A Baker's cyst is a buildup of joint fluid behind the knee. It creates a tight bump behind your knee.
Joint fluid helps the knee move smoothly. A Baker's cyst develops when there is too much of this fluid. The extra joint fluid is pushed out to the back of the knee. Extra fluid may be caused by:
- Arthritis—osteoarthritis is the most common type associated with Baker's cysts
- Cartilage tears, such as a torn meniscus
- Injury or accidents
- Infection in joint
In children, Baker's cyst may be related to a problem with the bursa. The bursa is a small fluid filled sac between the bone and soft tissue.
Copyright © Nucleus Medical Media, Inc.
Last reviewedDecember 2014by Michael Woods, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.