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Bakers Cyst

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Other Names

  • Popliteal synovial cyst
  • Ganglion cyst of the knee
  • Synovial cyst of the knee
  • Baker's Cyst
  • Parameniscal cyst
  • Perimeniscal cyst
  • Meniscal cyst
  • Pseudothrombophlebitis Syndrome
  • Primary popliteal cyst

Background

  • This page refers to a synovial or ganglion cyst of the knee, which when presenting posteriorly is referred to as a Baker's Cyst (BC)

History

  • Named after British surgeon William Morant Baker’s case series published in 1877[1]
  • First described by Robert Adams in 1840[2], and subsequently by Foucher in 1856[3]
  • Further characterized by Wilson in 1938 who dissected 30 knees, of which 58% had a direct connection with the knee joint[4]

Epidemiology

  • Found on 38% of knee MRIs on symptomatic patients[5]
  • Found in 40-54% of adult knees based on cadaveric studies[6]
  • Most commonly seen in adults between ages 35 and 70 (need citation)
  • Pediatric
    • Among children, most frequently seen between ages 4 and 7, reported in children as young as 2[7]
    • In pediatric knee MRI, prevalence estimated at 6.3%[8]

Pathophysiology

  • Communication
    • Occurs within a bursa between the Semimembranosus (SemiM) and medial head of the Gastrocnemius (Gastroc)
    • Joint-cyst communication considered to function like a 1-way valve
  • 1 way valve[9]
    • Allows synovial fluid to pass into bursa where it is sequestered
    • In flexion, valve is open allowing flow
    • In extension, valve is closed due to muscle tension of SemiM and Gastroc
  • Function
    • May provide protective effect against hydraulic pressure from knee effusions
    • Size of BC roughly correlates with size of knee effusion[10]
  • Histology
    • Cyst walls resemble synovial tissue with fibrosis suggesting chronic nonspecific inflammation[11]
    • Cyst fluid is often thickened by the presence of fibrin
    • Rauschnig et al found no difference in histopathology between symptomatic and asymptomatic knees
  • Pediatric considerations
    • Majority have no communication with the joint capsule and may arise spontaneously[12]
    • When they do communicate with the joint, resemble those seen in adults

Pathoanatomy

  • Cyst Anatomy
    • Bursal communication between the Semimembranosus (SemiM) and medial head of the Gastrocnemius (Gastroc)
    • There may be occasional involvement of the subgastrocnemius bursa[13]
    • Case report of synvial cyst herniating out laterally through the Iliotibial Band[14]

Associated Pathology

Risk Factors

Differential Diagnosis

Clinical Features

  • History
    • Patients may report insidious, posterior knee pain
    • Additionally fullness, achiness, mass, and stiffness
    • The most common symptoms are swelling (76%), posterior aching (32%)[18]
    • Pain with full or terminal knee extension
    • Often have symptoms consistent with meniscal or chondral injuries
  • Physical Exam: Physical Exam Knee
    • Findings often consistent with meniscal or chondral injuries
    • With large cysts, posteromedial fullness may be present but many smaller cysts are not palpable
  • Special Tests
    • Foucher Sign: Examine posterior mass in full knee extension and flexion, should be soft in flexion
    • Homan Sign: Extend knee, passively dorsiflex ankle and squeeze calf

Evaluation

Bakers Cyst ultrasound long axis
Bakers Cyst ultrasound short axis

Radiographs

  • Standard Knee Radiographs
    • Screening tool
    • Not typically useful for evaluating a bakers cyst
  • Can detect other pathology associated with bakers cyst
    • E.g.: Osteoarthritis, Gout, Osteochondral Defect
    • Loose bodies may be seen within the bakers cyst
  • Arthrography
    • Previously gold standard for evaluation[19]
    • Has fallen out of favor for MRI, US

Ultrasound

  • Advantages
    • Cheap, lacks radiation, ease of use
  • Disadvantages
    • User dependent, cant evaluate all soft tissue injuries
  • Findings
    • Anechoic or hypoechoic, circumferential structure
    • Lacks flow and doppler signal of vascular structures
  • Accuracy[20]
    • Sensitivity: 100%
    • Specificity: 100%
    • PPV: 100%
    • NPV: 100%
    • Accuracy: 100%

MRI

  • Gold standard for evaluating BC and other soft tissue structures
  • Findings
    • Appear as a water-intensity fluid collection (low signal intensity on T1, high signal intensity on T2-weighted images)[16]
  • Description
    • Most are small, unilocular but can also be septated or multiloculated
    • Size, sites of extension, rupture can change appearance of fluid collection
    • Loose bodies/debris can be present

Classification

  • No specific classification
  • Important to characterize
    • Communicating vs noncommunicating
    • Loculated, multiloculated or septated
    • Underlying etiology

Management

Nonoperative

  • General
    • Initial treatment of choice unless complications
    • Important to target the underlying disorder
  • Physical Therapy
    • Maintain range of motion and knee flexibility
  • Intra-articular Corticosteroid Injection
    • Intra-articular has been found to decrease size, symptoms of cyst[21]
  • Ultrasound-guided posterior cyst aspiration and Corticosteroid Injection
    • This is particularly valuable in the uncommon noncommunicating, multiloculated or septated cyst

Operative

  • Indications
    • Failure of conservative therapy
    • Complicated including infection, neurovascular insult
  • Technique
    • Arthroscopic debridement
    • Arthroscopic cyst decompression or excision
    • Less commonly, open cyst excision
    • Correction of intra-articular pathology

Rehab and Return to Play

Rehabilitation

  • There are no specific bakers cyst rehabilitation guidelines
  • Important to maintain full knee flexion and range of motion

Return to Play

  • There are no clear return to play guidelines

Complications and Prognosis

Prognosis

  • Surgical
    • Response to surgical excision seems to correlate with ability to correct intra-articular pathology
    • Rauschning et al: 46 surgical excisions, 63% recurred, 33% had wound complications or pseudothrombophlebitis after[22]
    • Rupp et al: Arthroscopic treatment for 16 intra-articular disorders, 11 cysts persisted of which 2 became larger at 1 year postop[23]
      • Chondral lesions appeared to be most important prognostic factor, all patients had outerbridge III or IV lesions

Complications

See Also

External

References

  1. ↑ Baker WM. On the formation of synovial cysts in the leg in connection with disease of the knee joint. 1877. Clin Orthop Relat Res. 1994;299:2-10.
  2. ↑ Adams R. Chronic rheumatic arthritis of the knee joint. Dublin J Med Sci. 1840;17:520-522.
  3. ↑ Foucher E. Memoire sur les kystes de la region poplitee. Arch Gen Med. 1856;2:313.
  4. ↑ Wilson PD, Eyre-Brook AL, Francis JD. A clinical and anatomical study of the semimembranosus bursa in relation to popliteal cyst. J Bone Joint Surg Am. 1938;20:963-984.
  5. ↑ 5.0 5.1 Sansone V, De Ponti A, Minio Paluello G, Del Maschio A. Popliteal cysts and associated disorders of the knee: critical review with MR imaging. Int Orthop. 1995;19:275-279.
  6. ↑ Taylor AR, Rana NA. A valve: an explanation of the formation of popliteal cysts. Ann Rheum Dis. 1973;32:419-421
  7. ↑ GRISTINA, ANTHONY G., and PHILIP D. WILSON. "Popliteal cysts in adults and children: a review of 90 cases." Archives of Surgery 88.3 (1964): 357-363.
  8. ↑ De Maeseneer, Michel, et al. "Popliteal cysts in children: prevalence, appearance and associated findings at MR imaging." Pediatric radiology 29.8 (1999): 605-609.
  9. ↑ Rauschning W. Anatomy and function of the communication between the knee joint and popliteal bursae. Ann Rheum Dis. 1980;39:354-358.
  10. ↑ Hill CL, Gale DG, Chaisson CE, et al. Knee effusions, popliteal cysts, and synovial thickening: association with knee pain in osteoarthritis. J Rheumatol. 2001;28:1330-1337.
  11. ↑ Rauschning W, Fredriksson BA, Wilander E. Histomorphology of idiopathic and symptomatic popliteal cysts. Clin Orthop Relat Res. 1982;164:306-311.
  12. ↑ Akagi, Ryuichiro, et al. "Natural history of popliteal cysts in the pediatric population." Journal of Pediatric Orthopaedics 33.3 (2013): 262-268.
  13. ↑ Akagi, Ryuichiro, et al. "Natural history of popliteal cysts in the pediatric population." Journal of Pediatric Orthopaedics 33.3 (2013): 262-268.
  14. ↑ Jensen KH, Jorgensen U. Lateral presentation of a Baker’s cyst. Clin Orthop Relat Res. 1993;287:202-203
  15. ↑ Tarhan S, Unlu Z. Magnetic resonance imaging and ultrasonographic evaluation of the patients with knee osteoarthritis: a comparative study. Clin Rheumatol. 2003;22:181-188.
  16. ↑ 16.0 16.1 Marti-Bonmati L, Molla E, Dosda R, Casillas C, Ferrer P. MR imaging of Baker cysts: prevalence and relation to internal derangements of the knee. MAGMA. 2000;10:205-210.
  17. ↑ Corten K, Vandenneucker H, Reynders P, Nijs S, Pittevils T, Bellemans J. A pyogenic, ruptured Baker’s cyst induced by arthroscopic pressure pump irrigation. Knee Surg Sports Traumatol Arthrosc. 2009;17:266-269
  18. ↑ Bryan RS, DiMichele JD, Ford GL., Jr. Popliteal cysts. Arthrography as an aid to diagnosis and treatment. Clin Orthop Relat Res. 1967;50:203-208.
  19. ↑ Torreggiani WC, Al-Ismail K, Munk PL, et al. The imaging spectrum of Baker’s (popliteal) cysts. Clin Radiol. 2002;57:681-691.
  20. ↑ Ward EE, Jacobson JA, Fessell DP, Hayes CW, van Holsbeeck M. Sonographic detection of Baker’s cysts: comparison with MR Imaging. AJR Am J Roentgenol. 2001;176:373-380.
  21. ↑ Acebes JC, Sanchez-Pernaute O, Diaz-Oca A, Herrero-Beaumont G. Ultrasonographic assessment of Baker’s cysts after intra-articular corticosteroid injection in knee osteoarthritis. J Clin Ultrasound. 2006;34:113-117
  22. ↑ Rauschning W, Lindgren PG. Popliteal cysts (Baker’s cysts) in adults: I. Clinical and roentgenological results of operative excision. Acta Orthop Scand. 1979;50:583-591
  23. ↑ Rupp S, Seil R, Jochum P, Kohn D. Popliteal cysts in adults: prevalence, associated intraarticular lesions, and results after arthroscopic treatment. Am J Sports Med. 2002;30:112-115.
  24. ↑ Eichinger JK, Bluman EM, Sides SD, Arrington ED. Surgical management of septic arthritis of the knee with a coexistent popliteal cyst. Arthroscopy. 2009;25:696-700.
  25. ↑ Ji JH, Shafi M, Kim WY, Park SH, Cheon JO. Compressive neuropathy of the tibial nerve and peroneal nerve by a Baker’s cyst: case report. Knee. 2007;14:249-252.
Created by:
John Kiel on 16 December 2020 21:18:39
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Last edited:
26 January 2023 19:57:13
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