A Baker’s cyst (or popliteal cyst) is a fluid-filled swelling that develops behind the knee. It occurs when synovial fluid (the lubricating fluid in the knee joint) accumulates and pushes into the popliteal bursa, forming a bulge. Some cysts are symptom-free, while others cause swelling, tightness, or pain behind the knee, particularly when standing, walking, or bending.
The 2 Main Types of Baker’s Cysts
Primary: Swelling arising from the joint, without any internal derangement
- Most common in children between 4-7 (Varacallo, Luo, & Johanson, 2023)
Secondary: Swelling is associated with a pathology in the knee that is causing swelling
- (e.g. osteoarthritis, cartilage tears, ligament injuries, etc)
When to Worry About a Baker’s Cyst
In many cases, Baker’s cysts are harmless and may even resolve on their own. However, there are some situations where medical attention is important.
Concerning signs include:
- A sudden increase in pain, swelling, or lump size, which can suggest rupture of the cyst
- Swelling, redness, or warmth in the calf, which may mimic deep vein thrombosis (DVT), which is a condition that requires urgent attention
- Difficulty bending or straightening the knee due to pain or pressure
- Untreated underlying joint pathology, such as arthritis or meniscal tears, which may worse or cause recurrence
Baker’s Cyst Treatment Options
The best management depends on your symptoms and any underlying knee issues.
- Swelling management: the first-line approach: rest, ice, compression, elevation (RICE), non steroidal anti-inflammatory drugs (NSAIDs)
- Conservative treatment: physiotherapy to help promote fluid return, as well as improve strength and joint mechanics. In the case of ‘secondary’ baker’s cyst, managing the underlying cause (arthritis, etc.) is key to preventing recurrence (Hasan et al., 2025).
- Aspiration and corticosteroid injection: removal of fluid with a syringe can relieve pain and reduce fluid buildup, but recurrence is common unless the underlying joint problem is addressed
- Surgery: (arthroscopic or open excision) is reserved for persistent or severe cases where conservative care has failed. Surgical treatment of the underlying joint issue typically has better outcome than simply removing the cyst itself (Hasan et al., 2025).
Key Takeaways
- Not all Baker’s cysts require treatment; many resolve or improve with time.
- If the cyst is painful, large, or causing movement problems, consult a healthcare professional.
- Red-flag symptoms like calf swelling, redness, or sudden pain should be reviewed urgently to rule out DVT or cyst rupture.
- Long-term success usually depends on treating the cause inside the knee, not just the cyst itself.
References
Hasan, M., Berkovich, Y., Sarhan, B., Steinfeld, Y., Ginesin, E., Hijaze, S., Sleiman, A., & Yonai, Y. (2025). Comprehensive analysis of knee cysts: Diagnosis and treatment. Knee Surgery & Related Research, 37, Article 23. https://doi.org/10.1186/s43019-025-00269-2
Varacallo, M., Luo, T. D., & Johanson, N. A. (2023). Baker cyst. In StatPearls. StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK430774/
