Multi-ligamentous knee injuries - MRI injury patterns at a glance

Transcription

1 Multi-ligamentous knee injuries - MRI injury patterns at a glance Poster No.: P-0068 Congress: ESSR 2015 Type: Educational Poster Authors: A. Rastogi, D. Whelan, R. Martin, W. Mak, D. Pearce ; Toronto/CA, Calgary/CA Keywords: Trauma, Education, MR, Musculoskeletal joint, Musculoskeletal bone, Extremities DOI: /essr2015/P-0068 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. Page 1 of 62

2 Learning objectives To describe and showcase MRI appearances of multi-ligamentous knee injuries. To guide and familiarize the reader with injury patterns with associations. Page 2 of 62

3 Background Ligamentous knee injuries are a major cause of disability in a patient with major trauma. Accurate identification of the injuries is important in guiding clinicians in appropriate treatment options. MRI is the investigation of choice for evaluation of post-traumatic ligamentous injuries. The reader will be shown a wide pattern of MRI ligamentous knee injuries. Page 3 of 62

4 Imaging findings OR Procedure Details Imaging Findings: Severe trauma like motor vehicle accident or knee dislocations is prone to multiligamentous knee injuries. Knee examinations can be limited in such setting and definite diagnosis is obtained using MRI. MRI has high detection rates for meniscal tears, cruciate and collateral injuries, bone contusions, cartilage and capsular injuries. Advantages of MRI is that it's non-invasive, uses no radiation, better anatomic and soft tissue delineation and is cost effective in reducing diagnostic arthroscopies. MRI in traumatic knee injuries can be challenging as there are usually many abnormalities but having a step by step approach can help the reader in evaluating all structures. A step by step approach can be performed to evaluate: Fractures and bone contusions - Effusion and capsular disruption - Cruciates - Collaterals - Menisci - Extensor mechanism - Posterior lateral and medial corner - Cartilage - Soft tissue. The most common MRI sequences used in such assessments are: Coronal and Sagittal proton density, along with fat suppressed sagittal and axial proton density / T2 weighted images. Fracture and bone contusions: Bone contusions with or without fractures are a common MRI finding seen in traumatic knee injuries. It can act as an indicator towards the mechanism of injury. These injuries can occur due to direct trauma, bone impacting adjacent bone or other traction type injuries. Some of the patterns seen include - Pivot shift (Fig. 1), clip/valgus injury (Fig. 2), lateral patellar dislocation (Fig. 3), hyperextension (Fig. 4), and dashboard injury. Page 4 of 62

5 Fig. 1: Pivot shift injury: Large contusions in the lateral femoral condyle and posterolateral tibial plateau (yellow star). There are associated injuries including posterior horn lateral meniscus radial tear (white arrow), large effusion (red arrow), and fat lobule in the effusion (blue arrow), Hoffa's fat impingement (green arrow) and soft tissue/muscle edema (black arrow). This injury is associated with anterior cruciate ligament tear (not shown). Page 5 of 62

6 Fig. 2: Clip type of injury seen in contact sports with valgus stress to the knee. The is large bony contusion to the lateral femoral condyle (red arrow) and complete (grade III) tear of the mid to distal medial collateral ligament (MCL) and associated haematoma (green arrow) Page 6 of 62

7 Fig. 3: Lateral patellar dislocation with large contusion in the lateral femoral condyle (red arrow), large haematoma (orange star), effusion (blue arrow) and complete medial patellar retinaculum tear (white arrows). Page 7 of 62

8 Fig. 4: Large bony contusions in the medial compartment involving the medial femoral condyle and medial tibial plateau (red arrow), with complete tear of proximal medial collateral ligament (white arrow). This pattern can occur in hyperextension or direct blow type of injury. There is resulting varus stress and injury to the lateral and posterolateral structures. Injury to iliotibial band is show above (blue arrow) with marked edema in the lateral aspect of the knee joint (orange star). Fractures are also a common finding on MRI and are an indication of the significant traumatic force involved in the injury. Commonly seen fractures are those associated with pivot shift pattern (Fig. 5), direct trauma (Fig. 6), tibial plateau (Fig. 7,8) and fibular fractures (Fig. 9). Page 8 of 62

9 Fig. 5: Pivot shift injury resulting in subchondral impaction fractures of the lateral femoral condyle and posterior lateral tibial plateau. (a) Sagittal PD image shows subchondral impaction fracture (red arrow) with contusion (white arrow). In addition there is also buckling of the posterior lateral tibial plateau (blue arrow). (b) Sagittal PD fat suppressed image shows lateral femoral condyle contusion (orange arrow) with posterior lateral tibial plateau contusion (green arrow) and joint effusion (orange star). Page 9 of 62

10 Fig. 6: Sagittal PD fat suppressed image shows fracture of medial femoral condyle (red arrow) with large contusion (yellow star) and haemarthrosis (orange star), this pattern can be seen in direct trauma. Page 10 of 62

11 Fig. 7: (a) Cor PD image shows depressed medial tibial plateau fracture with cartilage injury (red arrow) and subchondral contusion (black arrow). There are associated varus injures to posterolateral structures (all injuries not shown). There is complete lateral collateral ligament injury (green arrow), and capsular disruption with subcutaneous fluid leak and haematoma (orange star). (b) Cor PD image of a different patient shows subtle marginal medial tibial plateau fracture with cartilage injury (white arrow), there is also oblique tear in the mid body of medial meniscus and partial medial collateral ligament injury (orange arrows). Partial injury to lateral collateral ligament is also seen (blue arrow) with joint effusion (yellow star). Page 11 of 62

12 Fig. 8: (a&b) Cor PD image shows a communited depressed medial tibial plateau fracture with large fracture cleft and cartilage injury (red arrow). There is also intermarginal radial tear of the posterior horn of medial meniscus (blue arrow) with complete tear of the posterolateral corner structures, including conjoint tendon and lateral collateral ligament (green arrow). This has resulted in capsular injury and subcutaneous fluid leak (yellow star) with fat lobules (yellow arrow) and fracture skin blisters (white arrow). In addition there is also partial proximal medial collateral ligament injury (orange arrow). Page 12 of 62

13 Fig. 9: (a-d) demonstrate different patients with fibular head fractures from nondisplaced (white arrow) to widely displaced (blue arrow). Small bony debris is seen in the fracture site (fine orange arrows) with large joint effusions (yellow star). This injury pattern can be associated with posterolateral corner ligamentous injuries and haematoma. Large popliteal intramuscular haematoma is seen in patient (b) (red star). Effusion and capsular disruption: Page 13 of 62

14 Joint effusion can be one of the early signs in traumatic knee injury. Based on the cause and type of injury the effusion could be - simple, or complex which included haemarthrosis or lipohaemarthrosis (Fig. 10). The complex effusions are mostly associated with high velocity, multiple injuries, including fractures. Fig. 10: (a) Sag PD image shows impaction subchondral contusion (yellow star) and fracture (white arrow) with fat fluid level (blue arrow). (b) Axial PD FS image of a different patient shows fat fluid (blue arrow) and haematocrit levels (orange arrow). The joint capsule or capsular ligament is a synovial and fibrous membrane that surrounds the knee joint and allows for joint movement. Joint capsular disruption can result in reduced joint effusion as fluid leak through the tear, with pooling of fluid in the subcutaneous tissues. This can be seen on MRI as used as a sign for capsular injury (Fig. 11). Page 14 of 62

15 Fig. 11: (a&b) Images shows medial patellar retinaculum complete tear with injury to vastus medialis muscle (yellow arrow) and medial capsular injury resulting in leak of knee joint effusion into the subcutaneous tissues (yellow star). Anterior cruciate ligament: Anterior cruciate ligament (ACL) is an important knee stabilizer and injury to the ACL can lead to significant instability and long term disability. MRI evaluation of ACL on sagittal, coronal and axial planes improves accurate assessments. The ACL originates from the posteromedial surface of the lateral femoral condyle and has a broad fan like tibial insertion in the anterior intercondylar area, anterior and slightly lateral to the tibial spine. The ACL is composed of two bundles - anteromedial and posterolateral. A normal ACL is shown in Fig. 12. Page 15 of 62

16 Fig. 12: (a) Ax PD FS images shows an oval shaped normal ACL (red circle) from its femoral origin at the posteromedial lateral femoral condyle to its tibial insertion anterior to the tibial spine (left to right). Two bundles are also seen, anteromedial (yellow arrow) and posterolateral (white arrow). (b) Normal ACL (orange circle) seen in serial Cor PD images show the long femoral origin and fan like tibial insertion (black arrow). ACL injuries can be classified as partial or complete, with complete ACL tears (Fig. 13) commonly seen in traumatic knee injuries. ACL injuries can occur in isolation but in majority of cases these are associated with other injuries. Pivot shift pattern of injuries include ACL tears, medial collateral ligament and meniscal injuries with associated lateral compartment contusions (Fig. 14). Page 16 of 62

17 Fig. 13: (a) Normal sagittal image of ACL seen on 2 slices. The ligament is intact (green line) and parallels Blumesaat line (white line). (b-e) Sag PD images of different patients with complete ACL tear (red line). (b) ACL fibres are discontinuous, (c-d) different patients with mid ACL complete tear with flattened distal fibres. (e) Complete ACL tear with small bunched distal fibres. There is also complete tear of the proximal PCL (blue line). Page 17 of 62

18 Fig. 14: (Clockwise from top left) Sag PD, ax PD FS, Sag PD FS and Cor PD images depict some of the injuries in pivot shift pattern. Pivot shift pattern of bone contusion (yellow star), joint effusion (blue star), complete medial patellar retinaculum tear (red arrow), tear of medial collateral ligament (white arrow), and complete ACL tear (red line). Posterior cruciate ligament: Page 18 of 62

19 Posterior cruciate ligament (PCL) is also an important knee stabilizer. MRI evaluation of the PCL is performed on sagittal, coronal and axial planes for improved accurate assessment. PCL originates from the inner aspect of the medial femoral condyle and roof of the intercondylar notch and extends posteriorly and laterally to insert into the posterior portion of the tibia on the posterior intercondylar region (Fig. 15). It has a compact anatomy and can be injured in hyperextension, dashboard, and rotation with adduction/abduction force type injuries. These injuries could be partial (Fig.16) or complete. It is common to see PCL tears with other injuries when there is high mechanism of injury (Fig. 17). Fig. 15: Ax PD FS (top), Cor PD FS (mid), and Sag PD (bottom left) and Sag PD FS (bottom right) images showing normal PCL from femoral origin to tibial insertion within red, orange and green circles. Page 19 of 62

20 Fig. 16: Multi-planar images showing partial high grade tear of the mid-distal PCL (red arrow). Page 20 of 62

21 Fig. 17: Sag PD images of 6 different patients with complete PCL tears (red line). Note is also made of complete ACL tears in all cases. Medial Collateral ligament: Medial collateral ligament (MCL) is one of the medial supporting structures of the knee and injured in valgus injuries. Three layers have been described for the capsule and ligaments on the medial side of the knee: Layer 1- the deep crural fascia; layer 2- the superficial portion of the medial collateral ligament (MCL); and layer 3 - capsule and deep portion of MCL, meniscofemoral and meniscotibial extensions of the deep part of MCL. The MCL proximally attached to the medial epicondyle of the femur below the adductor tubercle and inferiorly it attaches to the medial condyle of the tibia at its medial surface (Fig. 18). On MRI the injury to MCL can be partial (Fig. 19 or complete (Fig. 20). Page 21 of 62

22 Fig. 18: Top row ax PD FS images (cranial to caudal from left to right) and bottom row Cor PD images (Anterior to Posterior) show normal MCL (within white oval area). Fig. 19: Cor PD images of 3 patients showing thickened MCL with some disruption of fibres proximally in keeping with partial tears. Page 22 of 62

23 Fig. 20: Cor PD images of different patients with complete distal MCL tear. Top left image shows complete disruption of distal fibres (yellow arrow). Top right and bottom left images show complete MCL tear with retracted and coiled up MCL (red arrow), tear of the medial meniscus is also seen (black arrow). Bottom right image shows complete discontinuity of MCL with hemorrhage (orange arrow) with muscle tears and hematoma in vastus lateralis (yellow star). Extensor mechanism, Anteromedial and lateral structures: Page 23 of 62

24 This includes the structures that help in patellar stability. It consists of quadriceps muscle and tendon, patella, patellar tendon, anteromedial and anterolateral structures including medial and lateral retinaculum including ligaments, iliotibial band and joint capsules (Fig. 21). Injury to the anteromedial or anterolateral structures (Fig ) can be seen in lateral patellar dislocation, direct trauma or knee valgus and varus stress injuries. Fig. 21: Ax PD FS images from left to right (cranial to caudal) show the parts of extensor mechanism. Quadriceps tendon (white arrow), medial patellar retinaculum (green arrow), lateral patellar retinaculum (orange arrow), including iliotibial band (red arrow), and patellar tendon (blue arrow). Page 24 of 62

25 Fig. 22: Complete tear of the medial patellar retinaculum with defect (white arrow) with retracted fibres in the patellofemoral compartment (yellow arrow). There is also a partial tear of the lateral patellar retinaculum (orange arrow) with lateral femoral condyle contusion (red star) and fascial edema (blue arrow). Fig. 23: Ax PD FS images (a) with complete medial patellar retinaculum tear (red arrow) and capsular disruption (orange star). (b) Shows complete lateral patellar retinaculum and iliotibial band tear (orange arrow) with capsular disruption (orange star). Bony contusions are seen on the contralateral femoral condyle (yellow star). Page 25 of 62

26 Fig. 24: Cor PD images from 3 different patients showing complete iliotibial band tear (red arrow) with capsular disruption (orange star) Posterolateral Corner: The posterolateral corner of the knee can be a clinically challenging area to assess due to several important structures. Injuries can occur in isolation or as a combination in multiligamentous injuries. The various structures include (Fig. 25) - Lateral collateral ligament, biceps and conjoint tendon, popliteal muscle and tendon, lateral head of gastrocnemius, posterior horn of lateral meniscus, popliteofibular, fabellofibular and arcuate ligaments. Other structures also include popliteomeniscal fascicles, and lateral coronary ligament. Fig. 25: Top row left to right (Ax PD FS) images from caudal to cranial, and bottom row Cor PD images from Anterior to posterior. Normal posterolateral structures are shown, popliteal muscle (red star), popliteal tendon (red arrow), lateral collateral ligament (blue arrow), biceps femoris tendon (green arrow), conjoint tendon (white arrow) and lateral head of gastrocnemius (yellow arrow). Page 26 of 62

27 The mechanism of injury includes direct blow to anteromedial tibia, directed posterolaterally with knee in full extension or external rotation hyperextension injury. The posterolateral corner injuries can be associated with anteromedial tibial fractures/ contusions (Fig. 26), arcuate fractures (Fig. 27), and capsular injuries (Fig. 26, 28) amongst others (Fig. 29). High grade injuries are usually associated with cruciate ruptures. Untreated posterolateral corner injuries in cruciate ligament reconstructions can result in graft failures. Fig. 26: (a) Sag PD,(b-c) Cor PD images shows anteromedial tibial plateau fracture (red arrow), complete MCL tear (yellow arrow), complete tear of iliotibial band (orange arrow), lateral collateral ligament tear (blue arrow) and biceps tendon tear (green arrow). This has resulted in tear of the posterolateral capsule with joint fluid leak into the subcutaneous tissues (red star). There is also a large complex joint effusion (yellow star). Note is also made of a mal-aligned knee joint Page 27 of 62

28 Fig. 27: Cor PD image shows arcuate fracture (red arrow), and popliteal muscle haematoma (yellow star).the popliteofibular ligament is also seen (blue arrow). Posteromedial corner and soft tissues: The posteromedial corner (PMC) of the knee consists posterior oblique ligament, semimembranosus tendon, oblique popliteal ligament, posterior horn of medial meniscus and medial head of gastrocnemius (Fig. 30). Injury to PMC can be easily overlooked and can result in chronic pain. Page 28 of 62

29 Fig. 30: Axial images show posteromedial corner structures - semimembranosus (red arrow), posterior oblique ligament (green arrow) and oblique popliteal ligament (blue arrow), medial head of gastrocnemius (orange arrow) and posterior horn of medial meniscus (yellow star). Page 29 of 62

30 Fig. 31: Ax PD FS image from a patient with multi-ligamentous injuries involving the posterolateral corner (green area), medial patellar retinaculum partial injury (blue arrow) and partial injury to posterior oblique ligament (red arrow). Soft tissue injury can vary from subcutaneous edema to degloving injuries. High mechanism of injuries can be associated with intramuscular or subcutaneous haematomas, blisters or rarely degloving injury (Fig. 32). Page 30 of 62

31 Fig. 32: Shows examples of soft tissue injuries, (a) subcutaneous haematoma (yellow star), (b) intramuscular haematoma (green star), (c) skin blisters in a patient with tibial fracture, and (d) patient with degloving injury. Meniscal and cartilage injury: Meniscal tears are common in traumatic knee injuries. Coronal and sagittal planes are most helpful to evaluate them. Fluid cleft/signal within the meniscus extending to the superior/articular surface or the apex of the meniscus indicates a tear. Tears can be Page 31 of 62

32 complete and can be associated with displaced meniscal tissue in traumatic knee injuries. Some examples are shown below (Fig ). Fig. 33: Shows complete radial tear of the medial meniscal posterior root (white arrow) on the coronal image, with corresponding area appearing as a 'ghost' meniscus on the sagittal image. Page 32 of 62

33 Fig. 34: Coronal PD weighted images show medial meniscal oblique tear in the anterior horn and body of medial meniscus with flipped flap lying over the posterior horn (orange arrow). Complete ACL (blue star), PCL tear (red star) and MCL tear (blue curved line) are also noted. Fig. 35: Show medial meniscal tears in different patients (a) complete radial tear of posterior horn, (b) vertical longitudinal tear, and (c) oblique inferiorly surfacing tear. All three patients have multiple other ligamentous injuries. Page 33 of 62

34 Cartilage injuries are mostly associated with articular surface fracture or significant contusions. Fig. 36: (a) sagittal image shows significant bone contusion with cartilage injury in lateral femoral condyle (orange arrows), (b) coronal image in a different patient with medial tibial plateau fracture as cartilage injury (red arrow). Page 34 of 62

35 Images for this section: Fig. 5: Pivot shift injury resulting in subchondral impaction fractures of the lateral femoral condyle and posterior lateral tibial plateau. (a) Sagittal PD image shows subchondral impaction fracture (red arrow) with contusion (white arrow). In addition there is also buckling of the posterior lateral tibial plateau (blue arrow). (b) Sagittal PD fat suppressed image shows lateral femoral condyle contusion (orange arrow) with posterior lateral tibial plateau contusion (green arrow) and joint effusion (orange star). Page 35 of 62

36 Fig. 6: Sagittal PD fat suppressed image shows fracture of medial femoral condyle (red arrow) with large contusion (yellow star) and haemarthrosis (orange star), this pattern can be seen in direct trauma. Page 36 of 62

37 Fig. 7: (a) Cor PD image shows depressed medial tibial plateau fracture with cartilage injury (red arrow) and subchondral contusion (black arrow). There are associated varus injures to posterolateral structures (all injuries not shown). There is complete lateral collateral ligament injury (green arrow), and capsular disruption with subcutaneous fluid leak and haematoma (orange star). (b) Cor PD image of a different patient shows subtle marginal medial tibial plateau fracture with cartilage injury (white arrow), there is also oblique tear in the mid body of medial meniscus and partial medial collateral ligament injury (orange arrows). Partial injury to lateral collateral ligament is also seen (blue arrow) with joint effusion (yellow star). Page 37 of 62

38 Fig. 8: (a&b) Cor PD image shows a communited depressed medial tibial plateau fracture with large fracture cleft and cartilage injury (red arrow). There is also inter-marginal radial tear of the posterior horn of medial meniscus (blue arrow) with complete tear of the posterolateral corner structures, including conjoint tendon and lateral collateral ligament (green arrow). This has resulted in capsular injury and subcutaneous fluid leak (yellow star) with fat lobules (yellow arrow) and fracture skin blisters (white arrow). In addition there is also partial proximal medial collateral ligament injury (orange arrow). Page 38 of 62

39 Fig. 9: (a-d) demonstrate different patients with fibular head fractures from non-displaced (white arrow) to widely displaced (blue arrow). Small bony debris is seen in the fracture site (fine orange arrows) with large joint effusions (yellow star). This injury pattern can be associated with posterolateral corner ligamentous injuries and haematoma. Large popliteal intramuscular haematoma is seen in patient (b) (red star). Page 39 of 62

40 Fig. 10: (a) Sag PD image shows impaction subchondral contusion (yellow star) and fracture (white arrow) with fat fluid level (blue arrow). (b) Axial PD FS image of a different patient shows fat fluid (blue arrow) and haematocrit levels (orange arrow). Page 40 of 62

41 Fig. 11: (a&b) Images shows medial patellar retinaculum complete tear with injury to vastus medialis muscle (yellow arrow) and medial capsular injury resulting in leak of knee joint effusion into the subcutaneous tissues (yellow star). Fig. 12: (a) Ax PD FS images shows an oval shaped normal ACL (red circle) from its femoral origin at the posteromedial lateral femoral condyle to its tibial insertion anterior to the tibial spine (left to right). Two bundles are also seen, anteromedial (yellow arrow) and posterolateral (white arrow). (b) Normal ACL (orange circle) seen in serial Cor PD images show the long femoral origin and fan like tibial insertion (black arrow). Page 41 of 62

42 Fig. 13: (a) Normal sagittal image of ACL seen on 2 slices. The ligament is intact (green line) and parallels Blumesaat line (white line). (b-e) Sag PD images of different patients with complete ACL tear (red line). (b) ACL fibres are discontinuous, (c-d) different patients with mid ACL complete tear with flattened distal fibres. (e) Complete ACL tear with small bunched distal fibres. There is also complete tear of the proximal PCL (blue line). Page 42 of 62

43 Fig. 14: (Clockwise from top left) Sag PD, ax PD FS, Sag PD FS and Cor PD images depict some of the injuries in pivot shift pattern. Pivot shift pattern of bone contusion (yellow star), joint effusion (blue star), complete medial patellar retinaculum tear (red arrow), tear of medial collateral ligament (white arrow), and complete ACL tear (red line). Page 43 of 62

44 Fig. 15: Ax PD FS (top), Cor PD FS (mid), and Sag PD (bottom left) and Sag PD FS (bottom right) images showing normal PCL from femoral origin to tibial insertion within red, orange and green circles. Page 44 of 62

45 Fig. 16: Multi-planar images showing partial high grade tear of the mid-distal PCL (red arrow). Page 45 of 62

46 Fig. 17: Sag PD images of 6 different patients with complete PCL tears (red line). Note is also made of complete ACL tears in all cases. Page 46 of 62

47 Fig. 18: Top row ax PD FS images (cranial to caudal from left to right) and bottom row Cor PD images (Anterior to Posterior) show normal MCL (within white oval area). Fig. 19: Cor PD images of 3 patients showing thickened MCL with some disruption of fibres proximally in keeping with partial tears. Page 47 of 62

48 Fig. 20: Cor PD images of different patients with complete distal MCL tear. Top left image shows complete disruption of distal fibres (yellow arrow). Top right and bottom left images show complete MCL tear with retracted and coiled up MCL (red arrow), tear of the medial meniscus is also seen (black arrow). Bottom right image shows complete discontinuity of MCL with hemorrhage (orange arrow) with muscle tears and hematoma in vastus lateralis (yellow star). Page 48 of 62

49 Fig. 21: Ax PD FS images from left to right (cranial to caudal) show the parts of extensor mechanism. Quadriceps tendon (white arrow), medial patellar retinaculum (green arrow), lateral patellar retinaculum (orange arrow), including iliotibial band (red arrow), and patellar tendon (blue arrow). Fig. 22: Complete tear of the medial patellar retinaculum with defect (white arrow) with retracted fibres in the patellofemoral compartment (yellow arrow). There is also a partial tear of the lateral patellar retinaculum (orange arrow) with lateral femoral condyle contusion (red star) and fascial edema (blue arrow). Page 49 of 62

50 Fig. 23: Ax PD FS images (a) with complete medial patellar retinaculum tear (red arrow) and capsular disruption (orange star). (b) Shows complete lateral patellar retinaculum and iliotibial band tear (orange arrow) with capsular disruption (orange star). Bony contusions are seen on the contralateral femoral condyle (yellow star). Fig. 24: Cor PD images from 3 different patients showing complete iliotibial band tear (red arrow) with capsular disruption (orange star) Page 50 of 62

51 Fig. 25: Top row left to right (Ax PD FS) images from caudal to cranial, and bottom row Cor PD images from Anterior to posterior. Normal posterolateral structures are shown, popliteal muscle (red star), popliteal tendon (red arrow), lateral collateral ligament (blue arrow), biceps femoris tendon (green arrow), conjoint tendon (white arrow) and lateral head of gastrocnemius (yellow arrow). Page 51 of 62

52 Fig. 26: (a) Sag PD,(b-c) Cor PD images shows anteromedial tibial plateau fracture (red arrow), complete MCL tear (yellow arrow), complete tear of iliotibial band (orange arrow), lateral collateral ligament tear (blue arrow) and biceps tendon tear (green arrow). This has resulted in tear of the posterolateral capsule with joint fluid leak into the subcutaneous tissues (red star). There is also a large complex joint effusion (yellow star). Note is also made of a mal-aligned knee joint Fig. 27: Cor PD image shows arcuate fracture (red arrow), and popliteal muscle haematoma (yellow star).the popliteofibular ligament is also seen (blue arrow). Page 52 of 62

53 Fig. 28: Posterolateral corner injury with complete tear of the lateral collateral ligament (blue arrow) and biceps tendon (white arrow). There is also avulsion of the popliteal tendon (not shown) with muscle edema (red star). There is fluid decompressed out of the lateral side of the knee joint into the subcutaneous tissues and interfacial plane (yellow star). Page 53 of 62

54 Fig. 29: The common peroneal nerve is injured with surrounding hematoma (white arrow) as seen on the coronal PD images. On the fat suppressed sequences there is demonstration of marked edema in the nerve (red arrow) in keeping with neural injury and neuritis. As a result there is marked edema in the anterolateral compartment muscles (yellow arrow) in keeping with denervation injury. Page 54 of 62

55 Fig. 30: Axial images show posteromedial corner structures - semimembranosus (red arrow), posterior oblique ligament (green arrow) and oblique popliteal ligament (blue arrow), medial head of gastrocnemius (orange arrow) and posterior horn of medial meniscus (yellow star). Fig. 31: Ax PD FS image from a patient with multi-ligamentous injuries involving the posterolateral corner (green area), medial patellar retinaculum partial injury (blue arrow) and partial injury to posterior oblique ligament (red arrow). Page 55 of 62

56 Fig. 32: Shows examples of soft tissue injuries, (a) subcutaneous haematoma (yellow star), (b) intramuscular haematoma (green star), (c) skin blisters in a patient with tibial fracture, and (d) patient with degloving injury. Page 56 of 62

57 Fig. 33: Shows complete radial tear of the medial meniscal posterior root (white arrow) on the coronal image, with corresponding area appearing as a 'ghost' meniscus on the sagittal image. Fig. 34: Coronal PD weighted images show medial meniscal oblique tear in the anterior horn and body of medial meniscus with flipped flap lying over the posterior horn (orange Page 57 of 62

58 arrow). Complete ACL (blue star), PCL tear (red star) and MCL tear (blue curved line) are also noted. Fig. 35: Show medial meniscal tears in different patients (a) complete radial tear of posterior horn, (b) vertical longitudinal tear, and (c) oblique inferiorly surfacing tear. All three patients have multiple other ligamentous injuries. Page 58 of 62

59 Fig. 36: (a) sagittal image shows significant bone contusion with cartilage injury in lateral femoral condyle (orange arrows), (b) coronal image in a different patient with medial tibial plateau fracture as cartilage injury (red arrow). Page 59 of 62

60 Conclusion Conclusion: In summary, we have shown various examples of multi-ligamentous knee injuries based on a check list approach. This will enable the reader to familiarize themselves with common patterns of traumatic multi-ligamentous knee injuries. Page 60 of 62

61 References Sanders et al, Bone Contusion Patterns of the Knee at MR Imaging: Footprint of the Mechanism of Injury. Radiographics 2000; 20:S135-S151 Dirim et al., Medial Patellofemoral Ligament: Cadaveric Investigation of Anatomy with MRI, MR Arthrography, and Histologic Correlation. AJR 2008; 191: Merican et al., Anatomy of the lateral retinaculum of the knee. J Bone Joint Surg, 2008; 90-B: Remer et al., Anterior cruciate ligament injury: MR Imaging diagnosis and patterns of injury. Radiographics 1992; 12: De Maeseneer et al., Three layers of the medial capsular and supporting structures of the knee: MR Imaging - Anatomic correlation. Radiographics 2000; 20:S83-S89 Sonin el al., MR Imaging of the posterior cruciate ligament: Normal, abnormal and associated injury patterns. Radiographics 1995; 15: Recondo et al., Lateral stabilizing structures of the knee: functional anatomy and injuries assessed with MR Imaging. Radiographics 2000; 20:S91-S102 Bondia Gracia et al., MRI of the Knee: A proposal for a systematic reading. ESSR 2014, P-0027 Davis et al., Understanding the 'dark side' of the knee: Imaging of the posterolateral corner. RSNA 2007 Page 61 of 62

62 Personal Information Dr. A. Rastogi, Joint Department of Medical Imaging, University of Toronto, Toronto Dr. D. Whelan, Department of Orthopaedics, St. Michael's Hospital, Toronto Dr. R. Martin, Section of Orthopaedics, University of Calgary, Calgary Dr. W. Mak, Department of Medical Imaging, St. Michael's Hospital, Toronto Dr. D. Pearce, Department of Medical Imaging, St. Michael's Hospital, Toronto Page 62 of 62