Baker's cyst

A few months ago I had this patient who consulted me over a swelling at the back of his right knee which he felt was growing bigger.

Having felt the swelling I suspected that it was a popliteal cyst.

To exclude any other possible causes such as tumors or meniscus cyst, I advised him to have an x-ray of his knee.

The x-ray did not show any abnormal tumor or extra calcification in the tendon or ligaments of the knee joint.

I decided to use a large syringe to drain the fluid with the consent of the patient to see whether I will be able to resolve the problem by aspiration of the cyst.

To prevent the fluid from returning to the cyst I had it fairly tightly bandaged and told him to release it if it is too tight but not to remove it.

2 weeks later he came back and told me that the swelling had recurred after he removed the bandage after 2 days.

So it was back to the aspiration again of the cyst and bandaging of the aspirated joint.

This time he did follow my instruction not to release the bandage.

When I saw him 2 more weeks later, the swelling had subsided.

I bandaged it again for another 2 weeks.

This time after 2 more weeks the bandage was removed and since then the swelling did not recur.

I was happy, so was the patient.

He had expected me to send him for a surgery if it did not improve.

Luckily for him he was well and did not require any surgery.

What is a Baker's cyst?

Baker's cyst is a medical condition in which the collection of joint fluid (synovial fluid) develops a swelling behind the knee.

A Baker's cyst (called a popliteal cyst) is a soft swelling sited in the popliteal space.

The term Baker's cyst is not a true cyst because the swelling is the result of synovial fluid distending the gastrocnemio-semimembranosus bursa.

In older patients it is frequently part of a chronic knee joint effusion which herniates between the two heads of the gastrocnemius and is most frequently secondary to degenerative or meniscal pathology.

1. Primary cysts have not been found to join directly with the knee joint.

These cysts normally happen in young people and do not have symptoms.

2. Secondary cysts communicate freely with the knee joint and contain fluid of normal viscosity.

They are believed to be caused by a combination of weakness around the knee, internal pathology and valvular opening between the knee joint and bursa.

These forms of cysts happen in older people, frequently produce symptoms and are linked with underlying articular diseases.

Secondary cysts are more frequent than primary cysts.

What are the causes of Baker's cyst?

Causes

A Baker's cyst is produced by swelling in the knee.

The swelling is produced by a higher volume in the fluid that produces lubrication of the knee joint (synovial fluid).

When the pressure builds up, fluid pushes into the back of the knee.

Knee damage produced by a sports-related injury or a blow to the knee can result in a Baker's cyst developing.

In adults, the cause of Baker's cyst may be linked to an inflammatory process, meniscal tears or mechanical intra-articular abnormalities of the knee joint.

Baker's cyst frequently happens with:

1. A tear in the meniscal cartilage of the knee

2. Osteoarthritis normally caused by age-related "wear and tear" of joints.

It especially involves the knees, hips, hands and big toe.

3. Inflammatory arthritis such as rheumatoid arthritis which is a less frequent form of arthritis and is produced by the immune system attacking the...