双源三维CT重建前交叉韧带股骨止点的印迹技术

目的 探讨双源CT(DSCT)三维重建前交叉韧带(ACL)股骨止点的印迹技术,尝试建立适用于关节镜下ACL解剖双束重建定位及测量系统,为临床实现个体化重建提供解剖学依据.方法 30名志愿者,对其双膝关节进行DSCT扫描,64排工作站(GE,Volume Share2-AW4.4版本软件)三维重建膝关节股骨外髁内侧壁三维模型,观察、圈画、标定ACL股骨止点双束印迹,定位股骨远端与股骨外髁滑车相交点O点；尝试测量ACL印迹长、短轴,两束中心点距离与股骨干之间夹角,双束中心点距离及印迹边缘至股骨髁软骨缘的距离等. 结果 采用DSCT技术再现的ACL股骨止点印迹为一凸起、平坦、形态不规则、灰度一致但与周围不同的区域；在股骨外髁三维模型上,成功建立了适用于关节镜下ACL解剖双束重建的“三点两角”定位系统.印迹长轴平均为(16.5±1.8) mm,印迹短轴平均为(8.0±1.3)mm,印迹角度平均为8 3°±4.9°,双束中心点距离平均为(7.8±1.0) mm,印迹边缘至股骨软骨远端最近距离平均为(1.6±1.5) mm,印迹边缘至股骨软骨后缘最近距离平均为(1.7±0.9)mm. 结论 采用DSCT三维重建技术可清晰重建ACL股骨印迹；ACL股骨止点自然印迹形态、位置存在个体化差异,“三点两角”定位法更适用于关节镜下定位,实现ACL解剖个体化重建.     

前交叉韧带重建术中胫骨骨道定位的应用解剖研究

[目的]探究前交叉韧带(anterior cruciate ligament,ACL)于胫骨止点处的解剖形态以及测量髁间窝顶线与胫骨平台交汇点至后交叉韧带前缘的距离对胫骨骨道定位的解剖学意义,为ACL重建术提供理论依据。[方法]选取新鲜成人膝关节标本8例,仔细剔除关节周围肌肉、后关节囊等结构,保留前后交叉韧带及两侧侧副韧带,保证膝关节正常屈伸范围。在屈伸膝关节时按照ACL纤维张力区将其分为前内束和后外束,在胫骨附着处将ACL切断制备ACL损伤模型。用测量工具和Phontoshop软件获取ACL基本解剖参数以及髁间窝顶线与胫骨平台的交汇点、ACL前缘、ACL胫骨止点的中心点分别至后交叉韧带前缘的距离。[结果]ACL平均体部直径为(11.21±0.76)mm,ACL在胫骨止点处的平均最大横径为(11.34±0.79)mm,平均最大前后径为(16.54±0.82)mm。前内束和后外束在胫骨止点处的平均面积分别为(113.35±29.65)mm~2和(83.29±16.99)mm~2。髁间窝顶线与胫骨平台的交汇点、ACL前缘以及ACL胫骨止点的中心点至后交叉韧带前缘的距离分别为(12.13±0.96)mm,(21.14±0.83)mm和(8.82±0.77)mm。[结论]利用胫骨平台骨道定位ACL在股骨的解剖止点现实可行,在ACL重建术中具有重要意义。     

双源CT三维重建评价前交叉韧带骨道位置的临床研究

目的 探讨双源CT三维重建前交叉韧带（ACL）股骨止点自然印迹与骨道中心点相对位置关系.方法 分别对55例志愿者110个膝关节和30例双束重建患者30个患膝关节进行双源CT扫描.使用CT图像后处理工作站行三维重建膝关节股骨外髁内侧壁三维模型,再现股骨外髁内侧壁ACL自然印迹及术后双束骨道,标记、测量自然印迹及骨道中心点相对位置,比较两者的位置关系,显著性差异设定P值0.05.结果 ACL自然印迹中心点相对位置与术后双束骨道中心点相对位置比较：前内束,h对=（26.2±2.2）%,h实=（23.6±8.5）%,中心点相对位置比较有统计学差异（t=4.906,P〈0.01）;t对=（25.0±2.1）%,t实=（25.2±3.9）%,中心点相对位置比较无统计学差异（t=0.480,P〉0.05）.后外束,h对=（46.5±3.2）%,h实=（45.0±4.6）%,中心点相对位置比较无统计学差异（t=0.608,P〉0.05）;t对=（34.2±2.5）%,t实=（37.9±4.2）%,中心点相对位置比较无统计学差异（t=0.530,P〉0.05）.结论 （1） DSCT三维重建可清晰重建出ACL股骨止点自然印迹和双束重建术后骨道位置;（2） DSCT 三维重建可用于ACL解剖双束重建术后骨道位置评估,对改进关节镜下ACL解剖双束重建有指导意义.     

膝关节前交叉韧带胫骨止点的软组织解剖标记

背景：膝关节前交叉韧带（ACL）重建时,胫骨骨道定位不准会产生重建韧带与髁间窝的撞击或起不到维持膝关节稳定性的作用。因此,确定ACL胫骨止点的位置非常重要。目的：研究膝关节ACL胫骨止点前内束（AMB）和后外束（PLB）与软组织标记后交叉韧带（PCL）和外侧半月板前角的距离,从而明确ACL胫骨止点在胫骨平台的位置,为ACL损伤双束重建提供理论支持。方法：解剖18个膝关节尸体标本（左膝10个,右膝8个）,测量ACL中点、AMB中点、PLB中点与PCL和外侧半月板前角的距离,并分析左、右膝关节是否存在差异。结果：AMB中点与PCL和外侧半月板前角的距离分别为（15.00±3.97）mm和（19.78±4.10）mm;PLB中点与两者的距离分别为（10.17±5.56）mm和（19.50±4.40）mm;ACL中点与两者的距离分别为（12.67±4.52）mm和（19.61±3.87）mm。左右膝关节ACL中点、AMB中点、PLB中点与软组织解剖标记的距离无明显统计学差异。结论：膝关节ACL损伤行手术重建时,可采用PCL和外侧半月板前角作为定位标记。     

股骨Blumensaat线的MRI测量及其对重建ACL的意义

目的应用MRI对股骨Blumensaat线的测量,为重建前交叉韧带(anterior cruciate ligament,ACL)提供参考。方法通过选择100例正常的膝关节伸直位磁共振检查结果,在适当的切面上绘制Blumensaat线延长线与胫骨平台的交点,测量其在胫骨矢状径位置及其与后交叉韧带(posterior cruciate ligament,PCL)的距离,并与ACL胫骨侧生理止点中心和PCL的距离比较。结果 Blumensaat线延长线与胫骨平台的交点在胫骨矢状径上距前缘(51.9±7.3)%,与PCL距离(14.2±2.5)mm,较ACL生理止点中心靠后。结论为避免髁间窝前方撞击,重建ACL胫骨侧止点定位于胫骨平台生理性止点中心后方或PCL前方8～10mm,个别人需更后方。     

前交叉韧带双束重建解剖影像学研究

目的测量并研究标准膝关节侧位X线片上前交叉韧带(ACL)股骨止点的相关骨性标志数据,为临床ACL重建提供参考。方法对10例成人膝关节标本进行解剖观察,标记ACL股骨止点前内侧束和后外侧束,摄标准膝关节正侧位X线片,利用图像分析软件测量两束止点中心(前内侧束为A点,后外侧束为B点)与股骨后髁弧形中心(i点)的距离,测量A点与过顶点、B点与过顶点的距离。结果解剖观察表明,ACL在中段根据其纤维走行及屈伸过程中的松紧变化,较易分为2束。A点与i点的距离为3.08~7.33(5.40±1.56)mm,B点与i点的距离为3.42~7.15(5.40±1.31)mm,A、B点与i点的距离差异无统计学意义(t=0.198,P=0.848)。A点与过顶点的距离为7.60~12.40(9.90±1.60)mm,B点与过顶点的距离为13.50~18.60(15.70±1.70)mm。结论股骨外髁弧形中心(单束重建等长点)与ACL前内侧束、后外侧束中心等距,支持单隧道双束重建ACL的理论要求。     

双源CT三维重建前交叉韧带股骨止点印迹的研究

目的 通过双源CT(DSCT)三维重建前交叉韧带(ACL)股骨止点,测量双束止点印迹,为临床实现解剖重建提供依据.方法 对55名志愿者双侧共110个膝关节进行DSCT扫描,其中男32名,女23名；年龄20～ 50岁,平均28岁.64排工作站三维重建膝关节股骨外髁,再现股骨外髁内侧壁ACL印迹,测量并比较不同性别及不同膝关节侧别印迹角、长短轴、印迹边缘至周围软骨的距离,以及双束中心点距离等.结果 110个膝关节的印迹角平均为6.8°±4.6°,印迹长轴平均为(16.8±1.7) mm,印迹短轴平均为(7.5±1.4) mm,印迹边缘至股骨软骨后缘最短距离(DPCM)平均为(1.9±1.0) mm,印迹边缘至股骨软骨远端最短距离(DDCM)平均为(1.5±1.3) mm,双束中心距离平均为(8.0±1.0)mm.男性左、右侧膝关节印迹角、印迹长轴、印迹短轴、DPCM、DDCM及双束中心距离比较差异均无统计学意义(P＞0.05).女性左、右侧膝关节印迹角、印迹长轴、印迹短轴、DDCM及双束中心距离比较差异均无统计学意义(P＞0.05),但左、右侧DPCM比较差异有统计学意义(P＜0.05).男、女性膝关节印迹角、印迹短轴比较差异均无统计学意义(P＞0.05),但男、女性印迹长轴、DPCM、DDCM及双束中心距离差异均有统计学意义(P＜0.05).结论 DSCT对正常人群ACL股骨止点自然印迹的测量结果可靠,具有代表性.ACL股骨止点自然印迹角、双束中心点距离以及与印迹至周围软骨距离等形态、位置参数存在个体差异.     

膝关节半月板根部附着区的解剖学测量

目的:测量国人膝关节内外侧半月板前后根部附着区的解剖学数据,为临床修复半月板根部损伤提供解剖学基础。方法:选取30个国人成人尸体膝关节标本,其中男16例,女14例;死亡年龄35～68(55.6±7.8)岁。对半月板根部附着区结构进行解剖,测量内外侧半月板根部附着区中心点与胫骨内外侧髁间棘、后交叉韧带前缘、内侧胫骨平台软骨后方外侧缘及外侧胫骨平台软骨后方内侧缘等标志点的位置关系和各个附着区的面积。结果:内侧半月板后根部附着区:中心点位于胫骨内侧髁间棘后方(11.73±3.10) mm、外侧(2.77±0.86) mm,后交叉韧带前缘前(2.76±0.76) mm,内侧平台软骨外侧缘外(3.92±0.22) mm,附着区面积(31.29±5.18) mm~2。内侧半月板前根部附着区:中心点位于胫骨内侧髁间棘前方(25.40±5.27) mm、外侧(3.01±0.86) mm,附着区面积(46.18±11.60) mm~2。外侧半月板后根部附着区:中心点位于胫骨外侧髁间棘后方(4.51±1.35)mm、内侧(1.85±0.34) mm,后交叉韧带前缘前(6.91±1.11) mm,外侧平台软骨内侧缘内(3.16±0.96) mm,附着区面积(44.10±6.23) mm~2。外侧半月板前根部附着区:中心点位于胫骨外侧髁间棘前方(12.97±2.92) mm、外侧(1.31±0.22) mm,附着区面积(60.84±14.98) mm~2。结论 :该试验定量描述内外侧半月板前后根部附着区的面积以及其中心点与相应标志点的位置关系,为临床修复半月板根部损伤提供一定的解剖学参考。     

由外向内与经前内侧入路法重建前交叉韧带股骨隧道的比较

目的：研究由外向内法（OI）与经前内侧入路法（AM）重建前交叉韧带（ACL）股骨侧隧道相关参数及隧道长度与股骨髁部大小的关系,探寻二者区别。方法取15具新鲜解冻膝关节标本,测量股骨髁部左右径及股骨外侧髁前后径大小,采用自行改进的内钩槽游标卡尺,定位ACL股骨侧止点中心,分别模拟采用OI法与AM法定位股骨外侧壁隧道口点。测量隧道长度、隧道口点与股骨外上髁位置关系。正侧位X线位上股骨隧道与膝关节线、股骨纵轴夹角。结果 OI法股骨隧道长度为（36.9±2.5）mm,AM法为（35.0±2.1）mm,差异有统计学意义（P＜0.05）;OI法与AM法股骨外侧壁隧道口点均位于股骨外上髁近前侧。 OI法较AM法偏近心端分布,但AM法更为集中;股骨髁部越大,隧道长度越长。 OI法较AM法隧道更为垂直。结论采用OI法与AM法均可满足ACL重建术对股骨隧道长度及位置的要求。 OI法相比下更随意,不受屈膝角度的影响。     

前十字韧带在维持膝关节稳定性上的重要性

前十字韧带（anterior cruciate ligament，ACL）是膝关节的四条主要韧带之一，其功能是与膝关节内部及周围的其他解剖结构共同维持膝关节的静态和动态平衡。ACL具有复杂的三维结构，传统上将ACL分为两束，前内侧束和后外侧束…，是以韧带在胫骨上的插入方向命名的（图1）。ACL起始于胫骨髁间隆起的前区，延伸至股骨髁间窝后外侧。[第一段]     

双源CT三维重建前交叉韧带股骨止点及隧道面积的临床研究

目的通过双源CT（DSCT）三维重建前交叉韧带（ACL）股骨止点印迹及骨隧道面积,为临床实现解剖重建提供依据。方法分别对55例志愿者110膝,30例双束重建60膝及30例单束重建患者60膝进行DSCT扫描。64排工作站（GE,Volume Share 2-AW4．4软件）三维重建膝关节股骨外髁三维模型,再现股骨外髁内侧壁ACL印迹,圈画、测量印迹及骨隧道面积,计算单、双束骨道面积覆盖率。结果ACL股骨自然印迹面积双膝之间：左（146．35±29．0）mm2,右（144．51±33．71）mm^2,两者间无统计学差异（t=0．52,P〉0．05）。性别间自然印迹面积比较：AMB：男（87．08±19．29）mm。,女（77．09±15．17）mm^2,两者间有统计学差异（t=2．04,P〈0．05）;PLB：男（62．82±15．19）mm^2,女（61．64±16．55）mm^2,两者间无统计学差异（t=0．27,P〉0．05）。术后隧道面积覆盖率比较：单束（53±18）％,双束（70±16）％,两者间有统计学差异（t=2．44,P〈0．05）。结论ACL股骨止点自然印迹面积存在性别间及个体化差异,双束重建止点面积覆盖率显著大于单束重建,要实现ACL解剖重建需采用个体化重建技术。     

Reconstruction Technique Affects Femoral Tunnel Placement in ACL Reconstruction

Grafts placed too anteriorly on the femur are reportedly a common cause of failure in anterior cruciate ligament reconstruction. Some studies suggest more anatomic femoral tunnel placement improves kinematics. The ability of the transtibial technique and a tibial tunnel-independent technique (placed transfemorally outside-in) to place the guide pin near the center of the femoral attachment of the anterior cruciate ligament was compared in 12 cadavers. After arthroscopic placement of the guide pins, the femur was dissected and the three-dimensional geometry of the femur, anterior cruciate ligament footprint, and positions of each guide pin were measured. The transtibial guide-pin placement was 7.9 ± 2.2 mm from the center of the footprint (near its anterior border), whereas the independent technique positioned the guide pin 1.9 ± 1.0 mm from the center. The center of the footprint was within 2 mm of an anteroposterior line through the most posterior border of the femoral cartilage in the notch and a proximodistal line through the proximal margin of the cartilage at the capsular reflection. More accurate placement of the femoral tunnel might reduce the incidence of graft failure and might reduce long-term degeneration observed after reconstruction although both would require clinical confirmation. The institution of the authors has received funding from Arthrex. Each author certifies that his or her institution has approved or waived approval for the human protocol for this investigation and that all investigations were conducted in conformity with ethical principles of research.     

Morphology of the femoral intercondylar notch

BACKGROUND: During anterior cruciate ligament reconstruction, proper femoral tunnel placement is important. The purpose of the present study was to characterize the osseous anatomy of the femoral intercondylar notch. METHODS: We studied the morphology of the femoral intercondylar notch in 200 human femora from skeletally mature donors, with specific attention being paid to the morphology of the ridge on the lateral wall of the intercondylar notch and the posterolateral rim of the intercondylar notch. The distances from the posterolateral rim of the intercondylar notch to the lateral intercondylar ridge and from the posterolateral rim of the intercondylar notch to the inlet of the intercondylar notch (notch depth) were measured at the nine, ten, and eleven o'clock positions for right knees and at the one, two and three o'clock positions for left knees. RESULTS: The lateral intercondylar ridge was present in 194 femora and absent in six. The mean distance from the posterolateral rim of the intercondylar notch to the lateral intercondylar ridge was 9.0, 11.0, and 12.7 mm at the nine, ten, and eleven o'clock positions in right knees and the one, two, and three o'clock positions in left knees, respectively. We observed three different types of morphology of the posterolateral rim of the intercondylar notch. The morphology of the posterolateral rim of the intercondylar notch was distinct in 183 of 200 specimens. A distinct, straight border (type 1) was seen in 175 femora (87.5%); a distinct, V-shaped border (type 2) was seen in eight (4%); and an indistinct border (type 3) was seen in seventeen (8.5%). CONCLUSIONS: The morphology of the femoral intercondylar notch varies little. Occasionally, the posterolateral rim of the intercondylar notch is not well-defined. In these knees, accurate placement of commercial femoral tunnel aiming guides may be difficult.     

Anatomic Anterior Cruciate Ligament Reconstruction

Anterior cruciate ligament reconstruction (ACLR) techniques have substantially evolved over the past several decades, driven by evidence that nonanatomic techniques increase the risk for instability, loss of motion, surgical failure, and posttraumatic osteoarthritis. Early techniques used transtibial femoral tunnel drilling, although improved understanding of the anatomy and biomechanics has led to independent femoral tunnel. Anatomic ACLR requires careful consideration of the native ACL dimensions and orientation. Although there is significant variation between patients, understanding of anatomic patterns allows for reliable identification of the ACL footprints and appropriate tunnel positioning, particularly in chronic injuries where the remanent ACL stump is degraded or absent. The femoral tunnel should be placed low and posterior on the lateral femoral condyle using the lateral intercondylar and bifurcate ridges as landmarks. The center of the tibial footprint can be determined by referencing the medial tibial spine and posterior border of anterior horn of lateral meniscus. Measurement of the dimensions of the native ACL and intercondylar notch is also critical for determining graft size and minimizing the risk of impingement, with a goal of reconstructing 50% to 80% of the tibial footprint area. Clinical outcome studies have demonstrated superior anteroposterior and rotatory knee stability with low surgical revision rates (reported between 3% and 5%). By adhering to the principles of anatomic ACLR, surgeons can produce an appropriately sized and located graft for the individual patient, thereby best restoring native knee kinematics and maximizing function. The aim of this infographic is to highlight essential features of anatomic ACLR techniques, which a focus on the native anatomy and surgical planning to achieve an anatomic ACLR.     

The shape of the inferior part of the glenoid: a cadaveric study

Previously, the shape of the inferior glenoid has been described as a circle with a bare spot being the center of that circle. This cadaveric study was done to test that statement. Forty cadaveric scapulae were used in this study. Two researchers used a digital image analysis program to assess the shape of the inferior glenoid and measured the distances from the bare spot to the anterior, inferior, and posterior cartilage and the bone rim. In 39 of 40 scapulae, the inferior glenoid had the shape of a true circle. Statistical analysis showed that the center of the bare spot is not the mathematical center of the inferior glenoid, but the differences in distances to the anterior, inferior, and posterior rims were very small (1.16-2.41 mm). Both observations can be used for further development of methods for measuring glenoid bone loss in patients with anterior glenohumeral instability.     

Identification of the optimal intercondylar starting point for retrograde femoral nailing: an anatomic study

BACKGROUND: Retrograde nailing of femoral shaft fractures is an effective and increasingly more popular method of fracture fixation. However, concern remains regarding the effect of the intercondylar entry-portal location on knee function. METHODS: The optimal entry-portal location was identified in cadaver femurs. Approximating the clinical intraoperative situation, a threaded guidewire was inserted into each of 26 distal femur specimens and positioned in the center of the femoral shaft as determined by anteroposterior and lateral fluoroscopic imaging. Each guidewire was then overdrilled with a 12-mm cannulated drill bit. All entry-portal locations were recorded relative to the posterior cruciate ligament attachment and the intercondylar groove and mapped relative to the known patellofemoral contact area. RESULTS: The starting holes averaged 6.21 mm anterior to the posterior cruciate ligament attachment and 2.67 mm medial to the intercondylar groove. Overall, 100% of starting portals were located in safe areas relative to the patellofemoral contact area. CONCLUSION: In the vast majority of femurs, the optimal entry portal for retrograde femoral nailing (in line with the long axis of the femur) is located in the expected safe position, anterior to the posterior cruciate ligament insertion and slightly medial to center of the intercondylar groove. However, because of anatomic variability, the ideal starting position occasionally may be located in a patellofemoral contact area. Potential compromise of the patellofemoral contact area by the retrograde nail entry portal can and should be recognized before nailing, allowing the surgeon the option of altering the surgical technique.     

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.     

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.     

Anatomy and function of the anterior cruciate ligament

The anterior cruciate ligament originates at the medial wall of the lateral femoral condyle and inserts into the middle of the intercondylar area. It contributes significantly to the stabilization and kinematics of the knee joint. The femoral origin is oval and is located in the posterior aspect of the lateral femoral condyle. Therefore, it is difficult to visualize the femoral origin arthroscopically. This might be one reason for anterior malpositioning of the femoral bone tunnel during anterior cruciate ligament reconstruction. The position of the femoral origin is behind the center of rotation of the knee joint; therefore, it becomes tense when the knee is extended. The tibial insertion is oval and its center is nearly in the middle of the tibial plateau. Definite landmarks for tibial tunnel placement in anterior cruciate ligament reconstruction are the distance between the central insertion point at the intercondylar floor and the posterior cruciate ligament (7-8 mm) and the anterior horn of the lateral meniscus. The anterior cruciate ligament consists of multiple small fiber bundles. From a functional point of view, one can differentiate the anteromedial and posterolateral fiber bundles. The anteromedial fibers are tense during a greater range of motion than the posterolateral fibers. The main part of the anterior cruciate ligament consists of type I collagen-positive dense connective tissue. The longitudinal fibrils of type I collagen are divided into small bundles by thin type III collagen-positive fibrils. In the distal third, the structure of the tissue varies from the typical structure of a ligament. In this region, the structure of the tissue resembles fibrocartilage. Oval-shaped cells surrounded by a metachromatic extracellular matrix lie between the longitudinal collagen fibrils. The femoral origin and the tibial insertion have the structure of a chondral apophyseal enthesis. Near the anchoring region at the femur and tibia, there should be various mechanoreceptors, which might have an important function for the kinematics of the knee joint. The blood supply of the anterior cruciate ligament arises from the middle geniculate artery. The ligament is covered by a synovial fold where the terminal branches of the middle and the inferior geniculate artery form a periligamentous network. From the synovial sheath, the blood vessels penetrate the ligament in a horizontal direction and anastomose with a longitudinally orientated intraligamentous network. The distribution of blood vessels within the anterior cruciate ligament is not homogeneous. We detected three avascular areas within the ligament: Both fibrocartilaginous entheses of the anterior cruciate ligament are devoid of blood vessels. A third avascular zone is located in the distal zone of fibrocartilage adjacent to the roof of the intercondylar fossa.