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A case report of an unusual location of pericruciate meniscal cyst with adjacent bony erosion
Journal of Clinical Imaging 26 (2002) 299 – 301
A case report of an unusual location of pericruciate meniscal cyst with adjacent bony erosion Chia-Ying Lua, Tsyh-Jyi Hiseha, Hsuan-Ti Huangb, Chien-Kuo Wanga,*, Gin-Chung Liua a
Department of Radiology, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung, Taiwan, ROC b Department of Orthopedic Surgery, Kaohsiung Medical University, Kaohsiung, Taiwan, ROC Received 10 February 2002
Abstract Meniscal cysts are uncommon cystic lesions around the knee, and pericruciate meniscal cysts are the most rare types. Here we present an unusual case of a pericruciate meniscal cyst located laterally to the anterior cruciate ligament (ACL), causing erosion of the adjacent tibial plateau. D 2002 Elsevier Science Inc. All rights reserved. Keywords: Knee; Cyst; Meniscal cyst; Bone erosion; MRI
1. Introduction Meniscal cyst, a rare kind of cystic lesion in the knee, usually results from the accumulation of synovial fluid after a meniscal tear. According to their location, meniscal cysts can be divided into three types: parameniscal cysts, intrameniscal cysts and pericruciate meniscal cysts. In this report, we present an unusual case of a meniscal cyst that extended medially from a horizontal tear of anterior horn of lateral meniscus and abutted the anterior cruciate ligament (ACL); beside, bony erosion was also noted in tibial plateau adjacent to the cyst.
2. Case report This 36-year-old male patient suffered from left knee pain after a traffic accident 9 years before. He felt the pain intermittently, but he did not pay much attention to it. Recently, the pain had become worse and worse, so he came to our hospital for help. Physical examination on his first visit revealed anterior instability of the left knee without loss of sensory or motor function.
* Corresponding author. Tel.: +886-7-320-8235; fax: +886-7-315-4208. E-mail address: [email protected] (C.-K. Wang).
The plain film of the left knee revealed small bony erosion at the tibial plateau (Fig. 1A). Magnetic resonance imaging of the left knee showed a well-defined cystic lesion about 1.2 1 1.2 cm3 located laterally to the tibial insertion of the ACL (Figs. 1B and 2). Minimal displacement of ACL and erosion of the adjacent tibial plateau were present. The cyst appeared with intermediate signal intensity on T1WI and high signal intensity on T2WI to muscle. Communication between the cyst and the horizontal tear of anterior horn of lateral meniscus was well demonstrated (Fig. 3A – E). Also, increasing signal intensity within the proximal portion of the ACL was appreciated. The posterior cruciate ligament (PCL), the medial and lateral collateral ligaments were intact. Arthroscopy revealed ACL partial tear and anterior horn of lateral meniscus horizontal tear. Debridement and meniscectomy were performed subsequently.
3. Discussion Cystic lesions around the knee can cause common clinical problems. Knee pain and a palpable mass are most frequently found. Baker cysts are the most common lesions and arise between the medial head of the gastrocnemius tendon and the semimembranous tendon. Other cystic lesions, such as meniscal cysts and ganglion cysts, are less common.
0899-7071/02/$ – see front matter D 2002 Elsevier Science Inc. All rights reserved. PII: S 0 8 9 9 - 7 0 7 1 ( 0 2 ) 0 0 4 3 4 - 5
300
C.-Y. Lu et al. / Journal of Clinical Imaging 26 (2002) 299–301
Fig. 1. (A) AP view of left knee. Bony erosion (arrow) at the tibial plateau adjacent to the tibial spine is identified. (B) Left knee coronal T2WI. A well-defined cystic lesion lateral to the ACL tibial insertion site with bony erosion and edema at the tibial plateau is noted. Beside, a tear is also identified at the anterior horn of lateral meniscus. A: ACL; C: meniscal cyst; E: bony erosion; T: meniscal tear.
Meniscal cysts are cystic lesions associated with horizontal meniscus tears, and the tracks between cysts and torn menisci are often identified. The dominant theory for the development of these cysts suggests that the synovial fluid is pumped out from torn menisci and accumulates within the menisci or the parameniscal soft tissues [1 – 3]. The cysts may present on the medial and lateral sides of the knee. The lateral side is more common than the medial side. The cysts can extend into the joint space or peripheral area. According to the location, meniscal cysts can be divided into three types. When the meniscal cysts are located in parameniscal soft tissue on the medial or lateral side of the knee, they are named as parameniscal cysts. When the cystic lesions are located within the menisci, they are intrameniscal cysts and are less common than parameniscal cysts [4]. The most unusual type is the pericruciate cyst. These cystic lesions extend centrally within the joint and abut on the cruciate ligaments. The appearance is similar to the intraarticular ganglion cysts. Letrakul et al. [1] offered four criteria to differentiate a pericruciate meniscal cyst from a PCL ganglion cyst using
MR images. First, the pericruciate meniscal cyst is always associated with a horizontal meniscus tear, but a PCL ganglion cyst is not [4]. Second, a track communicating between the cyst and the torn meniscus may be identified in a pericruciate meniscal cyst. Third, pericruciate meniscal cysts are usually located mainly posteriorly to the PCL, but PCL ganglion cysts are more frequently found at the femoral or tibial insertions of the PCL [5,6]. Fourth, pericruciate meniscal cysts may surround the PCL, while PCL ganglion cysts seldom do. In our case, a horizontal tear was noted at the anterior horn of the left lateral meniscus. A communication between the tear and a cystic lesion could be well appreciated, and the cyst was close to the tibial insertion of the ACL with adjacent bony erosion. These findings fit the criteria of Letrakul et al. , but the location was quite unusual. The sensitivity of arthroscopy is low, and it is not a good standard for the detection of meniscal cysts [4]. Arthroscopy does not easily identify parameniscal cysts due to their extraarticular locations [7,8]. In our case, the arthroscopy was an anterolateral approach and the pericruciate meniscal
C.-Y. Lu et al. / Journal of Clinical Imaging 26 (2002) 299–301
cyst was located laterally, abutting the tibial insertion of the ACL. The arthroscope showed a soft tissue bulging close to the ACL tibial insertion site and a horizontal tear at anterior horn of lateral meniscus. But the meniscal cyst could not be confirmed because the lesion was located near the arthroscope insertion site. It was quite difficult to evaluate that area. By comparison, MR images provide multiplanar images, clear evaluation of adjacent anatomic structures, and definition of the extent of the meniscal cyst [4]. In most cases, MR images can confirm the diagnosis. The arthroscope may be used for the management of the meniscal cyst, not only for confirming the diagnosis. We suggest that an insertion site of the arthroscope in opposite direction to the lesion may be helpful to obtain a better visual field. Bony erosions associated with meniscal cysts are exceedingly rare [9,10]. The bony structure was eroded probably due to a pressure effect. Reviewing the associated articles, we found that 14 cases of parameniscal cysts related to bony erosions have been reported [10]. Three of these cysts involved medial menisci and erosions at the margins of the tibial plateau, or femoral condyle was noted. Four of these cysts involved lateral menisci and erosions at the margins of the lateral tibial plateau. In our case, it was a pericruciate meniscal cyst, with associated bony erosion
301
Fig. 3. (A – E) Left knee T1WI sequential sagittal images. A horizontal tear with intermediate signal at anterior horn of lateral meniscus is noted. A pericruciate cystic lesion with communication to the torn meniscus is shown. A: ACL; C: meniscal cyst; E: bony erosion; T: meniscus tear.
identified at the tibial plateau adjacent to the ACL insertion site. To our knowledge, this is the only reported case of pericruciate meniscal cyst associated with bony erosion. It is reasonable that any slow-growing, benign, space-occupying lesion in a limited space would produce adjacent bony erosion due to abnormal pressure. And it was the only one clue that could be identified on plain film. So, if bony erosion around the knee joint is represented on the plain film, the possibility of a meniscal cyst with secondary bone change should be kept in mind [10].
References
Fig. 2. Left knee axial T2WI. It shows a cystic lesion located anteromedially to the tear at anterior horn of lateral meniscus. C: meniscal cyst; T: meniscus tear.
[1] Letrakul N, Skaf A, Yeh L, Roger B, Schweitzer M, Blasbalg R, Resnick D. Pericruciate meniscal cysts arising from tears of the posterior horn of the medial meniscus: MR imaging features that simulate posterior cruciate ganglion cysts. AJR, Am J Roentgenol 1999;172: 1575 – 9. [2] Barrie HJ. The pathogenesis and significance of meniscal cysts. J Bone Jt Surg, Br Vol 1979;61:184 – 9. [3] Burk DL, Dalinka MK, Kanal E, Schieber ML, Cohen EK, Prorok RJ, Gefter WB, Kressel HY. Meniscal and ganglion cysts of the knee: MR evaluation. AJR, Am J Roentgenol 1988;150:331 – 6. [4] Tyson LL, Daughters TC, Ryu RKN, Cruse JV. MRI appearance of meniscal cysts. Skeletal Radiol 1995;24:421 – 4. [5] Bui-Mensfield LT, Youngberg RA. Intraarticular ganglia of the knee: prevalence, presentation, etiology, and management. AJR, Am J Roentgenol 1997;168:123 – 7. [6] McLaren DB, Buckwalter KA, Vahey TN. The prevalence and significance of cyst-like changes at the cruciate ligament attachments in the knee. Skeletal Radiol 1992;21:365 – 9. [7] Burgan DW. Arthrographic findings in meniscal cysts. Radiology 1971;101:579 – 81. [8] Gallo GA, Bryan RS. Cysts of the semilunar cartilage of the knee: a report of sixteen cases including arthrographic study. Am J Surg 1968;116:65 – 8. [9] Juhng S, Lenchik L, Won J. Tibial plateau erosions associated with lateral meniscal cysts. Skeletal Radiol 1998;27:288 – 90. [10] Thanmaya RB, Schweitzer M, Resnick D. Meniscal cysts causing bone erosion: retrospective analysis of seven cases. Clin Imaging 1999;23:134 – 8.
A case report of an unusual location of pericruciate meniscal cyst with adjacent bony erosion Chia-Ying Lua, Tsyh-Jyi Hiseha, Hsuan-Ti Huangb, Chien-Kuo Wanga,*, Gin-Chung Liua a
Department of Radiology, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung, Taiwan, ROC b Department of Orthopedic Surgery, Kaohsiung Medical University, Kaohsiung, Taiwan, ROC Received 10 February 2002
Abstract Meniscal cysts are uncommon cystic lesions around the knee, and pericruciate meniscal cysts are the most rare types. Here we present an unusual case of a pericruciate meniscal cyst located laterally to the anterior cruciate ligament (ACL), causing erosion of the adjacent tibial plateau. D 2002 Elsevier Science Inc. All rights reserved. Keywords: Knee; Cyst; Meniscal cyst; Bone erosion; MRI
1. Introduction Meniscal cyst, a rare kind of cystic lesion in the knee, usually results from the accumulation of synovial fluid after a meniscal tear. According to their location, meniscal cysts can be divided into three types: parameniscal cysts, intrameniscal cysts and pericruciate meniscal cysts. In this report, we present an unusual case of a meniscal cyst that extended medially from a horizontal tear of anterior horn of lateral meniscus and abutted the anterior cruciate ligament (ACL); beside, bony erosion was also noted in tibial plateau adjacent to the cyst.
2. Case report This 36-year-old male patient suffered from left knee pain after a traffic accident 9 years before. He felt the pain intermittently, but he did not pay much attention to it. Recently, the pain had become worse and worse, so he came to our hospital for help. Physical examination on his first visit revealed anterior instability of the left knee without loss of sensory or motor function.
* Corresponding author. Tel.: +886-7-320-8235; fax: +886-7-315-4208. E-mail address: [email protected] (C.-K. Wang).
The plain film of the left knee revealed small bony erosion at the tibial plateau (Fig. 1A). Magnetic resonance imaging of the left knee showed a well-defined cystic lesion about 1.2 1 1.2 cm3 located laterally to the tibial insertion of the ACL (Figs. 1B and 2). Minimal displacement of ACL and erosion of the adjacent tibial plateau were present. The cyst appeared with intermediate signal intensity on T1WI and high signal intensity on T2WI to muscle. Communication between the cyst and the horizontal tear of anterior horn of lateral meniscus was well demonstrated (Fig. 3A – E). Also, increasing signal intensity within the proximal portion of the ACL was appreciated. The posterior cruciate ligament (PCL), the medial and lateral collateral ligaments were intact. Arthroscopy revealed ACL partial tear and anterior horn of lateral meniscus horizontal tear. Debridement and meniscectomy were performed subsequently.
3. Discussion Cystic lesions around the knee can cause common clinical problems. Knee pain and a palpable mass are most frequently found. Baker cysts are the most common lesions and arise between the medial head of the gastrocnemius tendon and the semimembranous tendon. Other cystic lesions, such as meniscal cysts and ganglion cysts, are less common.
0899-7071/02/$ – see front matter D 2002 Elsevier Science Inc. All rights reserved. PII: S 0 8 9 9 - 7 0 7 1 ( 0 2 ) 0 0 4 3 4 - 5
300
C.-Y. Lu et al. / Journal of Clinical Imaging 26 (2002) 299–301
Fig. 1. (A) AP view of left knee. Bony erosion (arrow) at the tibial plateau adjacent to the tibial spine is identified. (B) Left knee coronal T2WI. A well-defined cystic lesion lateral to the ACL tibial insertion site with bony erosion and edema at the tibial plateau is noted. Beside, a tear is also identified at the anterior horn of lateral meniscus. A: ACL; C: meniscal cyst; E: bony erosion; T: meniscal tear.
Meniscal cysts are cystic lesions associated with horizontal meniscus tears, and the tracks between cysts and torn menisci are often identified. The dominant theory for the development of these cysts suggests that the synovial fluid is pumped out from torn menisci and accumulates within the menisci or the parameniscal soft tissues [1 – 3]. The cysts may present on the medial and lateral sides of the knee. The lateral side is more common than the medial side. The cysts can extend into the joint space or peripheral area. According to the location, meniscal cysts can be divided into three types. When the meniscal cysts are located in parameniscal soft tissue on the medial or lateral side of the knee, they are named as parameniscal cysts. When the cystic lesions are located within the menisci, they are intrameniscal cysts and are less common than parameniscal cysts [4]. The most unusual type is the pericruciate cyst. These cystic lesions extend centrally within the joint and abut on the cruciate ligaments. The appearance is similar to the intraarticular ganglion cysts. Letrakul et al. [1] offered four criteria to differentiate a pericruciate meniscal cyst from a PCL ganglion cyst using
MR images. First, the pericruciate meniscal cyst is always associated with a horizontal meniscus tear, but a PCL ganglion cyst is not [4]. Second, a track communicating between the cyst and the torn meniscus may be identified in a pericruciate meniscal cyst. Third, pericruciate meniscal cysts are usually located mainly posteriorly to the PCL, but PCL ganglion cysts are more frequently found at the femoral or tibial insertions of the PCL [5,6]. Fourth, pericruciate meniscal cysts may surround the PCL, while PCL ganglion cysts seldom do. In our case, a horizontal tear was noted at the anterior horn of the left lateral meniscus. A communication between the tear and a cystic lesion could be well appreciated, and the cyst was close to the tibial insertion of the ACL with adjacent bony erosion. These findings fit the criteria of Letrakul et al. , but the location was quite unusual. The sensitivity of arthroscopy is low, and it is not a good standard for the detection of meniscal cysts [4]. Arthroscopy does not easily identify parameniscal cysts due to their extraarticular locations [7,8]. In our case, the arthroscopy was an anterolateral approach and the pericruciate meniscal
C.-Y. Lu et al. / Journal of Clinical Imaging 26 (2002) 299–301
cyst was located laterally, abutting the tibial insertion of the ACL. The arthroscope showed a soft tissue bulging close to the ACL tibial insertion site and a horizontal tear at anterior horn of lateral meniscus. But the meniscal cyst could not be confirmed because the lesion was located near the arthroscope insertion site. It was quite difficult to evaluate that area. By comparison, MR images provide multiplanar images, clear evaluation of adjacent anatomic structures, and definition of the extent of the meniscal cyst [4]. In most cases, MR images can confirm the diagnosis. The arthroscope may be used for the management of the meniscal cyst, not only for confirming the diagnosis. We suggest that an insertion site of the arthroscope in opposite direction to the lesion may be helpful to obtain a better visual field. Bony erosions associated with meniscal cysts are exceedingly rare [9,10]. The bony structure was eroded probably due to a pressure effect. Reviewing the associated articles, we found that 14 cases of parameniscal cysts related to bony erosions have been reported [10]. Three of these cysts involved medial menisci and erosions at the margins of the tibial plateau, or femoral condyle was noted. Four of these cysts involved lateral menisci and erosions at the margins of the lateral tibial plateau. In our case, it was a pericruciate meniscal cyst, with associated bony erosion
301
Fig. 3. (A – E) Left knee T1WI sequential sagittal images. A horizontal tear with intermediate signal at anterior horn of lateral meniscus is noted. A pericruciate cystic lesion with communication to the torn meniscus is shown. A: ACL; C: meniscal cyst; E: bony erosion; T: meniscus tear.
identified at the tibial plateau adjacent to the ACL insertion site. To our knowledge, this is the only reported case of pericruciate meniscal cyst associated with bony erosion. It is reasonable that any slow-growing, benign, space-occupying lesion in a limited space would produce adjacent bony erosion due to abnormal pressure. And it was the only one clue that could be identified on plain film. So, if bony erosion around the knee joint is represented on the plain film, the possibility of a meniscal cyst with secondary bone change should be kept in mind [10].
References
Fig. 2. Left knee axial T2WI. It shows a cystic lesion located anteromedially to the tear at anterior horn of lateral meniscus. C: meniscal cyst; T: meniscus tear.
[1] Letrakul N, Skaf A, Yeh L, Roger B, Schweitzer M, Blasbalg R, Resnick D. Pericruciate meniscal cysts arising from tears of the posterior horn of the medial meniscus: MR imaging features that simulate posterior cruciate ganglion cysts. AJR, Am J Roentgenol 1999;172: 1575 – 9. [2] Barrie HJ. The pathogenesis and significance of meniscal cysts. J Bone Jt Surg, Br Vol 1979;61:184 – 9. [3] Burk DL, Dalinka MK, Kanal E, Schieber ML, Cohen EK, Prorok RJ, Gefter WB, Kressel HY. Meniscal and ganglion cysts of the knee: MR evaluation. AJR, Am J Roentgenol 1988;150:331 – 6. [4] Tyson LL, Daughters TC, Ryu RKN, Cruse JV. MRI appearance of meniscal cysts. Skeletal Radiol 1995;24:421 – 4. [5] Bui-Mensfield LT, Youngberg RA. Intraarticular ganglia of the knee: prevalence, presentation, etiology, and management. AJR, Am J Roentgenol 1997;168:123 – 7. [6] McLaren DB, Buckwalter KA, Vahey TN. The prevalence and significance of cyst-like changes at the cruciate ligament attachments in the knee. Skeletal Radiol 1992;21:365 – 9. [7] Burgan DW. Arthrographic findings in meniscal cysts. Radiology 1971;101:579 – 81. [8] Gallo GA, Bryan RS. Cysts of the semilunar cartilage of the knee: a report of sixteen cases including arthrographic study. Am J Surg 1968;116:65 – 8. [9] Juhng S, Lenchik L, Won J. Tibial plateau erosions associated with lateral meniscal cysts. Skeletal Radiol 1998;27:288 – 90. [10] Thanmaya RB, Schweitzer M, Resnick D. Meniscal cysts causing bone erosion: retrospective analysis of seven cases. Clin Imaging 1999;23:134 – 8.