A Baker’s cyst is a swelling filled with joint fluid behind the knee. In adults, it often develops in association with irritation inside the knee joint. Identifying the underlying cause is therefore more important than the swelling alone.
A suddenly painful, swollen calf requires urgent assessment to exclude a blood clot. Additional breathlessness or chest pain requires immediate emergency help.
Causes and risk factors
Osteoarthritis, inflammatory joint conditions or meniscal changes can increase joint fluid. This collects through a connection behind the knee. Not every cyst causes symptoms.
Typical symptoms
A feeling of tightness, a palpable swelling and restricted bending may occur. If a cyst ruptures, fluid and pain can extend into the calf. This can resemble a blood clot and must be distinguished medically.
Diagnosis
The examination assesses the knee, the back of the knee and the lower leg. Ultrasound can show the fluid collection. The underlying knee condition is investigated further when necessary; MRI is not required in every case.
Non-surgical treatment
Cysts causing few symptoms can be monitored. Treatment focuses on the joint irritation and an appropriate exercise programme. Aspiration or injection is considered individually; the cyst may recur.
Surgical options
Surgical removal is rarely necessary. If surgery is considered, the cause, recurrent symptoms and risks behind the knee must be taken into account. A meniscal finding does not automatically need treatment because a cyst is present.
Aftercare and rehabilitation
Activity and knee bending are adjusted to pain and swelling. Follow-up also assesses the underlying joint problem. Recurrent swelling should not be assumed to have the same harmless explanation without examination.
Common questions
Is a Baker’s cyst a tumour?
A typical Baker’s cyst contains joint fluid. Nevertheless, a new swelling should be examined rather than self-diagnosed.
Does the cyst need to be removed?
Usually not. Treatment often focuses on the underlying cause within the knee.
Arrange a consultation
We discuss which treatment is suitable for your findings and which procedures are available within our outpatient service during a personal consultation. Outpatient operations take place at an external surgical centre.
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Further reading
Selected external resources about this condition. Some linked publications are in German.
Medical background
Sources & further information
These professional and patient resources provide further information about this condition. The text on this page is independently written.
AAOS: Baker’s cyst