Pelvis, acetabula——Anatomic study of internal fixation of acetabular anterior colmnn plate technique

Objective To study th best entry points, direction and length of screw in acetabular anterior colunm plate technique, and to prevent the serious complications of screw penetrating the joint surface. Methods Twenty male cadaveric adult semipelvic specimen were taken, and the distance from anterior acetabular margin, posterior acetabular margin to anterior inferior iliac spine, iliopubic eminence and pubic tubercle were measured respectively. Determine and make serial cross-sections of the acetabular anterior colunm,measure the safe angle of screw entry on all entry points of each cross-section,and put all data into software SPSS 10.0 for statistics process. Results The distance from anterior acetabular margin to anterior inferior lilac spine, iliopubic eminence and pubic tubercle was （25.4±1.4） mm,（11.8±0.7） mm and （37.4±1.5） mm respectively, the distance from posterior acetabular margin to anterior inferior lilac spine, iliopubic eminence was （15.5 ± 0.9） mm and （29.1 ±1.6） mm respectively. On each crosssection, the maximum of the safe entry angle of inclination in 0.5 cm, 1.0 cm and 1.5 cm entry point lateral to the linea terminalis of pelvis was （8.2 ± 2.2）°,（14.9 ± 3.4）° and （26.1 ± 4.5）° respectively. Conclusion When plate for internal fixation on acetabular region of anterior colunm is used, there are three ways to avoid screw penetrating the joint surface. The first way is using short screw, the direction of the screw as one＇ s pleases; the second way is using long screw close to the linea terminalis of pelvis, the direction of the screw is par allel to the quadrilateral plate; the third way is using dif ferent entry angle and length according to different entry point. 7 refs, 4 figs, 4 tabs.     

Application of spiral CT three dimentional reconstruction on developmental dysplasis of the hip in children

Objective To evaluate the value of surface shaded reconstruction (SSD) of CT scanning on developmental dysplasia of the hip (DDK). Methods Unilateral DDH in 39 cases was examined with Picker 2000S spiral CT to perform SSD of the affected pelvis. All patients were females with the age ranging from 3.5 to 8 years old ( average 4.25 years). Of 39 cases, 22 cases were complete dislocation the hip, 17 cases were subluxation of the hip. The measurement of SSD included of the depth and surface area of normal and affected acetabulum; the distances from the lowest point of the bottom of the acetabulum (O point) to the anterior end (A point) of the lateral margin of anterior acetabular column (OA), the middle point (point) of the acetabular roof (OB) and the posterior end (C point) of lateral margin of the posterior acetabular column (OC). Results In normal hip, the medial and lateral margin of the acetabular roof was overlapping, and in DDH, a bony defect was found in the lateral acetabular margin in three-dimen     

Anterolateral muscle sparing approach total hip arthroplasty:

Background Many kinds of approaches have been used for minimally invasive surgery of total hip arthroplasty （MIS-THA）. However, until now when considering the balance of efficacy and associated surgical injury there is no approach widely accepted for MIS-THA. In this study, a modified anterolateral muscle sparing approach was developed to optimize MIS-THA. Methods Twenty adult cadaver specimens （40 hips） were used for anatomic research. The distance from anterior origin of the gluteus medius on the iliac crest to the anterior superior iliac spine was measured; the course of the superior gluteal nerve and the distances from the nerve to the regional anatomic landmarks were recorded. Simulated surgeries were performed in three fresh cadaver specimens to evaluate the soft tissues injury around incisions. From October 2004 to June 2006, 57 patients （57 hips） were treated with anterolateral muscle sparing minimally invasive total hip arthroplasty, of which 17 were femoral neck fractures, 9 osteoarthritis, 16 developmental dysplasia of hip （DDH） and 15 avascular necrosis （AVN）. All the operations were performed by the same senior surgeon. Operation time, blood loss and drainage volume were recorded and the correlation between the local complications and the native anatomical characteristics was especially noted. All cases were followed for at least 12 months. Results The distance from the anterior origin of the gluteus medius to anterior superior iliac spine along the iliac crest was （61±4） mm （range, 55-68 mm）, and the distance from inferior branch of the superior gluteal nerve to the anterior tubercle of the greater trochanter was （74±6）mm （range, 60-88 mm）. In simulated surgeries, excessive distraction of tissue was found to be the main cause of the anterior border injury of the gluteus medius muscle. Of the 57 patients treated with anterolateral muscle sparing MIS-THA, the average incision length was 9 cm （range 7.5-13 cm）. Blood transfusions were performed in 11 patients.     

Strain rate imaging in assessing the size of acute ischemic myocardium in dogs

Background Since the size of ischemic myocardium is closely related with both global and regional function of the myocardium, it is of great significance to measure the size of ischemic myocardium with non-invasive methods. Methods Eleven mongrel dogs were subjected to occlusion of the left anterior descending coronary artery for acute ischemia. Strain rate imaging had M-mode of strain-rate （CAMM） curve pointed from the basal segment of the anterior wall to the basal segment of the inferior wall to detect the border of ischemia size. The strain rate （SR） defined the cut-off value of ischemic myocardium in a two-chamber apical view, and marked by the anterior and inferior wall on two-dimensional images respectively. Along the endocardium and epicardium, the ischemic size was curved on two-dimensional images by the trackball method and then compared with the pathologically ischemic size. And then longitudinal strain rates were compared in the cut-off value, adjacent non-ischemic and ischemic segments at which the cut-off point was defined by changing the curve M-mode of strain rate after ischemia. Results Linear correlation existed between pathology and strain rate ischemic size （r=0.884, P 〈0.001）. The SR parameters were lower in ischemia and cut-off point than in non-ischemic segments. The peak SRs of systole （SSR）, early diastole （EsR）, late diastole （ASR）, strain during ejection time （εet）, and the maximum length change during the entire heart cycle （Emax） in ischemic segments lowered （P〈0.05）. Time to onset of regional relaxation （TR） was prolonged （P=0.012）. Conclusion SR imaging can accurately assess the size of ischemic myocardium. Chin Med J 2009; 122（2）： 193-198     

Clinical study of the ascending aorta wall motion by velocity vector imaging in patients with primary hypertension

We studied the wall motion characteristics of the ascending aorta by velocity vector imaging （VVI） in primary hypertension patients. The ascending aortas both in 30 patients with primary hypertension and 30 normal controls were examined by Acuson sequoia 512 equiped with VVI. The maximum velocity （Vs, Ve） of every point on the anterior wall of ascending aorta both in systole and diastole was measured. The aortic diameter was wider in the hypertension patients than that in the healthy subjects （P〈0.05）. The movement amplitude of the anterior wall of the ascending aorta in long axis view in the hypertension patients was lower than that in the healthy subjects （P〈0.05）. The motion and time to peak in systole of each point of the ascending aorta in the healthy subjects had no significant difference （P〉0.05）. The velocity curves of the anterior wall of ascending aorta both in the hypertension and healthy subjects were regular, and the curve in systole was named S wave and that in diastole named E wave. The velocity of S wave and E wave was slower in the hypertension patients than that in the healthy subjects （P〈0.05）. The time to peak of S wave on the anterior wall of ascending aorta in systole was shorter in the hypertension patients than in the healthy subjects （P〈0.05）. VVI could be used to accurately and directly observe the movement character of the ascending aorta walls, which would help us understand the elasticity of great arteries in patients with hypertension.     

Evaluation of damage to trabecular bone of the osteoporotic human acetabulum at small strains using nonlinear micro-finite element analyses

Background With advance of age, alterations in bone quality, quantity and microarchitecture render osteoporotic trabecular bone become more sensitive to local failure. The aims of the present study were to clarify the extent to which the distribution of tissue-level stresses and strains was affected by structural changes and the extent to which osteoporotic acetabular trabecular bone was damaged at small strains. Methods Using a DAWING 4000A supercomputer, nonlinear micro-finite element （μFE） analyses were performed to calculate the tissue-level strains and stresses for each element in the trabecular bone of one osteoporotic acetabulum at small strains to quantify the tissue-level damage accumulation and mechanical properties. Results In contour plots of the tissue, maximum principal logarithmic strains, high tissue-level strains, both compressive and tensile, were observed in the osteoporotic trabecular bone at small apparent strains from 0.2% to 0.5% strain. The compressive apparent stress-strain curve showed typical nonlinear behavior and tangent modulus reduction with increasing strains. The microdamage curve suggested that microdamage began at 0.2% apparent strain in the osteoporotic trabecular bone and increased sharply, although very few microfractures occurred. The quartiles of the maximum principal logarithmic strains, minimum principal logarithmic strains and Von Mises stresses increased nonlinearly. For the inter-quartile range of the Von Mises stresses, a leap occurred at small strains ranging from 0.2% to 0.3% while microdamage commenced. Conclusions Extensive microdamage was primarily responsible for the large loss in apparent mechanical properties that occurred in the trabecular bone of the osteoporotic acetabulum at small strains. With increasing apparent strains, continuous nonlinear increments of tissue-level strains and stresses resulted in microdamage that propagated throughout the specimen with very few microfractures. Chin Med J 2009; 122（17）：2041-204 7     

Hipbone Biomechanical Finite Element Analysis and Clinical Study after the Resection of Ischiopubic Tumors

Objective To investigate the changes of hipbone biomechanics after the resection of ischiopubic tumors and their relationships with the complications in the convalescent stage, and directing the postoperative pelvic reconstruction. Methods DICOM data were used to create an intact hipbone finite element model and postoperative model. The biomechanical indices on the same region in the two models under the same boundary condition were compared. The differences of displacement, stress, and strain of the two models were analyzed with statistical methods. Results The distribution areas of the hipbone nodes’ displacement, stress, and strain were similar before and after the simulated operation. The sacroiliac joint nodes’ displacement (P=0.040) and strain (P=0.000), and the acetabular roof nodes’ stress (P=0.000) and strain (P=0.005) of two models had significant differences, respectively. But the sacroiliac joint nodes’ stress (P=0.076) and the greater sciatic notch nodes’ stress (P=0.825) and strain (P=0.506) did not have significant differences. Conclusions The resection of ischiopubic tumors mainly affect the biomechanical states of the homolateral sacroiliac joint and acetabular roof. The complications in the convalescent stage are due to the biomechanical changes of the sacroiliac joint and the acetabular roof and disappearances of the stabilization and connection functions of the pubic symphysis and superior ramus of pubis.     

An anatomical comparison of two minimally invasive pelvic reconstructive surgeries using fresh female cadavers

Background During the past decade, graft materials have been widespread used in the vagina in order to correct pelvic organ prolapse. The aim of this study was to describe and compare the exact anatomical position of the puncture devices and their relations to the relevant anatomical structures in the ProliftTM and a modified pelvic reconstructive surgery with mesh. Methods Twelve fresh cadavers were allocated randomly to either the ProliftTM or the modified pelvic reconstructive surgery group. Each group had six fresh cadavers. Relevant distances between the puncture devices and anatomical structures were recorded in both minimally invasive puncture surgeries. Results The mean distances from the posterior puncture points of the obturator membrane to the posterior branch of obturator arteries were shorter （（0.60＋0.36） cm and （0.78＋0.10） cm） when compared with the distances to the anterior branch of obturator arteries （（1.53＋0.46） cm and （1.86＋0.51） cm） for the reconstruction of the anterior compartment in both surgeries （all P 〈0.05）. The distance from the puncture points of the pelvic floor through the ischiorectal fossa to the coccygeal and inferior gluteal arteries in the ProliftTM technique （（0.88＋0.10） cm） and （（1.59＋0.36） cm））were much shorter than that in the modified pelvic reconstructive surgery （（2.95＋0.09） cm） and （（3.40＋0,36） cm）） for the reconstruction of the middle and posterior compartments （all P 〈0.05）. Conclusions Compared with the ProliftTM technique, the modified pelvic reconstructive surgery with mesh would be safer not to cause great damage to the inferior gluteal arteries and the coccygeal arteries, The posterior branch of obturator arteries would be easier to be injured than the anterior branch of obturator arteries during anterior compartment reconstruction in both surgeries.     

Selection of allografts for impaction bone grafting for bone defect reconstruction on the acetabular side

Objective To review the choices of allografts for bone defect reconstruction in acetabular revision surgery using the technique of impaction bone grafting.Data sources The data cited in this review were mainly obtained from articles listed in PubMed that were published from January 1993 to July 2009. The search terms were ＂impaction bone grafting＂, ＂particle size＂, ＂mechanical property＂and ＂biological behavior＂.Study selection Articles relevant to the choices of allografts and their results for bone defect reconstruction on the acetabular side were selected.Results Different choices of allografts, including the particle size, process of irradiation or fat reduction, composition and particle grade, are made to improve the survival rate of a prosthesis in acetabular revision surgery. This review,which compares both mechanical and biological factors, summarizes the experimental and clinical results for different techniques.Conclusions Fresh frozen cancellous allografts with particle sizes ranging from 7 to 10 mm are a favorable choice for reconstruction of bone defects of American Academy of Orthopedic Surgeons （AAOS） types Ⅱ （cavitary defect） and Ⅲ（combined cavitary and segmental defect） on the acetabular side. A fat-reducing procedure with saline or solvent/detergent is controversial. Adding autologous marrow into irradiated allografts, which provides reliable mechanical stability and biological safety, may be a substitute for fresh frozen allografts. Cortical bone can be a supplementary material in cases of insufficiency of cancellous allografts. Cartilage should be excluded from the graft material. Further research is required to demonstrate the best particle grade, and randomized controlled trials in clinical practice are required to obtain more information about the selection of allografts.     

Assessment of right ventricular function by pressure-volume loops in off-pump coronary artery bypass surgery

Background Right ventricular function plays an important role in the hemodynamic derangement during off-pump coronary artery bypass （OPCAB） surgery. Pressure-volume loops have been shown to provide load-independent information of cardiac function. Therefore, the aim of this study was to investigate the feasibility of construction of right ventricular pressure-volume loops with pressure and volume data measured by a volumetric pulmonary artery catheter （PAC） and to evaluate right ventricular systolic and diastolic function by end-systolic elastance （EEs） and end-diastolic stiffness （EED） in OPCAB surgery.
Methods Twenty-eight patients who underwent OPCAB surgery were included. After anesthesia induction, a volumetric PAC was placed via the right internal jugular vein. Data were recorded at： anesthesia steady-state before skin incision （T1）; 5 minutes after the stabilizer device was placed for anastomosis on the heart＇s anterior wall （T2）, lateral wall （T3）, posterior wall （T4）, respectively; after sternal closure （T5）. Three sets of data were collected at each time point： first, hemodynamic variables were measured; second, right ventricular EEs and EED were calculated; third, right ventricular pressure-volume loops were constructed with pressure and volume data measured from end-diastole point, end-isovolumic systole point, peak-ejection point, end-systole point and end-isovolumic diastole point.
Results Right ventricular pressure-volume loops generally shifted to the left during OPCAB surgery. Especially, the end-diastolic point shifted upward and to the left at T2--T5 compared with that at T1. Decrease in right ventricular ejection fraction, stroke volume index and end-diastolic volume index occurred （P 〈0.05） at T4 compared with values at TI. Pulmonary vascular resistance index at T4 increased relatively compared with that at T2 and T3. The change of EEs was not statistically significant during operation. Right atrial pressure increased only during coronary an     

骨盆后环微创螺钉的钉道设计及骨盆三维有限元分析

目的 收集测量骨盆后环解剖数据,设计微创螺钉的钉道,并通过建立骨盆有限元模型,进行三维有限元分析,为后续骶骨骨折及微创螺钉的研究设计打下基础。方法 测量20例健康志愿者骨盆数据,初步筛选确定骨盆后环微创螺钉的设计数据,并建立骨盆有限元模型,进行三维有限元分析,分别进行静态和动态力学加载,进行骨盆有限元模型验证。结果 完成健康志愿者骨盆CT数据测量后,对骨盆进行三维重建,并选择A、B、C 3条髂骨钉钉道,获取钉道A、B、C相关数据,测量结果显示:B、C钉道长度和宽度大于A钉道,钉道进钉点与软组织的距离较A钉道短。建立正常骨盆有限元模型后,静态力学加载结果显示,在施加500 N的外旋载荷下,骨盆受到的最大Von Mises应力为582.05 Pa;骶髂复合体处的受力为107.38 Pa;应变分布显示,在500 N的外旋载荷下,应变分布最大的部位在同侧骶髂关节软骨,对侧骶髂关节软骨和耻骨联合的应变次之。位移分布显示,在500 N的外旋载荷下,位移分布最大的部位在同侧髂骨,沿着同侧对侧方向,位移分布呈梯度降低。同侧髂前上棘处的位移最大为0.35 cm。动态力学加载结果显示,髂前上棘在Z轴方向的位移是1.5 mm,在X轴方向的位移是1.8 mm,在Y轴方向的位移是-0.2 mm。耻骨联合在Z轴方向的位移是0.8 mm,在X轴方向的位移是1.0 mm,在Y轴方向的位移是0.03 mm。Y轴,即沿冲击方向的位移最大。等效应力在耻骨支、坐骨、髂前上棘、骶骨、髋臼等骨折易发生处应力相对较大。随着冲击力的增加,骨盆受到的应力随着时间增大,冲击力下降,其应力也呈下降趋势。冲击力、应力、骨盆位移的最大值在10 ms处,即达到峰值力时候的冲击时间。在4 000 N和5 000 N的冲击力作用下,骨组织的应力超过了200 MPa,超过了其平均屈服强度,提示此时可能会出现骨盆骨折。结论 通过数据测量及分析,得出B/C钉道作为主钉道,A钉道作为辅钉道的设计合理;建立的骨盆有限元模型可作为后续骶骨骨折及内固定模型研究及对比研究的基础。     

垂直应力影响骨盆环应力分布的实验研究

目的：应用三维光弹力学实验，研究垂直应力对骨盆环应力分布的影响。方法：我敏材料E－51环氧树脂制作人体骨盆三维光弹模型共8具（16个髋关节）。骨盆模型加模型垂直作用力，模型应力冻结，测量和分析骨盆环的应力分布及应力改变。结果：双腿站立及垂直应力下，等色线条纹集中在骶髂关节和髋臼附近，垂直应力主要通过骶髂关节，髂骨弓状线处，髋臼穹顶及骶骨传导，随着垂直应力的增加，骶髂关节，髂骨弓状线处，髋臼穹顶及骶骨等部位的应力明显增大（P＜0．05）；耻骨上支的应力也增大（P＞0．05）。结论：垂直应力作用下，骨盆环的应力分布复杂，骨折易发生在骶髂关节，髂骨，髋臼穹顶骶骨等部位，耻骨上支传导部分垂直应力；治疗垂直不稳定型骨盆骨折时应复位及内固定上述损伤部位。     

多层螺旋CT三维重建技术与X线影像学检查在盆骨骨折诊治中应用比较

目的多层螺旋CT三维重建技术与X线影像学检查在骨盆骨折诊治中应用比较。方法选取我院2014年7月至2016年7月70例骨盆骨折患者为研究对象,所有患者均给予多层螺旋CT三维重建与X线影像学检查,以病理学诊断结果为准,比较两种影像学检查对骨盆骨折的诊断结果。结果 70例患者共有113处骨折,多层螺旋CT三维重建对各种部位骨折的诊断率均为100%,X线片对髋臼后唇、后柱及骶髂关节骨折漏诊5例,髋臼中间壁骨折漏诊4例,髋臼顶壁、骶尾骨、髂骨翼骨折漏诊各3例,诊断准确率为79.65%。多层螺旋CT三维重建与X线检查对髋臼前唇、前柱,髋臼顶壁,耻骨上、下支,坐骨上、下支,骶尾骨,髂骨翼,耻骨联合分离诊断率比较无统计学意义(P0.05);多层螺旋CT三维重建对髋臼后唇、后柱,髋臼中间壁及总骨折诊断率均高于X线片,有统计学意义(P0.05)。结论多层螺旋CT三维重建可明确诊断各种类型的骨盆骨折,诊断率非常高,还可全面、精确地反映出骨折部位的空间构象及骨盆的立体形态,具有较好的临床应用价值。     

犬髋臼后壁重建模型的建立及其生物力学分析

目的建立一种模拟髋臼后壁缺损的动物模型,评价不同后壁重建方法对髋臼与股骨头间接触特性的影响。方法获取6具新鲜成年家犬骨盆股骨标本,采用后壁截骨法建立髋臼后壁60°弧1/2缺损的动物标本模型;两侧缺损区分别选用不同的重建方法 ,采用压敏片检测不同状态下头臼接触面积及接触应力。结果与完整髋臼相比,后壁重建使头臼接触面积有所减少;在250N载荷下,解剖重建组头臼接触面积与普通重建组比较差异无统计学意义;其平均接触应力小于普通重建组(P<0.05),说明解剖重建组应力集中小于普通重建组。结论后壁截骨法建立的犬髋臼后壁缺损模型可有效模拟临床实际;解剖重建使后壁头臼接触面积及应力分布恢复比较理想,接近正常髋关节,避免了局部应力集中。     

髋臼发育不良的生物力学实验研究

目的：应用三维光弹性实验研究髋臼发育不良的生物力学特性,方法：应用光敏材料E－51环氧树脂制作4套髋臼发育不良的骨盆模型,模型加载,应力冻结,测量分析髋臼的应力分布及形态改变。结果：髋臼发育不良之髋臼内壁剪切应力异常集中于髋臼顶部及后上缘,较髋臼前缘应力增加4－6倍,负重后正常骨盆髋臼外口呈椭圆形改变,髋臼发不良时髋臼无明显形态改变。结论：髋臼发育不良可引起髋臼生物力学环境发生改变;髋臼内壁应力分布不均以及髋臼顶部剪切应力成倍增加,交导致髋关节骨关节炎的发生。     

常规C型臂X线机下骨盆髋臼骨折置钉技术及影像学评估

目的探讨和总结在常规C型臂X线机下骨盆髋臼术中螺钉位置的影像学评估。方法根据文献资料和笔者骨盆髋臼骨折手术病例,介绍在常规C型臂X线机下髂骨螺钉、耻骨上支螺钉（前柱螺钉）、坐骨螺钉（后柱螺钉）、骶髂关节螺钉技术和术中螺钉位置的影像学评估。结果出口一闭孔斜位能显示髂骨内外板,此影像可用来判断外固定支架髂嵴螺钉固定针植入深度和是否位于髂骨内外板之间;髋臼上缘外固定支架固定针从髂前下棘至髂后上棘的致密骨道,在闭孔-出口位相上,螺钉或固定针应位于泪滴中央、髂骨斜位证实螺钉进入深度和位于坐骨大切迹上方;髂后上棘螺钉可利用出口-闭孔斜位相见螺钉在泪滴征中央,入口-闭孔斜位可证实螺钉在骨皮质中;前柱螺钉位置监测可采用出口-闭孔斜位、入口-髂骨斜位和入口位来完成;后柱螺钉位置和长度通过髂骨斜位来判断;骶髂螺钉固定植人过程中,骶骨侧位结合出口位、入口位判断螺钉的正确位置。结论临床医生应熟悉骨盆正常骨性结构、血管位置、骨折类型、骨折移位情况和术中不同的位相意义。     

组配式人工半骨盆假体置换术后骨盆静态生物力学三维有限元分析

目的研究分析正常骨盆及术后重建骨盆健侧与组配式人工半骨盆假体在不同体位下应力分布情况,从静态生物力学角度为组配式人工半骨盆假体置换术的合理性及安全性提供依据。方法采用CT薄层扫描采集原始数据,分别建立正常骨盆和组配式人工半骨盆假体置换术后骨盆及假体的三维有限元模型,并分别在双脚站立、患侧单脚站立及坐位3种静力状态下进行生物力学加载,分析正常骨盆及术后骨盆和假体在不同体位下应力分布情况。结果在正常骨盆和重建后骨盆两种模型中,不同体位相同载荷下健侧骨盆应力值相差不大,在骶骨正中面上部、骶髂关节、坐骨大切迹上缘骨皮质及坐骨结节处达到最大值,其应力最大值远小于健侧骨盆的疲劳强度;患侧组配式半骨盆假体不同体位时应力最大值均出现在髋臼杯上方CS内固定器与髋臼杯连接部内侧,所受最大应力均远低于其疲劳强度;组配式半骨盆假体重建后骨盆不同体位时应力的分布规律与正常骨盆基本一致。结论组配式人工半骨盆假体置换术对健侧骨盆影响较小;静态不同体位下健侧半骨盆及组配式人工半骨盆假体的最大应力值均明显小于各自的的疲劳强度,健侧骨盆和组配式人工半骨盆假体安全性好;采用组配式人工半骨盆假体重建后的骨盆符合人体正常生物力学规律。     

髋臼三维有限元模型的建立

目的:构建髋臼三维有限元模型.方法:选择成年湿髋臼尸体标本行CT扫描成像得到髋臼每层横截面图像,提取边界坐标,利用有限元分析软件ANSYS5.6构建髋臼三维有限元模型,三维十结点四面体实体单元进行网格划分.结果:所构建髋臼模型共划分为121 239个结点、112 491个单元,客观反映髋臼真实解剖形态及生物力学行为.结论:构建的髋臼三维有限元模型为髋臼骨折内固定的记忆力学研究提供可循模型.     

计算机辅助影像导航经皮螺钉内固定治疗髋臼骨折的实验研究

目的 确定标准的术中透视图像,作为计算机辅助影像导航经皮螺钉内固定治疗髋臼前、后柱骨折的注册图像.方法 选取干燥尸体骨盆4具、模型骨盆4具作为骨折模型.直视徒手将2.5 mm导针置入髋臼前、后柱(双侧);双侧前柱导针分别采用逆行及顺行置入,后柱导针采用逆行植入;目视确认导针位置满意后,将骨盆固定于影像导航手术模拟操作模块,应用C形臂x线透视机,针对髋臼结构的前、后、外、内4个虚拟平面的垂直方向进行多角度连续动态透视,选择并确认能够清楚显示导针与前后柱、髋臼关节面的透视影像,作为导航手术的注册图像,记录此时c形臂x线透视机与骨盆、手术床的相对空间位置.依此注册图像,在导航手术系统辅助下,应用6.5 mm的钛中空螺钉进行髋臼前、后柱螺钉置入.每个骨折模型,每侧进行1次操作,共16次.目测螺钉位置、分别记录为获取标准注册图像C形臂摆放时间、透视时间、手术操作时间(导航系统建立,软件界面操作及螺钉植入操作的总时间).结果 所有螺钉置入位置满意,未进关节;前柱螺钉置入需要闭孔斜位(Judet-Letoumel斜位)、闭孔人口位、闭孔斜出口位、骨盆正位像;后柱螺钉置入需要髂骨斜位、闭孔斜位、骨盆入口位、闭孔斜出口位像;为获取前柱、后柱标准注册图像摆放C形臂X线透视机的时间平均分别为9.5、7.3 min,前柱、后柱每枚螺钉置入术中透视时间平均分别为2.9、1.7 S,前柱、后柱每枚螺钉置人操作时间平均分别为11.7、9.2 min.结论 导航注册图像不同与传统的Judet-Letoumel影像,如何正确获取标准的术中透视注册图像,是确保安全、准确实施影像导航辅助经皮螺钉内固定手术的关键.     

Perfect与Replace种植体延期负重颈部骨应力比较

目的：研究延期负重时Perfect种植体与Replace种植体颈部骨质应力分布情况。方：借助医用CT电子扫描技术、图像传输与转换技术以及三维有限元软件模拟建立上颌骨前牙区的三维有限元模型,分别模拟植入Perfect种植体及对照组的Replace种植体,比较分析两种种植体在即刻负重时牙槽嵴顶皮质骨的应力分布情况。结果：延期负重时,Perfect种植体在牙槽嵴顶部的等效应力和压应力略小于Replace种植体在牙槽嵴顶部的等效应力和压应力,拉应力则略大于Replace种植体在牙槽嵴顶部的拉应力。结论：延期负重条件下,Perfect种植体在牙槽嵴皮质骨的应力分布与Replace种植体相似,仅从生物力学方面考虑,Perfect种植体不会加快种植体颈部牙槽嵴的吸收速度。