MRI grading of postero-lateral corner and anterior cruciate ligament injuries Poster No.: C-2533 Congress: ECR 2012 Type: Educational Exhibit Authors: J. Lopes Dias, J. A. Sousa Pereira, L. Fernandes, H. A. M. R. 1 2 1 3 1 1 2 2 Tinto, R. D. T. Mesquita, P. Alves ; Lisboa/PT, Lisbon/PT, 3 Porto/PT Keywords: Trauma, Imaging sequences, MR, Musculoskeletal joint DOI: 10.1594/ecr2012/C-2533 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. www.myesr.org Page 1 of 20
Learning objectives To illustrate the MRI findings in anterior cruciate ligament (LCA) and posterolateral corner (PLC) injuries. Page 2 of 20
Background The anterior cruciate ligament (ACL) is an important stabilizing structure of the knee, which originates from the posterior aspect of the femur and courses medially, inserting on the anterior aspect of the tibia. The ACL primarily limits the anterior translation and internal rotation of the tibia, and once injured may lead to knee instability. Approximately 70 percent of ACL tears are noncontact sport-related injuries that mainly occur during deceleration of the lower extremity when the quadriceps is maximally contracted and the knee is on full or near full extension, a position that increases ACL tensile force and minimally contracts the hamstrings, which normally act as posterior ACL stabilizers. The remaining 30 percent of ACL injuries are caused by contact and require a fixed lower leg that suffers a strong torsion force. A conventional radiographic knee evaluation should be the initial imaging tool, essentially with the goal of evaluating knee alignment and assessing for the presence of a bone fragment which may represent an avulsion of the intercondylar tibial eminence. However, the procedure of choice to diagnose ACL tears is MR, an imaging technique that reaches rates of sensitivity and specificity rounding 86 and 95 percent, respectively. MRI has other high-value additional advantages, by allowing the recognition of meniscal injuries, collateral ligament tears, and bone contusions. An ACL tear may be recognized in MRI by its absence or anomalous course, and by abnormal high signal intensity within the ligament, representing an obvious disruption or an area of edema. A torn ACL may be also indirectly suspected by indentifying a bended posterior cruciate ligament (PCL). Posterolateral corner (PLC) represents a complex unit of soft tissue structures that work in knee joint stabilization. PLC injuries represent approximately 2% of all acute knee ligamentous injuries and usually occur concomitantly with tears of the cruciate ligaments, menisci and medial collateral ligament. The majority of these injuries are sportrelated and result from a direct impact against the anteromedial tibia in extension, with consequent varus stress. Despite many author discrepancies about the classification of posterolateral corner structures and the normal anatomic variations, there are several structures that should be generally assessed on a MRI study: #bularcollateral ligament, posterollateral capsule, biceps femoris tendon, popliteal tendon, popliteo#bular ligament, fabello#bular ligament and arcuate ligament. Nevertheless, the last three structures are inconsistently indentified on MR examinations. Moreover, it should be also assessed the peroneal nerve and the PCL. Page 3 of 20
Imaging findings OR Procedure details MR of the knee is currently the most effective imaging tool in the diagnosis of ligamentous and meniscal injuries, being frequently requested by orthopaedic specialists. When compared to CT scan and conventional radiography, this technique allows a more accurate assessment not only of soft tissue injuries but also of bone contusion lesions. In spite of the utility of ultrasound on the recognition of synovitis, bursitis, joint effusion and tendinopathy, many examinations are followed by MRI in order to exclude ligament and meniscal tears. A proper protocol is essential in order to obtain high diagnostic accuracy rates. At our institution, we perform a routine knee protocol that includes axial, sagital and coronal DP FAT SAT 3mm sequences, a sagital DP 3D, a coronal T1 WI 3mm, sagital T2* FAT SAT WI 3mm and a sagital T2 FAT SAT 3mm sequence. We report here several cases of anterior cruciate ligament (ACL) and posterolateral corner (PLC) tears diagnosed by MR. Page 4 of 20
Images for this section: Fig. 1: T2W sagital image: low grade (grade I sprain) of the ACL. The Ligament maintains its course but there is intersticial thickening and delamination. Page 5 of 20
Fig. 2: Sagital DP FAT SAT WI: grade I ACL injury with tendon thickening and high signal intensity at the proximal insertion but no loss of the normal ligament course. Page 6 of 20
Fig. 3: Sagital DP FAT SAT WI: high grade ACL injury with loss of the normal ligament course and difuse high signal intensity. Page 7 of 20
Fig. 4: Sagital DP FAT SAT WI: low grade posterolateral corner injury with mild trabecular bone edema on the posterolateral tibia. Page 8 of 20
Fig. 5: Sagital DP FAT SAT WI: low-grade injury to the miotendinous juntion of the popliteus muscle (arrows) Page 9 of 20
Fig. 6: Sagital DP FAT SAT WI: high grade complete proximal LCA rupture with disruption and loss of continuity of the proximal insertion. Page 10 of 20
Fig. 7: Sagital DP FAT SAT WI: plantaris rupture (long arrows) associated with a high grade ACL injury (not shown). The popliteus tendon miotendinous junction is normal. Page 11 of 20
Fig. 8: SAGITAL DP FAT SAT WI: posterolateral corner injury with popliteus tendon sprain(thin arrow), arcuate ligament thickening (short thick arrow). The superior popliteomeniscal fascicle is intact (red thin arrow). A meniscal rupture is also seen(long thick arrow). Page 12 of 20
Fig. 9: Sagital T2 FAT SAT WI: bone contusions on the lateral femoral condile and tibia associated with a ACL injury. Fig. 10: Sagital DP FAT SAT WI: posterolateral corner injury with rupture of the inferior popliteomeniscal fascicle (thin arrow) and a bone contusion on the posterolateral tibia (thick arrow). Page 13 of 20
Fig. 11: Sagital T2 WI: chronic complete ACL rupture with no sinovitis on the Intercondylar notch. Page 14 of 20
Fig. 12: Sagital DP FAT SAT WI: middle third ACL rupture with loss of 50% of the normal ligament thickness. Page 15 of 20
Fig. 13: Coronal DP FAT SAT WI: fibular colateral ligament grade I sprain and lateral meniscus horizontal rupture. Page 16 of 20
Fig. 14: Sagital DP FAT SAT WI: posterolateral corner injury with partial Rupture of the miotendinous junction of the popliteus tendon (thick arrow) and difuse thickening na loss of normal planes of the popliteomeniscal fascicles and arcuate ligament (short thin arrows). Page 17 of 20
Conclusion LCA injuries are common findings in day to day MRI examinations. The clinical and imaging findings are usually typical and well described, but the clinical examination however may be difficult to perform in the acute scenario and associated injuries may be missed. Radiologists performing MRI examinations should be aware of the associated findings in LCA injuries, especially in the posterolateral corner, an area of difficult clinical and arthroscopic evaluation. Page 18 of 20
Personal Information Page 19 of 20
References 1. Cimino F, Volk BS, Setter D. Anterior Cruciate Ligament Injury: Diagnosis, Management, and Prevention. American Family Physician. 2010;82(8):917-922. 2. Shelbourne KD, Rowdon GA. Anterior cruciate ligament injury. The competitive athlete. Sports Med. 1994;17(2):132-140. 3. Remer EM, Fitzgerald SW, Friedman H, et al. Anterior cruciate ligament injury: MR imaging diagnosis and patterns of injury. RadioGraphics.1992;12:901-915 4. Pacholke DA, Helms CA. MRI of the Posterolateral Corner Injury: A Concise Review. J. Magn. Reson. Imaging. 2007;26:250-255. 5. Vinson EN, Helms CA. Imaging for evaluation of posterolateral corner injury. J Knee Surg. 2005;18:151-156. 6. Covey DC. Injuries of the posterolateral corner of the knee. J Bone Joint Surg. 2001;83A:106-118. Page 20 of 20