Baker's Cysts and Psoriatic Arthritis

Psoriatic arthritis (PsA) can sometimes trigger another painful condition called a Baker's cyst. A Baker's cyst (popliteal or synovial cyst) is a fluid-filled lump that develops behind your knee. It causes an ache that worsens when you are doing anything that requires you to extend your knee.¹

Why do Baker's cysts form?

Baker's cysts can occur after the knee joint has been damaged and has become swollen. Causes of this damage can include:²

• Gout
• Ligament or cartilage tear
• Arthritis (rheumatoid or osteoarthritis)
• Other source of inflammation

Arthritis or injury can cause the knee to make too much of a thick, bone-cushioning liquid called synovial fluid. This buildup of fluid is what causes a Baker's cyst.²

What is the link between Baker's cysts and PsA?

PsA is a persistent inflammatory infection that occurs in people with psoriasis. PsA attacks joints and places where ligaments and tendons join to the bones in your body, such as the knees. The condition may appear at any age, including in childhood. It usually affects people ages 30 to 50, around 10 years after they developed psoriasis.³

If you have an existing issue with your knee, like PsA, you are more likely to develop a Baker's cyst than people who do not. Osteoarthritis and rheumatoid arthritis also are often linked to Baker's cysts.⁴

What are the symptoms of a Baker's cyst in people with PsA?

A Baker's cyst may show up in the following ways:¹

• Pain
• Restricted movement of the knee
• Swelling
• Knee stiffness
• A fluid-filled sac behind the knee

If you have been physically active, you may notice that your symptoms get worse.

How do doctors diagnose Baker's cysts?

Your doctor will start by learning more about your medical history, including any past injuries to your knee. They can also figure out whether you have a Baker's cyst by running tests, including:²

• Ultrasound. An ultrasound uses sound waves to discover if the sac is filled with fluid or solid.
• MRI. A magnetic resonance imaging (MRI) scan gives your doctor insight into what may be causing your Baker's cyst. MRI uses magnetic waves to make 3D images of organs and tissues.
• X-ray. This test will help find out if there is arthritis in your knee, since it is one of the possible causes of a Baker's cyst.

How is a Baker's cyst treated?

Doctors treat Baker's cysts with both non-surgical and surgical treatments. Nonsurgical treatments recommended for Baker's cyst include:²

• Using compression wraps around the knee
• Icing the knee
• Resting and elevating the knee
• Using a cane or crutch for support
• Keeping a healthy body weight so that there is less weight on the joints
• Doing only low-impact activities
• Taking ibuprofen or other anti-inflammatory medicine

Your doctor may recommend surgery only if you have a severe Baker's cyst. It is reserved mainly for people with unbearable knee pain and restricted range of motion.