膝横韧带所致外侧半月板前角假撕裂的发生机制与鉴别方法

目的 明确膝横韧带所致外侧半月板前角假撕裂的发生机制，探讨外侧半月板前角假撕裂与真撕裂的鉴别方法。方法 采用40例成人尸体膝关节标本，观察膝横韧带与外侧半月板前角的关系。对50例正常膝进行矢状及冠状位MR扫描，观察膝横韧带的MRI表现。结果 膝横韧带在尸膝标本的出现率为80％，该韧带与外侧半月板前角及其中央腱性附着部之间以脂肪组织分隔。在MR矢状像上，可见脂肪组织在膝横韧带与外侧半月板前角之间形成的线样稍高信号裂隙，类似外侧半月板前角撕裂，被称为假撕裂。这种假撕裂的出现率为30％，多表现为外侧半月板形态规则、撕裂线斜行，矢状位图像可连续显示膝横韧带，冠状位图像能显示该韧带的长轴。结论 根据外侧半月板前角形状、撕裂线方向、观察矢状和冠状位图像，可正确区分外侧半月板前角的真、假撕裂。     

正常成年人膝关节的MR测量及其成像

目的通过对正常成年人膝关节MRI的半月板及韧带的测量,为膝关节损伤性疾病的诊断提供参考值.方法 53例正常对照组成人膝关节MRI检查资料,选择矢状位及冠状位PDWI成像序列,分别测量正常成年人半月板、前、后交叉韧带、内、外侧副韧带、胫骨平台的有关数据,并与解剖文献的大体测量结果进行比较.其中13例同时做了矢状位及冠状位的T2WI及PDWI压脂序列扫描,分析、比较压脂序列对显示半月板及韧带的优势.结果半月板的MR测量值较大体解剖测量值大,外侧半月板后角较半月板的其余部分厚.内侧半月板体部横径与胫骨平台宽径及体重呈线性相关.前交叉韧带与Blumensaat线的夹角小于15°,后交叉韧带的角度约为(120.89±5.63)°.结论膝关节的MR测量值较大体解剖测量值更能反映活体的真实情况,为临床膝关节损伤性疾病的诊断提供正常参考值,外侧半月板后角较前角及内侧半月板厚;内侧半月板体部横径与胫骨平台宽径及体重间可建立多元线性回归方程,体重对内侧半月板体部横径的作用稍大于胫骨平台的作用;MR特别是T2WI及PDWI压脂序列对显示膝关节结构具有较高的价值.     

平衡式稳态自由进动序列成像正常椎管内臂丛神经根解剖研究

目的：应用MRI平衡式稳态自由进动（Balance SSFP）序列成像多平面重建描述椎管内臂丛正常形态解剖。材料与方法：本组20例自愿者行MRI检查;从283例同时行CTM和MRI检查中筛选CTM未见椎管内臂丛神经根结构损伤的28例与MRI比较。行冠状、矢状及斜横轴位重建,测量20例自愿者各组神经根。结果：冠状图像显示完整的神经前、后根结构,前根表现为“机翼状”,后根表现为“毛刷状”;矢状位脊髓旁层面显示各组神经根与相应椎体位置关系;斜横轴位图像显示神经根连续性更完整,避免了上下组神经根重叠。结论：应用Balance-SSFP序列成像,冠状位、矢状位及斜横轴位重建图像,可提供更多的椎管内臂丛的形态解剖学信息。     

内侧半月板后角根部撕裂MRI各扫描方位诊断价值

目的：研究膝关节内侧半月板后角根部撕裂在MRI不同扫描方位的诊断价值。方法收集我院经MRI检查,并经关节镜证实的32例内侧半月板后角根部撕裂资料进行分析;选取32例同年龄段的半月板其他节段损伤而无根部撕裂资料组进行对照。病例组分别在矢、冠、轴位图像上观察各扫描方位撕裂特征性征象,统计各扫描方位诊断的敏感性,特异性,阳性预测值和阴性预测值。结果32例内侧半月板后角根部撕裂中,矢状位上主要表现为“鬼影征”;冠状位主要表现为“截断征”,具体各表现略有不同;轴位上主要表现为“钝圆征”或“裂隙征”。上述征象在病灶组均明显好发于对照组（P＜0.05）。敏感性,特异性,阳性预测值和阴性预测值在病例组矢状位观察分别为：100%、80%、80%和100%;冠状位上分别为：100%、95%、93.8%和100%;轴位上为：93.8%、90.7%、90.9%和93.5%。结论 MRI扫描矢、冠、轴三个方位显示内侧半月板后角根部撕裂各有其特征性征象,明显好发于对照组。根部撕裂矢状位诊断的敏感性非常高,但会出现假阳性现象;冠状位敏感性同样非常高,而且诊断特异性优于矢状位;轴位图像是显示内侧半月板根部撕裂的容积形态的最好方位,但诊断价值受限于扫描到的半月板层数太少。     

正常后交叉韧带MRI表现

目的：探讨MRI显示后交叉韧带（PCL）的方法及其正常表现。方法：对40例正常志愿者膝关节行T2WI对比的三维梯度回波多回波成像（3D-MEDIC）检查,通过多平面重建显示PCL的形态。结果：经过多平面重建,在横轴位、矢状位和冠状位层面显示PCL良好的形态和较清晰的边界。PCL解剖测量值：中段宽度（1.13±0.17）cm,厚度（0.49±0.10）cm;长度,后内侧缘（2.58±0.35）cm,前外侧缘（3.78±0.36）cm;偏离角,后内侧缘19.1°±5.5°,前外侧缘24.0°±4.6°;PCL仰角40.1°±4.43°。结论：利用高分辨三维MRI成像多平面重建技术有助于更好的观测PCL。     

膝关节前交叉韧带损伤的MRI成像方法及诊断研究

目的:结合膝关节交叉韧带的解剖学特点及MRI表现,探寻前交叉韧带(ACL)最佳MRI成像方法、观测ACL损伤的MRI表现,为临床诊断ACL损伤提供可靠的影像学资料。方法:选择成人膝关节ACL损伤30例,分别进行膝关节伸直位、微曲位和屈曲位的快速自旋回波序列垂直矢状位和斜矢状位的MR扫描,观察不同位置、不同角度矢状面交叉韧带的显示效果及MRI表现。结果:①ACL损伤的显示:ACL损伤在伸直位垂直、斜矢状面完整显示率分别为46.7%、53.3%;微曲位垂直、斜矢状面上ACL在斜矢状面上完整显示率分别为80.0%、80.0%;屈曲位垂直、斜矢状面上ACL完整显示率分别为90.0%、90.0%。②ACL损伤的MRI表现:ACL部分性撕裂韧带中出现的局限性高信号,完全性撕裂韧带显示局限性中断或完全缺损或韧带附着处出现团状高信号影或韧带纤维难于辨认。结论:ACL在MRI上屈曲位斜矢状面显示最佳,可作为诊断前交叉韧带损伤的有效手段;ACL的形态、信号的变化对ACL损伤的诊断具有重要的指导意义。     

1.5TMRI在膝关节损伤中的诊断价值

目的:探讨膝关节损伤特征,通过分析膝关节损伤的1.5T MRI影像表现,为有效诊治运动所致膝关节损伤提供准确诊断依据。材料与方法:本次收集25例膝关节损伤病例,平均年龄30岁。全部病例均用1.5TMRI膝关检查,应用膝关节线圈,斜矢状位TSE T_1WI、TSE T_2WI、PD-SPIR和冠状位、轴位TSE T_2WI扫描。所有影像学特征均与临床及关节镜手术结果对照分析。结果:(1)半月板损伤:20例内侧半月板后角Ⅲ度损伤,20例外侧半月板前角Ⅲ度损伤,13例外侧半月板后角Ⅲ度损伤;(2)韧带损伤:13条前交叉韧带完全断裂,与关节镜诊断完全符合率为82.00%。6条前交叉韧带撕裂(部分断裂),与关节镜断完全符合率100%。1条前交叉韧带胫骨端撕脱,与关节镜诊断符合率为100%。17例内侧副韧带II度损伤,5例内侧副韧带Ⅲ度断裂损伤;8例外侧副韧带断裂,8例腘肌腱断裂;2例髌韧带断裂,8例髌腱炎。(3)软骨损伤:20例髌骨软骨Ⅲ度损伤,2例髌骨软骨IV度损伤。(4)骨质改变:8例骨折分别位于髌骨上极、胫骨平台塌陷骨折、胫骨前交叉韧带止点骨折,10例骨挫伤。(5)25例均表现为关节囊内的长T_1长T_2信号,其中1例患者为关节积血。结论:1.5T MRI能够最佳地显示膝关节多发运动损伤、急慢性损伤以及对损伤程度的判定,有助于指导运动过程中膝关节功能保护和损伤康复及治疗。     

螺旋CT多平面重建对膝交叉韧带MR扫描方式的指导价值

目的：通过螺旋CT多平面重建技术探寻膝关节交叉韧带成像的最佳方位,指导交叉韧带MR扫描方式,提高交叉韧带MR图像的显示程度。方法：随机选取2009年1月~2010年3月50例成人膝关节螺旋CT检查阴性者,调取双侧膝关节薄层横断面重建图像,利用多平面重建技术进行任意角度矢状面重建,分析所得图像交叉韧带的显示程度。结果：膝关节自然伸直位,当定位线平行于股骨髁间窝层面的外侧髁内缘时,所得矢状面图像膝关节交叉韧带显示完整（一个层面以上）,前交叉韧带显示率为98%,后交叉韧带显示率为100%,明显优于其他方位。依上述方位做矢状面定位,20例MR检查阴性者图像示前、后交叉韧带显示完整,显示率为100%。结论：利用螺旋CT多平面重建技术探寻膝关节交叉韧带成像的最佳方位,操作简单,结论准确,对膝关节交叉韧带MR扫描方式具有明确的指导价值。     

磁共振检查病案精选(五十四)(骨肌系统)

髌韧带是指髌骨尖向下行并止于胫骨粗隆的致密纤维组织带,是股四头肌腱向髌骨下方的延续结构,并与髌内、外侧支持带相延续,位置浅在,厚实坚韧。伸膝时松弛,屈膝时紧张。该韧带膝关节囊滑膜间为膝脂体,与胫骨间有髌下深囊。髌韧带损伤是膝关节软组织损伤之一,常为直接暴力致伤;亦可过度屈膝、股四头肌强力收缩,牵引性致伤。临床上有剧痛、肿胀和压痛等症状。MRI表现,矢状位是显示髌韧带损伤的最佳检查方位,横断位亦可了解其损伤的细节和程度。T1加权像显示髌韧带损伤处明显增粗、肿大或小同程度中断.呈等或稍高信号,断端分离或变形,局部皮肤和皮下组织肿胀,膝脂体受压。T2加权像显示稍高或高信号,并可同时了解有无关节韧带、半月扳等损伤。压脂后显示髌韧带明显高信号影,可了r解出血灶的程期变化.以及周围组织水肿等。磁共振检查病案精选(五十四)(骨肌系统)@邓开鸿$四川大学华西医院放射科!四川成都610041 @唐汉军$四川大学华西医院放射科!四川成都610041     

膝关节前交叉韧带与冠状面成角分析和斜冠状位扫描的建立

目的：明确膝关节前交叉韧带解剖取向轴和冠状面成角，从而进一步调整MRI扫描角度，建立新的扫描方法。 方法：实验于2004—09／2005—01分别在解放军第三军医大学西南医院四肢关节核磁共振室、第三军医大学解剖实验室完成。对既往前交叉韧带全长显示清楚的120例成人（男女各60例）的MRI影像（斜矢状位）按左右膝、性别分组，在Artoscan—C上测量前交叉韧带与冠状面成角及前交叉韧带长度和厚度。将国人新鲜成人膝关节标本在改进的TK-6350型数控铣床上，进行矢状位冰冻薄层解剖切片，对前交叉韧带进行解剖观察。以前交叉韧带与冠状面所成角度试行膝关节斜冠状位扫描，使MRI扫描方向与前交叉韧带斜冠方向上的解剖取向轴一致，并分析简化操作，建立斜冠状位扫描方法。 结果：①左右膝关节前交叉韧带的测量值在斜矢状位差异无显著性意义（P〉0．05）。②男性前交叉韧带在斜矢状位测量长度和厚度高于女性，差异有非常显著性意义[分别为（36．45&;#177;1．98），（34．52&;#177;1．93）mm；（6．09&;#177;1．07），（5．45&;#177;1．13）mm，P〈0．01]，和冠状面的角度高于女性，差异有显著性意义[分别为（36．4&;#177;2．5）&;#176;，（35．4&;#177;2．5）&;#176;，P〈0．05]。伸膝位下前交叉韧带与冠状面的角度相对较恒定，走行平直，可以依据该角度行平行于前交叉韧带的薄层斜冠状位MRI扫描。 结论：薄层斜冠状位MRI扫描是一种显示前交叉韧带解剖结构较好的方法。     

双能CT成像在显示膝关节韧带中的价值

目的 初步探讨双能CT成像在显示膝关节韧带中的价值.方法 对 12 例志愿者行膝关节双能CT 扫描,并均行容积显示(VRT)和多平面重建(MPR)等二维及三维图像后处理,用以显示膝关节的韧带.由2名有经验的放射科医生对图像进行分析.结果 膝关节部分韧带(膑韧带、前、后交叉韧带和腓侧副韧带)亦可清晰的显示;而较薄的韧带(胫侧副韧带)、横行的韧带(如膑内、外侧支持带)和后方的韧带(如恫斜韧带)显示欠佳.结论 双能CT是一种能够多方位、立体、直观地显示膝关节韧带的新方法,对临床应用具有一定的价值.     

Tibial tuberosity anteriomedialization vs. medial patellofemoral ligament reconstruction for treatment of patellar instability related to malalignment: Computational simulation

BackgroundMedial patellofemoral ligament reconstruction and tibial tuberosity anteromedialization are common treatment options for recurrent lateral patellar instability, although ligament reconstruction is not commonly applied to knees with lateral malalignment.MethodsMultibody dynamic simulation was used to assess knee function following tibial tuberosity anteromedialization and medial patellofemoral ligament reconstruction for knees with lateral malalignment. Dual limb squatting was simulated with six models representing knees being treated for patellar instability with an elevated tibial tuberosity to trochlear groove distance. The patellar tendon attachment on the tibia was shifted medially (10 mm) and anteriorly (5 mm) to represent tibial tuberosity anteromedialization. A hamstrings tendon graft was represented for medial patellofemoral ligament reconstruction. Patellar tracking was quantified based on bisect offset index. The patellofemoral contact pressure distribution was quantified using discrete element analysis. Data were analyzed with repeated measures comparisons with post-hoc tests.FindingsBoth procedures significantly reduced bisect offset index, primarily at low flexion angles. The decrease was larger for tibial tuberosity anteromedialization, peaking at 0.18. Tibial tuberosity anteromedialization shifted contact pressures medially, significantly increasing the maximum medial contact pressure at multiple flexion angles, with the maximum pressure increasing up to 1 MPa.InterpretationThe results indicate tibial tuberosity anteromedialization decreases lateral patellar maltracking more effectively than medial patellofemoral ligament reconstruction, but shifts contact pressure medially. Tibial tuberosity anteromedialization is likely to reduce the risk of post-operative instability compared to medial patellofemoral ligament reconstruction. The medial shift in the pressure distribution should be considered for knees with medial cartilage lesions, however.     

MRI 对一过性髌骨外侧脱位的诊断价值

【目的】探讨一过性髌骨外侧脱位(TLPD)患者的 MRI 影像特征。【方法】回顾性分析本院收治的56例 TLPD 患者的临床 MRI 资料,对有无骨或软骨损伤、关节内游离体、内侧髌股韧带损伤、关节积液、髌骨半脱位和外倾、解剖异常等进行判断分析,并结合临床资料、X 线片及关节镜图像分析,总结该类患者影像学特征。【结果】初次就诊时被误诊、漏诊有26例(46.4%)。MRI 显示56例(100%)患者均存在“对吻征”所致不同程度的骨软骨损伤,其中股骨外髁外侧前缘有10例(17.9%)软骨骨折,骨软骨骨折6例(10.8%);髌骨下极内侧缘有16例(28.6%)软骨骨折,10例(17.9%)骨软骨骨折。关节内游离体20例(35.7%);50例(89.3%)有不同程度的内侧髌股韧带损伤和关节积液;髌骨半脱位和外倾36例(64.3%);56例患者中存在股骨滑车发育不良者 16例(28.6%),高位髌骨者14例(25.0%),TT-TG>20 mm 者6例(10.7%)。【结论】TLPD 患者误诊、漏诊率较高,MRI 能准确地显示各解剖结构的损伤及程度,有助于明确诊断,应作为该病的首选检查方法。     

Comparison of muscle activation levels and knee valgus between individuals with medial patellofemoral ligament reconstruction and healthy individuals during fatiguing step down task

BackgroundMedial patellofemoral ligament reconstruction becomes first-choice surgical procedure for patients with a history of lateral patellar dislocations but there is limited knowledge about neuromuscular activation patterns of individuals with a history of patellar dislocation who underwent medial patellofemoral ligament reconstruction.ObjectiveThe aim of this study was to compare muscle activation levels and knee valgus during step down performance test between individuals with a history of medial patellofemoral ligament reconstruction and healthy individuals.MethodsFifteen individuals with medial patellofemoral ligament reconstruction and 15 healthy individuals were included. Vastus medialis obliquus, vastus lateralis and gluteus medius muscle activation levels and knee valgus were measured during 60-s- step down performance test. Two-way repeated-measures of analysis of covariance was used for statistical analysis.FindingsCompared to the healthy individuals, individuals with medial patellofemoral ligament reconstruction showed lower vastus medialis obliquus (p = .04) and gluteus medius (p = .005) activation levels, and higher knee valgus (p = .002) in last period of the step down performance test.InterpretationSince the significant results were only observed in the fatiguing section of the test, endurance tests may provide more information about neuromuscular control of the individuals with history of medial patellofemoral ligament reconstruction. Future studies should investigate whether endurance exercises that target to improve vastus medialis obliquus and gluteus medius activity result in better clinical outcomes than conventional programs for individuals with medial patellofemoral ligament reconstruction.     

The quantitative influence of current treatment options on patellofemoral stability in patients with trochlear dysplasia and symptomatic patellofemoral instability - a finite element simulation

BackgroundTrochlear dysplasia is highly associated with patellofemoral instability. The goal of conservative and surgical treatment is to stabilize the patella while minimizing adverse effects. However, there is no literature investigating the quantitative influence of different treatment options on patellofemoral stability in knees with trochlear dysplasia. We created and exploited a range of finite element models to address this gap in knowledge.MethodsMRI data of 5 knees with trochlear dysplasia and symptomatic patellofemoral instability were adapted into this previously established model. Vastus medialis obliquus strengthening as well as double-bundle medial patellofemoral ligament reconstruction and the combination of medial patellofemoral ligament reconstruction and trochleoplasty were simulated. The force necessary to dislocate the patella by 10 mm and fully dislocate the patella was calculated in different flexion angles.FindingsOur model predicts a significant increase of patellofemoral stability at the investigated flexion angles (0°-45°) for a dislocation of 10 mm and a full dislocation after medial patellofemoral ligament reconstruction and the combination of medial patellofemoral ligament reconstruction and trochleoplasty compared to trochleodysplastic (P = 0.01) and healthy knees (P = 0.01–0.02). Vastus medialis obliquus strengthening has a negligible effect on patellofemoral stability.InterpretationsThis is the first objective quantitative biomechanical evidence supporting the place of medial patellofemoral ligament reconstruction and medial patellofemoral ligament reconstruction combined with trochleoplasty in patients with symptomatic patellofemoral instability and trochlear dysplasia type B. Vastus medialis obliquus strengthening has a negligible effect on patellar stability at a low total quadriceps load of 175 N.     

Study of patellar kinematics after reconstruction of the medial patellofemoral ligament

Background

Medial patellofemoral ligament reconstruction is currently the technique of choice for the treatment of patellar instability. But what should be the most appropriate graft tension for optimal restoration of patellofemoral kinematics?

Methods

Six freshly frozen cadaveric knees were studied, the three bone segments were respectively equipped with opto-reflective markers. The acquisitions were made using the Motion Analysis System®. Six successive acquisitions were performed for each knee under different levels of graft tension.

Findings

With an intact medial patellofemoral ligament, the medial patellar tilt increased up to a mean value of 2.02° (SD 3.1), the medial patellar translation gradually increased up to a mean value of 3.3 mm (SD 2.25) with a slight lateral rotation over the first 30° of knee flexion with a maximum mean value of 1.22° (SD 0.8) at 20° of knee flexion.Reconstruction of the medial patellofemoral ligament was performed using different levels of tension applied to the graft. Only 10 N of graft tension could restore normal patellar tilt, lateral shift and rotation, with results approximating those measured on healthy knee.

Interpretation

This study confirms the role of the medial patellofemoral ligament in providing adequate patellar stability during the first 30° of knee flexion. According to our findings, a 10 N tension applied to the graft appears sufficient to ensure proper control of patellar tracking whereas 20, 30 and 40 N of tension are excessive tension values inducing a major overcorrection in all studied parameters.     

Increased internal femoral torsion can be regarded as a risk factor for patellar instability — A biomechanical study

BackgroundIncreased internal femoral torsion is regarded as a risk factor for patellar instability. Biomechanical investigations confirming this hypothesis are missing.MethodsEight fresh-frozen cadaver knees were tested on a specially designed simulator. Patellar motion and patellofemoral pressure were evaluated for 0°, 10°, and 20° of increased internal and external femoral torsion with native and with transected medial patellofemoral ligaments used to simulate patellar instability. A regression analysis was used for statistical analysis.FindingsIn native medial patellofemoral ligaments, there were no significant changes in mean or peak pressures for any torsional states (P ≥ 0.07). At 20° increased internal femoral torsion, there was a significant center of force shift towards the lateral side (P = 0.01). Patellar shift was directed laterally at low knee flexion angles up to 30°. Lateral patellar tilt increased significantly at 10° and 20° of increased internal femoral torsion (P ≤ 0.004). In transected medial patellofemoral ligaments, mean pressure (P ≤ 0.005) and peak pressure (P ≤ 0.02) decreased significantly for all torsional states. There was a significantly greater lateral center of force shift with increased internal femoral torsion (P ≤ 0.04). Lateral patellar tilt increased significantly (P < 0.001). Patellar shift did not change significantly with increased internal femoral torsion (P ≥ 0.30).InterpretationIn a native medial patellofemoral ligament, 20° of increased internal femoral torsion can be regarded as a significant risk factor for patellar instability. With an insufficient medial patellofemoral ligament, 10° of increased internal femoral torsion already represents a significant risk factor.     

Superior-inferior position of patellar component affects patellofemoral kinematics and contact forces in computer simulation

BackgroundAnterior knee pain has been reported as a major postoperative complication after total knee arthroplasty, which may lead to patient dissatisfaction. Rotational alignment and the medial-lateral position correlate with patellar maltracking, which can cause knee pain postoperatively. However, the superior-inferior position of the patellar component has not been investigated. The purpose of the current study was to investigate the effects of the patellar superior-inferior position on patellofemoral kinematics and kinetics.MethodsSuperior, central, and inferior models with a dome patellar component were constructed. In the superior and inferior models, the position of the patellar component translated superiorly and inferiorly, respectively, by 3 mm, relative to the center model. Kinematics of the patellar component, quadriceps force, and patellofemoral contact force were calculated using a computer simulation during a squatting activity in a weight-bearing deep knee bend.FindingsIn the inferior model, the flexion angle, relative to the tibial component, was the greatest among all models. The inferior model showed an 18.0%, 36.5%, and 22.7% increase in the maximum quadriceps force, the maximum medial patellofemoral force, and the maximum lateral patellofemoral force, respectively, compared with the superior model.InterpretationSuperior-inferior positions affected patellofemoral kinematic and kinetics. Surgeons should avoid the inferior position of the patellar component, because the inferior positioned model showed greater quadriceps and patellofemoral force, resulting in a potential risk for anterior knee pain and component loosening.