A Digital Anatomy Research For Improved Nailing On Supra-Acetabular Of Pelvic External Fixation

Objective: By means of analysing and summurying all the previous research datas about using external fixator to treat and cure pelvic fracture through nailing on supra-acetabular by centering anterior inferior iliac spine.We improved the supra-acetabular nail tract to optimize the clinical operations.Here,We accurately did the surveying research for the improved the supra-acetabular nail tract with the digital anatomy measurement tool.Method: One hundred normal pelvic computed tomography(CT)scans and three-dimensional digital model reconstruction image datas from 2014-9-1to 2015-9-1 were chooosed,including 60 cases of male and 40 females(average44 years)and all patients' image datas come from The First hospital of QinHuangDao imaging department,to be measured some datas of improved technology for nailing on supra-acetabular through using the PACS image browsing software.These measurement datas are divided into two parts according to their different functions.Firstly,Selecting the pelvic CT scans image that corresponds to anterior inferior iliac spine,we used its liner measurement tools to measure the length and diameter of the improved supra-acetabular nail tract which the bone of the plane corresponding to anterior inferior iliac spine above the acetabulum can provide;we used its angular measurement tools to measure the angle between nail tract and sagittal plane of body;Taking the anterier-positerior image of pelvic,the distance relationships between the nail point(the center of anterior inferior iliac spine)and the center of anterior uperior iliac spine were measured by its calibrating tool.All results will be divided and compared according to gender.Secondly,Choosing the three-dimensional digital reconstruction image of pelvic,respectively selecting fixed two level from anterior inferior iliac spine and anterior superior iliac spine on the iliac wing,we compared the value of CT(the CT value is behalf on the attenuation after absorbed when the X-rays pass through organization)for these two level.All datas were analyzed by SPSS17.0 software package.Results: The effective length of the improved supra-acetabular nail tract which the bone of the plane corresponding to anterior inferior iliac spine above the acetabulum can provide in male is(79.08±1.03)mm,while in female is(74.08±0.68)mm.The minimum diameter of the nail tract in male is(19.13±0.61)mm,versus in female is(14.36±0.64)mm.The transverse distance from anterior superior iliac spine to anterior inferior iliac spine in male is(24.13±0.76)mm,while in female is(22.35±0.57)mm.The vertical distance from in male is(28.49±0.91)mm,,while in female is(26.93±0.68)mm;The angle of improved pin tract in male is(20.51±0.65o),while in female is(22.22±0.62o);All datas are accord with normal distribution,and compared between groups which are divided by sexes.They are conformed to the homogeneity of variance and the statistically difference is significant(P <0.05);The CT values of level from anterior inferior iliac spine and anterior superior iliac spine on the iliac wing were measured.All datas were divided into different groups according to age and compared by bar charts.The average CT values of anterior inferior iliac spine all are higher than the level of anterior superior iliac spine on the iliac wing,and all bone's density reduce along with the age growth.Conclusion: When using external fixation to cure pelvic fracture,especially the type B pelvic fracture whose anterior pelvic ring is unstable,we can Nail above the acetabulum to fixed firmly and get biomechanical advantages.Now we will improve the means of nailing on supra-acetabular :taking anterior inferior iliac spine as the nail point,paralleling the coronal plane of body,nailing on the anterior inferior iliac spine above acetabular within the security scope of angle between nail tract and sagittal plane of body.This new nailing means can make the operation simply and reduce the unnecessary damage.The bone of the plane corresponding to anterior inferior iliac spine above the acetabulum is large enough to provide the safe and effective width and length of nail tract;while its bony density is so high that can provide the stable union area for nail and bone.Doctors who master the relevant data and angle of this new nail tract,will operate quickly and accurately and avoid deputy injury extremely.