How to Diagnose Popliteal Cyst

A popliteal cyst, also known as a Baker cyst, is a sac lined with a synovium and filled with synovial fluid. It the most common mass in the popliteal space. A popliteal cyst is formed when synovial fluid escapes from a knee joint or bursa. A popliteal cyst may protect the knee by absorbing pressure caused by intra-articular disorders. The following steps will show how to diagnose a popliteal cyst.

Instructions

1. Look for conditions associated with popliteal cysts. Arthritis is the most common cause of popliteal cysts, especially osteoarthritis. The occurrences of these cysts are directly related to the severity of osteoarthritis and the presence of knee effusion. Inflammatory arthritis is much less common but has the highest prevalence of popliteal cysts.

2. Perform a plain radiography to eliminate the possibilities of a displaced atherosclerotic artery, internal calcifications or a soft tissue mass. A radiograph also may be needed to identify bony involvement from a large older cyst in rare cases.

3. Run an ultrasound scan as the fastest and most cost-effective method of diagnosing a popliteal cyst. A simple popliteal cyst does not return echoes because it is filled with fluid and has a sharply defined posterior wall.

4. Review the ultrasound for signs of less typical popliteal cysts. A complex cyst may have internal echoes and may contain calcified loose bodies with a mobile echogenic appearance similar to cholelithiasis in a gall bladder.

5. Use the ultrasound results to exclude a deep venous thrombosis.