【作者】 盛伟超；

【导师】 钟世镇；

【作者基本信息】 南方医科大学 ， 人体解剖与组织胚胎学， 2009， 博士

【摘要】 研究背景和目的:传统的解剖学研究方法是利用测量工具（直尺、游标卡尺、量角器）和解剖器械（解剖刀、解剖剪,锯）在标本上直接测量,但他受到标本来源、标本质量和观测者主观因素等限制;对于外形复杂的组织、器官（不规则腔隙、骨等）,解剖测量和描述也非常困难。现有的研究方法主要有活体或标本测量、X线投影测量分析、二维CT（two-dimensional computed tomography 2D-CT）测量等。但用二维的方法来测量分析三维形态的物体存在明显局限性,特别是对外形复杂的组织、器官,其准确性和可靠性较低;同时因为二维CT缺乏立体感,主要依靠医生的想象来形成三维的印象,对大多数临床医师来说,阅片比较困难,且比较费时。螺旋CT扫描重组后得到多组二维和三维影像,能清晰显示目标器官解剖形态,并可以进行立体的各平面间的测量,但其所得CT测量数据能否真实反映目标器官解剖结构还无定论。Gavelston技术最早由Allen和Ferguson应用,它利用金属棒行髋臼上,髂骨间植入技术进行腰、骨盆固定,最早应用于神经源性和特发性脊柱侧弯的矫形;但由于将光滑金属棒置入髂骨内,抗拔出力差,术后常出现内固定松动,拔出甚至失败等并发症;并且在对棒进行预弯和植入时,手术操作较麻烦,目前已被髂骨螺钉代替,特点是在髂骨内外板之间放置全螺纹螺钉,腰椎椎弓根螺钉与髂骨螺钉通过折弯的金属棒相连,达到坚强的内固定,目前广泛应用于神经源性和特发性脊柱侧弯的矫形,骶骨肿瘤切除术后的稳定性重建,腰椎滑脱的复位固定,骶骨不稳定骨折和髂骨后部的骨折。近年来切开复位内固定成为骨盆骨折和髋臼骨折的一种重要治疗手段,在骨盆内固定过程中有时会发生医源性损伤盆腔内重要血管或神经等严重并发症;在髂骨间、骨盆界线水平放置多根较长全螺纹螺钉要求临床医生对骨盆空间结构有详细了解,掌握可以放置螺钉的路线和区域,并且对骨盆侧壁及其毗邻血管、神经解剖有详细的掌握,以避免在置钉过程中出现医源性损伤。因此了解盆腔的形态结构和重要血管、神经距盆壁的距离以及它们在骨盆表面的投影是防止发生血管和神经意外损伤的基础和关键本文将以骨盆标本为对象,探讨标本测量、二维CT测量、Mimics 10.0软件三维重建图像测量结果的一致性,为三维图像重建软件的广泛应用提供理论基础;并结合CT扫描和三维重建,探讨找出一种兼顾解剖安全和力学强度的置钉通道和最大置钉区域,并对置钉通道和置钉区域进行较为详细的解剖学描述,为临床工作提供解剖学基础。同时对骨盆侧壁的血管、神经进行解剖学观察,测定盆腔内重要血管和神经与骨盆壁的距离,并将这些血管和神经投影图同时画在骨盆外侧面,使临床医生对骨盆的形状、各个部位的重要血管和神经的走行及其与骨盆壁的距离、体表投影有大致的了解,从而有效减低手术中医源性损伤的发生。方法:标本、二维CT、Mimics 10.0软件的三维重建图像测量结果的一致性研究1.标本测量:测量右侧骨盆自髂后上棘（posterior superior iliac spine PSIS）至髂前下棘（anterior inferior iliac spine AIIS）的线性距离,以下记为L_PSIS;同时测量右侧L_PSIS与矢状面所成角度。2.二维CT测量:将骨盆标本置于CT扫描床,通过垫衬,使L_PSTS与扫描标志线重合,此时进行CT扫描（Philips Brilliance 190P 64排螺旋CT,Brilliance 64;Philips Medical Systems,Cleveland,USA）,得到单张DICOM格式CT图像;利用CT工作站自带图像浏览器（Mxliteview DICOM Viewer software,PhilipsMedical Systems,Cleveland,USA）对右侧L_PSIS的线性距离及其与矢状面所成角度进行测量。3.三维CT测量:将骨盆标本置于CT扫描床,仰卧位,保持髂前上棘和耻骨联合在同一额状面上,从髂骨棘扫描至坐骨结节,刻盘保存,在个人电脑上导入MIMICS 10.0软件（MIMICS software by Materialise N.V.,Haasrode,Belgium）进行三维实体重建,并对所得到的三维图像沿L_PSIS进行切割,就可以得到沿L_PSIS的断面图像,在所得的断面图像上对右侧L_PSIS的线性距离及其与矢状面所成角度进行测量。采用SPSS 13·0统计学软件对三种不同方法测量的相关数据进行随机单位组设计资料的方差分析。并对二维CT测量、Mimics 10.0软件的三维重建图像测量结果与标本测量结果进行相关回归分析。髂骨螺钉的临床解剖学研究1.标本解剖学观察:在骨盆标本上对以下骨性通道进行观察:双侧骨盆自髂后上棘至髂前下棘,以下记为L_PSIS:双侧骨盆自髂粗隆（iliac tubercle IT）至髂前下棘,以下记为L_IT;双侧骨盆自髂后下棘（posterior inferior iliac spine PIIS）至髂前下棘,以下记为L_PSIS。2.二维CT测量:将骨盆标本置于CT扫描床,通过垫衬,使双侧L_PSIS、L_IT、L_PIIS三条线分别与CT扫描标志线重合,此时进行CT扫描。可分别得到沿三条线平面的单张DICOM格式二维CT图像;测出双侧L_PSIS、L_IT、L_PIIS的线性长度及其与矢状面所成角度。3.骨盆可上钉区域重建:在Mimics软件中重新导入DICOM格式的全骨盆CT图像,设定域值和选定兴趣区域后,利用Edit Masks工具在每张DICOM格式的CT图像上进行兴趣区修改,自后向前我们只选择髂骨内外板间距离大于6.5mm区域,小于6.5mm区域及其前部区域予以删除;同时在CT图像上观察等于6.5mm区域髂骨最窄处,以了解放置螺钉时的限制点。进行三维重建后对对可放置螺钉区域进行解剖学观察,测量其坐骨大切迹以上最小距离和前、后区域的纵向距离。骨盆壁血管神经的应用解剖,采用12具防腐骨盆标本进行如下观察测量:1.动脉系统观察:首先观察盆腔内动脉的分支及走行情况,然后测量髂总动脉及各个分支动脉到盆腔侧壁垂直距离（包括髂总动脉、髂内动脉、髂外动脉、闭孔动脉）。2.静脉系统观察:观察盆腔内静脉主干走行情况,然后测量静脉到盆腔侧壁垂直距离（包括髂内静脉、髂外静脉、闭孔静脉）。3.神经系统观察:观察盆腔侧壁神经走行情况,然后测量股外侧皮神经、生殖股神经、股神经和闭孔神经到盆腔侧壁垂直距离。4.模拟手术操作,将骨盆标本腹卧位放置,从后向前沿骨盆L_PSIS钻入3.5mm钢针,观察盆腔内血管神经和钢针空间关系,找出在放置钢针时血管神经易损伤区域和易损伤器官。5.纵向劈开骨盆,用直径1mm克氏针沿髂内动脉、髂外动脉、闭孔动脉、髂外静脉、股外侧皮神经、生殖股神经、股神经和闭孔神经的走行,自其始以10mm的间距自骨盆内侧面钻孔至穿透骨盆外侧面,钻孔方向垂直于骨盆外侧面。用数码照相机进行拍照,输入到Photoshop中打开,分别用不同色彩进行走行轨迹标记,在骨盆侧壁形成投影。结果:1.1.经统计学处理显示三种测量方法所进行的长度测量处理组间F=0.196,p=0.823,三种测量方法的长度测量无显著差异;配伍组间F=1423.577,p=0,骨盆个体间有显著差异,说明配伍设计非常有效。三种测量方法所进行的角度测量处理组间F=0.124,p=0.884,三种测量方法的角度测量无显著差异;配伍组间F=271.681,p=0,骨盆个体间有显著差异,说明配伍设计非常有效。三种测量方法所测结果无显著性差异,具有一致性,利用二维CT和Mimics软件三维重建图像进行测量并不影响测量结果。2.双侧L_PIIS的标本观察中,多数标本（男6例、女5例）上该线低于或者刚好位于坐骨大切迹顶,所以L_PⅡS不能作为髂骨螺钉的放置处3.经L_PSIS,在女性标本中,骨性通道长为125.3mm,宽为10.8mm,其与矢状面所成角度平均为25.5°;而在男性标本中,该骨性通道长为135.6 mm,宽度为13mm,其与矢状面所成角度平均为26.30°考虑到所有标本中的最小值,男性11 5 mm长,女性95 mm长的髂骨螺钉经髂后上棘到髂前下棘放置是安全的;相比较而言,自髂粗隆至髂前下棘的骨性通道相对较短,在女性标本中的平价值为117.1 mm长,8.2 mm宽,其与矢状面所成角度平均为26.5°;在男性标本中的平价值为126.9mm长,10.1 mm宽,其与矢状面所成角度平均为25.8°。考虑到所有标本中的最小值,男性95mm长,女性90 mm长的髂骨螺钉经髂粗隆到髂前下棘放置是安全的。4.髂骨翼上可置钉区域双侧基本对称,主要位于坐骨大切迹之上;坐骨大切迹顶以上最小距离为31-42 mm。其前端纵向距离为41-56 mm;而在其后部,可置钉区域的纵向距离为90-106 mm左右,放置螺钉的限制点基本在坐骨大切迹顶点前后。5.经髂后上棘到髂前下棘放置髂骨螺钉时,比较危险的区域在骨盆侧壁和腹股沟、髋臼区;如果进针角度过大,就有可能误入髋臼;如果进针角度过小或者内固定器械偏长,就有可能刺入骨盆腔内损伤闭孔血管和闭孔神经,也有可能损伤腹股沟区血管神经。6.盆腔内重要血管和神经可以在骨盆外壁形成直观、形象的投影图,使临床医生对骨盆的形状、各个部位的重要血管和神经的走行有大致的了解。结论:1.标本、二维CT、Mimics 10.0软件的三维重建图像测量具有一致性,利用二维CT和Mimics软件三维重建图像进行测量并不影响测量结果,Mimics 10.0软件可以作为一种较为实用的研究工具对骨性结构进行研究。2.沿L_PSIS和L_IT水平双侧髂骨翼有一骨性通道存在,骨松质、骨皮质厚度比值接近1,可有效锚入直径6.5 mm以上的髂骨螺钉;L_PⅡS低于或经过坐骨大切迹顶,所以不能作为髂骨螺钉的放置处。3.髂骨翼可置钉区域双侧基本对称,主要位于坐骨大切迹和髋臼之上;在髂骨翼后部有充足的区域进行从后向前方向的螺钉放置,并可根据需要进行平行置钉或成角置钉等多根组合;在髂骨后方可植钉区域垂直距离较长,可进行后方垂直放置螺钉。4.遵循正确的进钉路线和进钉角度,经髂后上棘到髂前下棘是可以安全放置髂骨螺钉。进钉时比较危险的区域在骨盆壁侧方和髋臼及腹股沟区。主要创新点:1.首次对标本、二维CT、Mimics 10.0软件的三维重建图像测量一致性进行研究,证实三种测量方法所测结果无显著性差异,具有一致性,利用二维CT和Mimics软件三维重建图像进行测量并不影响测量结果,Mimics 10.0软件可以作为一种较为实用的研究工具对骨性结构进行研究。2.利用标本、二维CT、Mimics 1 0.0软件对骨盆的骨性结构进行详细的解剖学观察和CT扫描,对髂骨螺钉的进钉通道进行研究,得出适合中国人的螺钉长度、直径、进钉角度,为临床治疗提供解剖学基础,也为相关器械制造提供较为精确的数据。3.首次利用Mimics 10.0软件对髂骨上的最大置钉区域进行研究,证实在坐骨大切迹和髋臼之上有充足的区域进行髂骨螺钉放置,在髂骨后方可植钉区域垂直距离较长,可进行后方垂直放置螺钉。4.首次证实中国人群中髂后下棘至髂前下棘通道不能进行髂骨螺钉放置。5.对骨盆侧壁的血管、神经进行解剖学观察,找出髂骨螺钉植钉区域相毗邻的重要脏器,进行解剖学描述,并对这些血管、神经距离骨盆壁之距离进行测量,同时将这些血管、神经的走行路线投影到螺钉置钉区,使临床医生对螺钉置钉区域之血管、神经的分布、走行有清晰的认识,提高置钉的安全性;更多还原

【Abstract】 Background:The traditional means of human anatomy observation have always relied on ruler, caliper,conimeter and operation instrument to study the relationship of anatomic structure.Obviously,it is strongly limited by the source,quality of specimen and the ability of researchers themselves.As results,the tissues and organs with sophisticated shapes is hardly described actually by traditional methods.Radiography is still chosen frequently to diagnose problems involving bones and joints.However,it is difficult to display spatial position and orientation of the bone sufficiently with irregular shape.In clinical practice,it is difficult to display spatial position and orientation of the pelvic structures obtained from the two-dimensional computed tomography（2D-CT）images,sectional anatomy,plain radiogram.Difficult conceptual processes are required for a doctor to image the spatial position and orientation of the pelvic structures from 2D images.The large numbers of images are cumbersome,time consuming,and expensive to display on film.Recently, three-dimensional（3D）computer-based image reconstruction and analysis technique has been developed and to be widely used in the medical field that,with advances in computer technology,can be performed using a personal computer.The 3D structures of the human body can be displayed in any direction,angle and plane and any diameters,distances and angles of the reconstructed structures could be easily measured.These advantages can provide significant benefit for abundant spatial information and simplify the doctor’s conceptual processes,and also provide a 3D anatomic basis for diagnostic imaging and surgical operations.Generally speaking, the 3D-reconstruction algorithm is divided into two methods of surface fitting and direct volume rendering.Different algorithm has different advantage and disadvantage,some of which are well known.Therefore,the relative accuracy or contradiction is possible appeared while the image proceeded.In current stag,the 3D computer-based image reconstruction and analysis technique,which original data come from either 2D-CT,histological sections,magnetic resonance imaging and ultrasound,has been developed and widely used in the medical field.On the other hand,the conformity among the anatomic findings,2D-CT image and reconstruction 3D image are rarely seen in the medical literature.In 1984,the Luque-Galveston technique was introduced for lumbosacral fixation, but this technique was technically demanding,especially bending rods into the appropriate alignment.Iliac support has been shown in a number of publications to improve biomechanical strength and seems to provide acceptable clinical results.One of the advantages of iliac screws compared to the conventional Galveston technique is that they can be used in combination with sacral screws,providing more rigid fixation of the sacropelvic unit.One after another,the supra acetabular,transiliac implantion have promoted the management of spine deformity,postradical sacrectomy,revision spondylolisthesis surgery,unstable H-or U-shaped sacral fractures,and fractures and dislocations of the pelvic ring.In clinical management,repeated attempts to optimize the transiliac screw position will undoubtedly decrease the biomechanical results. Moreover,the vicinal vessels,nerves and organs will be damaged once the screw punctures the cortical table.Therefore,Familiarity with the anatomy of the ilium is of paramount importance for accurate iliac screw placement.Furthermore,it is essential to obtain more than one screw anchor for stable lumbopelvic fixation in management the severe posterior pelvic ring fracture,revision surgery with diminished bone stock at the posterior superior iliac spine（PSIS）after bone grafting,and sacroiliac joint tuberculosis or tumor,which require at least two different starting points and screw paths or use uncommon trajectory.In recent years much progress has been made in the classification,imaging,and physiopathology of pelvic traumas.Surgical techniques that result in the restoration of pelvic anatomy and early mobilization of patients have been developed and are routinely applied.The potential complications of the operation include injuries to the adjacent major vessels,nerves,and major viscera（i.e.,intestines,bladder,and urethra）.The operative risks associated with placement of iliac screws are considerable because there is no visual monitor to reduce the potential danger of intrapelvic vascular injury（e.g.,to the external iliac artery when excessive drilling is done for fixation of the iliac screws or to the obturator artery when the iliac screws are incorrectly inserted）.To minimize such risks,it is helpful to define the location of these intrapelvic vascular and nervous structures and measured the distance to the lateral wall of pelvic.Objectives:1.To testify the conformity among anatomic measurement,2D-CT and 3D-image.2.Making some morphologic measurements on ilium anchorage for transiliac screws of the eastern population using 2D-CT to determine the length,angle and diameter of supra sciatic transiliac implant anchor sites,to define maximum safe section of the anchor with purpose of that,the results obtained in this research could give a light on the surgical procedures and hardware manufacture.3.To observe the location of the pelvic vessels and nerves on the pelvic sides, measure the vertical distance from vessels and nerves to pelvic sides,and draw the projection of important blood vessels and nerves on the outer surface of the pelvis respectively.Consequently,the results obtained in this research could give a light on the surgical procedures.Methods:In accordance with the rules and regulations of the university,we used 18 embalmed cadaveric pelves（9 male,9 female）without any gross structural abnormalities to testify of the conformity among anatomic measurement,2D-and 3D-image.1.Anatomic measurements included the length from PSIS to anterior inferior iliac spine（AIIS）on the right side ilium of each skeleton with a calliper.At the same time,the drilling angle of the passageway in the horizontal plane was determined with a goniometer.2.The remaining studies were performed on a 64-row CT scanner.Each pelvis specimen was placed into the CT scanner in a supine position with L_psisline in bilateral ilium mentioned above oriented vertically.An almost transverse plane image was thus obtained,showing the shape and orientation of iliac columns.The digitized scans were imported into Mxliteview DICOM Viewer software.CT measurements included the length and angle of the right side of Lpsis in the horizontal plane.3.Subsequently,all specimens underwent spiral CT scanning again in the supine position.Correct stance was achieved by alignment of the anterior superior iliac spine, pubic symphysis in a coronal plane and the ischial tuberosities in a horizontal plane. The scanning range was from the top of the iliac crests to the bottom of ischial tuberosity.After the imaging data had been stored in a DICOM（Digital Imaging and Communication in Medicine）file,the digitized scans were imported into MIMICS 10.0 image analysis software.For an accurate measurement of the cortical bone geometric parameters,an edge recognition application was performed based on gray level thresholds to extract the cortical surfaces of the pelvis.In this study,a lower threshold of 84 Hounsfield units（HU）and an upper threshold of 1273 HU were used. The length and angle of L_PSISwas measured on 3D-image with the tools of“measure 3D distance and measure 3D angle”after the 3D-image was cut through L_PSIS.For statistical analysis we used two-way analysis of variance and bivariate correlations.SPSS 13.0 statistical software was used to analyse the data:P-value below 0.05 was considered to be significant.Applied anatomy of iliac anchorage for transiliac screws1.Anatomic observation included three screw trajectories on bilateral ilium of each skeleton.L_ITextended from the iliac tubercle（IT）to AIIS.L_PSISextended from PSIS to AIIS.L_PIISextended from the posterior inferior iliac spine（PUS）to AIIS.2.The remaining studies were performed on a 64-row CT scanner.Each pelvis specimen was placed into the CT scanner in a supine position with the three lines in bilateral ilium mentioned above oriented vertically.An almost transverse plane image was thus obtained,showing the shape and orientation of three iliac columns respectively.The digitized scans were imported into Mxliteview DICOM Viewer software.CT measurements included the length,smallest medullary width,and angle of three columns in the horizontal plane mentioned above.Window/Level adjustment was an essential tool to represent the boundary between cortical and cancellated bone.3.Subsequently,all specimens underwent spiral CT scanning again in the supine position.Correct stance was achieved by alignment of the anterior superior iliac spine and pubic symphysis in a coronal plane,the ischial tuberosities in a horizontal plane. The scanning range was from the top of the iliac crests to the bottom of ischial tuberosity.The digitized scans were imported into MIMICS 10.0 image analysis software. For an accurate measurement of the cortical bone geometric parameters,an edge recognition application was performed based on gray level thresholds to extract the cortical surfaces of the pelvis.In this study,a lower threshold of 84 Hounsfield units （HU）and an upper threshold of 1273 HU were used.Continually,the 3D-image was reconstructed once again with the same gray level threshold.In this stage,we deleted the iliac area where the medullary width less than 6.5 mm and the area anterior to the constriction which the smallest medullary width less than 6.5 mm on each 2D-image. With the same proceeding,the 3D-images were obtained which demonstrated the maximum safe section for transiliac screws on bilateral ilium.At last,we take anatomic measurement on the safe section for the clinical aim.Applied anatomy of the pelvic vessels and nerves1.Arterial system:we observed the patterns and locations of the iliac arterial branches,and measured the vertical distance from vessels（including external iliac artery,internal iliac artery,obturator artery and common iliac artery）to pelvic sides.2.Venous system:we observed the patterns and locations of the iliac venous branches,and measured the vertical distance from vessels（including external iliac venous,internal iliac venous and obturator venous）to pelvic sides.3.Nervous system:we observed the patterns and locations of the pelvic nerves, and measured the vertical distance from nerves（including lateral femoral cutaneous nerve,genitofemoral nerve,femoral nerve and obturator nerve）to pelvic sides.4.Subsequently,all specimens underwent sham operated in the ventral decubitus. K-wire was drilled from PSIS to AIIS and the spatial relation can be observed between the wire and the vessles and nervous.At last,the dangerous region on pevic wall can be located while the wire was drilling. 5.The projection of important blood vessels and nerves on the outer surface of the pelvis:Following intestinal evisceration,each specimen was bisected in the median plane.A K-wire was used to drill the pelvic wall along lateral femoral cutaneous nerve,genitofemoral nerve,external iliac artery,internal iliac vein,internal iliac artery,obturator artery,femoral nerve and obturator nerve.After taking photos with digital camera,we import the photos into Photoshop software to draw the projection of important blood vessels and nerves with different colors on the outer surface of the pelvis respectively.Results:1.The length and angle of L_PSIS obtained from anatomic measurement,2D-and 3D-image are shown consistently.There was no significant difference among three sort values.2.In the majority measurement of L_PIIS（5 from female and 6 from male）,we found the line was below or just located the top of greater sciatic notch.As a result, the length,smallest medullary width and angle of L_PIIS were not recorded.3.All specimens had relatively straight and rectangular shaped iliac columns along L_PSIS that would allow for implant of the entire length of the column.On average,the typical female pelvis had iliac columns along L_PSIS that were 125.3 mm in length,10.8 mm in width,with the drilling angle in the horizontal plane of 25.5°laterally directed from the midsagittal plane.Generally,the typical male pelvis had iliac columns that were 135.6 mm in length,13 mm in width,with the angle of 26.3°. Considering the minimum intrailiac distances,screw lengths of 115 mm and 95 mm should always be possible for transiliac insertion into L_PSIS of male and female, respectively.Relatively,the canal length along L_IT is shorter than L_PSIS in both sexes. The typical female pelvis had iliac columns that were 117.1 mm in length,8.2 mm in width,with the drilling angle in the horizontal plane of 26.5°laterally directed from the midsagittal plane.Generally,the typical male pelvis had iliac columns that were 126.9 mm in length,10.1 mm in width,with the angle of 25.8°.Considering the minimum intrailiac distances,screw lengths of 95 mm and 90 mm should always be possible for transiliac insertion into L_IT of male and female,respectively.4.The 3D-image was reconstructed with the smallest medullary width more than 6.5 mm.Therefore,the 3D-image demonstrated the maximum safe section of the anchor for transiliac screws on bilateral ilium.Generally speaking,the safe section majority located above the greater sciatic notch without significant difference between bilateral ilium.The minimal distance above the greater sciatic notch of the safe section was approximately 31 to 42 mm.The portrait distance of anterior region between the top of the section and the superior rim of the acetabulum,just above and below the AIIS,was approximately 41 to 56 mm.Similarly,the portrait distance of posterior region from the iliac crests to the PIIS was approximately 90 to 106 mm.5.The dangerous region was located on the lateral wall of pelvic and inguinal region.The K-wire may stick into acetabulum if the drilling angle is smaller.On the other hand,the obturator artery,obturator nerve and deep iliac circumflex artery will be injured while the drilling angle is larger or the screw is longer.6.It was easily to draw the projection of important blood vessels and nerves on the outer surface of the pelvis directly and clearly.To understand the projection of the pelvis deeply may prevent vital blood vessel and nerve from accidental injury during the operation of internal fixation of pelvic fracture.Conclusions:1.There was no significant difference among anatomic measurement,2D-and 3D-image.Therefore,it implies the measurements obtained from three techniques are consistent,effective and reliable.2.All specimens had relatively straight and rectangular shaped iliac columns along L_PSISthat would allow for implant of the entire length of the column.We believe the screw lengths of 115 mm and 95 mm should always be acceptable for transiliac insertion in the eastern population of male and female,respectively.3.After 18 specimen research,we located the safe section approximately above the greater sciatic notch.Generally speaking,it could be divided into anterior and posterior parts.The anterior part was approximately same to the position previously described by other authors.The posterior part,extending from the top of iliac crests to PIIS,was mainly situated at the posterior pelvic ring.It is important in management of the severe posterior pelvic ring fracture,revision surgery after bone grafting, sacroiliac joint tuberculosis or posterior pelvic ring tumors which require at least two different starting points and screw paths or use uncommon trajectory.4.The srew can be implanted safly from PSIS to AIIS with suitable drilling ange and length.Importantly,the dangerous region was located on the lateral wall of pelvic and inguinal region.更多还原