Mucoid degeneration of the posterior cruciate ligament

Mucoid degeneration of the posterior cruciate ligament Poster No.: C-2278 Congress: ECR 2010 Type: Educational Exhibit Topic: Musculoskeletal - Joints Authors: P. Papadopoulou, I. Kalaitzoglou, I. Tsifoundoudis, P. PsychidisPapakirytsis, N. Michailidis, A. Koutsourlis, A. S. Dimitriadis; Thessaloniki/GR Keywords: Posterior cruciate ligament, Mucoid degenaration, Ganglia Keywords: Musculoskeletal joint, Musculoskeletal system DOI: 10.1594/ecr2010/C-2278 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 15

Learning objectives To draw attention to a quite uncommon pathology, the mucoid degeneration of the Posterior Cruciate Ligament (PCL). Page 2 of 15

Background Mucoid degeneration is the presence of amorphous mucoid matrix between the collagen fibers of the ligaments or tendons. The pathogenesis of this entity is unknown and patients may be symptomatic or asymptomatic. The condition is rare and usually affects the ACL. Degeneration of the posterior cruciate ligament is extremely rare and has received very little attention in the literature. The normal PCL on page 4 is composed of collagen fibers, which display diffuse low signal intensity on MR images. It lacks the striations seen in the Anterior Cruciate Ligament (ACL), except near the femoral insertion. Page 3 of 15

Images for this section: Fig. 0: The normal PCL has a homogeneous low signal intensity on all pulse sequences. Radiology Department, Asklipios - Thessaloniki/GR Page 4 of 15

Imaging findings OR Procedure details We reviewed 2018 knee examinations preformed in our institution from July 2007 to July 2009 and found four cases of PCL mucoid degeneration. Patient age ranged from 45 to 68 years. All four patients were referred for symptoms of internal derangement. On MR images, PCL mucoid degeneration was seen as a bulky ligament with increased signal intensity on all pulse sequences but without discontinuity of the fibers. Discreet fibers were better distinguished on T2-W images. On sagittal images the affected PCLs had a tramline-like morphology, with two parallel lines of low signal intensity surrounding a central portion of increased signal intensity on all pulse sequences. The increased signal was lower than the signal of intraarticular fluid on T2 W images. Fig.: Mucoid degeneration of the posterior cruciate ligament. The ligament is bulky but intact. Mucoid matrix displaces normal fibers. References: Radiology Department, Asklipios - Thessaloniki/GR In one case, pigmented villonodular synovitis was also identified. Page 5 of 15

Fig.: PCL mucoid degeneration and PVNS. The posterior cruciate ligament is enlarged due to the presence of mucoid matrix between its fibers. There is also diffuse synovial thickening with synovial enhancement, and diffuse profound hypointensity attributed to the paramagnetic effects of heavy hemosiderine pigmentation. References: Radiology Department, Asklipios - Thessaloniki/GR The tram-like appearance of PCL mucoid degeneration is in distinction to the appearance of ACL mucoid degeneration where the high signal is interspersed with normal fibers and the ligament has the characteristic "celery" morphology. Page 6 of 15

Fig.: ACL mucoid degeneration. The ligament is bulky and normal fibers are seen as linear low signal intensity structures in a high signal intensity background. This is the characteristic celery appearance of the ACL. References: Radiology Department, Asklipios - Thessaloniki/GR Mucoid degeneration can be differentiated from rupture on basis of history and absence of ancillary findings such as bone bruises or injury of other ligaments but the key finding is the absence of fiber discontinuity. Fig.: PCL rupture. There is discontinuation of the fibers, edema and striation. The discontinuation of the fibers is the key finding that differentiates rupture from mucoid degeneration. References: Radiology Department, Asklipios - Thessaloniki/GR Page 7 of 15

Fig.: Partial PCL rupture and patellar fracture due to overextension injury References: Radiology Department, Asklipios - Thessaloniki/GR PCL ganglion cysts are similar to mucoid degeneration in terms of pathology but quite different on imaging studies. These intraarticular ganglia appear as distinct cystic structures of high signal intensity on T2 W images, similar to the signal intensity of synovial fluid, in close contact with the ligament. Fig.: PCL ganglion. A small ganglionic cyst is seen behind the ligament and in close contact with it. References: Radiology Department, Asklipios - Thessaloniki/GR Page 8 of 15

Images for this section: Fig. 0: Mucoid degeneration of the posterior cruciate ligament. The ligament is bulky but intact. Mucoid matrix displaces normal fibers. Radiology Department, Asklipios - Thessaloniki/GR Page 9 of 15

Fig. 0: PCL mucoid degeneration and PVNS. The posterior cruciate ligament is enlarged due to the presence of mucoid matrix between its fibers. There is also diffuse synovial thickening with synovial enhancement, and diffuse profound hypointensity attributed to the paramagnetic effects of heavy hemosiderine pigmentation. Radiology Department, Asklipios - Thessaloniki/GR Fig. 0: ACL mucoid degeneration. The ligament is bulky and normal fibers are seen as linear low signal intensity structures in a high signal intensity background. This is the characteristic celery appearance of the ACL. Page 10 of 15

Radiology Department, Asklipios - Thessaloniki/GR Fig. 0: PCL rupture. There is discontinuation of the fibers, edema and striation. The discontinuation of the fibers is the key finding that differentiates rupture from mucoid degeneration. Radiology Department, Asklipios - Thessaloniki/GR Fig. 0: Partial PCL rupture and patellar fracture due to overextension injury Radiology Department, Asklipios - Thessaloniki/GR Page 11 of 15

Fig. 0: PCL ganglion. A small ganglionic cyst is seen behind the ligament and in close contact with it. Radiology Department, Asklipios - Thessaloniki/GR Page 12 of 15

Conclusion Mucoid degeneration is a distinct clinical entity not to be confused with partial rupture of PCL or ganglion cysts. Page 13 of 15

References 1. Papadopoulou P. The celery stalk sign. Radiology 2007;245(3):916-7. 2. Fernandes JL, Viana SL, Mendonça JL, Freitas FM, Bezerra AS, Lima GA, Matos VL, Cunha NF, Martins RR, Freitas RM. Mucoid degeneration of the anterior cruciate ligament: magnetic resonance imaging findings of an underdiagnosed entity. Acta Radiol. 2008;49(1):75-9. 3. Hensen JJ, Coerkamp EG, Bloem JL, De Schepper AM. Mucoid degeneration of the anterior cruciate ligament. JBR-BTR. 2007;90(3):192-3. 4. Nishimori M, Sumen Y, Sakaridani K. Mucoid degeneration of the anterior cruciate ligament--a report of two cases. Magn Reson Imaging. 2004;22(9):1325-8. 5. Viana SL, Fernandes JL, Mendonça JL, Freitas FM. Diffuse intrasubstance signal abnormalities of the posterior cruciate ligament: the counterpart of the mucoid degeneration of the anterior cruciate ligament? A case series. JBR-BTR. 2008;91(6):245-8. 6. Bergin D, Morrison WB, Carrino JA, Nallamshetty SN, Bartolozzi AR. Anterior cruciate ligament ganglia and mucoid degeneration: coexistence and clinical correlation. AJR Am J Roentgenol. 2004 May;182(5):1283-7. 7. McIntyre J, Moelleken S, Tirman P. Mucoid degeneration of the anterior cruciate ligament mistaken for ligamentous tears. Skeletal Radiol. 2001;30(6):312-5. 8. Melloni P, Valls R, Yuguero M, Sáez A. Mucoid degeneration of the anterior cruciate ligament with erosion of the lateral femoral condyle. Skeletal Radiol. 2004 Jun;33(6):359-62 9. Kumar A, Bickerstaff DR, Grimwood JS, Suvarna SK. Mucoid cystic degeneration of the cruciate ligament. J Bone Joint Surg Br. 1999;81(2):304-5. 10. Narvekar A, Gajjar S. Mucoid degeneration of the anterior cruciate ligament. Arthroscopy 2004;20:141-146. 11. Viana SL, Fernandes JL, Mendonça JL, FreitasFM. Diffuse intrasubstance signal abnormalities of the posterior cruciate ligament: The counterpart of mucoid degeneration of the anterior cruciate ligament? JBR-BTR, 2008, 91: 245-248. 12. Stoller D.W., Tirman P.F., BredellaM.A.: Diagnostic imaging: Orthopaedics. 1st edition, Salt Lake City, Utah, 2004, pp. 5-50-5-52. Page 14 of 15

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