My patient recently underwent total knee arthroplasty (TKA) and is now found to have a Baker’s cyst. Is Baker’s cyst a postoperative complication of TKA?

Not likely! There is no evidence that TKA causes Baker’s cyst (also known as popliteal cyst). Instead, the finding of Baker’s cyst following TKA may be best explained by its well-known association with osteoarthritis, one of the main indications for TKA.1,6,7

In a study of 2025 patients who underwent primary TKA, 0.6% were diagnosed with Baker’s cysts within 6 weeks to 2 years postoperatively (75% symptomatic), but whether the cysts were present prior to TKA was unclear. There was no reported association between surgical technique or perioperative course and Baker’s cyst diagnosis.9

Actually, there might be a correlation between TKA and Baker’s cyst resolution.2,3 Among patients with known cysts preoperatively, 15% and 67% of patients may experience resolution of the cyst at 1 year and 4-6 years following surgery, respectively. 2,3

A Baker’s cyst is a fluid-filled pocket in the posterior aspect of the knee, typically seen in adults with degenerative changes in the patellofemoral joint, as may occur with meniscal tears and arthritis. When symptomatic, it can be treated non-operatively with ultrasound-guided aspiration and corticosteroid injection or operatively with surgical excision or attempted repair of the underlying defect. 4,8


Bonus Pearl: Did you know that the ‘crescent sign’ (bruising below the medial malleolus associated with fluid from ruptured cyst moving inferiorly toward the ankle) was first described in 1976 and may help distinguish calf pain due to Baker’s cyst from that of deep venous thrombophlebitis? 5

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 Contributed by Anamika Veeramani, Medical Student, Harvard Medical School



  1. Guermazi A., Hayashi D., Roemer F, et al. Cyst-like lesions of the knee joint and their relation to incident knee pain and development of radiographic osteoarthritis: The MOST study. Osteoarthritis and Cartilage 2010; 18:1386-1392. doi:10.1016/j.joca.2010.08.015.
  2. Hommel H., Becker R., Fennema P., et al. (2020). The fate of Baker’s cysts at mid-term follow-up after total knee arthroplasty. The Bone & Joint Journal, 2020;102-B(1):132-136. doi:10.1302/0301-620x.102b1.bjj-2019-0273.r2.
  3. Hommel, H., Perka, C., Kopf, S. The fate of Baker’s cyst after total knee arthroplasty. The Bone & Joint Journal 2016;98-B(9):1185-1188. doi:10.1302/0301-620x.98b9.37748.
  4. Leib AD, Roshan A, Foris LA, et al. Baker’s Cyst. [Updated 2020 Mar 16]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from:
  5. Mizumoto, J. The crescent sign of ruptured baker’s cyst. Journal of General Family Medicine, 2019;20(5): 215-216. doi: 10.1002/jgf2.261.
  6. Rupp, S., Seil, R., Jochum, P., & Kohn, D. Popliteal Cysts in Adults. The American Journal of Sports Medicine 2002; 30(1): 112-115. doi:10.1177/03635465020300010401.
  7. Sansone, V., Ponti, A. D., Paluello, G. M., & Maschio, A. D. Popliteal cysts and associated disorders of the knee. International Orthopaedics 1995;19(5): 275-279. doi:10.1007/bf00181107.
  8. Smith, M., Lesniak, B., Baraga, M., Kaplan, L., Jose, J. Treatment of Popliteal (Baker) Cysts with Ultrasound-Guided Aspiration, Fenestration and Injection: Long-term Follow-up. Sports Health 2015; 7(5): 409-414. doi: 10.1177/1941738115585520.
  9. Tofte, J. N., Holte, A. J., & Noiseaux, N. Popliteal (Baker’s) Cysts in the Setting of Primary Knee Arthroplasty. The Iowa Orthopedic Journal 2017;37:177-180.


Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Massachusetts General Hospital, Harvard Catalyst, Harvard University, its affiliate academic healthcare centers, or its contributors. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!

My patient recently underwent total knee arthroplasty (TKA) and is now found to have a Baker’s cyst. Is Baker’s cyst a postoperative complication of TKA?

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