| ObjectiveUsing internal fixation for treat Sacroiliac joint dislocation was a conventiontreatment recently. The majority of surgical approach included sacroiliac joint screw,anterior plate screw internal system, posterior plate screw internal system. Externalfixation fixed sacroiliac joint infirmly, and easily leads failure, which was instead byinternal fixation by gradually. Extensive exposure of soft tissue was necessity whenusing anterior plate screw internal system, which must be bring patients apparenttrauma. The stability of efficient fixing was unsatisfied. Sacroiliac screw fixed andclosed nailing under the guidance of the navigation system. However, in the case ofclosed nailing, can not ensure that the sacroiliac joint can reset, and likely to causedamage of the nerves and blood vessels. It was difficult to use the sacroiliac screw tothe fatty patients or whom with the complications of iliac fractures. To reducing atrauma and complications, promoting the accuracy of reconstruction to the joint,stabilizing sacroiliac joint firmly, the experiment designed a kind of anatomicalposterior sacroiliac joint plate-screw system. To expecting applied a new method forfixing sacroiliac joint.MethodsBased the applied anatomy of18pelvic specimens of the ilium and sacrum, thestatistics of two sides and sexual gap of pelvic specimens distance measurement ofthe distance between the intersection of the lower edge of the articular processhorizontal line and the lateral edge of the articular process to auricular surface (a);theintersection of the lower edge of the articular process horizontal line and thelateral edge of the articular process to the upper edge of S1PF (b); a distance betweenthe intersection of the midpoint of lateral edge of S1PF to auricular surface (c); a distance between intersection of the mid-point of connection of the midpoint of lateraledge of S1PF and the midpoint lateral edge of S2PF to Auricular surface (d); a distancebetween the intersection of the lower edge of the articular process horizontal lineand the lateral edge of the articular process to intersection of the mid-point ofconnection of the midpoint of lateral edge of S1PF and the midpoint lateral edge ofS2PF (e); the distance between the ST to SIPS(f); the thickness of the intersection ofthe upper edge of S1PF to iliac wing(g); the thickness of posterior iliac wing to theupper edge of SIIS(h); a distance between the midpoint of posterior iliac wing to of themidline of the upper edge of S1PF horizontal line to the upper edge of SIIS(i); theangle posterior iliac wing to sagittal(j); the angle of the connection line between theintersection of lower edge of the articular process horizontal line and the lateral edge ofthe articular process to the intersection of anterior edge of pedicle to vertebral tosagittal(k); the angle of the connection line between the intersection of lower edge ofthe articular process horizontal line and the lateral edge of the articular process to theintersection of posterior edge of pedicle to vertebral to sagittal(l); the angle of themidpoint of the connection line of intersection the articular process horizontal lineand the lateral edge of the articular process and the intersection to S1PF upper edge tolateral edge to Auricular surface and the intersection of S1PF upper edge to lateral edgeto the intersection of1stanterior sacral foreman upper horizontal line to Auricularsurface of sagittal(m), was provide technical guidance and anatomical referencedata for the rational design internal fixation system. The parameter of polyaxial lockingplate of posterior sacroiliac joint was accorded to the measurement of anatomical data.The instrument analogy applied on cadavers.According anatomical parameters from the first part of the experiment and pelvicbiomechanics to determine sacroiliac joint posterior polyaxis locking plate shapestructure, the number of nail holes, size, type, position. Determine the choice screwtype, size. Plate nail holes and screw parameters, design of polyaxis locking ring. Thedrawing of plate and screws designed with software CAD2007. Using Pro/E2008optimized the structure of plate, and producing the3D drawing. The plate produced byCNC through delivered the drawing into computer. Observing the incision size, the damage of soft tissue and bone, the angle ofscrews, the solid of fixing, surgical operation requires time, when stimulatedapplications in the cadavers. Imaging observation have installed the cadavers, the useof pelvic plain films, imported bit-slice and export-bit chip to observe the screws in thesacral and iliac fixed.ResultsThe measurement of18pelvic specimens of the ilium and sacrum demonstratedthat the meaning date of (1)was30.55±2.48mm(M),30.12±2.09mm(F);(2)was12.18±1.64mm (M),12.43±1.51mm (F);(3)was26.87±1.15mm (M),25.98±1.01mm(F);(4)was25.71±1.12mm(M),25.63±1.46mm(F);(5)was28.45±2.83mm(M),26.64±2.62mm(F);(6)was31.32±2.72(M),30.43±2.56mm(F);(7)was20.55±2.48mm(M),20.12±2.09mm(F);(8)was30.28±3.06mm(M),29.70±3.52mm(F);(9)was35.64±3.85mm(M),33.82±4.02mm(F);(10)was25.4±4.8°(M),27.6±3.6°(F);(11)was76.4±10.7°(M),78.7±9.8°(F);(12)was6.5±0.5°(M),6.8±0.8°(F);(13)was28.5±4.8°(M),29.3±3.6°mm(F);There was no significant difference betweensexual gaps between all team dates.There were three parts in the plate, such as sacral part, connection part, and iliacpart. The plate designed three nail holes at sacral side, in accordance with the orderfrom top to bottom, the first nail holes was the S1pedicle locking hole, the secondanail hole was the S1polyaxis locking holes, the third nail holes was the S2polyaxislocking hole. The S1pedicle locking hole had within30degrees of inclination of theplate, the angle had designed from the anatomic parameters of the S1pediclescrewangle. The S1polyaxis locking hole and the S2polyaxis locking hole can inclined0-20degree inward or outward, which could adjust the screw channel that in accordancewith plate been fixed. The connection part of the plate was stepwise increased, whichmade the sacral part and iliac part of plate were not at the same lever. The heightdisparity between two part of the plate was1.2cm. Iliac part of the plate appeared an20°angle to sacral side of plate, and the screw hole had an20°angle to sagittal axis.The locking ring was a drum-style like. There were two sizes of locking ring in internal fixation. The diameter was designed according to the size of screw, and the lockinghole of the plate. There were three kinds of locking screw in this internal fixationsystem. The diameter of the S1pedicel locking screw was designed5.0mm. Thediameter of the S1, S2polyaxis locking screw was designed3.5mm. The iliac lockingscrew was designed of diameter7.0mm polyaxis screw locking threaded matchedwith locking ring to the thread. When the screws screwed into the locking ring, it canmake the lock ring to play an expansive role.When using plate to simulate clinical application, the anatomy relationship ofsacroiliac joint was distinctly demonstrated in surgical operative field. The entireprocedure only stripping the muscles attached to the sacral iliac rear clearance, didnot damage the rear of the sacroiliac ligaments and the sacroiliac ligaments. Bite inaddition to the iliac medial plate of about4cm×0.5cm×1cm size piece of bone.S1pedicle screw angle plate has set the angle, ie, tilting30°; Sacral lateral mass of thepolyaxis hole into the nail inclination is about15°to the head about5°partial. Upperiliac polyaxis tilting about10°to lock the screw into the nail angle about10°partial tothe head; lock the bottom of iliac polyaxis tilting about10°to the head about15°partial. Polyaxial locking plate of posterior sacroiliac joint could adjust screwchannel flexibility. X-ray film showed the screw direction of the screw channel in linewith the experimental pre-design requirements, the sacral side of the screw does notbreak through the presacral cortex, iliac side of the screws are located in the iliaccrest, lateral plate, did not break the ischial big bear in mind the back of thebone. Throughout the operation time of38min. When fastening polyaxial lockingplate by locking screw, the effect of fixation of plate was effective.ConclusionThe Polyaxial locking plate of posterior sacroiliac joint deposed through openingreduction style operation, which could make the relationship of sacroiliac jointobserved clearly; And innovation of Polyaxial locking plate of posterior sacroiliac jointwas based on the date of anatomy of Chinese, which accordance with feature ofposterior sacroiliac joint; The internal fixation has a small size, which can reduce the incision of surgical field; Designation simulated with Locking plate system, can play abridge role of mechanism; Poylaxial fixation had a benefit for adjust screws’ direction.The Polyaxial locking plate of posterior sacroiliac joint was an applied internal fixation,which supplying a reliable method for sacroiliac joint dislocation. |
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