[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Conditions](https://durgical.com/en/conditions/) › Baker's (Popliteal) Cyst

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# Baker's (Popliteal) Cyst

A Baker's cyst is a fluid-filled swelling at the back of the knee, usually connected to the knee joint.

Updated 2026-10-23

## Structures involved

Tap one to see what it is and open it in 3D.

- [Joint capsule](https://durgical.com/en/anatomy/articular-capsule-of-knee-joint/)
- [Semimembranosus tendon](https://durgical.com/en/anatomy/tendon-of-semimembranosus/)

## Why it happens

- [Synovial joints: capsule, synovial membrane and articular cartilage](https://durgical.com/en/histology/synovial-joints-capsule-synovial-membrane-and-articular-cartilage/)

## What it is

Fluid-filled swelling in the popliteal fossa, usually communicating with the knee joint.

## Symptoms and signs

- Fullness or a lump behind the knee
- Pain or tightness with full flexion

## Diagnosis

**Clinical**
Palpable mass in the popliteal fossa

**Imaging**
Ultrasound or MRI

## Treatment

**Conservative**
Treat the underlying knee condition.

## Complications

- Rupture mimicking deep-vein thrombosis

## Related conditions

- [Deep vein thrombosis](https://durgical.com/en/conditions/deep-vein-thrombosis/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Baker's Cyst](https://www.ncbi.nlm.nih.gov/books/NBK430774/) (StatPearls (NCBI Bookshelf), 2024).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/conditions/baker-s-cyst/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/baker-s-cyst/