Partial and complete tear of the anterior cruciate ligament

PURPOSE: To analyze MR direct and indirect signs for knees with anterior cruciate ligament (ACL) partial or complete tear. MATERIAL AND METHODS: According to documented MR direct and indirect signs for ACL tear, we retrospectively reviewed the incidence of those signs in 15 partial ACL tear and 17 complete ACL tear patients. The findings were also compared with duration of injury (less or more than 6 weeks, as acute or chronic stages). RESULTS: A residual straight and tight ACL fiber in at least one pulse sequence was more frequently detected in partial ACL tears. The empty notch sign, a wavy contour of ACL, bone contusion at lateral compartment and lateral meniscus posterior horn tear were significantly more frequently seen in complete tear cases. The posterior cruciate ligament angle in chronic complete ACL tear cases (109 degrees +/-20 degrees ) had a tendency to be less than in chronic partial ACL tear cases (119+/-18 degrees ). CONCLUSION: The empty notch sign, a wavy ACL, bone contusion, and posterior horn of lateral meniscus tears are suggestive of a complete ACL tear. A residual straight and tight ACL fiber seen in at least one image section is a helpful sign to diagnosis of partial ACL tear. In the acute ACL injury stage, a focal increase of the ACL signal intensity is more suggestive of a partial ACL tear.     

Mucoid degeneration of the anterior cruciate ligament mistaken for ligamentous tears

Objective. To describe the MR features of mucoid degeneration of the anterior cruciate ligament (ACL) in a series of patients with MRI findings that were mistaken for tears in the majority of cases but who were found to have an intact ligament at arthroscopy. We will suggest a pathologic entity corresponding to this finding and describe some characteristic features that can be used to identify this entity on MRI. Design. A retrospective analysis of 10 MRI examinations of the knee was performed after arthroscopic evaluation. Prearthroscopic MRI findings had been interpreted as a tear in six patients prospectively and in the remaining four the diagnosis of mucoid degeneration was suggested and ultimately proven. All patients had an intact ACL by preoperative clinical examination, examination under anesthesia, and at arthroscopy. Results. MRI examinations demonstrated an ill-defined ACL, greater in girth than the normal ligament and characterized by increased signal on all sequences. The high-signal ligament was oriented in the normal direction of the ACL. The overall appearance of the ligament was retrospectively described as like a celery stalk. Arthroscopy demonstrated mechanically intact ligaments with a normal to expanded external appearance. Probing of three of the ligaments caused a material to be expressed and pathologic evaluation resulted in the diagnosis of cystic, mucoid degeneration. Conclusion. Mucoid degeneration and an intact ACL can be suspected when an apparently thickened and ill-defined ligament with increased signal intensity on all sequences is identified in a patient with a clinically intact ligament. Received: 10 April 2000 Revision requested: 18 July 2000 Revision received: 13 November 2000 Accepted: 27 November 2000     

膝关节前十字韧带撕裂的MRI诊断价值

目的：评价MRI诊断前十字韧带撕裂的价值。方法：对临床拟诊为膝关节前十字韧带撕裂的12例患者，对照分析其MRI资料及手术结果。结果：MRI矢状面9例，冠状面7例显示前十字韧带撕裂。12例中8例前十字韧带内有不规则高信号，4例前十字韧带前缘呈不规则波浪状，1例前十字韧带不连续。12例中6例伴后外侧胜分平台分析。MRI确诊11例。结论：MRI诊断前十字韧带撕裂是有价值的，膝关节后外侧胜管平台分析高度提示急性前十字韧带撕裂。     

膝关节韧带损伤的MRI诊断

目的:探讨膝关节韧带损伤的MRI表现及诊断价值。方法:36例临床怀疑膝关节损伤的患者于关节镜及手术前行MRI检查,以关节镜结果作为金标准,前瞻性分析膝关节韧带损伤的MRI表现及诊断价值。结果:关节镜证实前交叉韧带损伤21例,其中完全撕裂15例,部分撕裂6例,后交叉韧带损伤12例,正常患者15例。MRI诊断前交叉韧带损伤的敏感度为95.2%,特异度为80%,准确度为88.9%;诊断后交叉韧带损伤的敏感度为100%,特异度为95.8%,准确度为97.2%。结论:MR1是诊断膝关节韧带损伤的理想检查方法,具有较高的临床应用价值。     

膝关节交叉韧带低场强MRI表现及其损伤诊断

目的 :研究膝关节正常交叉韧带MRI特点和交叉韧带损伤的的MRI表现。方法 :对 2 0 0例正常膝关节交叉韧带的MRI进行回顾性分析 ,对 2 5例临床可疑交叉韧带损伤患者的MRI资料和关节镜检查行对比研究。结果 :正常膝关节矢状位MRI上显示交叉韧带最佳 ,冠状位和横断位作为补充 ,交叉韧带损伤的MRI表现为韧带连续性中断、局灶性或弥漫性肿胀、信号强度增高及断端移位 ;以关节镜检查结果为标准 ,MRI诊断交叉韧带损伤的敏感度为 91.3 % ,特异度为 91.6% ,符合率为 91.4%。结论 :MRI多方位扫描是一种准确诊断交叉韧带损伤的方法 ,矢状位显示交叉韧带最佳。     

前交叉韧带撕裂的MRI诊断

目的:研究膝关节前交叉韧带撕裂的MRI表现。方法:回顾分析30例经关节镜证实的前交叉韧带撕裂MR图像及40例完好的ACL,分析其直接及间接征象的特征。结果:在评价的直接征象中,ACL不连续和ACL走行异常均具有相对高的诊断敏感性、特异性;在评价的间接征象中,后交叉韧带角、Blumensaat角、后交叉韧带指数、半月板后移征、“对吻性”骨挫伤、胫骨前移位等6个征象具有相对高的特异性,后交叉韧带角、Blumensaat角具有较高的敏感性。结论:ACL损伤的直接征象为诊断主要依据,ACL损伤的间接征象具有辅助诊断意义。     

Anterior cruciate ligament tears: MR imaging-based diagnosis in a pediatric population

PURPOSE: To evaluate the diagnostic accuracy of primary and secondary magnetic resonance (MR) imaging findings of anterior cruciate ligament (ACL) tears in young patients with immature skeletal systems. MATERIALS AND METHODS: MR images obtained in 43 patients aged 5-16 years who underwent arthroscopy were retrospectively reviewed. Two reviewers evaluated primary findings (abnormal signal intensity, abnormal course as defined by Blumensaat angle, and discontinuity), secondary findings (bone bruise in lateral compartment, anterior tibial displacement, uncovering of posterior horn of lateral meniscus, posterior cruciate ligament line, and posterior cruciate angle), and meniscal and other ligamentous injuries. RESULTS: There were 19 ACL tears and 24 intact ACLs. Overall sensitivity and specificity of MR imaging in detecting ACL tears were 95% and 88%, respectively. Sensitivities of the primary findings were 94% for abnormal Blumensaat angle; 79%, abnormal signal intensity; and 21% discontinuity. The specificity of all primary findings was 88% or greater. The sensitivity and specificity of the secondary findings, respectively, were 68% and 88% for bone bruise; 63% and 92%, anterior tibial displacement; 42% and 96%, uncovered posterior horn of lateral meniscus; 68% and 92%, positive posterior cruciate line; and 74% and 71%, abnormal posterior cruciate angle. Fifteen (79%) patients had meniscal tears, and five (26%) had collateral ligament injuries. CONCLUSION: Primary and secondary findings of ACL tears in young patients have high specificity and are useful for diagnosis.     

Association of peripheral vertical meniscal tears with anterior cruciate ligament tears

OBJECTIVE: The purpose of this article is to describe a type of meniscal tear seen on magnetic resonance (MR) imaging, the peripheral vertical tear, and to determine the prevalence of anterior cruciate ligament (ACL) tears in knees with this type of meniscal tear compared to knees with other types of meniscal tears. MATERIALS AND METHODS: Following Institutional Review Board approval, a retrospective review of 200 knee MR examinations with imaging diagnoses of 'meniscal tear' was performed to assess the location and morphology of the meniscal tear, and to assess the status of the ACL. RESULTS: Nineteen peripheral vertical meniscal tears were identified in 17 patients, 14 of whom had acute ACL tears, prior ACL reconstruction, or chronic ACL deficiency. Three peripheral vertical tears were seen in the setting of a normal ACL. Of the 183 examinations with other types of meniscal tears, there were 17 cases with acute ACL tears, prior ACL reconstruction, or chronic ACL deficiency. The difference in the prevalence of ACL tear, reconstruction, or deficiency in knees with meniscal tears of the peripheral vertical type (82.4%) compared with the prevalence of ACL tear, reconstruction, or deficiency in knees with other types of meniscal tears (9.3%) was statistically significant (P < 0.001). The calculated specificity of the presence of peripheral vertical tear morphology in detecting an ACL injury in patients with meniscal tears was 98.2%. CONCLUSIONS: Peripheral vertical meniscal tears, particularly when involving the posterior horn, are highly associated with ACL tear, deficiency, or reconstruction. The finding of this type of tear on knee MR imaging should prompt close inspection of the ACL for evidence of acute or chronic injury, and its presence may help make the diagnosis of ACL tear in equivocal cases.     

Graded stress radiography of injured anterior cruciate ligaments.

Fifty-five patients with clinical suspicion of injury to their anterior cruciate ligament (ACL) were examined by graded stress radiography before arthroscopic verification in an effort to determine the loss of ACL function as a result of ligament tearing. Using a commercially available stress device capable of applying varying pressures to the mid-calf, anterior drawers were measured from lateral radiographs at 0-, 7-, 14-, and 21-kiloPascal pressures and used to calculate the equivalent elastic modulus of the remaining ACL fibers. According to viscoelastic theory, this modulus is proportional to the number of elastically active fibers in the ligament. To verify the validity of this concept, the stress-strain relationship of a freshly excised ACL ligament was examined in a tensile testing machine, and the procedure was repeated after the ligament had been partially transsected with a scalpel. Comparison with the elastic modulus of the (intact) ACL of the opposite knee permits an estimate of the percentage of rupture in cases of partial tears. Overstretched ligaments show essentially normal viscoelastic properties once the slack in the ligament has been taken up. Complete tears, on the other hand, show a complete breakdown in the viscoelastic properties of the ACL. The results show that partial tears can be diagnosed by graded stress radiography with a sensitivity of 20% and specificity of 90%. Diagnosis of overstretched ligaments had sensitivity of 50% and specificity of 94%. Complete tears were detected with sensitivity of 88% and specificity of 75% as diagnosed against all other ACL lesions and including normals.(ABSTRACT TRUNCATED AT 250 WORDS)     

Tears of cruciate ligaments and menisci: evaluation with cine MR imaging

A cine magnetic resonance (MR) imaging technique, involving the acquisition of kinematic sagittal images during knee movement, was used to evaluate 52 symptomatic knee joints. Results were compared with those obtained by means of static three-dimensional (3D) MR imaging. Twenty-seven of the 28 anterior cruciate ligament (ACL) tears and 22 of 24 normal ligaments were correctly identified at cine MR imaging for a sensitivity of 96% and a specificity of 92%. Static 3D MR imaging yielded a sensitivity of 71% and a specificity of 88%. All four posterior cruciate ligament tears were identified at cine and 3D MR imaging. For meniscal tears, cine MR imaging yielded a sensitivity of 48% and a specificity of 96%; the sensitivity and specificity for 3D MR imaging were 71% and 96%, respectively. Cine MR imaging proved to be more useful than static MR imaging in assessing the tightness of cruciate ligaments, especially of those that were partially torn, and in assessing the movement of meniscal-free fragments. The increased information obtained with cine MR imaging may warrant continued investigation and clinical application.     

Ex-vivo MR imaging of the cruciate ligaments

Eight pairs of cruciate ligaments were obtained at autopsy for ex-vivo MR imaging. Image analysis demonstrated no differences in intrinsic signal characteristics between the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL). Histologic examination showed no differences in ligament organization. These findings support the hypothesis that the normal signal intensity difference between the ACL and PCL noted on clinical images is due to a volume-averaging artifact.     

Magnetic resonance diagnosis of meniscal tears in patients with acute anterior cruciate ligament tears

OBJECTIVE: To evaluate the accuracy of magnetic resonance imaging in the diagnosis of meniscal tear in patients with acute anterior cruciate ligament tears. METHODS: Magnetic resonance images obtained from 41 patients imaged within 6 weeks of injury who had acute anterior cruciate ligament tears identified at arthroscopy were retrospectively reviewed for meniscal tear. RESULTS: With MR imaging the sensitivity, specificity and accuracy for diagnosing meniscal tears in the presence of acute anterior cruciate ligament tears were 71%, 93%, and 88%; for the lateral meniscal tears were 57%, 100% and 85%; and for the medial meniscal tears were 100%, 88%, 90%. All false negative cases (n = 6) involved the posterior horn of the lateral meniscus. CONCLUSION: In the presence of acute anterior cruciate ligament tears, MRI imaging has relatively low sensitivity for detecting meniscal tears due to missed tears in the lateral meniscus.     

O'Donoghue's triad: magnetic resonance imaging evidence

Objective The objective was to search for magnetic resonance imaging evidence of medial collateral ligament (MCL) injury in knees with proven tears of the anterior cruciate ligament (ACL) and medial meniscus; the three abnormalities that make up O'Donoghue's triad. Although the MCL injury can be unapparent clinically, knee joint stability may be compromised. Design The superficial portion of the MCL was evaluated on 19 MR studies of 16 knees with arthroscopically proven ACL and medial meniscal tears. MCL thicknesses were compared to those on MR images of 19 normal knees. Patients The injured knees were of 13 men and 3 women, ranging in age from 19 to 56 years; the normal knees were of 10 men and 9 women, ranging in age from 19 to 55 years. Results and conclusions The medial collateral ligaments of all injured knees were abnormal, and, as a group, they had greater thicknesses and more intraligamentous thickness variability than normal knees. The MR appearance of both ACL and medial meniscal tears served as indirect evidence of MCL injury, with irregular MCL thickening indicative of prior injury.     

前交叉韧带断裂的MRI征象研究

目的 研究前交叉韧带(ACL)断裂的MRI表现,探讨其直接征象和间接征象的产生机制及诊断价值.方法 本组男37例,女3例;年龄16～49岁,平均33岁.急性期断裂28例,慢性期断裂12例,均经关节镜检查和手术证实.采用1.5 T西门子MRI扫描仪,SE或TSE序列T1、12、质子压脂、medic和横断位、矢状位、冠状位多方位成像.组织3名高年资医师进行回顾分析,对ACL断裂的MRI直接征象和间接征象进行统计分析.结果 ACL断裂4|D例中完全性断裂35例,部分断裂5例.急性期断裂的28例直接征象分别为信号中断或不连续24例(86%),信号不均匀18例(64%),韧带肿胀增厚10例(36%);而慢性期断裂的12例分别韧带增厚11例(92%),信号中断或不连续9例(75%),信号不均匀7例(58%),其中韧带增厚征象主要见于慢性期的ACL断裂(P＜0.01).完全性断裂的35例中,28例(80%)发生在中段,上端、下端发生率低;5例部分断裂均发生在前内侧束.ACL断裂的间接征象中,后交叉韧带(PCL)"7"字变形34例(85%);半月板外露26例,其中外侧半月板外露16例(62%);骨损伤15例,其中胫骨撕裂骨折8例(53%);关节间隙增宽9例,其中78%属于慢性断裂;胫骨前移23例(57%).本组40例中,术前正确诊断37例,正确率为92%;3例部分断裂术前未能诊断,漏诊率为8%.结论 根据ACL断裂的直接征象和间接征象,结合外伤史,术前诊断比较容易.     

Value of the coronal plane in MRI of internal derangement of the knee

Sagittal images usually receive the most scrutiny in the magnetic resonance evaluation of meniscal and anterior cruciate ligament tears. We assessed the relative contribution of the coronal view. All knee magnetic resonance examinations performed over a 2-year period that had surgical confirmation were reviewed with respect to the presence of meniscal and anterior cruciate ligament tears. The appearance of an attenuated but uninterrupted anterior cruciate ligament was also evaluated. The coronal and sagittal plane images were evaluated separately. The study included 68 medial menisci, 67 lateral menisci, and 71 anterior cruciate ligaments. The coronal view is especially useful in the evaluation of the lateral meniscus. An anterior cruciate ligament that appears attennated but uninterrupted should be considered intact. The anterior cruciate ligament may be evaluated on the coronal view. The coronal view should be regarded as similar to the lateral chest radiograph, which supplements, but does not replace, the frontal chest radiograph.Presented at the Annual Meeting of the Radiological Society of North America, December 2, 1992, Chicago, Illinois     

MR imaging of the knee. Part I. Traumatic disorders

One hundred thirty patients with a diversity of knee joint injuries were evaluated with a high-resolution magnetic resonance (MR) imaging technique. The authors report the accuracy of this technique in the evaluation of 105 patients with suspected meniscal tears, 26 patients with suspected cruciate ligament tears, and eight patients with suspected patellar tendon injuries. Of those menisci rated as definitely or probably torn on MR imaging, 80% were found to be torn at subsequent arthroscopy. The predictive value of negative MR imaging results was 100%. MR imaging was 92% accurate in predicting the clinical outcome in patients with suspected meniscal tears who did not undergo surgery. MR permitted complete disruption of the patellar tendon to be differentiated from partial tears, ligamentous inflammation, and localized effusion of the infrapatellar bursa. Injuries to the anterior and posterior cruciate ligaments were identified on MR images, and the status of synthetic grafts of the anterior cruciate ligament was ascertained.     

The MR appearance of cruciate ganglion cysts: a report of 16 cases

Intra-articular ganglion cysts arising from the cruciate ligaments are unusual lesions, there being only nine previously reported cases. We report 16 cases and describe their MR appearance. Nine ganglia originated from the posterior cruciate ligament, most often appearing as well-defined multilocular lesions. The seven ganglia arising from the anterior cruciate ligament most often appeared as fusiform cystic lesions extending along and interspersed within the fibers of the ligament. Although uncommon, intra-articular ganglion cysts arising from the knee appear to have a distinctive MR appearance which should allow their correct diagnosis.     

膝关节损伤的MR应用价值

目的 :分析膝关节损伤的MR表现并评价其应用价值。方法 :选择 60例经临床或手术证实的膝关节损伤患者 ,回顾性分析、总结其MR表现。采用 1 .0TMR扫描机 ,常规应用矢状位 ,SET1 W、T2 W ,冠状位T1 W、T2 W成像。结果 :2 9例半月板损伤 ,其中Ⅰ° 1 0例 ,Ⅱ°1 2例 ,Ⅲ°7例 ;前交叉韧带损伤 1 8例 ,撕裂 2 2例 ;后交叉韧带损伤 7例 ,撕裂1例 ;内侧侧副韧带损伤 2 8例 ,撕裂 1 7例 ;外侧侧副韧带损伤 1 2例 ,撕裂 9例 ;韧带损伤表现为韧带不同程度增粗 ,但韧带连续性仍然存在 ,正常低信号内出现不规则高信号影 ,韧带撕裂表现为韧带明显增粗 ,呈弥漫性高信号 ,韧带的连续性部分或完全中断 ;股骨下端或胫骨上端骨质损伤 9例 ;关节积液 54例 ;多种损伤可同时出现。结论 :MR检查可很好显示膝关节损伤的各种表现 ,可作为膝关节损伤检查的重要或首选手段     

Bone signal abnormalities in the posterolateral tibia and lateral femoral condyle in complete tears of the anterior cruciate ligament: a specific sign?

Thirty-two patients with acute, complete tears of the anterior cruciate ligament (ACL) proved at surgery underwent examination with magnetic resonance (MR) imaging. Bone impaction sites were present in the posterolateral tibial plateau in 30 patients (94%) and in the lateral femoral condyle (LFC) in 29 patients (91%). The bone abnormalities had low signal intensity on T1-weighted images and high signal intensity on T2-weighted images when compared with the signal intensity of normal marrow. It is assumed that the bone changes occur during injury when the LFC impacts into the posterior tibia, either during the initial rotary subluxation or as the LFC recoils to return to anatomic alignment. Only one of six partial ACL tears had a bone signal change. In patients with acute knee injury, bone impaction sites in the posterolateral tibia and the LFC suggest that a complete ACL tear is present.     

Anomalous insertion of the medial meniscus into the anterior cruciate ligament: the MR appearance

The aim of this study was to determine the characteristic MR findings of the anomalous insertion of the medial meniscus (AIMM) into the anterior cruciate ligament (ACL), and to document potential pitfalls in its interpretation. We reviewed 1326 consecutive knee arthroscopic studies to identify patients with an AIMM. 30 knees of 26 patients (4 females, 22 males; average age, 31.3 years; range, 14-50 years) were included in this study. We evaluated the presence of an AIMM and analysed the MR findings, including the ACL attachment sites of the AIMMs, the absence of the transverse ligament, meniscal tears and a discoid meniscus. AIMMs were detected by MR imaging in 16 knees of 18 patients (60%, 18/30). The AIMMs showed a linear band with low signal intensity on T2 weighted sagittal images running parallel to the ACL. The AIMMs were inserted into the lower portion of the ACL in eight knees, the middle portion in five knees, and the intercondylar notch in five knees. Meniscal tears (10 medial, 10 lateral) were found in 20 knees of 16 patients. Six knees of five patients showed a discoid meniscus. 15 knees of 14 patients showed no transverse ligament on MR imaging. An AIMM has the potential to be misinterpreted as a meniscal tear, ACL tear or infrapatellar plica on knee MR imaging. Familiarity with the characteristic MR findings can aid in the detection of an AIMM into the ACL.