Causes of Ganglion Cysts
Ganglion cysts arise from mucoid degeneration of connective tissue associated with joint capsules, tendon sheaths, ligaments, and menisci, though the exact mechanism remains incompletely understood. 1, 2
Primary Pathophysiologic Mechanism
The most widely accepted theory holds that extra-articular mucin "droplets" coalesce to form the main cyst body, with the cyst wall and pedicle (connecting stalk to the joint) forming only subsequently. 3 These cysts lack a true synovial epithelial lining, distinguishing them from true synovial cysts. 1
Contributing Factors
The mucoid degeneration process appears triggered by several mechanisms:
- Chronic repetitive injury and mechanical irritation of the connective tissue structures 1
- Chronic ischemia to the affected tissue 1
- Trauma history is present in some patients, though many cases occur without identifiable injury 4, 5
- Flaws or defects in joint tissues may predispose to cyst formation 4
Anatomic Origins
Ganglion cysts can develop from multiple structures throughout the body:
- Joint capsules (most common origin) 2, 3
- Tendon sheaths 1, 2
- Ligaments (including the anterior and posterior cruciate ligaments) 6, 5
- Menisci 1
- Bursae (such as the semimembranosus-gastrocnemius bursa) 2
Common Pitfalls
Do not confuse ganglion cysts with Baker's cysts, particularly around the knee—ganglion cysts require different treatment approaches and do not respond to measures used for Baker's cysts, such as addressing underlying meniscal pathology. 2 The key distinguishing feature is that ganglion cysts have a thin fibrous wall without epithelial lining on histologic examination. 2
Post-arthroscopic ganglion cysts can develop in portal regions following knee arthroscopy, representing a specific subset where surgical trauma may contribute to cyst formation. 4