance with the provisions of the entrance point, angle, depth of insertion to buy nails.⑵. Two entrance points are secure entrance point, did not enter the spinal canal, did not enter the presacral hole, the largest plane in the pedicle safety course, the X-Kok is the E (22.13±1.98) degrees , a screw hole in the presacral lateral margin of nails Road depth (26.01±1.68) mm, X E Kok is the point (36.03±3.74) degrees, the ear-shaped screw in the face of fate, nail depth Road (33.08±1.12) mm; Y Kok is the point E (36.67±1.49) degrees, a screw hole in the presacral lateral margin of nails Road depth (30.06±0.82) mm, Y E Kok is the point (43.77±1.33) degrees, the ear-shaped screw in the face of fate, nails Road depth (35.51±0.97) mm. Entrance direction (E Kok, Kok F) and the entrance point to the limitations of this method will not enter the spinal damage nerves and blood vessels.⑶. X entrance point near the back of the sacrum partial lateral location in the upper lumbar pedicle screws into the bottom of the screw, easy connections. Y entrance point and lumbar pedicle screw entrance point of the vertical distance of more than 20 mm, not convenient connections.⑷. Sacral vertebrae 2 adjacent anatomical structures and their corresponding individual differences in the larger, it is proposed that expert sacral 2 screw placement, the use of CT examination is essential to clear the entrance preoperative method entrance site selection, nail into perspective and choose suitable diameter, length of the screw.Conclusion:⑴. Sacral 2 pedicle screw fixation is feasible, the two screw entrance point (X, Y) are safe entrance point. Y location of the point of not conducive to connect lumbar screws, point X facilitate connecting link.⑵. Front vessels and nerves due to vertebral Traveling in a nail point adjacent to single-layer cortical screw fixation fixed screw placement should be in strict accordance with the entrance point, angle, depth of insertion to buy nails.⑶. Sacral vertebrae 2 adjacent anatomical structures and their corresponding individual differences in the larger, it is proposed that expert sacral 2 screw placement, the use of CT examination is essential to clear the entrance preoperative method entrance site selection, nail into perspective and choose suitable diameter, length of the screw.