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Parameniscal Cyst

From WikiSM

Other Names

  • Meniscal Cyst
  • Parameniscal Cyst
  • Intrameniscal cysts
  • True meniscal cyst

Background

  • This page refers to parameniscal or meniscal cysts, Bakers Cysts are discussed separately

History

  • Needs to be updated

Epidemiology

  • Prevalence reported to be between 1% and 8%[1]
  • Diagnosed at an average age of 30 to 40 years[2]

Introduction

Illustration of parameniscal cyst[3]
(A) Clinical appearance of the patient (white arrow shows the swelling). Anteroposterior (B) and lateral (C) knee radiographs show a distinct lesion.[4]
Meniscal anatomy and relationship to important structures of the knee joint[5]

General

  • Believed to be extrusion of synovial fluid through a tear in the meniscus
  • Often asymptomatic, found incidentally on imaging, however can become symptomatic
  • Treatment may be either non surgical aspiration or surgical with cyst decompression and meniscus repair

Pathoanatomy

  • Literature is conflicting on medial vs lateral being more common
  • Initially thought the most common location is peripheral portion of mid-third of lateral meniscus[6]
  • A systemic review of MRI literature says medial and lateral cysts occur equally[7]

Intrameniscal Cysts

  • Uncommonly encountered compared to parameniscal cysts[8]

Associated Conditions

  • Meniscus Tear
    • Greater than 95% of cysts have an associated meniscus tear
    • Cysts usually seen in a horizontal tear or a horizontal cleavage tear
  • Discoid Meniscus

Anatomy of the Meniscus

  • Pair of medial and lateral crescent shaped wedges of fibrocartilage oriented circumferentially
  • Positioned between the tibial plateaus and the femoral condyles in the medial and lateral compartments
  • Thick peripherally and thin centrally
  • Primary function is to reduce compression stress at the tibiofemoral joint

Risk Factors

  • History of trauma[9]

Differential Diagnosis

Differential Diagnosis of Palpable Knee Mass

Differential Diagnosis Knee Pain

Clinical Features

a Lateral meniscal cyst is visible in 45° of knee flexion in the right knee. b Disappearance of the cyst with full flexion. c The clear appearance of the lateral meniscal cyst with external rotation of the tibia (L lateral, M medial, Arrow lateral meniscal cyst)[10]

History

  • The patient may have a history of trauma or knee injury, recent or remote
  • Onset of pain is often insidious and the patient may be entirely asymptomatic
  • Patient may report activity-related knee pain, swelling, knee locking and popping, and/or instability
  • Rarely, weakness or claudication if neurovascular impingement

Physical Exam

  • Can often be palpated on exam, especially from the lateral meniscus[11]
  • Palpation of the mass is prominent along the joint line with the knee in 20-30 degrees flexion
  • It is firmly fixed to underlying tissues, not mobile in subcutaneous tissues

Special Tests

  • Pisani Maneuver: mass present with knee in extension, disappears in flexion
  • McMurrays Test: passive flexion and extension of the knee with the patient supine

Evaluation

Coronal (A) and axial (B) T2-weighted MRI shows a giant medial parameniscal cyst (asterisk). (C) Sagittal proton-density-weighted MRI demonstrates a horizontal medial meniscal tear (white arrow).[4]
Cyst with few septa abutting lateral meniscus. A hypoechoic cleft is noted in lateral meniscus - possibly a tear[12]

Radiography

  • Standard Radiographs Knee
    • Initial imaging modality of choice
    • Often normal
    • May show soft tissue swelling at unexpected locations

MRI

  • Gold standard for diagnosis
  • Useful to exclude other pathology
  • Findings
    • High intensity on T2 images that communicate with tears of the meniscus
  • Indication
    • Concerned about meniscal tears and considering surgical intervcention
    • When there is diagnostic uncertainty

Ultrasound

  • Can easily diagnose meniscal cyst
  • Findings
    • Anechoic or hypoechoic lesion with cystic appearance
    • Meniscus tear can sometimes be seen as well
  • Ultrasound is also used for aspiration/ injection

Classification

  • Meniscal: cystic structure at the level of the meniscus
  • Parameniscal: adjacent to the meniscus, extend beyond the margins
  • Peri- or intra-meniscal: within the meniscus

Management

Nonoperative

Operative

  • Indication
    • Failure of conservative management
  • Technique
    • Surgical excision or decompression
    • Often accompanied by meniscectomy or meniscus repair

Rehab and Return to Play

Rehabilitation

  • Needs to be updated

Return to Play/ Work

  • Needs to be updated

Prognosis and Complications

Prognosis

  • Recurrence
    • Rate of recurrence is higher with non surgical management[13]

Complications

  • Peroneal Nerve Palsy
  • Erosion or scalloping of the tibial plateau
  • Inappropriate osteogenesis of the lower extremity

See Also

References

  1. ↑ Passler, J. M., et al. "Arthroscopic treatment of meniscal cysts." The Journal of Bone & Joint Surgery British Volume 75.2 (1993): 303-304.
  2. ↑ Schuldt, Dennis R., and Richard D. Wolfe. "Clinical and arthrographic findings in meniscal cysts." Radiology 134.1 (1980): 49-52.
  3. ↑ Fajin Dong, M. D., et al. "Ultrasound Guided Aspiration of Lateral Parameniscal Cysts Causing Iliotibial Band Friction Syndrome."
  4. ↑ 4.0 4.1 Kose, Ozkan, et al. "A giant medial parameniscal cyst of the knee joint." Case Reports 2013 (2013): bcr2013009440.
  5. ↑ Torres, Stephen J., Jason E. Hsu, and Robert L. Mauck. "Meniscal anatomy." Meniscal Injuries: Management and Surgical Techniques (2014): 1-7.
  6. ↑ Ollerenshaw R (1921) Cysts in semilunar cartilage. Br J Surg 8:409–412
  7. ↑ Campbell S, Sanders T, Morrison W. MR Imaging of Meniscal Cysts: Incidence, Location, and Clinical Significance. AJR Am J Roentgenol. 2001;177(2):409-13
  8. ↑ Tyson LL, Daughters TC Jr, Ryu RK, Crues JV. MRI appearance of meniscal cysts. Skeletal Radiol 1995; 24:421-424
  9. ↑ Raine, G. E. T., and L. C. L. Gonet. "Cysts of the menisci of the knee." Postgraduate Medical Journal 48.555 (1972): 49-51.
  10. ↑ Pinar, Halit, et al. "A contribution to Pisani’s sign for diagnosing lateral meniscal cysts: a technical report." Knee Surgery, Sports Traumatology, Arthroscopy 17 (2009): 402-404.
  11. ↑ De Smet, Arthur A., Ben K. Graf, and Alejandro Munoz del Rio. "Association of parameniscal cysts with underlying meniscal tears as identified on MRI and arthroscopy." American Journal of Roentgenology 196.2 (2011): W180-W186.
  12. ↑ Case courtesy of Maulik S Patel, Radiopaedia.org, rID: 18575
  13. ↑ Handy JR. Popliteal cysts in adults: a review. Semin Arthritis Rheum. 2001; 31(2): 108-18.
Created by:
John Kiel on 12 December 2024 14:38:36
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Last edited:
12 December 2024 20:07:22
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