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Popliteal (Baker's) cyst

Simon M Helfgott, MD
Section Editor
Zacharia Isaac, MD
Deputy Editor
Paul L Romain, MD


Popliteal synovial cysts, also known as Baker's cysts, are a common occurrence in adults and children [1,2]. They present as swelling in the popliteal fossa due to enlargement of the gastrocnemius-semimembranosus bursa, which lies between these two muscles on the medial side of the fossa slightly distal to the center crease in the back of the knee [3].

Popliteal cysts in adults are often secondary to degenerative or inflammatory joint disease or joint injury; they usually communicate with the adjacent knee joint space, especially in older patients with knee pathology. Communicating cysts contain synovial fluid. In children, popliteal cysts are usually a primary process, arising directly from the gastrocnemius-semimembranosus bursa; they do not communicate with the joint space. (See 'Popliteal (Baker's) cyst in children' below.)

The epidemiology, pathogenesis, clinical features, diagnosis, and management of popliteal (Baker's) cyst will be presented here. The clinical and radiographic evaluation of knee pain is reviewed separately. (See "Approach to the adult with unspecified knee pain" and "Knee bursitis" and "Radiologic evaluation of the acutely painful knee in adults" and "Radiologic evaluation of the chronically painful knee in adults" and "Approach to acute knee pain and injury in children and skeletally immature adolescents" and "Approach to chronic knee pain or injury in children or skeletally immature adolescents".)


Most popliteal cysts are asymptomatic and are detected incidentally by an imaging study performed for some other reason. They tend to occur in adults from ages 35 to 70 [4].

In general, the prevalence of popliteal cysts varies based upon the imaging technique used, the age of the patient population, and/or whether the cyst is secondary or primary.

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Literature review current through: Nov 2017. | This topic last updated: Jun 30, 2017.
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  1. Fritschy D, Fasel J, Imbert JC, et al. The popliteal cyst. Knee Surg Sports Traumatol Arthrosc 2006; 14:623.
  2. Handy JR. Popliteal cysts in adults: a review. Semin Arthritis Rheum 2001; 31:108.
  3. 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 1938; 20:963.
  5. Miller TT, Staron RB, Koenigsberg T, et al. MR imaging of Baker cysts: association with internal derangement, effusion, and degenerative arthropathy. Radiology 1996; 201:247.
  6. Fielding JR, Franklin PD, Kustan J. Popliteal cysts: a reassessment using magnetic resonance imaging. Skeletal Radiol 1991; 20:433.
  7. Sansone V, de Ponti A, Paluello GM, del Maschio A. Popliteal cysts and associated disorders of the knee. Critical review with MR imaging. Int Orthop 1995; 19:275.
  8. Hayashi D, Roemer FW, Dhina Z, et al. Longitudinal assessment of cyst-like lesions of the knee and their relation to radiographic osteoarthritis and MRI-detected effusion and synovitis in patients with knee pain. Arthritis Res Ther 2010; 12:R172.
  9. Wolfe RD, Colloff B. Popliteal cysts. An arthrographic study and review of the literature. J Bone Joint Surg Am 1972; 54:1057.
  10. Lindgren PG, Willén R. Gastrocnemio-semimembranosus bursa and its relation to the knee joint. I. Anatomy and histology. Acta Radiol Diagn (Stockh) 1977; 18:497.
  11. Lindgren PG, Rauschning W. Radiographic investigation of popliteal cysts. Acta Radiol Diagn (Stockh) 1980; 21:657.
  12. Katz RS, Zizic TM, Arnold WP, Stevens MB. The pseudothrombophlebitis syndrome. Medicine (Baltimore) 1977; 56:151.
  13. Kraag G, Thevathasan EM, Gordon DA, Walker IH. The hemorrhagic crescent sign of acute synovial rupture. Ann Intern Med 1976; 85:477.
  14. Gerber NJ, Dixon AS. Synovial cysts and juxta–articular bone cysts. Semin Arthritis Rheum 1974; 3:323.
  15. Hench PK, Reid RT, Reames PM. Dissecting popliteal cyst simulating thrombophlebitis. Ann Intern Med 1966; 64:1259.
  16. Vela P, Pascual E, Ronan J, Rosas J. Cutaneous manifestation of ruptured popliteal cyst. Clin Rheumatol 1991; 10:340.
  17. Macfarlane DG, Bacon PA. Popliteal cyst rupture in normal knee joints. Br Med J 1980; 281:1203.
  18. Dash S, Bheemreddy SR, Tiku ML. Posterior tibial neuropathy from ruptured Baker's cyst. Semin Arthritis Rheum 1998; 27:272.
  19. Canoso JJ, Goldsmith MR, Gerzof SG, Wohlgethan JR. Foucher's sign of the Baker's cyst. Ann Rheum Dis 1987; 46:228.
  20. Fam AG, Wilson SR, Holmberg S. Ultrasound evaluation of popliteal cysts on osteoarthritis of the knee. J Rheumatol 1982; 9:428.
  21. Torreggiani WC, Al-Ismail K, Munk PL, et al. The imaging spectrum of Baker's (Popliteal) cysts. Clin Radiol 2002; 57:681.
  22. Tan SS, Chong BK, Thoo FL, et al. Diagnosis of deep venous thrombosis: accuracy of colour doppler ultrasound compared with venography. Singapore Med J 1995; 36:362.
  23. Marra MD, Crema MD, Chung M, et al. MRI features of cystic lesions around the knee. Knee 2008; 15:423.
  24. Levitin PM. Letter: Diagnosis of Baker cyst. JAMA 1976; 236:253.
  25. Hermann G, Yeh HC, Lehr-Janus C, Berson BL. Diagnosis of popliteal cyst: double-contrast arthrography and sonography. AJR Am J Roentgenol 1981; 137:369.
  26. Tatari H, Baran O, Lebe B, et al. Pigmented villonodular synovitis of the knee presenting as a popliteal cyst. Arthroscopy 2000; 16:13.
  27. Acebes JC, Sánchez-Pernaute O, Díaz-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.
  28. Nakano KK. Entrapment neuropathy from Baker's cyst. JAMA 1978; 239:135.
  29. Ahn JH, Lee SH, Yoo JC, et al. Arthroscopic treatment of popliteal cysts: clinical and magnetic resonance imaging results. Arthroscopy 2010; 26:1340.
  30. Sansone V, De Ponti A. Arthroscopic treatment of popliteal cyst and associated intra-articular knee disorders in adults. Arthroscopy 1999; 15:368.
  31. Bandinelli F, Fedi R, Generini S, et al. Longitudinal ultrasound and clinical follow-up of Baker's cysts injection with steroids in knee osteoarthritis. Clin Rheumatol 2012; 31:727.
  32. Seil R, Rupp S, Jochum P, et al. Prevalence of popliteal cysts in children. A sonographic study and review of the literature. Arch Orthop Trauma Surg 1999; 119:73.
  33. Szer IS, Klein-Gitelman M, DeNardo BA, McCauley RG. Ultrasonography in the study of prevalence and clinical evolution of popliteal cysts in children with knee effusions. J Rheumatol 1992; 19:458.
  34. De Maeseneer M, Debaere C, Desprechins B, Osteaux M. Popliteal cysts in children: prevalence, appearance and associated findings at MR imaging. Pediatr Radiol 1999; 29:605.
  35. Akagi R, Saisu T, Segawa Y, et al. Natural history of popliteal cysts in the pediatric population. J Pediatr Orthop 2013; 33:262.