Popliteal cysts in adults: A review*,**
Section snippets
Epidemiology
The presence of popliteal cysts varies depending on the technique of investigation and the studied population. Of 400 consecutive magnetic resonance imaging (MRI) studies from patients referred for knee problems to an orthopedic clinic, 77 (19%) popliteal cysts were found (4). Of 1,113 MRI studies (5) of knees evaluated for internal derangement, 55 (5%) had cysts. Using arthrography (6) to find internal derangement, 58 of 247 (23%) knees from military aircrews and 64 of 202 (32%) knees from a
Clinical presentation
The usual patient complaints resulting from popliteal cysts are swelling, a mass, pain, or stiffness, often aggravated by activity. There may be a bulge and tightness in the back of the knee on walking (2) or vague posterior knee pain (1). A mass was the chief concern in 68 of 82 patients with surgically treated cysts (3). Forty-six of the 82 had local “aching” and 13 were stiff. Nine of the 82 had knee swelling; 7 of these 9 had no recognized joint pathology. One third of the 82 had no
Pathogenesis
The pathogenesis of popliteal cysts is explained by the interconnection between the knee joint and the bursae, as well as fluid mechanics. Such a connection was found in 30% to 50% of cadaveric dissections 1, 21, 22, 23, 55% of surgically proven cysts (7), 37% of arthroscopically examined knees (24), and in 50% of arthrograms of normal knees (25). By injecting dye into the knee joint as well as directly into the cysts, a valvelike mechanism has been shown (26). During flexion the communication
Cysts: Pathologic or physiologic?
The presence of G-S bursal filling, even large distentions, does not necessarily indicate disease (25). Arthrographically, clinically evident cysts are no different than nonclinically appearing (6). Of 940 arthrograms for suspected meniscal tears, 234 cysts were found of which 179 were asymptomatic (32). The author believed these were normal variations of the G-S bursa. Of 62 patients with cysts shown by arthrography, 56% had no palpable mass and only 35% had popliteal fossa pain (17). The 10
Imaging
Figures 1 to 3 show some arthrogram characteristics of popliteal cysts.
Associated conditions and differential diagnosis
Knee pathology associated with popliteal cysts includes OA, RA, and torn meniscus, with rarer associations including tuberculosis, Charcot joint, pigmented villonodular synovitis, Reiter's syndrome, gonococcal arthritis, and Still's disease (2). Medial meniscal posterior horn lesions may cause cysts by producing synovitis 49, 69. The differential diagnosis of popliteal cysts 2, 48 includes popliteal artery aneurysm, venous thrombosis, lipoma, liposarcoma, popliteal varices, hematoma, ganglionic
Complications: Pseudothrombophlebitis
The imperative consideration in the differential diagnosis is to distinguish DVT from ruptured popliteal cyst 17, 71, 72, 73, 74. Missed thrombophlebitis risks pulmonary embolism, and anticoagulants, given for a dissecting cyst falsely diagnosed as thrombophlebitis and perhaps requiring hospitalization, may cause cyst hemorrhage with prolonged convalescence (75).
The enlarged cyst, compressing an adjacent vein, may cause lower leg and ankle swelling, mimicking venous thrombosis (71).
Cyst complications
Dissecting cysts are more common than ruptured cysts (17). Crescentic violaceous discoloration inferior to the malleolus, not seen in venous thrombosis, is occasionally present in cyst rupture, as the bloody synovial fluid dissects inferiorly and is strong evidence against thrombosis (83), although the ecchymosis may be on the dorsum of the foot (84). A hemorrhagic ruptured cyst produces an ecchymosis of the posterior calf from the popliteal fossa to the ankle (85). Arthrographically, a
Treatment
Asymptomatic popliteal cysts found incidentally need no treatment. Symptoms may require bed rest, although no details of bed rest (eg, duration, frequency, or benefit) could be found in the literature. If knee effusion is present, joint aspiration with intra-articular corticosteroids usually is beneficial. If necessary, contrast dye can be instilled into the joint through the same needle (2). There are numerous descriptions of rapid improvement of popliteal cysts, with or without calf
References (96)
Popliteal cysts: variations on a theme of Baker
Semin Arthritis Rheum
(1982)- et al.
Prospective study of thrombophlebitis and “pseudothrombophlebitis.”
Lancet
(1980) - et al.
Acute synovial rupture in rheumatoid arthritis
Lancet
(1964) - et al.
Ultrasonography of the knee
Radiol Clin North Am
(1988) - et al.
Ultrasonography of the popliteal fossa and lower extremities
Radiol Clin North Am
(1988) - et al.
Baker's cysts mimicking the symptoms of deep vein thrombosis: diagnosis with venous duplex scanning
J Vasc Surg
(1997) CT of swollen legs
Clin Radiol
(1990)- et al.
Popliteal artery stenosis caused by a Baker's cyst
J Vasc Surg
(1986) - et al.
Baker's cyst simulating deep vein thrombosis
Clin Radiol
(1990) - et al.
The pseudothrombophlebitis syndrome: a reappraisal
Semin Arthritis Rheum
(1981)
Posterior tibial neuropathy from ruptured Baker's cyst
Semin Arthritis Rheum
A clinical and anatomical study of the semimembranosus bursa in relation to popliteal cyst
J Bone Joint Surg
Popliteal cyst: a clinicopathologic study
J Bone Joint Surg
MR imaging of Baker cysts: association with internal derangement, effusion, and degenerative arthropathy
Radiology
Popliteal cysts: a reassessment using magnetic resonance imaging
Skeletal Radiol
Popliteal cysts
J Bone Joint Surg
Popliteal cysts in adults and children
Arch Surg
Gastrocnemio-semimembranosus bursa and its relation to the knee joint
Acta Radiol
Double-contrast arthrography of the knee
J Bone Joint Surg
Popliteal cysts and synovial rupture in osteoarthrosis
Rheumatol Rehab
Popliteal cyst rupture in normal knee joints
Br Med J
Ultrasound evaluation of popliteal cysts in osteoarthritis of the knee
J Rheum
Popliteal cysts (Baker's cysts) in adults 1. Clinical and roentgenological results of operative excision
Acta Orthop Scand
Foucher's sign of the Baker's cyst
Ann Rheum Dis
Lateral presentation of a Baker's cyst
Clin Orthop
Ultrasound evaluation of the popliteal space
Mayo Clin Proc
The pseudothrombophlebitis syndrome
Medicine
Baker's cyst in rheumatoid arthritis: an ultrasonographic study with a high resolution technique
Clin Exp Rheumatol
Ethanol injection sclerotherapy for Baker's cyst, thyroglossal duct cyst, and branchial cleft cyst
Ann Plast Surg
Gastrocnemio-semimembranosus bursal region of the knee
AJR Am J Roentgenol
A valve: an explanation of the formation of popliteal cysts
Ann Rheum Dis
Anatomy and function of the communication between knee joint and popliteal bursae
Ann Rheum Dis
The popliteal bursa (Baker's cyst): an arthroscopic perspective and the epidemiology
Arthroscopy
Baker's cyst and the normal gastrocnemio-semimembranosus bursa
Am J Roetgenol
Radiographic investigation of popliteal cysts
Acta Radiol Diag
Gastrocnemio-semimembranosus bursa and its relation to the knee joint
Acta Radiol Diag
Intraarticular pressure during continuous passive motion of the human knee
J Orthop Res
Joint fluid pressure in chronic knee effusions
Ann Rheum Dis
Valvular mechanisms in juxta-articular cysts
Ann Rheum Dis
Asymptomatic popliteal cysts
J Am Osteopath Assoc
Diagnosis of popliteal cyst: double-contrast arthrography and sonography
Am J Roentgenol
Arthrography, tenography and bursography.
Case report 731
Skeletal Radiol
Ultrasonography in the study of prevalence and clinical evolution of popliteal cysts in children with knee effusions
J Rheumatol
Ultrasound diagnosis of Baker cyst
JAMA
Sonomorphologic variants of popliteal cysts
J Clin Ultrasound
Diagnostic ultrasound.
Diagnosis of Baker cyst
JAMA
Cited by (126)
Radiographic techniques for imaging knee joint
2023, Cartilage Tissue and Knee Joint Biomechanics: Fundamentals, Characterization and ModellingPopliteal Vein Aneurysm Masquerading as a Baker's Cyst Leading to Pulmonary Embolism
2021, American Journal of MedicineHip and Knee Injuries
2020, Primary Care - Clinics in Office PracticeExtra-articular endoscopic excision of symptomatic popliteal cyst with failed initial conservative treatment: A novel technique
2019, Orthopaedics and Traumatology: Surgery and ResearchClinical neurophysiology of lower extremity focal neuropathies
2019, Handbook of Clinical NeurologyBaker Cyst
2018, Essentials of Physical Medicine and Rehabilitation: Musculoskeletal Disorders, Pain, and Rehabilitation
- *
Address reprint requests to John R. Handy, MD, 2916 Sussex Rd, Augusta, GA 30909.
- **
John R. Handy, MD: Associate Clinical Professor of Medicine, Division of Rheumatology, Department of Medicine, Medical College of Georgia, Augusta, GA.