Popliteal Cysts: A Current Review

Abstract

Baker's cyst, or popliteal cyst, is a fluid-filled mass that is a distention of a preexisting bursa in the popliteal fossa, most commonly the gastrocnemio-semimembranosus bursa. This bursa is unique in that it communicates with the knee joint, unlike other periarticular bursae, via an opening in the joint capsule posterior to the medial femoral condyle. Many have theorized that this opening creates a valve-like mechanism in the presence of effusion that contributes to the formation of these cysts in adults. Popliteal cysts rarely manifest alone and are most often found in conjunction with other intra-articular pathologies and inflammatory conditions, such as osteoarthritis, meniscus tears, and rheumatoid arthritis. In children, popliteal cysts are only occasionally associated with these conditions and are more often an incidental finding discovered during a routine physical examination. Popliteal cysts may present as either a chronically persistent or relapsing condition or as an acute and dramatic condition that can occur in the case of cyst rupture presenting as pseudothrombophlebitis. Ultrasound and magnetic resonance imaging have proven to be consistent and accurate in the confirmation of popliteal cysts, with magnetic resonance imaging becoming the modern imaging modality of choice. This review discusses the anatomy and etiology of popliteal cysts, describes the common clinical presentations, reviews the differential diagnoses, and provides guidance for proper diagnostic imaging. It also provides a comparison of current conservative, minimally invasive, and invasive treatment options, along with a discussion of results. Postoperative rehabilitation depends largely on the condition associated with the popliteal cyst.

Ultrasound of knee osteoarthritis: interobserver agreement and correlation with Western Ontario and McMaster Universities Osteoarthritis

“…Presence of hypertrophied synovium in patients with osteoarthritis is sign of disease activity [32,33]. Popliteal cyst is often simple and may be containing linear bands or debris [34]. Ultrasound is sensitive method for detection of meniscal extrusion in knee osteoarthritis [35].…”

Arthroscopic patterns of the poster-medial aspect of the knee joint: classification of the gastrocnemius-semimembranosus gateway and its relationship with Baker’s cyst

“…The treatment of symptomatic BC can be conservative or surgical 34 . The conservative treatment is sustained by few Authors which report good success rate but those results are probably not accepted by the most of the Authors who prefer surgical approach; infiltrative therapy could be more effective when intrarticular disease is at an early stage 35 .…”

“…It was described in 1877 by Baker as a distention of the popliteal bursa 4 . The BC is located in a specific area between the Oblique Popliteal Ligament (OPL) reinforced by an expansion of the semimembranosus tendon and the medial tendon of the gastrocnemius 5 . When such a communication exists, knee joint effusions may replete the gastrocnemius-semimembranosus bursa (GSB) with synovial fluid and if the fluid outflow is hindered by an unidirectional valve-like mechanism, the GSB enlarges, giving rise to a pseudocystic cavity referred to as Baker's cyst 1 .…”

Musculotendinous Disorders in the Lower Leg

“…Popliteal cyst rupture typically presents with acute calf pain and swelling. 42,43 Rarely, a compartment syndrome may result. 44,45 In a retrospective review of patients presenting to a hospital vascular surgery department with leg swelling, who underwent US, a ruptured popliteal cyst was identified in 2.4% of affected limbs.…”