正常膝关节几何学及其参数的测量

目的 建立正常典型的膝关节三维解剖模型，并对之进行测量。方法 对正常膝关节进行扫描，以数字化的形式输入到计算机中，建立典型膝关节三维解剖模型，并对其线性、角度等15项指标进行测量。结果 ①所建立的膝关节三维解剖模型，代表了绝大多数人的膝关节特征；②膝关节线性尺寸之间、身高与线性尺寸之间均有很好的相关性；③角度指标是相对独立的一组指标。结论 典型的膝关节三维解剖模型，能为膝关节参数的测量提供一种可靠的方法。     

正常人与尸体膝关节MRI二维图像重建前交叉韧带三维模型的比较研究

目的探讨基于MRI二维图像重建正常成人膝关节前交叉韧带(anterior cruciate ligament,ACL)三维模型的真实性。方法选择20例新鲜成人尸体双膝关节标本及20例正常成人志愿者双膝关节,采用MRI对膝关节进行扫描,获得层厚为1.0 mm连续图像资料,将其导入医学有限元仿真软件Mimics 10.01进行三维重建,建立包含ACL的完整双膝关节三维模型(尸体模型组及正常模型组)。利用医学有限元仿真软件Mimics 10.01自带测量工具测量ACL解剖指标;并对20例新鲜成人尸体双膝关节标本进行解剖,测量ACL解剖指标(尸体标本组)。结果尸体模型组各测量指标与尸体标本组比较,差异均无统计学意义(P>0.05);与正常模型组比较,差异亦无统计学意义(P>0.05)。结论采用MRI二维图像数据可三维重建正常成人膝关节ACL三维模型,且具有真实性。     

国人正常膝关节三维几何形态测量及相关研究

目的:利用计算机辅助设计技术建立国人正常膝关节三维模型并行骨形态测量研究,得到国人膝关节相关指标正常参考值,探讨此方法对假体设计的指导意义.方法:对120例240个正常成人膝关节CT扫描输出的原始数据进行三维重建,测量相关参数.结果:股骨内、外侧髁宽度与胫骨内、外侧平台宽度相近;股骨髁宽相对于胫骨平台宽比值在1.01～1.08之间,相对于股骨髁前后径比值在1.12～1.23之间;股骨髁宽与胫骨平台宽呈正相关.股骨后髁内、外侧关节面呈半径相等的圆形结构,股骨髁上轴线在膝关节屈曲时可以近似为屈曲固定轴.结论:建立了国人正常膝关节相关参数指标正常参考值;计算机辅助设计技术为膝关节复杂表面几何大体形态学研究提供一种良好的手段.     

浅议骨骼CT图像的三维重建及其临床意义

目的通过骨骼三维图像重建研究其方法和阐述其临床意义。方法对正常的髋膝关节和髋关节中心性脱位各1例CT扫描图像进行三维图像重建,分4步进行,设定层厚、层距行CT扫描并将图像输入工作站中;锐化各CT图像层面的骨组织边界并建立文件;建立网格立体图,经修正后获得光滑三维骨骼图像;在三维图像上行测量和模拟匹配。结果不同角度观察骨骼形态及其比邻关系和髓腔内三维形态,测量骨骼的长度、角度、弧度、面积和容积等,模拟假体在三维图像上行匹配,从中选择最佳假体。结论骨骼的三维重建克服了X线片和CT图像的不足;可进行常规方法难以完成的解剖测量;可形象准确选取最佳型号的髋臼假体;可模拟再现手术过程;是将来计算机辅助手术的重要基础。     

膝关节有限元解剖模型的构建及其力学分析

目的通过多模态CT和MRI影像数据融合构建膝关节有限元解剖模型,并进行有限元分析和验证,为膝关节力学仿真研究提供可靠的有限元模型。方法采集正常膝关节CT和MRI影像数据,导入到Mimics软件中,构建膝关节骨骼、半月板、关节软骨、韧带等结构的三维模型。以外部标记为参照点进行模型配准,融合成膝关节整体模型。在Hypermesh软件中进行网格划分,构建膝关节有限元模型。通过解剖观察和测量对有限元模型进行解剖真实度评估,对其设置材料属性、建立边界条件和施加载荷,进行有限元分析,并验证。结果基于CT和MRI影像数据构建出包含骨骼、半月板、关节软骨、韧带等多种组织结构的膝关节有限元整体模型,模型保持了膝关节的解剖学特征,有限元分析结果与文献报道的结果一致,显示有限元模型可靠、有效。结论通过多模态CT和MRI影像数据融合可以构建符合解剖学特征的膝关节有限元整体模型,能为研究膝关节生物力学行为提供可靠、有效的有限元模型。     

准确构建个体化膝关节有限元解剖模型的方法

目的利用多模态影像数据融合和多种建模软件协同应用的方法准确构建膝关节有限元解剖模型,为研究膝关节生物力学行为奠定基础。方法采集正常膝关节CT和MRI影像数据,导入Mimics软件,提取骨、软骨、韧带和半月板,分别构建三维工程化模型。以外部标记物为参照进行模型的配准融合。将膝关节工程化模型导入SC/Tetra和Hypermesh软件,分别进行干涉面删除、网格自定义划分、局部网格优化和体网格划分,构建包含多解剖结构的膝关节有限元模型。结果基于CT和MRI影像数据构建出膝关节骨、软骨、韧带和半月板的三维工程化模型。以三维工程化模型为基础,多种建模软件协同应用构建的有限元模型充分保持了膝关节各结构的解剖学特征。结论利用CT和MRI影像数据融合和多种建模软件协同应用的方法可以构建活体膝关节有限元模型,并保持膝关节各解剖结构的解剖真实性,为准确模拟膝关节生物力学特征提供前提。     

基于CT和MRI影像数据融合构建个体化OA膝关节三维解剖模型

目的探究一种基于CT和MRI影像数据融合构建包含主要解剖结构的骨关节炎(OA)膝关节三维模型的方法,并准确表达膝关节OA的解剖学特征。方法采集膝关节OA患者的CT和MRI影像数据,以DICOM格式导入Mimics软件中构建膝关节骨性结构模型和非骨性结构模型,基于图像特征的同层多点至多点的配准方法进行配准融合,构建OA膝关节三维解剖模型。结果基于CT和MRI影像数据融合构建出包括膝关节骨骼及关节软骨、半月板、韧带等结构的膝关节OA三维解剖模型,模型显示了关节间隙狭窄、半月板损伤、关节软骨磨损等膝关节OA的解剖学特征。结论通过CT和MRI影像数据融合可以个体化构建膝关节OA三维解剖模型,该模型能够真实且直观地展示骨性结构和非骨性结构的解剖学特征和空间解剖关系,为相关解剖学及生物力学研究提供三维解剖模型。     

正常髌骨几何学及其参数的测量

目的建立正常髌骨三维解剖模型,并对其参数进行测量。方法对96个正常髌骨进行三维CT扫描,按身高不同分为3组(Ⅰ组:156~165 cm,Ⅱ组:166~175 cm,Ⅲ组:176~185 cm),每组左右髌骨各16个,建立每1个髌骨的三维解剖模型,并对其关节面的高与宽、嵴的厚度、嵴距外缘、嵴距内缘、内侧关节面中心厚度、外侧关节面中心厚度进行测量。结果①建立的髌骨三维解剖模型,代表了大多数人的特征;②髌骨厚度Ⅰ组:左(19.99±0.28)mm,右(20.00±0.30)mm;Ⅱ组:左(23.17±0.26)mm,右(23.22±0.11)mm;Ⅲ组:左(25.38±0.16)mm,右(25.51±0.09)mm;髌骨关节面宽度Ⅰ组:左(36.90±0.14)mm,右(36.78±0.21)mm;Ⅱ组:左(42.50±0.30)mm,右(42.61±0.05)mm;Ⅲ组:左(46.81±0.21)mm,右(45.95±0.33)mm;髌骨关节面高Ⅰ组:左(28.78±0.23)mm,右(28.61±0.18)mm;Ⅱ组:左(31.89±0.12)mm,右(32.01±0.08)mm;Ⅲ组:左(33.82±0.23)mm,右(33.80±0.20)mm。结论典型的髌骨三维解剖模型,能为正常人髌骨参数测量提供可靠的依据。     

半月板三维有限元模型建立及力学分析

目的:建立正常膝关节及半月板三维有限元模型,较真实模拟膝关节及半月板的解剖形态及特点,通过初步有限元生物力学分析验证模型的有效性,并阐释半月板的部分生物力学机制。方法:利用CT和MRI扫描一健康男性志愿者膝关节获得其图像信息,导入至Mimics 10.01及Geomagic Studio软件构建膝关节各组织结构三维模型,利用ANSA软件对结构模型进行组合建立完整的膝关节模型,并对模型进行网格划分,最终建立了完整膝关节三维有限元模型。最后将有限元模型导入到ANSYS软件中,设置材料属性、建立边界条件和施加载荷,进行有限元分析,验证模型有效性,并分析半月板的生物力学特性。结果:所建立的模型包含膝关节骨、关节软骨、半月板及主要韧带结构,能有效模拟膝关节及半月板的解剖形态及特点。内侧半月板接触面积为771.05 mm2,外侧半月板接触面积为634.31 mm2,内外侧半月板接触面积比为1.216。内外侧半月板的应力分布均匀,但内侧半月板所受应力高于外侧半月板,其峰值应力分别出现在内侧半月板后角及外侧半月板前角,其峰值应力为4.11 MPa。半月板最大位移位于其体部,内侧较外侧形变更大,最大位移形变值为0.33 mm。所获得的力学分析结果于文献相一致,验证了模型的有效性。结论:本研究所建立的膝关节及半月板有限元模型具有有效性,可为半月板撕裂及半月板切除术等有限元分析研究提供有效的模型。所获得的有限元分析结果能够阐释半月板的部分生物力学机制,为临床半月板损伤和治疗提供理论指导。     

虚拟现实互动技术在交叉韧带等长重建计算机辅助设计中的应用

目的 利用虚拟现实技术还原膝关节骨性结构在屈伸运动过程中的三维空间形态，为观测膝关节面交叉韧带附丽区的相对位置变化和进一步研究前、后交叉韧带等长重建最佳等长点提供计算机辅助设计新方法。方法 采用实验与计算机仿真相结合的方法，对新鲜人体膝关节标本进行屈伸运动实验，并通过激光三维扫描方法记录、计算膝关节的空间活动指标，然后重建膝关节计算机三维模型。通过实验中的空间活动指标控制此模型虚拟运动，再现膝关节各屈伸角度下股骨、胫骨和腓骨的空间位置。结果 计算机还原出各运动角度下膝关节骨性结构（股骨、胫骨及关节面）的空间形态，利用软件Geomagic的几何计算功能可分别测量模型中各个运动状态交叉韧带附丽区两点间的三维空间距离。讨论本研究方法可以真实地记录和再现膝关节三维运动过程，从空间结构上更精确、合理地寻找重建等长点，对膝关节交叉韧带手术重建有重要临床意义。     

A study on knee joint geometry in Chinese: significance to prosthesis design]

This study for the first time provided the geometric parameters of knee joints in Chinese, which are indispensable for the design of domestic knee prosthesis. Thirty five items, including linear, radial and angular measurements, were taken from 105 cadaver knees and knee X-ray films of 100 subjects. The method and calculation for proper correction of the X-ray image magnification and joint cartilage space was established. Correlation between the X-ray correction coefficients and the body weight was found to exist, and it formed the basis for individualized correction of X ray measurements. Statistical analysis revealed that most of the linear and radial measurements were highly related while the angular measurements were independent of others. Principal component analysis showed that the width of femoral condyle might be taken as the leading index in determining the dimension of the knee, and regression functions were established. Multivariate discriminate functions could aid the selection of knee prosthesis.     

Knee morphology as a guide to knee replacement.

The complexity of knee geometry requires correct prosthesis design and size selection for the recipient. This study analyzes the morphological relationships within the knee; 16 linear anatomical parameters were measured on 30 cadaveric knees. The marginal femoral condylar contour was geometrically described by two tangent radii. Standardized radiographic techniques were developed to obtain a modified tunnel and true lateral view of the knee. Subsequently, X-rays were taken from 11 cadaver knees to achieve reproducible magnification factors. From X-rays of 53 normal subjects, 11 comparable linear dimensions were measured. The linear dimensions and condylar contour measurements were analyzed for their interrelationships by computer techniques. The width of the femur was found to be dimensionally related (correlation coefficient significant at the one per cent level) to the measured parameters with the exception of the intercondylar notch and interspinous widths. Using regression analysis, nomograms were developed to predict the linear and marginal femoral contour dimensions from the femur width. The resulting standard deviations were low, ranging from 1.0 mm for ascertaining the tibial width to 3.5 mm for determination of the femoral width at the level of the intercondylar notch. The nomograms we developed will aid the surgeon in a more precise, preoperative, morphological evaluation and may be used as a guide for future knee prosthesis design.     

Reproducibility of navigation based kinematic analysis of the knee – A cadaveric investigation

Purpose

Several navigation-based kinematic studies of the knee have been published recently, but little information is available about reproducibility and reliability of the acquired data. The aim of the present study first is to determine reproducibility and reliability of kinematical measurements of healthy knees and knees after TKA (total knee arthroplasty) with regards to rotational and translational measurement parameters. Second the mathematical background, applicability, and limitations of investigating navigation-based kinematics should be compiled.

膝关节外翻畸形股骨侧形态学参数分析

目的探讨膝关节外翻畸形股骨侧形态结构改变特点,并分析各参数的异常分布。方法收集2010年1月至2012年12月北京积水潭医院矫形骨科收治的68例(68膝)膝关节外翻畸形患者的影像学资料,包括下肢全长X线片和膝关节CT容积性数据。在下肢全长X线片上测量解剖学股胫角(aFTA)和解剖学股骨远端外侧角(aLDFA),将DICOM格式的CT容积性数据导入MIMICS17.0软件,测量股骨远髁角(DCA)和股骨后髁角(PCA)。分析膝关节外翻畸形股骨侧各参数异常的构成比,并绘制散点图分析各参数的线性相关性。结果股骨侧形态学参数测量结果:aFTA为(18.42±6.42)°,aLDFA为(74.71±4.63)°,DCA为(6.64±1.36)°,PCA为(4.51±1.82)°,其中DCA异常人数占比最高(95.59%)。DCA、PCA和aLDFA均存在异常的人数占比为51.47%。DCA与PCA和aLDFA之间均不存在线性相关。结论股骨外侧髁远端形态结构异常是膝关节外翻畸形股骨侧骨组织异常的主要来源。约1/2的患者同时存在股骨外侧髁远端、后方和股骨干骺端形态结构异常。     

Tibiofemoral bony morphology features associated with ACL injury and sex utilizing three-dimensional statistical shape modeling

Statistical shape modeling was employed to assess three-dimensional (3D) bony morphology between distal femurs and proximal tibiae of anterior cruciate ligament (ACL) injured knees, the contralateral uninjured knees of ACL injured subjects, and knees with no history of injury. Surface models were created by segmenting bone from bilateral computed-tomography scans of 20 subjects of their ACL injured knees and non-injured contralateral knees, and 20 knees of control subjects with no history of a knee injury. Correspondence particles were placed on each surface, and a principal component analysis determined modes of variation in the positions of the correspondence particles describing anatomical variation. ANOVAs assessed the statistical differences of 3D bony morphological features with main effects of injury state and sex. ACL injured knees were determined to have a more lateral femoral mechanical axis and a greater angle between the long axis and condylar axis of the femur. A smaller anterior–posterior dimension of the lateral tibial plateau was also associated with ACL injured knees. Results of this study demonstrate that there are more bony morphological features predisposing individuals for ACL injury than previously established. These bony morphological parameters may cause greater internal and valgus torques increasing stresses in the ACL. No differences were determined between the ACL injured knees and their uninjured contralateral knees demonstrating that knees of ACL injured individuals are at similar risk for injury. Further understanding of the effect of bony morphology on the risk for ACL injury could improve individualized ACL injury treatment and prevention.     

Functional gait analysis of trans-femoral amputees using two different single-axis prosthetic knees with hydraulic swing-phase control: Kinematic and kinetic comparison of two prosthetic knees

This paper reports a comparison of the gait patterns of trans-femoral amputees using a single-axis prosthetic knee that coordinates ankle and knee flexions (Proteor's Hydracadence system) with the gait patterns of patients using other knee joints without a knee-ankle link and the gait patterns of individuals with normal gait. The two patient groups were composed of 11 male trans-femoral amputees: six patients had the Hydracadence joint (Group 1) and five patients had other prosthetic knees (Group 2). The reference group was made up of 23 normal volunteers (Group 3). In this work, trunk, hip, knee, and ankle 3-D motion was assessed using the VICON system. Kinetic data were collected by two AMTI force plates, and the knee moment was calculated via the 3-D equilibrium equations. An original questionnaire was used to assess the participants' activity level and clinical background. The results reveal that, during stance, all knee types guaranteed security. After heel strike, the plantar flexion of the ankle enabled by the Hydracadence prosthesis seems to increase stability. During swing phase, hip and knee sagittal motion was nearly the same in both Group 1 and Group 2. By contrast, hallux and sole vertical positions were significantly higher in Group 1 than in Group 2; thus, it seems the link between the ankle joint and the knee joint makes foot clearance easier. No alteration of the lateral bending of the trunk was observed. The protocol proposed in this paper allows a functional comparison between prosthetic components by combining clinical data with objective 3-D kinematic and kinetic information. It might help to determine which prosthetic knees are best for a specific patient.     

Knee cartilage topography,thickness, and contact areas from MRI: in-vitro calibration and in-vivo measurements

Objective: This study assessed the three-dimensional accuracy of magnetic resonance imaging (MRI) for measuring articular surface topographies and cartilage thicknesses of human cadaveric knee joints, by comparison with the calibrated stereophotogrammetric (SPG) method.Methods: Six fresh frozen cadaveric knees and the knees of four volunteers were imaged with a three-dimensional spoiled gradient-recalled acquisition with fat suppression using a linear extremity coil in a 1.5 T superconducting magnet. The imaging voxel size was 0.47×0.47×1.0 mm. Both a manual and a semi-automated segmentation method were employed to extract topographic measurements from MRI. Following MRI, each of the six cadaveric knees was dissected and its articular surfaces quantified using stereophotogrammetry. The MRI surface measurements were compared numerically with the SPG measurements.Results: For six cadaveric knees, the average accuracies of cartilage and subchondral bone surface measurements were found to be 0.22 mm and 0.14 mm respectively and the thickness measurements demonstrated an average accuracy of 0.31 mm. It was found that while most of the error may be attributed to random measurement error, the accuracy was somewhat affected by systematic errors. For each bone of the knee, accuracies were most favorable in the patella, followed by the femur and then the tibia. The more efficient semi-automated method provided equally good and sometimes better accuracies than manual segmentation.Conclusions: This study demonstrates that clinical MRI can provide accurate measurements of cartilage topography, thickness, contact areas and surface curvatures of the knee.     

In vivo pre- and postoperative three-dimensional knee kinematics in unicompartmental knee arthroplasty

Background

Pre- and postoperative knee kinematics in unicompartmental knee arthroplasty (UKA) can be theoretically related to clinical outcome and longevity after UKA with regard to ligament function and the degree of arthritic changes. However, the preoperative knee kinematics of patients indicated for UKA remain to be elucidated, and it is also unclear whether the preoperative kinematics can be maintained by the UKA procedure. The objective of this study was to examine the in vivo pre- and postoperative three-dimensional knee kinematics in UKA while referencing the normal knee kinematics reported in our previous study.

Methods

We analyzed the knee kinematics in 17 knees (14 patients) undergoing UKA via a three-dimensional to two-dimensional registration technique employing femoral condylar translation and femoral axial rotation. The pre- and postoperative knee kinematics during squat motion were evaluated in the same subjects, employing consistent evaluation parameters.

Results

On average, both pre- and postoperative knee kinematics in the range 10–100° of knee flexion demonstrated near-consistent femoral external rotation and anterior translation of the medial condyle and posterior translation of the lateral condyle. However, the mean femoral external rotation angle and the posterior translation of the lateral condyle postoperatively were significantly smaller than the values observed preoperatively.

Discussion

Although the patterns of preoperative knee motion were similar to those seen in normal knees, the magnitude of this motion varied widely between patients, so it was not necessarily representative of normal knees. These variations may be due to the varying degrees of arthritic changes caused by osteoarthritis. Although the patterns of knee kinematics were largely maintained by the UKA procedure, the causes of the significant reductions in the magnitude of motion upon performing the UKA procedure should be investigated in subsequent studies with a larger number of patients.     

国人胫骨平台截骨面与西方进口胫骨假体解剖学参数的偏差

 目的 测量中国北方汉族人胫骨平台截骨面与进口胫骨假体解剖学参数的偏差。方法 中国北方汉族健康志愿者82名（135膝）,男52名（85膝）,女30名（50膝）;年龄19～82岁,平均47.2岁。行膝关节横断面CT扫描,获得“.dicom”格式图像。将图像存储至与CT机联网的计算机三维重建工作站（Adw 4.3）,利用三维容积重建软件建立膝关节三维图像。对三维图像的胫骨进行旋转、切割,测量不同截骨高度及后倾角度各截骨面的胫骨近端横径、前后径及纵横比;采用5 mm容差范围法对三种西方进口假体（A、B、C）与国人胫骨平台截骨面的匹配程度进行初步评估。结果 男性胫骨近端截骨面横径平均值为（78.03±2.92） mm,女性为（69.85±2.70） mm;男性胫骨近端截骨面前后径平均值为（50.62±2.46） mm,女性为（46.14±2.61） mm;男性胫骨近端截骨面纵横比平均值为0.649±0.032,女性为0.661±0.031。不同性别胫骨近端截骨面横径与前后径的差异均有统计学意义,男性大于女性;纵横比平均值女性大于男性,差异有统计学意义。假体A对所有受试者各截骨面的平均涵盖率为42.55%,假体B平均为44.61%,假体C平均为27.41%。A与B两种假体涵盖率的差异无统计学意义,而两者与假体C涵盖率的差异均有统计学意义。结论 国人正常胫骨平台截骨面的几何形态与西方进口假体的匹配度普遍较低。     

基于X线的颅面部软组织三维重建及测量分析研究

目的：利用头颅定位X线片实现颅面部软组织的三维重建及测量。方法：同期分次摄取侧位、45°位和正位头颅定位X线片。利用侧位和45°位X线片上相匹配的外加金属标志点,获得颅面部软组织的三维信息,进行颅面部软组织形态的三维重建。在所建面部三维模型基础之上选8个解剖标志点,进行10项测量,并与人群的正常值进行比较研究。结果：利用侧位和45°位的两张X线片,对颅面部软组织实现三维重建。建立了颅面部软组织的三维测量系统,测量结果同正常值相比较,除面宽和下颌宽有较大的差异外,测量值都具有很好的同一性,面部比例指数除去面宽和下颌角宽的影响大多数都有较好的一致性。结论：本系统基于头颅定位X线片实现颅面部软组织的三维重建和测量,为面部畸形的诊断,正颌手术的定量化手术设计,术后疗效评价提供新的技术方法。