When people think of knee pain, they often imagine arthritis, ligament strains, or cartilage injuries. But there’s one cause of swelling and stiffness that tends to fly under the radar — even though it can have a big impact on everyday comfort and mobility.
That’s the Baker’s cyst.
What is a Baker’s Cyst?
A cyst is a pocket or sac of fluid that can develop in different parts of the body. A Baker’s cyst is one that develops behind the knee, sometimes causing swelling, pain and stiffness.
What Causes Baker’s Cysts?
Baker’s cysts usually develop because of another issue within the knee joint- when the knee is irritated, it can produce extra joint fluid which sometimes forms a cyst. Some common causes include:
- Injury to the knee e.g. meniscus or ligament tears
- Arthritis
- Infection
- Unknown reasons, where no clear cause is found
Signs and Symptoms
Symptoms vary depending on the size of the cyst and how irritated the knee is. Common signs include:
- A feeling of tightness, discomfort, or pain behind the knee
- Swelling or a noticeable lump at the back of the knee
- Pain that increases with activity
- Reduced ability to fully bend or straighten the knee
In some cases, a Baker’s cyst can burst, causing sudden pain and swelling in the calf. This can sometimes feel similar to a blood clot, so it’s important to have it checked if that happens.
Diagnosis is usually made through a physical examination and confirmed with an ultrasound or MRI if needed.
Treatment
Treatment depends on how severe the cyst is and what is causing it.
For mild cases, management may include:
- Rest and avoiding activities that make it worse
- Adjusting activity levels
- Taking anti-inflammatory medication (if recommended by your doctor)
- Physiotherapy and exercises to strengthen and support the knee
Because Baker’s cysts usually develop due to another knee problem, it’s important to treat the underlying cause for the best long-term results.
If symptoms don’t improve or become more severe, further options may include:
- Corticosteroid injections to help reduce inflammation
- Draining the cyst (aspiration)
- Surgery
Summary
A Baker’s cyst is one cause of pain, swelling and discomfort behind the knee. Most cases improve with simple treatment like rest, exercise, and managing the underlying cause. If you have ongoing swelling or pain behind the knee, speak with your physiotherapist or doctor for a proper assessment and tailored advice.
