Popliteal cysts in adults: a review

Area of Science:

• Orthopedic Surgery
• Radiology
• Rheumatology

Background:

• Popliteal cysts, also known as Baker's cysts, are fluid collections in the popliteal fossa.
• They are associated with intra-articular knee pathology, especially in older adults.
• Their pathogenesis involves abnormal communication between the knee joint and the gastrocnemio-semimembranosus bursa.

Purpose of the Study:

• To comprehensively review the epidemiology, clinical presentation, pathogenesis, diagnostic imaging, differential diagnoses, complications, and treatment of popliteal cysts.
• To highlight the diagnostic utility of various imaging modalities, with a focus on sonography.
• To outline current management strategies for symptomatic and asymptomatic popliteal cysts.

Main Methods:

• A literature review of MEDLINE database from 1985 to 1998 was conducted.
• Search terms included "Popliteal Cyst" with subheadings for relevant imaging techniques.
• Pertinent references were included, excluding studies focused on pediatric cases.

Main Results:

• Popliteal cysts occur in 5% to 32% of knee problems, with bimodal age incidence peaks (4-7 years and 35-70 years).
• Physical examination misses approximately half of these cysts; imaging is essential for detection.
• Sonography is the preferred imaging modality; complicated cysts can mimic phlebitis.
• Most symptomatic cysts respond to intra-articular corticosteroid injections; surgical excision is rarely required.

Conclusions:

• Popliteal cysts are relatively common but frequently undiagnosed on physical examination.
• Imaging, especially sonography, is crucial for accurate diagnosis.
• Treatment is typically conservative, involving intra-articular injections, with surgery reserved for refractory cases.