膝关节软骨人体标本解剖与磁共振成像的比较研究

目的 探讨膝关节尸体标本解剖与磁共振成像(MRI)三维序列-扰相梯度回波序列(3D-FS-SPGR)测量关节软骨厚度的差异,并分析软骨组织主要成分在关节软骨不同位置的差异.方法选用国人青壮年中等身材、无明显关节病变的成年男性尸体膝关节标本2具,首先进行3D-FS-SPGR序列矢状位扫描.复冻后按解剖部位进行矢状位解剖,分别对股骨及胫骨内、外髁负重区前、后面及髌骨面软骨厚度进行测量.关节软骨石蜡切片进行维多利亚蓝-丽春红复合染色并观察.结果 软骨尸体标本解剖与3D-FS-SPGR序列测得的膝关节软骨厚度:股骨外侧髁前负重面平均分别为2.25、2.25 mm,股骨外侧髁后负重面平均分别为2.70、2.75 mm,胫骨外侧髁前负重面平均分别为2.00、2.10 mm;胫骨外侧髁后负重而平均分别为2.35、2.25 mm,股骨内侧髁前负重面平均分别为2.20、2.20 mm,股骨内侧髁后负重面平均分别为2.15、2.30 mm,胫骨内侧髁前负重面半均分别为2.20、2.45mm,胫骨内侧髁后负重面平均分别为2.70、2.95 mm,髌骨面软骨平均分别为3.08、3.15 mm.软骨组织学染色显示:关节软骨表层胶原纤维含量相对较多,软骨细胞及其周围基质相对较少;在关节软骨深层,胶原纤维含量相对较少,而软骨及软骨周围基质相对较多.结论 3D-FS-SPGR序列能够相对真实地反映关节软骨的形态及厚度.胶原纤维主要集中在软骨表层,其分布与软骨的功能相一致.

Abstract：

Objective To compare corpse sampling and MR imaging with 3D-FS-SPGR sequences in measurement of the articular cartilage thickness and to investigate knee cartilage topography. Methods Two fresh specimens of the knee joint were obtained from 2 normal young adult male corpses of medium stature. MR1 scanning was carried on the 2 specimens in sagittal 3D-FS-SPGR MR sequences. After defrosted,the knee specimens were dissected longitudinally, and the cartilage thicknesses were measured at different locations of the knee joint. Paraffin sections of the knee cartilage were observed following compound staining with victoria blue and ponceau red. Results The average cartilage thicknesses measured by dissection and MR imaging sequence were respectively: 2. 25 mm and 2. 25 mm at the anterior weight-loading surface of the femoral lateral condyle, 2. 70 mm and 2. 75 mm at the posterior weight-loading surface of the femoral lateral condyle, 2. 00 mm and 2. 10 mm at the anterior weight-loading surface of the tibial lateral condyle,2. 35 mm and 2. 25 mm at the posterior weight-loading surface of the tibial lateral condyle, 2. 20 mm and 2. 20mm at the anterior weight-loading surface of the femoral medial condyle, 2. 15 mm and 2. 30 mm al the posterior weight-loading surface of the femoral medial condyle, 2. 20 mm and 2.45 mm at the anterior weight-loading surface of the tibial medial condyle, 2. 70 mm and 2. 95 mm at the posterior weight-loading surface of the tibial medial condyle and 3. 08 mm and 3. 15 mm at patella cartilage surface. Collagen fibers were rich at the periphery of the articular cartilage with sparse chondrocytes and matrixes, while the opposite was observed at the center of the articular cartilage. Conclusions MR imaging with 3D-FS-SPGR sequences can display the actual knee cartilage topography. Collagen fibers mainly concentrate at the periphery of the articular cartilage, which accounts for the function of the articular cartilage.     

后交叉韧带与相关结构的生物力学

人们对膝关节后交叉韧带（posterior erueiate ligament，PCL）的基本解剖和功能已有了一定的认识。PCL有一个相对密集的胫骨附着部，位于内、外侧半月板后角之间，关节线下方的胫骨后窝，纤维向上前方走行，呈扇形，在股骨有相对更广泛区域的附着部，位于股骨内侧髁的髁间窝面，自临近髁软骨面的前上部向后下延伸。许多研究己表明PCL是跨越膝关节最强大的韧带，主要限制胫骨后移。尽管有了这些基本知识，但PCL仍是未解之谜，     

成人正常膝关节的运动状态分析

目的分析成人正常膝关节运动状态,为改进和设计符合国人解剖特点的膝关节假体提供参考数据。方法随机选取120名(240膝,男女各半)膝关节正常的中国成年人,年龄21～40岁,平均30.6岁,身高1.60～1.75m。受试者作膝关节的过屈膝运动,通过X线透视成像技术,获得双侧膝关节不同体位时的连续侧位X线片。股骨髁上前方的关节球面为伸展面(extensionfacet,EF),后方的关节球面为屈曲面(flexionfacet,FF);两个球面的圆心分别定义为伸展面球心(extensionfacetcenter,EFC)和屈曲面球心(flexionfacetcenter,FFC)。然后测量关节在不同体位时,后部胫骨皮质与同侧股骨髁后方关节面球心的间距,通过胫骨内外侧软骨下骨性标志中最突出的两个点引一条直线,再引第二条直线垂直于前者,并与后部的胫骨皮质正切。屈曲面球心FFC到第二条直线的距离为d1,伸展面球心EFC到第二条直线的距离为d2,分别测量关节在不同体位时d1和d2的长度。不同体位时d1、d2长度变化的绝对值即为膝关节屈曲时股骨和胫骨的相对运动范围。所得数据用SAS软件进行双因素方差分析。结果不同性别、侧别间膝关节股骨内侧髁及外侧髁的运动范围差异均无统计学意义。成人正常膝关节屈曲时股骨和胫骨的相对运动范围:内侧髁(1.4±0.3)mm,外侧髁(15.9±4.7)mm。结论国人正     

膑股关节疾病

膑股关节面以中央脊(mediam ridge)、副脊(secondary ridgc)为界可分为外侧关节面、内侧关节面及特别面(odd facet)三个小关节面、膝关节中,膑骨软骨面最厚达7mm,股骨髁和胫骨平台软骨面分别是3mm和4mm.膝关节在屈伸过程中,膑骨的三个关节面有规律地和股骨膑面接触并在其前面上下滑动,称为膑股关节适合(Patellofemoral congruence).如果各种原因使膑股关节之间的适合性改变,关节软骨退行性变性,或关节间相对解剖位置异常,就引起以膑关节前方疼痛为主的各类膑股关节疾病.     

兔自体松质骨颗粒修复关节软骨损伤

目的研究兔自体松质骨颗粒在膝关节软骨损伤处移植后能够诱导软骨组织生成、促进关节软骨损伤修复的现象。方法 12只新西兰大白兔麻醉后在兔的右侧膝关节股骨远端内、外侧髁负重区用电钻分别造成直径、深度均为3 mm的骨软骨缺损创面,取同侧髂骨松质骨,制成直径约为1 mm松质骨颗粒植入股骨内侧髁软骨缺损处,作为实验组,外侧髁软骨缺损不做处理作为对照组。术后12周进行膝关节大体观察、病理切片染色,评估关节软骨损伤的修复情况。结果兔膝关节实验组软骨缺损处被新生软骨填充,软骨面光滑,组织切片染色显示有关节软骨形成。对照组缺损创面仍然凹陷,仅在缺损边缘有少量软骨生长。结论兔自体松质骨颗粒在膝关节软骨损伤处能够诱导软骨生成,促进关节软骨的修复,是一种良好的关节软骨损伤修复方法。     

同侧膑骨股骨髁部及胫骨平台骨折1例报告

患者男性,30岁,骑摩托翻车撞伤头部及左膝10小时入院.检查:左膝关节高度肿胀,膝前外侧皮肤擦伤,浮膑试验(+),膑骨压痛明显,膝关节活动受限,足背动脉搏动良好.X线检查:左膑骨粉碎性骨折,在股骨外髁骨折.伤后1周在腰麻下手术,取膝关节后外侧切口,见股骨外侧髁部(前十辽韧带附丽部)冠状面骨折,骨折块约有5.0×4.0×2.0cm, 因十字韧带牵拉致骨折块翻转90度,胫骨内侧平台后外侧缘骨折,骨折块约有1.5×1.3×1.0cm,移位明显.术中清除关节内积血,股骨外侧髁部骨折给予解剖复位,用一枚长螺丝钉固定,螺帽埋于关节软骨面下2mm,胫骨平台骨折块关节面失完整难以复位及固定,将其切     

膝关节结构及运动的特点

膝关节是全身中结构最复杂、最大、所受杠杆作用力最强的一个关节.它虽为屈戊关节,但其运动则是二维的.运动范围虽不及肩、髋关节广泛,却具有更为精确、复杂的规律.关节结构膝关节包括由股骨下端和胫骨上端构成的内侧和外侧胫股关节,以及由膑骨和股骨滑车构成的膑股关节.股骨下端膨大.为内髁及外髁,其间为髁间窝,内髁之横径较外髁者长,而纵径(前后径)则较外髁为短;内外髁之软骨面与胫骨上端者相关节,其前方两髁之间软骨面则与膑骨之后软骨面相关节.     

同种异体半月板移植的研究现状

1 研究背景 1.1半月板的解剖与功能 半月板是膝关节内的软骨盘,位于胫骨平台与股骨髁之间,内侧为C型,外侧为近似O型.均分为前角、后角和体部.前后角借助"止点"结构固定于胫骨平台,内侧半月板前角止于胫骨髁间前斜坡处,后角止于内侧髁间棘后侧、后交叉韧带止点之前;外侧半月板前角止于外侧髁间棘前部,部分纤维与前交叉韧带相延续,后角止于外侧髁间棘后缘.     

内外侧半月板后根部损伤有限元力学研究

[目的]探讨内外侧半月板后根部损伤对膝关节生物力学的影响。[方法]膝关节正常志愿者4例作为研究对象,采用MRI对左膝关节进行扫描,建立膝关节各部位有限元模型,在股骨部分垂直加1 150 N垂直力模拟人体正常周期中的伸直状态,测量应力分布。在完整膝关节有限元模型中同时删除内、外侧半月板根部相应单元和节点,模拟内外测半月板根部同时损伤模型;将完整膝关节模型设为对照组;分别加载1 000 N轴向压缩载荷和134 N向前剪切力,测量不同部位的最大压应力和最大剪切应力。[结果]人体正常走平路膝伸直状态时,承受应力的大小依次为:外侧半月板前部>内侧胫骨平台>股骨外侧髁>内侧半月板后部>股骨内侧髁>外侧胫骨平台>双股骨髁后部。损伤组股骨内髁、股骨外髁、内侧胫骨平台、外侧胫骨平台软骨、外侧半月板最大压应力显著高于完整组(P<0.05)。损伤组股骨内髁、股骨外髁、内侧胫骨平台、外侧胫骨平台软骨、外侧半月板最大剪切力显著高于完整组(P<0.05)。[结论]内、外侧半月板后根部同时损伤导致膝关节各部位承载应力显著增加。     

膝骨关节炎患者股骨后髁软骨磨损差异对人工全膝关节置换术中股骨假体旋转定位的影响

目的通过测量膝骨关节炎患者股骨内、外侧后髁软骨厚度以及后髁角(posterior condylar angle,PCA),探讨其对人工全膝关节置换(total knee arthroplasty,TKA)术中截骨的影响。方法选择2011年5月-12月拟行TKA治疗的53例(60膝)膝骨关节炎患者作为研究对象(骨关节炎组),男12例(14膝),女41例(46膝);年龄57～82岁,平均71.9岁。胫股角为(183.2±2.6)°。以15例(30膝)健康志愿者膝关节作为对照(对照组),男6例,女9例;年龄59～68岁,平均66.3岁。将MRI扫描膝关节获得数据导入Mimics10.01交互式医学影像控制系统,测量内、外侧股骨后髁软骨厚度和包括与不包括后髁软骨时的PCA,进行统计学分析。结果对照组股骨内、外侧后髁软骨厚度分别为(1.85±0.33)mm及(1.92±0.27)mm,包括与不包括后髁软骨时的PCA分别为(5.0±0.9)°和(5.1±0.8)°,差异均无统计学意义(P>0.05)。骨关节炎组股骨内、外侧后髁软骨厚度分别为(0.45±0.40)mm及(1.78±0.51)mm,包括与不包括后髁软骨时的PCA分别为(3.3±1.7)°和(4.8±1.8)°,差异均有统计学意义(P<0.05)。骨关节炎组股骨内、外侧后髁软骨厚度差为(1.33±0.45)mm,与包括与不包括后髁软骨时的PCA角度差(1.5±1.3)°成正相关(r=0.75,P=0.01)。结论膝骨关节炎患者股骨后髁软骨磨损程度存在差异,导致内、外侧后髁软骨厚度和包括与不包括后髁软骨时的PCA存在差异,TKA术中行截骨时,应将股骨后髁软骨厚度差异纳入考虑范围内。     

Bone bruise of the knee Histology and cryosections in 5 cases

We evaluated the histopathologic and cryosectional appearance of bone bruise injuries of the knee detected on MRI. Histologic evaluation of bone biopsies from 3 patients revealed microfractures of cancellous bone, edema and bleeding in the fatty marrow. Between intact lamellar bone trabecules, fragments of hyaline cartilage mixed with highly fragmented bone trabecules were found.

Postmortem specimens were obtained from 2 more patients, killed in motor vehicle accidents. MRI revealed bone bruise injuries of the lateral femoral condyle and of the lateral tibial plateau in 1 knee and anterior cruciate ligament disruption, a medial meniscus tear and bone bruise injury of the tibial plateau and of the lateral femoral condyle in the other specimen. The specimens were embedded in physiologic saline solution and frozen to -3°C. By rota-tioncryotomy, 1 mm slices were removed from the surface of the specimens and documented on photographs. Subchondral lesions and bleeding were found, corresponding to the MR images.     

Maturation-dependent change and regional variations in acoustic stiffness of rabbit articular cartilage: an examination of the superficial collagen-rich zone of cartilage

OBJECTIVE: The purpose of the study was to investigate maturation-dependent changes of acoustic (ultrasound) stiffness and other ultrasound features of articular cartilage in healthy rabbit knees. METHODS: Five groups of rabbits of various ages (3 weeks, 8 weeks, 6 months, 1 year, 2.5 years) consisting of five rabbits per group were examined. Signal intensity (index of stiffness), signal duration (index of surface irregularity) and interval between signals (index of thickness) of the ultrasound reflection from articular cartilage were examined at four sites: posterior lateral femoral condyle, posterior medial femoral condyle, lateral tibial plateau, and medial tibial plateau. The sites were observed macroscopically and microscopically with a light microscope and a polarized light microscope. RESULTS: At the lateral and medial condyles and the lateral tibial plateau, signal intensity was least in 3-week-old specimens. The intensity increased until 6 months or 1 year of age. At these sites, the signal durations and intervals between signals were least at the ages of 6 months or 1 year. At the medial tibial plateau, the intensity was the least at 2.5 years of age and the interval between signals was least at 3 weeks of age; there was no effect of age on signal duration. Cartilage surfaces of all specimens were smooth and no degenerative changes were macroscopically or microscopically evident. The surface brightness of cartilage under the polarized light microscope was consistent with signal intensity values. CONCLUSIONS: The response of articular cartilage to ultrasound was maturation-dependent. Acoustic properties differed from mechanical stiffness properties, which were determined using indentation. Ultrasound may detect properties of the surface collagen of the articular cartilage.     

Magnetic resonance evaluation of the interrelationship between articular cartilage and trabecular bone of the osteoarthritic knee

OBJECTIVE: To use high-resolution magnetic resonance imaging (MRI) to determine the relationship between articular cartilage degeneration and trabecular bone changes of the femur, condyles and tibia in human knees with osteoarthritis (OA).METHODS: Subjects were divided into three groups: without OA (OA0), mild OA (OA1) and severe OA (OA2). Sagittal images of the knee (0.234 x 0.234mm2, 2-mm slice thickness) were obtained at 1.5T and used for calculating the volume and thickness of the femoral and tibial cartilage. Axial images (0.195 x 0.195mm2, 1-mm slice thickness) were used for calculating the trabecular bone structure parameters: apparent bone volume fraction, trabecular number, trabecular separation and trabecular thickness.RESULTS: Cartilage volume and thickness were less in patients with OA compared to normal controls (P<0.1). Articular cartilage thinning is associated with bone structure loss in the opposite femoral condyle (P<0.05). In varus OA, there were extensive correlations between medial tibia and medial femoral cartilage degeneration, and loss of bone structure in the lateral tibia and lateral condyle. Additional correlations existed between the compartmental differences (lateral minus medial) of cartilage thickness and bone structure.CONCLUSION: Degradation of articular cartilage within a compartment correlates with a loss of bone structure in the opposite compartment. The correlation between the (L-M) differences corroborates this relationship. Malalignment of the knee due to cartilage degeneration is associated with bone formation in the diseased condyle and bone resorption in the opposite compartment.     

No Sex Differences Exist in Posterior Condylar Offsets of the Knee

BackgroundRestoration of posterior condylar offset during TKA is believed to be important to improving knee kinematics, maximizing ROM, and minimizing flexion instability. However, controversy exists regarding whether there are important anatomic differences between sexes and whether a unisex knee prosthesis can restore the anatomy of knees in males and females.Questions/purposesThe purposes of our study were to determine if sex differences exist in (1) absolute posterior condylar offset size, (2) relative posterior condylar offset size in relation to total condylar height, and (3) posterior condylar articular cartilage thickness.MethodsWe identified 100 patients (50 men and 50 women) without a history of arthritis, deformity, dysplasia, osteochondral defect, fracture, or surgery about the knee who had MRI of the knee performed. All MR images were ordered by primary care medical physicians for evaluation of nonspecific knee pain. Using a previously described three-dimensional MRI protocol, we measured posterior condylar offset, total condylar height, and articular cartilage thickness at the medial and lateral femoral condyles and compared values to evaluate for potential sex differences. We performed an a priori power calculation using a 2-mm posterior condylar offset difference as the minimum clinically important difference; with 2n = 100, our power to detect such a difference was 99.8%.ResultsCompared with females, males had greater medial posterior condylar offset (30 mm [95% CI, 29.3–30.7 mm; SD, 2.5 mm] vs 28 mm [95% CI, 27.0–28.5 mm; SD, 2.7 mm]), lateral posterior condylar offset (27 mm [95% CI, 26.2–27.3 mm; SD, 2.0 mm] vs 25 mm [95% CI, 24.2–25.4 mm; SD, 2.0 mm]), medial condylar height (63 mm [SD, 3.2 mm] vs 57 mm [SD, 4.4 mm]), and lateral condylar height (71 mm [SD, 5.2 mm] vs 65 mm [SD: 4.0 mm]) (all p values < 0.001). However, the mean ratio of medial posterior condylar offset to medial condylar height (0.48 [SD, 0.04] vs 0.49 [SD, 0.05]) and the mean ratio of lateral posterior condylar offset to lateral condylar height (0.38 [SD, 0.05] vs 0.38 [SD, 0.03]) were not different between sexes (p = 0.08 and p = 0.8, respectively). There also was no sex difference in mean articular cartilage thickness at either condyle (medial condyle: 2.7 mm [SD, 0.5 mm] vs 2.5 mm [SD, 0.7 mm]; lateral condyle: 2.6 mm [SD, 0.6 mm] vs 2.5 mm [SD, 0.8 mm]) (both p values ≥ 0.1).ConclusionsResults of our study showed that knees in males exhibited greater posterior condylar offset and greater total condylar height at the medial and lateral femoral condyles, however, there were no sex differences in the ratio of posterior condylar offset to condylar height at either condyle.

Clinical Relevance

These findings suggest that a unisex knee prosthesis design is adequate to recreate the normal posterior condylar offsets for men and women.     

Lack of posteromedial tibiofemoral congruence at full flexion as a causative factor in isolated medial meniscal tears

The aim of the current study was to investigate posteromedial tibiofemoral congruence at full flexion of the knee in control knee joints and those affected by an isolated medial meniscal tear, to examine whether lack of such congruence was a causative factor in isolated medial meniscal tears. In this study, 1677 knee joints in 875 subjects were evaluated. The joints were classified as a control group (1345 joints), an isolated medial meniscal tear group (224 joints), and a contralateral isolated medial meniscal tear group (108 joints). Posteromedial tibiofemoral congruence was examined on a lateral radiograph of the knee joint at full flexion. The tangent touching the anterior and posterior parts of the articular surface of the medial tibial condyle was assumed to be the X-axis. To evaluate posteromedial tibiofemoral congruence, we measured the angle formed by the tangent that maximized the gradient of the tangent on the articular surface of the medial femoral condyle, and the tangent that maximized the gradient of the tangent on the articular surface of the medial tibial condyle. The mean angle differed significantly between the control and the isolated medial meniscal tear groups, regardless of sex. Isolated medial meniscal tears were found to be strongly related to an abnormally decreased angle, and, therefore, incongruence of the posteromedial tibiofemoral articulation at full flexion was considered to be one of the causes of isolated medial meniscal tears. Received: May 22, 2001/ Accepted: October 24, 2001     

Three-dimensional tibiofemoral articular contact kinematics of a cruciate-retaining total knee arthroplasty

BACKGROUND: Accurate knowledge of the location of tibiofemoral articular contact following total knee arthroplasty is important in order to understand polyethylene wear and the mechanisms of component failure. The present study was performed to determine the three-dimensional tibiofemoral articular contact patterns of a posterior cruciate ligament-retaining total knee replacement during in vivo weight-bearing flexion. METHODS: Nine osteoarthritic patients who were managed with a single design of a posterior cruciate ligament-retaining total knee implant were investigated with the use of an innovative dual orthogonal fluoroscopic imaging system. The position of the components during in vivo weight-bearing flexion was measured from full extension to maximum flexion in 15 degrees intervals. Tibiofemoral articular contact was determined by the overlap of the tibiofemoral articular surfaces. The centroid of the surface intersection was used to report the point of contact location. The average tibiofemoral contact points on both the medial and lateral tibial component surfaces were reported as a function of flexion. RESULTS: The average maximum weight-bearing flexion angle was 113.3 degrees +/- 13.1 degrees (range, 96 degrees to 138 degrees ). In the anteroposterior direction, the contact location was relatively constant in the medial compartment and moved posteriorly by 5.6 mm in the lateral compartment as the knee flexed from full extension to 90 degrees of flexion. The range of the contact location in the mediolateral direction was 3.7 mm in the medial compartment and 4.8 mm in the lateral compartment. For both compartments, posterior translation of the contact point was significant from 90 degrees to maximum flexion, but the contact point at maximum flexion was not observed to reach the posterior edge of the polyethylene tibial insert articular surface. CONCLUSIONS: While the minimum anteroposterior translation of the contact point on the medial side might be interpreted as a medial pivot rotation during knee flexion, the contact point did move in the mediolateral direction with flexion. Beyond 90 degrees , both medial and lateral contact points were shown to move posteriorly but stopped before reaching the posterior edge of the polyethylene tibial insert articular surface. It seemed that the current component design did not allow the femoral condyle to roll off the polyethylene edge at high degrees of flexion because of the geometry at the posterior lip.     

Anterior tibial post impingement in a posterior stabilized total knee arthroplasty.

Despite the numerous long-term success reports of posterior stabilized (PS) total knee arthroplasty (TKA), recent retrieval studies of various PS TKA designs revealed wear and deformation on the anterior side of the tibial post. This study investigated the mechanisms of anterior impingement of the post with the femoral component. Seven cadaveric knees were tested to study kinematics and tibial post biomechanics during simulated heel strike using an in vitro robotic testing system. Intact knee kinematics and in situ anterior cruciate ligament (ACL) forces were determined at hyperextension (0 degree to -9 degrees) and low flexion angles (0 degrees to 30 degrees) under the applied loads. The same knee was reconstructed using a PS TKA. The kinematics and the tibial post contact forces of the TKA were measured under the same loading condition. The ACL in the intact knee carried load and contributed to knee stability at low flexion angles and hyperextension. After TKA, substantial in situ contact forces (252.4 +/- 173 N at 9 degrees of hyperextension) occurred in the tibial post, indicating anterior impingement with the femoral component. Consequently, the TKA showed less posterior femoral translation compared to the intact knee after the impingement. At 9 degrees of hyperextension, the medial condyle of the intact knee translated 0.1 +/- 1.1 mm whereas the medial condyle of the TKA knee translated 5.6 +/- 6.9 mm anteriorly. The lateral condyle of the intact knee translated 1.5 +/- 1.0 mm anteriorly whereas the lateral condyle of the TKA knee translated 2.1 +/- 5.8 mm anteriorly. The data demonstrated that anterior tibial post impingement functions as a substitute for the ACL during hyperextension, contributing to anterior stability. However, anterior post impingement may result in additional polyethylene wear and tibial post failure. Transmitted impingement forces might cause backside wear and component loosening. Understanding the advantages and disadvantages of the tibial post function at low flexion angles may help to further improve component design and surgical techniques and thus enhance knee stability and component longevity after TKA.     

MRI序列及三维重建在膝关节软骨损伤的诊断价值

目的观察脂肪抑制三维扰相梯度回波序列（FS-3D-SPGR）、FS-FSE-T2W序列及三维重建对软骨损伤的诊断价值。方法41个膝关节关节面共205个区域进入研究,MR检查至少包括FS-FSE-T2W、3D-FS-SPGR序列,对损伤进行分级。在工作站上采用HDMIP进行三维重建,其结果与关节镜对照。结果3D-FS-SPGR序列对软骨损伤显示的敏感度为89．47％,特异度为97．65％;FS-FSE-T2W序列的敏感度为78．57％,特异度为94．71％。结论3D-FS-SPGR能准确评价关节软骨的损伤程度,但对软骨下骨及骨髓损伤不敏感;FS-FSE-T2W能准确反应软骨下骨及骨髓损伤的程度及范围,二者结合是目前诊断软骨损伤的最佳扫描序列。关节软骨的三维重建图像能够较真实准确地显示软骨损伤的部位与范围。