A Baker’s cyst is a build up of fluid at the back of the knee.
These cysts may cause pain and pressure effect. They may limit knee bend if they are particularly large. Occasionally they may burst and cause pain and swelling in the calf; this can be confused with a blood clot (deep vein thrombosis or DVT)
The most common causes are osteoarthritis and degenerative cartilage tears within the knee. Other causes include knee injury, inflammatory arthritis such as rheumatoid arthritis or gout.
This is normally made by examination alone although MRI is very often used to confirm the diagnosis and the possible cause.
If you have a Baker’s cyst that isn’t causing any symptoms, treatment will not normally be required.
If the cyst is symptomatic, over-the-counter painkillers and anti-inflammatories will help alleviate pain and swelling. A compression bandage or an ice pack should also help. Take care not to place ice directly on the skin as it can cause a burn. Instead, wrap the ice (or bag of peas) in a tea towel.
It is important to identify and treat any underlying cause such as rheumatoid arthritis.
Surgery is very occasionally required to drain or remove the cyst.