A Baker's cyst, also known as a popliteal cyst, is a fluid-filled bulge behind the knee caused by an escape of synovial fluid from the knee joint. It is most common in children aged 4-7 and adults aged 35-70. A primary cyst develops spontaneously while a secondary cyst is usually caused by an underlying knee problem like arthritis. Symptoms may include swelling, pain, and tightness behind the knee. Ultrasound and MRI scans can confirm the diagnosis. Treatment focuses on addressing the underlying knee issue through rest, ice, compression, elevation, physiotherapy, injections, or occasionally surgery.

1. Popliteal Cyst (Baker’s Cyst)
Siwaporn Khureerung

2. What is a Baker's cyst?
Popliteal cyst is a distend bursa or herniation of
synovial membrane through the posterior part of capsule
of the knee or escape of fluid through normal
communication of bursa with the knee. It is filled with
synovial inside the knee joint. (semimembranosus or
medial gastrocnemius bursa)
 most common in children aged 4 to 7 years and in
adults aged 35 to 70 years.
 more common in adults than in children.

5. Causes of a Baker's cyst
• A primary Baker's cyst  idiopathic Baker's cyst. It
usually develops in younger people and children.
• A secondary Baker's cyst  most common type.
Develop if there is underlying problem within the
knee, such as arthritis (osteoarthritis and rheumatoid
arthritis), or a tear in the meniscal cartilage that lines
the inside of the knee joint. or an infection within the
knee joint.

6. Symptoms
 Some people do not have any symptoms.
 Symptoms can include pain, swelling and tightness
behind the knee especially when standing up.
 Larger the Baker's cyst, the more likely it is to produce
symptoms
 symptoms related to underlying knee problem such as
arthritis  ‘knee pain’
 Less commonly, you may feel a sensation of clicking or
locking of your knee.

7. Physical Examination
 The popliteal fossa (area behind the knee) may be
swollen
 Translumination test :: Positive
 If the lump grows quickly or have night pain ,severe
pain ,fever need more test to make sure other type
of tumors

8. Differencial diagnosis
 Thrombophlebitis ,thrombosis
 Benign soft tissue tumor
peripheral nerve sheath tumor (neurolemmoma)
 Lopoma , malignancy , vascular mass

9. Ultrasound scan
good investigation to show a Baker's cyst
and to help to exclude a DVT

10. MRI SCAN
used to confirm the diagnosis.
Appears as a high signal intensity
homogenous cystic mass

11. Arthroscopy

12. Management
• No specific treatment is needed.
• Treatment of any underlying knee problem
• Treatment to help relieve symptoms
 Support stockings NSAIDs
 Physiotherapy  ICE
 Fluid drainage  Crutches
 Cortisone (steroid) injection
 Surgery

13. Complications
 Rupture (split open).
 Deep vein thrombosis even if the cyst does not
rupture.
 Infected.
 Posterior compartment syndrome
 Common peroneal nerve and tibial nerve
compression

14. Home care
R.I.C.E
- R est your leg
- I ce the inflamed area
- C ompress your knee
- E levate your leg ,especially at night