Ultrasound in synovial cyst of popliteal space (Baker cyst) diagnosis (pictorial review)
Baker cysts are the most common pathological finding in posterior knee ultrasound. The aspects of etiology, epidemiology, pathogenesis, clinical presentation, and treatment of Baker cysts are discussed in the literature review, with particular attention paid to the diagnosis. Baker cyst has a very variable ultrasound appearance. It is necessary to assess at longitudinal and transverse planes the contours of cyst’s walls (regularity, continuity, dissection, rupture), walls structure (the presence of synovial hypertrophy with villi thickening or parietal growths, septations), presence of intraarticular bodies (chondral, osteochondral, calcifications). Color Doppler imaging may be used to assess vascularity. Possible complications of long-existing Baker cysts include dissection of inferior part of the cyst capsule, without complete rupture; rupture of the cyst capsule in the inferior part with fluid outflow to the interfacial (intermuscular) space of the posterior calf and subcutaneous fat of the calf.