What is the Baker's Cyst?

A Baker's cyst is a soft, localized accumulation of synovial fluid on the back of the knee. These cysts occur most often when the knee is damaged due to arthritis, gout, an injury, or from inflammation of the joint lining. Baker’s cyst produce discomfort on behind the knee, it may enlarge and extend downward into the calf muscles.

Causes

A baker’s cyst forms when the joint lining produces too much joint fluid. The extra fluid leaks or pushes through the joint lining and forms a cyst.
Baker’s cyst come from many condition including:

• Arthritis / Osteoarthritis (most common type associated with Baker’s cyst)
• Injury or accidents
• Joint effusion
• Cartilage tears

 

Symptoms

The symptoms caused by a baker’s cyst are one or more of the following. Aching or tenderness, especially when moving the knees, with exercise the knee may give way. You may also see or feel a bulge on the back of your knee. The cyst may swell with increased activity and shrink with rest.

 

Diagnosis

You doctor during a physical exam will look for a soft mass in the back of the knee. The following tests and procedures may be done:

 

• Trans-illumination-shining a light through the cyst to show the mass is fluid-filled
• Ultrasound and CT scan
• MRI, This can be helpful to visualize the cyst and show any meniscal injury
• X-ray. The Baker’s cyst will not appear on X-ray but it will show arthritis or other knee abnormalities

 

Treatment

In adults, often no treatment is necessary (unless they are symptomatic), since many baker’s cysts resolve on their own within a two-year period. The following treatment option is available but you may talk to your doctor about the best treatment plan for you,

 

• Resting and elevating the leg
• Draining excess knee fluid
• Anti-inflammatory drugs to relieve pain and inflammation
• Physical therapy
• Pain medications
• Joint injection with steroids
• Needle aspiration
• Wearing an elastic bandage
• For large cysts surgery is required to remove cysts and to repair tears in the meniscus

Written by Medpages Editorial Team
Last Editorial Review: 18/1/2010