MRI of distended bursa around the knee

Transcription

1 MRI of distended bursa around the knee Poster No.: C-2240 Congress: ECR 2010 Type: Educational Exhibit Topic: Musculoskeletal Authors: P. Papadopoulou, I. Kalaitzoglou, N. Michailidis, I. Tsifoundoudis, P. Psychidis-Papakirytsis, A. Koutsourlis, A. S. Dimitriadis; Thessaloniki/GR Keywords: Knee, Bursa, MRI DOI: /ecr2010/C-2240 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 16

2 Learning objectives To describe and illustrate the multiple bursae around the knee. Background Knee bursae appear as cystic structures around the knee joint. Other common cystic structures in the same location are ganglia and meniscal cysts. Bursae are normal, synovial lined cavities serving to reduce friction between neighbouring moving structures such as tendons, ligaments and bones. They become visible on imaging studies only when they are distended due to accumulation of fluid, usually as a result of traumatic, inflammatory, degenerative or other pathologic processes. Distended bursae may be symptomatic or asymptomatic and may be incidentally discovered on imaging studies. When symptomatic they may present as a palpable mass, painful knee, mechanical dysfunction or limitation in range of motion. The symptoms may mimic pathology of adjacent structures, i.e. ligaments, menisci or bone. They are grouped according to location into anterior, posterior, medial and lateral bursae. The frontal bursae include the suprapatellar, prepatellar, the subcutaneous infrapatellar and the deep infrapatellar or pretibial bursa. In the posterior aspect of the knee, the gastrocnemiussemimembranosus bursa or popliteal or Baker cyst is found and is the commonest cystic lesion in the knee area. This is in fact a posterior extension of the medial gastocnemius bursa located in the medial compartment. The medial bursae also include the anserine bursa, the semimembranosus-tibial collateral ligament bursa and the medial collateral ligament or tibial bursa. The lateral bursae include the lateral gastrocnemious bursa, the fibular and fibulopopliteal and the subpopliteal bursa. Imaging findings OR Procedure details We retrospectively reviewed a total of 517 knee examinations preformed in our institution from January 2009 to July Examinations were preformed in 1.5 T unit and images were obtained in coronal, sagittal and axial planes with T1-W, T2-W, 3D T2 W GRE and PD W fat sat sequences. Evidence of bursitis was present in 138 examinations. The distension was attributed to a variety of pathologies including trauma, inflammation, arthritis, pigmented villonodular synovitis, synovial osteochondromatosis. Distended bursae are also found in asymptomatic individuals. We present characteristic examples of knee bursitis according to location and underline pathology. Page 2 of 16

3 The appearance of a distended bursa reflects its serous contents. Fluid has high signal intensity on T2 W images and low signal intensity on T1 W images. The signal is more heterogeneous when hemorrhage, thickened inflamed synovium, calcification, or loose bodies complicate the procedure. Anterior and posterior bursae are better demonstrated on sagittal and axial images while medial and lateral bursae are better demonstrated on coronal and axial images. Anterior Suprapatellar bursa The suprapatellar bursa is located between the quadriceps tendon and the femur. It usually communicates freely with the articular cavity but sometimes a complete septum, the suprapatellar plica, forms a closed cavity. Fig.: Suprapatellar bursa. The bursa is distended with inhomogeneous signal intensity due to synovitis. The thickened synovium displays vivid contrast enhancement. Prepatellar bursa The prepatellar bursa is located anterior to the patella, between the patella and patellar tendon and the overlying skin. Bursitis is usually the result of repetitive micro trauma and/ or inflammation and is also called housemaid's knee or carpet layer's knee. Page 3 of 16

4 Fig.: Prepatellar bursa. The prepatellar bursa, between the patella and the skin is distended with fluid. Fig.: Prepatellar bursa. In this example the prepatellar bursa extends between thepatella and the patellar tendon and the overlying skin Superficial infrapatellar or pretibial This bursa, also called pretibial bursa, is located between the tibial tuberosity and the overlying skin. Bursitis in this location is rare and it may be caused by occupational kneeling, known as clergyman's knee, or by trauma. The fluid collection is usually ill defined and it may be heterogeneous Page 4 of 16

5 Fig.: Superficial infrapatellar bursa. An ill-defined fluid collection is seen superficially to the patellar tendon insertion and the tibial tuberosity. Fig.: Prepatellar and superficial infrapatellar bursae. There is fluid in both superficial anterior knee bursae. A small enchondroma is seen in the femur. Deep infrapatellar The deep infrapatellar bursa is located between the distal end of the patellar tendon and the tibia. It does not communicate with the articular cavity. Deep infrapatellar bursitis is usually the result of repetitive stress, especially in runners and jumpers. A small amount of fluid may be seen in asymptomatic individuals. Page 5 of 16

6 Fig.: Deep infrapatellar bursa. A small amount of fluid, as in this example, is a common finding in this small bursa between the patellar tendon and the tibia. Posterior Gastrocnemius-semimembranosus bursa or popliteal or Baker cyst This is the commonest cystic lesion around knee joint. Popliteal or Baker cysts are the result of extension of joint fluid to the gastrocnemius-semimembranosus bursa through a week point at the posteromedial joint capsule. The collection may be unilocular or multilocular. It is identified crossing the space between the medial head of gastrocnemius and the semimembranosus tendon; it wraps around the medial head of gastrocnemius and is concave towards the midline. Fig.: Baker's cyst. There is a meniscus shaped fluid collection between the medial head of gastrocnemious and the semimembranosous tendon. Page 6 of 16

7 Rupture is a common complication of a Baker cyst and may be clinically confused with thrombophlebitis. On imaging studies fluid is seen dissecting along the medial head of gastrocnemious. Proximal dissection may result in pressure and symptoms from the sciatic nerve. Fig.: Baker's cyst rupture. The popliteal cyst is ill-defined and fluid dissects along the medial head of gastrocnemious. Medial Pes anserine bursa The anserine bursa separates the conjoined tendons of sartorius, gracilis and semitendinosus from the distal tibial collateral ligament. Bursitis in this location is usually caused from overuse, especially in runners. On MR imaging a fluid collection in the medial aspect of the joint is seen. This collection does not communicate with the knee joint, in distinction to meniscal cysts. Page 7 of 16

8 Fig.: Pes anserine bursa. Fluid is seen along the tendons of sartorius, gracilis and semitendinosus. MCL or tibial collateral bursa The tibial collateral ligament bursa is located between the superficial and deep layers of the medial collateral ligament. Imaging reveals a circumscribed and elongated fluid collection, which spans the joint line. Smaller fluid collections must sometimes be differentiated from meniscal cysts and meniscocapsular separation. Fig.: MCL bursa. Fluid distends the cavity between the superficial and deep portion of the ligament. In case of ligament rupture, the fluid is seen in a different location, superficial to the ligament. Semimembranosous-tibial collateral ligament bursa This is a coma-shaped fluid collection between the semimembranosus tendon and the tibial collateral ligament at the level of the medial tibial condyle. This bursa does not communicate with the joint cavity or other medial bursa but multifocal bursitis may be present. Page 8 of 16

9 Fig.: Semimembranosus-tibial collateral ligament bursa. This bursa has a typical, coma-shaped appearance and is located near the posteromedial corner of the knee. Fluid in the anserine bursa coexists. Lateral Fibular collateral ligament bursa The fibular collateral ligament - biceps femoris bursa is located superficial to the fibular collateral ligament. It is a constant finding on cadaveric studies with the distal end at the insertion of the ligament to the fibular head and the proximal end at the superior edge of the anterior arm of the long head of the biceps. It often has an inverted J shape on axial images. Fig.: Fibular collateral ligament bursa. This is an uncommonly distended bursa. A popliteal (Baker's) cyst coexists in this example. Page 9 of 16

10 Images for this section: Fig. 1: Prepatellar bursa. The prepatellar bursa, between the patella and the skin is distended with fluid. Fig. 2: Prepatellar bursa. In this example the prepatellar bursa extends between thepatella and the patellar tendon and the overlying skin Page 10 of 16

11 Fig. 3: Superficial infrapatellar bursa. An ill-defined fluid collection is seen superficially to the patellar tendon insertion and the tibial tuberosity. Fig. 4: Prepatellar and superficial infrapatellar bursae. There is fluid in both superficial anterior knee bursae. A small enchondroma is seen in the femur. Fig. 5: Deep infrapatellar bursa. A small amount of fluid, as in this example, is a common finding in this small bursa between the patellar tendon and the tibia. Page 11 of 16

12 Fig. 6: Baker's cyst. There is a meniscus shaped fluid collection between the medial head of gastrocnemious and the semimembranosous tendon. Fig. 7: Baker's cyst rupture. The popliteal cyst is ill-defined and fluid dissects along the medial head of gastrocnemious. Fig. 8: Pes anserine bursa. Fluid is seen along the tendons of sartorius, gracilis and semitendinosus. Page 12 of 16

13 Fig. 9: MCL bursa. Fluid distends the cavity between the superficial and deep portion of the ligament. In case of ligament rupture, the fluid is seen in a different location, superficial to the ligament. Fig. 10: Semimembranosus-tibial collateral ligament bursa. This bursa has a typical, coma-shaped appearance and is located near the posteromedial corner of the knee. Fluid in the anserine bursa coexists. Fig. 11: Suprapatellar bursa. The bursa is distended with inhomogeneous signal intensity due to synovitis. The thickened synovium displays vivid contrast enhancement. Page 13 of 16

14 Fig. 12: Fibular collateral ligament bursa. This is an uncommonly distended bursa. A popliteal (Baker's) cyst coexists in this example. Page 14 of 16

15 Conclusion Knee bursitis is a common condition, which should not be overlooked. The anatomic location along with the characteristic morphology of the various distended bursae help to identify, correctly characterize, and also differentiate them from other common cystic lesions around the knee. Personal Information peggy_pap@yahoo.co.uk References 1. Janzen DL, Peterfy CG, Forbes JR, et al. Cystic lesions around the knee joint: MR imaging #ndings. AJR Am J Roentgenol 1994;163: Steiner E, Steinbach LS, Schnarkowski P, et al.ganglia and cysts around joints. Radiol Clin North Am 1996;34: Lindgren PG, Willen R. Gastrocnemio-semimembranosus bursa and its relation to the knee joint. Anatomy and histology. Acta Radiol 1977;18: Torreggiani WC, Al-Ismail K, Munk PL, et al. The imaging spectrum of Baker's (popliteal) cysts. Clin Radiol 2002;57: McCarthy CL, McNally EG. The MRI appearance of cystic lesions around the knee. Skeletal Radiol 2004;33: Tschirch FTC, Schmid MR, P#rrmann CWA, et al. Prevalence and size of meniscal cysts, ganglionic cysts, synovial cysts of the popliteal space, #uid-#lled bursae, and other #uid collections in asymptomatic knees on MR imaging. AJR Am J Roentgenol 2003;180: Radiology 1993;188: Marti-Bonmati L, Molla E, Dosda R, et al. MR imaging of Baker cysts -prevalence and relation to internal derangement of the knee. MAGMA 2000;10: Miller TT, Staron RB, Koenigsberg T, et al. MR imaging of Baker cysts: association with internal derangement, effusion and degenerative arthropathy. Radiology 1996;201: Page 15 of 16

16 9. Beaman FD, Peterson JJ. MR Imaging of Cysts, Ganglia, and Bursae About the Knee Radiol Clin N Am ; Marra MD, Crema MD, Chung M, Roemer FW, Hunter DJ, Zaim S, Diaz L, Guermazi A. MRI features of cystic lesions around the knee. Knee Dec;15(6): Page 16 of 16