MR evaluation of the "arcuate" sign of posterolateral knee instability

OBJECTIVE: The purpose of this study was to evaluate associated knee injuries using MR imaging in patients with the "arcuate" sign, a term referring to avulsion fracture of the proximal fibula on conventional radiographs. MATERIAL AND METHODS: MR imaging of 18 cases (17 patients, both knees in one patient) with the arcuate sign on conventional radiographs was retrospectively interpreted to evaluate the associated meniscal, ligamentous, and bony injuries. In 12 cases, MR findings were correlated with surgical results. RESULTS: In all cases, avulsed bony fragments from the proximal pole of the fibula were attached to the fibular collateral ligament, the biceps femoris tendon, or both. Tear of the posterolateral capsule was seen in 12 cases (67%). Injury of the cruciate ligaments was noted in 16 cases (89%): injury to both the anterior cruciate ligament and posterior cruciate ligament was seen in nine cases (50%), injury to only the anterior cruciate ligament was seen in four, and injury to the posterior cruciate ligament only was noted in three. Bone bruises or gross fractures were seen in all cases: bone bruises on the anteromedial femoral condyle were noted in nine cases (50%) and were seen on the anteromedial tibial condyle in five cases (28%). Tear of the medial meniscus was seen in five cases (28%) and tear of the lateral meniscus in four cases (22%). Injury to the popliteus was seen in six cases (33%). Joint effusion was associated in all cases. CONCLUSION: MR imaging is useful for evaluation of associated soft-tissue injuries in patients with the arcuate sign on conventional radiographs. Avulsion injury to the proximal fibula is an important indicator of the internal derangement of the knee and for predicting the mechanism of an injury with varus stress. Cruciate ligament tear and bone bruises on the anteromedial condyle of the femur and tibia are common associated findings.     

Arcuate sign of posterolateral knee injuries: anatomic,radiographic, and MR imaging data related to patterns of injury

Objective The arcuate sign is considered a pathognomonic sign for injuries of the posterolateral (PL) corner of the knee. The purpose of our study was to identify different patterns of injury to the fibular head that may associate with injuries to specific ligaments and tendons of the PL corner of the knee. The anatomic relations between the insertions of fibular collateral ligament (FCL), biceps femoris tendon (BFT), popliteofibular ligament (PFL), and arcuate ligament in normal cadaveric knees were also investigated.Design and patients Magnetic resonance imaging was performed in two cadaveric knees which subsequently were dissected. Radiopaque markers were placed upon the fibular insertions of the FCL, BFT, PFL, and arcuate ligament in the dissected knees, and knee radiographs were then obtained. Twelve patients with radiographic or MR imaging evidence of isolated injury to the PL corner of the knee were retrospectively reviewed, with regard to avulsion fractures and marrow edema in the fibular head and the integrity of the ligaments of the PL corner of the knee.Results and conclusions The PFL and arcuate ligament were seen to attach directly to the posterior and medial aspect of the styloid process of the fibular head. The FCL and BFT attached as a conjoined structure on the lateral aspect of the fibular head lateral, anterior and inferior to the attachment site of the PFL and arcuate ligament. Injury to the arcuate ligament or PFL was diagnosed in 8 patients who presented with a small avulsion fracture of the styloid process of the fibula (n=2), bone marrow edema in the medial aspect of the fibular head (n=3), or both (n=3). In 4 patients with injury to the conjoined tendon or FCL, a larger avulsion fragment and more diffuse proximal fibular edema were seen. Radiographic and MR imaging findings in injuries of the posterolateral corner of the knee may suggest injury to specific structures inserting in the fibular head.Presented at the 87th Annual Meeting of the Radiologic Society of North America, 2001.     

MR imaging of posterior cruciate ligament injuries

Posterior cruciate ligament(PCL) injuries are less frequent than anterior cruciate ligament(ACL) injuries, but are presumably more common than once thought. Thirty-nine patients with PCL injuries identified on MR images were studied. The criteria for PCL injury were complete tear, partial tear, and avulsion fracture. The approximate site of a partial tear was categorized as proximal, midsubstance, distal, or combination. Fourteen patients(35.9%) had complete tears of the PCL, 21 patients(53.8%) had partial tears, and four patients(10.3%) had avulsion fractures. A total of 12 patients (30.7%) had isolated PCL injuries, while the remaining 27 patients demonstrated evidence of other coexistent knee injuries, such as meniscal tears and ligamentous injuries. Of coexistent knee injuries, meniscal tears(18 patients, 46.2%) were most often seen.     

Humeral avulsions of the glenohumeral ligament: imaging features and a review of the literature

OBJECTIVE: We describe the radiologic findings of the humeral avulsion of the glenohumeral ligament (HAGL lesion) and its commonly associated injuries. MATERIALS AND METHODS: A retrospective review of six cases of HAGL lesion diagnosed at our institution from October 1996 to February 2001 was performed. We reviewed the radiology reports, radiologic examinations, medical records, and operative notes. All patients had undergone radiography, and four patients had undergone MR imaging of the shoulder before diagnostic arthroscopy. RESULTS: All the patients were men who ranged in age from 19 to 41 years (mean, 26 years). Four patients (67%) had an anterior shoulder dislocation. Three of the HAGL lesions (50%) were detected on radiologic examinations, either by radiography or MR imaging. One patient had a bony HAGL. All patients had associated injuries. The most common associated abnormalities were osteochondral injury of the humeral head (n = 3), rotator cuff tear (n = 3), Bankart lesion (n = 3), Hill-Sachs lesion (n = 2), avulsion of the middle glenohumeral ligament (n = 1), partial tear of the biceps brachii tendon (n = 1), and comminuted fracture of the clavicle (n = 1). CONCLUSION: With an incidence of 7.5% and 9.4% in two large series of patients, the HAGL lesion is an important cause of anterior instability of the glenohumeral joint. The majority (68%) of patients with an HAGL lesion have associated injuries.     

Iliotibial band avulsion fracture: a case report with differential diagnosis

Avulsion injuries of the knee are common sequelae of significant trauma given the number of ligamentous and tendinous insertions around the joint. Commonly discussed avulsion fractures of the lateral knee include the Segond fracture of the lateral tibial plateau and the arcuate complex avulsion fracture of the fibular styloid process. A less common avulsion fracture is the iliotibial (IT) band avulsion fracture involving the anterolateral corner of the tibia (Gerdy’s tubercle). It is crucial to identify IT band avulsion fractures because of the frequent associated internal derangements of the knee. This case report describes the imaging of an acute IT band avulsion fracture and compares these findings with other lateral knee avulsion fractures.     

Posterior cruciate ligament: MR imaging

The authors reviewed 610 consecutive magnetic resonance (MR) examinations of patients with suspected internal derangements of the knee, paying special attention to the posterior cruciate ligament (PCL). The normal PCL shows a low MR signal intensity and an arcuate shape. An accessory anterior or posterior meniscofemoral ligament was identified in 58.5% of examinations. Among 202 patients who underwent arthroscopy or arthrotomy, MR imaging depicted 11 PCL injuries: eight complete or incomplete ligament disruptions and three avulsions. All were confirmed by means of arthroscopy or arthrotomy. MR findings of PCL injury were anatomic disruption, increased signal intensity in the ligament, and redundancy of an avulsed ligament. Of the 11 PCL injuries, four were not detected at initial clinical examination. In none of the 202 patients in whom arthroscopy or surgery was performed was an abnormal PCL identified in the presence of a normal MR examination. MR imaging is a reliable method for the detection of PCL injuries.     

The reverse Segond fracture: not associated with knee dislocation and rarely with posterior cruciate ligament tear

The aims of this study were to assess the incidence of reverse Segond fracture, to examine the associated ligamentous injuries, and to examine how often reverse Segond fracture coexists with a knee dislocation. At a level 1 trauma center, an 11-year period of emergency department multidetector-row computed tomography (MDCT) examinations for knee trauma was evaluated for reverse Segond and Segond fractures. Surgical findings served as the reference standard for intra-articular injuries. The hospital discharge register was searched for the diagnosis of knee dislocation from August 2000 through the end of August 2011. A total of 1,553 knee MDCT examinations were evaluated. Ten patients with a reverse Segond fracture were found, comprising 0.64 % of emergency room acute knee trauma MDCT examinations. Seven patients who had a reverse Segond fracture were operated: Three had an avulsion fracture of the anterior cruciate ligament, one had an avulsion fracture of posterior cruciate ligament, two had a lateral meniscal tear, and two had a medial collateral ligament tear. The ratio of reverse Segond fractures to Segond fractures was 1:4. None of the 71 knee dislocation patients had a reverse Segond fracture. Reverse Segond fracture is a rare finding even in a level 1 trauma center. Cruciate ligament injuries appear to be associated with avulsion fracture, but every patient does not have PCL injury, as previously reported. Our results do not support the association of knee dislocation with reverse Segond fracture.     

MRI of fractures of the distal radius: comparison with conventional radiographs

Objective. To compare the evaluation of fractures of the distal radius with MRI and conventional radiographs. To demonstrate the ability of MRI to detect unsuspected soft tissue derangement accompanying this common injury. Design and patients. Twenty-one consecutive inpatients admitted following fracture of the distal radius underwent preoperative evaluation with both conventional radiographs and MRI. In each case, analysis was made of both the osseous and soft tissue injury. MRI findings were compared with those identified on conventional radiographs and at subsequent surgical fixation. Results. Of 21 patients with fractures of the distal radius, 20 had extension to the radiocarpal articulation, 14 had distal radio-ulnar joint extension and 5 had avulsion of the ulnar styloid.Occult carpal bone fractures accompanying fracture of the distal radius were identified in two patients: one of the capitate and the other of the second metacarpal base. Ten patients (48%) had associated soft tissue injury: six patients had scapholunate ligament rupture, two patients had disruption of the triangular fibrocartilage, one patient had extensor carpi ulnaris tenosynovitis and one patient had a tear of a dorsal radiocarpal ligament. Of five patients with ulnar styloid avulsions, none had evidence of triangular fibrocartilage tears. Conclusion. MRI affords better evaluation of osseous injury accompanying distal radial fractures than conventional radiographs. Intra-articular soft tissue injury accompanies distal radial fractures in almost 50% of cases. Scapholunate ligament disruption commonly accompanies intra-articular fracture through the lunate facet of the distal radius. Fracture of the ulnar styloid is infrequently associated with tear of the triangular fibrocartilage.     

Semimembranosus tendon avulsion fracture of the posteromedial tibial plateau associated with posterior cruciate ligament tear and capsular rupture

Semimembranosus tendon avulsion fractures are an uncommon occurrence and are often associated with anterior cruciate ligament (ACL) and medial meniscus tears. We present the imaging features of an unusual case of semimembranosus avulsion fracture of the posteromedial tibial plateau associated with posterior cruciate ligament (PCL) tear, medial meniscus tear, and capsular rupture in a 26-year-old man with a football injury.     

Lateral tibial rim (Segond) fractures: MR imaging characteristics

The magnetic resonance (MR) imaging characteristics of lateral tibial rim (Segond) fractures and their associated injuries were reviewed in 12 patients with radiographic evidence of this fracture. Bone marrow adjacent to the fracture emitted a focally abnormal MR signal, which indicated an injury of the lateral capsular junction. The Segond fragment, however, was seen on MR images in only four of 12 patients. Associated ligamentous and meniscal injuries identified with MR imaging and arthroscopy involved the anterior (n = 11) and medial (n = 7) cruciate ligaments and the lateral (n = 4) and medial (n = 1) menisci. Focal bone marrow edema was due to injury of the lateral capsular junction. MR imaging evidence of such edema should indicate the presence of a lateral capsular injury and fracture, if one has not already been demonstrated with conventional radiography. A high association of Segond fractures with tears of the anterior cruciate ligament was confirmed, and MR imaging signs of a Segond fracture may therefore be used as indirect evidence for tears of that ligament.     

低场磁共振GE序列在膝关节侧副韧带损伤诊断中的应用评价

目的：探讨损伤的膝关节侧副韧带在低场MRIGE序列中的表现。方法：对经手术或临床证实的48例共54条损伤的侧副韧带进行回顾性MRI对比观察。结果：54条侧副韧带损伤，单纯胫侧副韧带27条，单纯腓侧副韧带18条，两侧侧副韧带同时损伤10条。Ⅰ级侧副韧带损伤27条；Ⅱ级侧副韧带损伤17条；Ⅲ级侧副韧损伤10条。30例（62．5％）出现并发症，其中前交叉韧带损伤19条。后交叉韧带损伤14条，半月板损伤18个，骨挫伤及骨折11例，关节囊积液30例。结论：GE序列能缩短检查时间，清晰显示膝关节侧副韧带解剖结构，准确诊断侧副韧带损伤并能进行分级，发现多种并发症，宜列为膝关节外伤的常规扫描序列。     

A physeal-sparing fibular collateral ligament and proximal tibiofibular joint reconstruction in a skeletally immature athlete

The purpose of this report was to describe the surgical technique for and outcomes after a modified physeal-sparing posterolateral corner reconstruction in a 12-year-old skeletally immature male with a mid-substance fibular collateral ligament tear, a proximal posterior tibiofibular ligament tear, and an anterior cruciate ligament avulsion fracture of the medial tibial eminence. A modified physeal-sparing posterolateral corner reconstruction was used to provide a near-anatomic reconstruction of the fibular collateral ligament and proximal posterior tibiofibular ligament. An anterior cruciate ligament repair was also performed. Varus stress radiographs obtained at 6 months postoperatively demonstrated resolution of lateral knee stability. Physical examination results demonstrated stability to anterior tibial translation and a stable proximal tibiofibular joint. Computed tomography showed that the surgical technique successfully avoided breeching the patient’s physes.     

The knee: surface-coil MR imaging at 1.5 T1

Seven normal knees (in five volunteers) and seven injured knees (in seven patients) were examined by high-resolution magnetic resonance (MR) imaging at 1.5 T with a surface coil. Seven medial meniscal tears, three anterior cruciate ligament tears, one posterior cruciate ligament avulsion, an old osteochondral fracture, femoral condylar chondromalacia, and one case of semimembranous tendon reinsertion were identified. MR images correlated well with recent double-contrast arthrograms or results of surgery. All tears were identified in both the sagittal and coronal planes. Because of its ability to demonstrate small meniscal lesions and ligamentous injuries readily, MR imaging with a surface coil may eventually replace the more invasive arthrography.     

Posteromedial tibial plateau injury including avulsion fracture of the semimembranous tendon insertion site: ancillary sign of anterior cruciate ligament tear at MR imaging.

PURPOSE: To evaluate posteromedial tibial plateau injuries of or about the semimembranous tendon insertion site and their association with anterior cruciate ligament (ACL) tears on magnetic resonance (MR) images. MATERIALS AND METHODS: A retrospective study of MR images and conventional radiographs was performed in 10 patients with posteromedial tibial plateau injuries, including avulsion fractures of the semimembranous tendon insertion site. Associated abnormalities were analyzed, including ACL tears, medial meniscal tears, and other lateral femorotibial compartment injuries. Findings from the clinical history and physical examination were correlated with radiographic and MR imaging findings. Nine patients had arthroscopically or surgically documented ACL tears. RESULTS: All 10 patients had ACL tears at MR imaging. Five patients had posteromedial tibial plateau fractures: Four had avulsion fractures of the tendon insertion site, and one had a fracture lateral to the site. Five patients had posteromedial tibial plateau bruises: Two had bruises at the tendon insertion site. Five patients had tears of the posterior horn of the medial meniscus. Two patients had posterior meniscocapsular separations. Three patients showed evidence of the O'Donoghue triad. Six patients had bruises of the lateral tibial plateau and of the lateral femoral condyle. CONCLUSION: There appears to be an association between posteromedial tibial plateau injuries and ACL tears. Posteromedial tibial plateau injuries may be predictive of ACL status.     

MRI of anterior cruciate ligament injuries and associated findings in the pediatric knee: changes with skeletal maturation

OBJECTIVE: The objective of our study was to evaluate the MRI characteristics of anterior cruciate ligament (ACL) injuries and associated findings relative to skeletal maturity. We also contrast the frequency of findings in this younger population to adult data. MATERIALS AND METHODS: Eighty-two consecutive knees with an MRI report diagnosis of ACL injury (partial tear, sprain, or complete tear) or tibial spine avulsion fracture imaged over 4 years were retrospectively reviewed. Patients were grouped by degree of skeletal maturity as determined from the MR images. The examinations were reviewed for the type of ACL injury, secondary imaging findings, and associated knee injuries. Findings were correlated to skeletal maturity, and frequencies were compared with adult data. RESULTS: ACL injuries were more common in boys in the skeletally immature group, but more common in girls in the skeletally mature group (p = 0.03). Tibial spine avulsion fractures were most common in skeletally immature patients (p < 0.01), whereas complete tears of the ACL were most common in skeletally mature patients. Associated injuries were less common in the skeletally immature group, but this trend did not reach statistical significance. Most secondary signs of ACL injuries occurred at similar rates in all groups with frequencies similar to those reported in adults. CONCLUSION: ACL injuries in skeletally immature patients are seen more often in boys. Tibial avulsion fractures and partial tears are more common in younger, less rigid skeletons that may absorb the forces of trauma. As children mature, complete ACL tears and associated injuries occur in frequencies approaching those patterns seen in adults. Similarly, skeletally mature girls are affected more often than mature boys.     

Adult tibial intercondylar eminence fracture: evaluation with MR imaging

Tibial intercondylar eminence (TIE) fractures are well described in the pediatric orthopedic literature. Adult TIEs are much less common, and limited literature exists on the subject. Adult knee hyperextension injuries commonly result in anterior cruciate ligament (ACL) injury; however, with significant trauma, a TIE enters the differential diagnosis. Identification and classification of TIE fractures typically has been provided by radiography. The incidence of concomitant injuries with magnetic resonance (MR) imaging in patients with adult TIE fractures has not been determined. We present a case of an adult type III TIE fracture seen on radiography that only with further MR imaging revealed a concomitant lateral tibial plateau fracture. Utilization of MR imaging altered the surgeon's course of treatment and postoperative care. Radiographic and MR images and a review of the literature are provided.     

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.     

Cruciate ligament avulsion fractures: Anatomy, biomechanics, injury patterns, and approach to management

Injury to the ACL or PCL of the knee most commonly involves a tear of the collagenous fibers of the ligament. Less frequently, a cruciate ligament injury involves an avulsion fracture at the origin or insertion of the ligament, usually from the insertion site on the tibial surface. Avulsion fractures of the cruciate ligaments are important, as they can be identified on radiographs, allowing a specific diagnosis. Although more common in children, when they occur in adults, they are more commonly associated with other injuries. The treatment of cruciate ligament avulsion fractures is different than the treatment of intrasubstance tears of the cruciate ligaments. These injuries can be treated conservatively or surgically with good outcomes. Recently arthroscopic fixation of these injuries with various fixation devices has become more frequent. Treatment largely depends on the type of fracture, particularly, the size, displacement, comminution, and orientation of the avulsed fracture fragment, in addition to the integrity of the attached cruciate ligament. This review article covers the anatomy and biomechanics of the cruciate ligaments, their injury patterns, and approach to management.     

外伤性膝关节前外侧韧带损伤的MR影像特征及相关性分析

目的探讨外伤所致膝关节前外侧韧带损伤病人的MR影像特征,并分析其与前交叉韧带撕裂、外侧半月板撕裂及骨挫伤的相关性,为深入研究前外侧韧带对膝关节稳定性的作用提供可靠依据。方法回顾性分析2016年1月—2017年2月间因外伤进行膝关节MRI检查的320例病人(共321膝)的影像资料。采用美国GE公司生产的Signa HDe 1.5 T MR扫描设备,分别行膝关节斜矢状面T1WI、质子密度加权成像(PDWI)和冠状面、横断面PDWI扫描。根据前外侧韧带的完整性和损伤部位对所有病人进行分类统计。采用独立性卡方检验对前外侧韧带撕裂与前交叉韧带撕裂、外侧半月板撕裂及骨挫伤的相关性进行分析。结果全部病人膝关节MR影像均可显示前外侧韧带,显示率为100%。151/321膝(47.0%;95%CI为41.6%~52.5%)存在前外侧韧带损伤,其中累及胫骨部、股骨部及半月板部的分别为97膝、96膝及65膝。前交叉韧带撕裂158膝,外侧半月板撕裂98膝,股骨外侧髁挫伤58膝,外侧胫骨平台挫伤71膝,分别与前外侧韧带撕裂具有相关性(均P0.001)。结论 MRI检查可以很好地显示前外侧韧带解剖及其损伤情况。膝关节前外侧韧带损伤与前交叉韧带撕裂、外侧半月板撕裂及膝外侧骨挫伤具有相关性。     

MR imaging,MR arthrography,and specimen correlation of the posterolateral corner of the knee: an anatomic study

OBJECTIVE: We sought to evaluate the anatomy of the posterolateral aspect of the knee with anatomic dissection, MR imaging, MR arthrography, and sectional anatomy. MATERIALS AND METHODS: We assessed the posterolateral corner of the knee during dissection of one gross anatomic specimen. MR imaging and MR arthrography were performed in seven additional knee specimens. T1-weighted spin-echo MR images were obtained in the standard imaging planes as well as in the coronal oblique plane. The specimens underwent T1-weighted spin-echo MR imaging after administration of intraarticular contrast material and were sectioned into planes corresponding to those of the MR images. RESULTS: At anatomic dissection, the following posterolateral structures were identified: the arcuate ligament (medial and lateral limbs), fabellofibular ligament, popliteofibular ligament, popliteus tendon and its two posterior attachments to the lateral meniscus, fibular collateral ligament, direct and anterior arms of the tendon of the long head of the biceps femoris muscle, and direct and anterior arms of the tendon of the short head of the biceps femoris muscle. Correlation of MR imaging and anatomic findings showed that the popliteofibular ligament and oblique popliteal ligament were found in 57% and 100% of specimens, respectively. At least one of the two limbs of the arcuate ligament was identified in 71% of specimens. The fabellofibular ligament was not identified on MR images in any of the specimens. The anteroinferior and posterosuperior popliteomeniscal fascicles were identified in all specimens. CONCLUSION: The posterolateral corner of the knee comprises complex and variable anatomic structures. Recognition of these variations is important in the assessment of MR images of the knee.