Bone and soft tissue variants of knee with Magnetic Resonance.

Transcription

1 Bone and soft tissue variants of knee with Magnetic Resonance. Poster No.: C-2420 Congress: ECR 2013 Type: Educational Exhibit Authors: M. C. Ruibal Villanueva, P. Sucasas-Hermida, C. Saborido Avila, M. Rodríguez Álvarez, A. Nieto Parga, D. Fernández Alonso; Vigo/ ES Keywords: Education and training, Normal variants, MR, Musculoskeletal system DOI: /ecr2013/C-2420 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 82

2 Learning objectives Study and recognition of bone and soft tissue anatomical knee variants with magnetic resonance imaging (MRI). Background MRI is the most useful imaging technique to characterize knee variants contributing to determinate their clinical relevance and its recognition allow us to establish a correct diagnosis. In the table below we show the most frequent anatomical knee variants. Fig. 1 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES Page 2 of 82

3 Images for this section: Fig. 1 Page 3 of 82

4 Imaging findings OR Procedure details PATELLA The patella is the largest sesamoid bone of the human body. There are some anatomical variants such as: BIPARTITE OR MULTIPARTITE PATELLA: They are described as the failure of one or more secondary ossification centers to fuse with the patellar body. Most often is an incidental finding but it may become symptomatic and cause anterior knee pain. On patients with symptoms MRI shows bone marrow edema within both fragments and in the syncondrosis. In its differential diagnosis fractures are included. There are three different types of bipartite patella: a) Type I: the fragment is located at the inferior pole of the patella. b) Type II: lateral margin type. c) Type III (the most frequent): supero-lateral type. Page 4 of 82

5 Fig. 2 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES Page 5 of 82

6 Fig. 3 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES Page 6 of 82

7 Fig. 4 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES CAUDAL EXTENSION OF THE PATELLA: It is infrequent in adult patients and it has no clinical relevance. Page 7 of 82

8 Fig. 5 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES PATELLA BAJA AND PATELLA ALTA: These conditions refer to the relationship between the length of the patella and the patellar tendon. In order to know if a patella is a patella alta or a low riding patella the Insall and Salvati index is used on lateral plain radiographs (ratio of the patella tendon length (LT) to the length of the patella (PL)). If LT/PL < 0.8 is patella baja and if it is >1.2 is patella alta. The patella alta associates with chondromalacia, more likeliness of subluxation and patellar and quadricipital tendinopathy. Page 8 of 82

9 Fig. 6 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES Page 9 of 82

10 Fig. 7 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES DORSAL DEFECT OF THE PATELLA: It is a well-defined and apparently "lytic" lesion located in the supero-lateral aspect of the patella. On plain radiographs a round contour and an sclerotic margin are shown. Its etiology is unknown but it has been postulated that may be due to traction at the site of insertion of the vastus lateralis muscle (it inserts onto the supero-lateral aspect of the patella). On MRI appears as a cortical defect in the superolateral margin of the patella with a compensatory overgrowth of the articular cartilage. Most of cases are asymptomatic and differential diagnosis with osteochondritis dissecans must be made. Page 10 of 82

11 Fig. 8 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES MORPHOLOGICAL VARIANTS OF THE PATELLA: Wiberg classification differentiates three types of patella: - Type I: the facets are concave, symmetrical and of equal size. - Type II: the medial facet is rather smaller than the lateral facet. The lateral facet is concave. - Type III: the medial facet is convex and markedly smaller than the lateral facet. Page 11 of 82

12 Fig. 9 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES FABELLA It is a sesamoid bone located on the postero-lateral side of the knee, embedded in the gastronecmius lateral head tendon. It is often bilateral and asymptomatic although, very occasionally, can act as a source of knee pain and when this happens it is usually due to fracture or dislocation. It must not be mistaken for a loose body. Page 12 of 82

13 Fig. 10 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES Page 13 of 82

14 Fig. 11 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES FEMUR FEMORAL PSEUDO-OSTEOCHONDRITIS: It is seen in children and teenagers. It refers to the irregularity of the ossification of the femoral condyles but, unlike the osteochondritis dissecans, these femoral condylar irregularities will have intact overlying cartilage and marrow edema is usually abscent. Page 14 of 82

15 Fig. 12 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES IRREGULARITY OR AVULSIVE CORTICAL DEFECT, CORTICAL DESMOID OR FEMORAL DISTAL METAPHYSIS IRREGULARITY: It is a benign self-limiting lesion that appears in the growing skeleton from mild childhood through late adolescence. It is tipically seen in the posteromedial aspect of the femoral distal metaphysis. It is generally asymptomatic. The lesion heals until skeletal maturity and is rare in adults. It is believed to result from repetitive mechanical pull at the medial head of gastronecmius origin or the aponeurosis of the adductor magnus at its site of insertion. On MRI, it is hypointense on T1-weighted images and hyperintense on T2weighted images with peripheral sclerosis and it may enhance after contrast injection. Differential diagnosis with cortical fibrous defect must be made: the cortical desmoid persists on its location at the origin of the medial head of gastrocnemius whereas the cortical fibrous defect begins in a metaphyseal location buy may extend craneally into the diaphysis with skeletal growth and cortical erosion may be shown. Page 15 of 82

16 Fig. 13 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES DISTAL FEMORAL GROOVES: They are normal notches in the throclear surface and the medial and lateral femoral condyles and they should not be mistaken from impaction fractures. Page 16 of 82

17 Fig. 14 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES PROMINENT INSERTION OF THE MEDIAL GASTRONECMIUS ONTO THE POSTERIOR ASPECT OF THE DISTAL FEMORAL METAPHYSIS: It is a lesion due to traction. Page 17 of 82

18 Fig. 15 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES TIBIA We show an example of a normal cortical spur in the internal tibial metaphysis. Page 18 of 82

19 Fig. 16 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES MENISCI MENISCAL OSSICLE: It is a focus of ossification usually involving the posterior horn of the medial meniscus and it moves with the rotation of the knee. It may represent a developmental disorder or be acquired after meniscal trauma with posterior heterotopic ossification. Patients with meniscal ossicles may be asymptomatic or have knee pain, locking, swelling, and joint effusion. These symptoms happen because the ossicle alters the meniscus contour making more likely the risk of degeneration and tear. On MRI the signal intensity characteristics of fat may be seen within the ossicle as it may contain bone marrow. It must be differentiated from loose osteochondral fragments and osteochondritis dissecans by localizing the ossicle within the meniscus rather than free within the synovial space and identifying a clear donor site in the two latter entities. Page 19 of 82

20 Fig. 17 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES Page 20 of 82

21 Fig. 18 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES MENISCAL FLOUNCE: It is a single symmetric fold along the free edge of the medial meniscus. It is considered a normal positional variant and modifies with the anatomical knee position. It is not seen when the knee is maximally extended. It appears truncated on coronal plane MR images and may mimic a meniscal tear or degeneration. Page 21 of 82

22 Fig. 19 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES DISCOID MENISCUS: abscense of bow-tie appearance, a discoid meniscus is said to be present if it is seen on three or more standard sagittal images (5 mm-thick slices) or a meniscal body >15 mm wide on coronal images. A discoid meniscus is more prone to injury (degeneration, tear) than normal meniscus. Lateral meniscus is the most often involved. Watanabe et al describe three different types of lateral discoid meniscus based on its arthroscopic appearance. These are: type I (complete), type II (incomplete) and type III (also the Wrisberg ligament type). The first ones are stable because they have normal posterior peripheral attachments. The third type includes cases without normal posterior meniscotibial attachment, thus allowing increased mobility and unstability causing pain. Page 22 of 82

23 Fig. 20 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES MENISCAL PITFALLS: - Speckled anterior horn of the lateral meniscus: it may mimic a meniscal tear of the anterior horn but it is a normal variant created by the insertion of fibers of the ACL into the meniscus. Page 23 of 82

24 Fig. 21 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES - Transverse intermeniscal ligament: it may mimic a meniscal tear of the anterior horn of both menisci. Page 24 of 82

25 Fig. 22 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES - Menisco-meniscal and menisco-femoral ligaments may also simulate a tear of the posterior horn of the lateral meniscus, but the continuity of these structures in consecutive slices on MRI helps to make an accurate diagnosis. Page 25 of 82

26 Fig. 23 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES - Popliteus tendon pseudotear: the popliteus tendon adjacent to the posterior horn of the lateral meniscus and the capsule can also mimic a meniscal tear because of fluid tracking along the intraarticular portion of the tendon. Page 26 of 82

27 Fig. 24 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES - Pulsation from popliteal artery: pulsatile flow artifacts of the popliteal artery can mimic a fragmentation of the posterior horn of the lateral meniscus. - False image of meniscal fragment due to the insertion of the semimebranous muscle. Page 27 of 82

28 Fig. 25 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES LIGAMENTS: - Oblique menisco-meniscal ligament: It arises from the anterior meniscal horn of one meniscus and inserts into the posterior horn of the other coursing through the intercondylar notch between ACL and PCL. There are two different types: medial and lateral, depending on its anterior meniscal origin. On MRI appeasr as a hypointense linear intermeniscal structure that runs obliquely from the anterior horn of one meniscus to the posterior horn of the opposite meniscus. Page 28 of 82

29 Fig. 26 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES Page 29 of 82

30 Fig. 27 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES - Menisco-femoral ligaments: also called Humphrey or Wrisberg ligaments depending on if they pass anterior or posterior to the PCL at the intercondylar notch, respectively. They follow an oblique course in the intercondylar notch going from the posterior horn of the lateral meniscus to the medial femoral condyle or PCL. Page 30 of 82

31 Fig. 28 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES - Transverse intermeniscal ligament: It joins the anterior horn of both menisci. It may mimic an oblique tear of the anterior horn of the lateral meniscus on sagittal plane images. Page 31 of 82

32 Fig. 29 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES - Menisco-peroneal ligament: It goes from the postero-inferior third of the lateral meniscus to the fibular head. - Fabello-peroneal ligament: It joins the fabella with the stiloid process of the fibular head. - Popliteo-peroneal ligament: It is part of the posterolateral stabilizing complex of the knee. MUSCLE Page 32 of 82

33 One of the most important accessory muscles for their relevance is: - Accesory medial or lateral slip of the gastrocnemius muscle: It may cause symptoms of calf claudication due to popliteal artery entrapment syndrome Fig. 30 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES PLICAE The most frequent plicae are the suprapatellar and the infrapatellar. The mediopatellar plica is the most often symptomatic. Plicae are folds of embryonic remnants of synovial membrane into the knee joint. There are three different types of synovial plicae. Page 33 of 82

34 Suprapatellar plica: its extents from the inferior portion of the quadriceps tendon to the medial aspect of the knee joint. Mediopatellar plica: localized in the medial aspect of the knee joint descending oblicually and inserts on the synovial lining of the Hoffa s fat pad. Infrapatellar plica: also known as ligamentum mucosum. It arises from the intercondylar notch, widens as it descends through the infrapatellar fat pad, anterior to the ACL On MRI the plicae appear as linear low signal intensity structures surrounded by articular fluid and they are usually asymptomatic. Some conditions such as direct trauma or overuse may affect the pliability of the synovial folds and can become symptomatic. The mediopatellar plica is considered the most likely to cause problems. In these cases the plica becomes thickened, with high signal on T2 WI and chondral lesions in the medial aspect of the patella may be associated. Fig. 31 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES Page 34 of 82

35 Fig. 32 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES Page 35 of 82

36 Fig. 33 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES RECESSES: - In the Hoffa s fat pad there are two recesses: the suprahoffatic recess (with a vertical orientation) and the infrahoffatic recess (with a horizontal orientation). Page 36 of 82

37 Fig. 34 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES Page 37 of 82

38 Fig. 35 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES - Normal synovial recesses: suprapatellar, posterior or perimeniscal-central recesses. Page 38 of 82

39 Fig. 36 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES Page 39 of 82

40 Fig. 37 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES BONE MARROW: Hematopoietic bone marrow hyperplasia: low signal on T1WI and high signal on T2WI in the femoral metaphysis with epiphysis spared. Its differential diagnosis includes pathological bone marrow infiltration. Page 40 of 82

41 Fig. 38 References: Magnetic Resonance, Galaria. Empresa Pública de Servicios Sanitarios, Complexo Hospitalario Universitario de Vigo - Vigo/ES Page 41 of 82

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81 Conclusion - MRI is the non-ionizing imaging technique of choice and the most requested for knee examination in our Service. - Knee variants are frequent and we must know them to avoid mistakes in their interpretation, as well as unnecessary image tests or treatments. -These bone and soft tissue variants may be cause of pain. References Tyler P, Datir A, Saifuddin A. Magnetic resonance imaging of anatomical variations in the knee. Part 1: ligamentous and musculotendinous. Skeletal Radiol (2010) 39: Tyler P, Datir A, Saifuddin A. Magnetic resonance imaging of anatomical variations in the knee. Part 2: miscellaneous. Skeletal Radiol (2010) 39: Hedyati B, Saifuddin A. Focal lesions of the patella. Skeletal Radiol (2010) 38: Kontogeorgakos VA, Xenakis T, Papachristou D et al. Cortical desmoid and the four clinical sacenarios. Arch Orthop Trauma Surg (2009) 129: Schnarkowski P, Tirman PF, Fuchigami KD et al. Meniscal ossicle: radiographic and MR imaging findings. Radiology (1995) 196 (1): Park JS, Ryu KN, Yoon KH. Meniscal flounce on knee MRI: correlation with meniscal locations after positional changes. AJR 2006; 187: Sanders TG, Linares RC, Lawhorn KW et al. Oblique meniscomeniscal ligament: another potential pitfall for a meniscal tear - anatomic description and appearance at MR imaging in three cases. Radiology 1999; 213: Garcia-Valtuille R, Abascal F, Carezal L, et al. Anatomy and MR imaging appearances of sinovial plicae of the knee. Radiographics 2002; 22: Page 81 of 82

82 Personal Information Page 82 of 82