Baker's cyst causes

A Baker’s cyst is caused by swelling in the knee. The swelling is due to an increase in synovial fluid – the fluid that lubricates the knee joint. When pressure builds up, fluid bulges into the back of the knee.

Baker’s cyst commonly occurs with:

• A tear in the meniscal cartilage of the knee
• Knee arthritis (in older adults)
• Rheumatoid arthritis
• Other knee problems