Popliteal cysts in adults: a review

OBJECTIVE: To review the epidemiology, clinical presentation, pathogenesis, imaging, differential diagnosis, complications, and treatment of popliteal cysts. METHODS: References were taken from MEDLINE from 1985 to 1998 under the subject "Popliteal Cyst" with subheadings of Radiography, Ultrasonography, and Radionuclide Imaging. Other pertinent references were used. Childhood cysts were excluded. RESULTS: Depending on the studied population and the imaging technique, 5% to 32% of knee problems may have these cysts, with 2 age-incidence peaks of 4 to 7 years and 35 to 70 years. In older patients there is usually coexistent joint pathology. Symptoms may arise in the popliteal fossa from the cyst itself or be dominated by knee pain from coexisting knee pathology. Many cysts are asymptomatic. Physical examination will miss one half of these cysts. Pathogenesis depends on the connection between the joint and bursa, with a valvelike effect allowing passage of fluid from the joint into the bursa with subsequent distention producing these cysts. Some bursae have no such joint-bursal communication, and the cysts arise primarily as bursitis of the gastrocnemio-semimembranosus bursa. Imaging is performed by plain x-ray, ultrasound, arthrography, computerized axial tomography, magnetic resonance imaging, or nuclear scan; sonography is the method of choice. Complicated cysts with extension or rupture into the calf mimic phlebitis, an important differential diagnosis. Asymptomatic cysts found incidentally need no treatment; most symptomatic cysts respond to intra-articular corticosteroid injections. Surgical excision is rarely necessary. CONCLUSIONS AND RELEVANCE: Popliteal cysts are fairly common, may not be found on physical examination, require imaging (preferably sonography) to be identified, mimic phlebitis when extending into the calf, and often respond to intra-articular steroid or, rarely, surgical resection.     

Anterolateral rupture of popliteal cysts in rheumatoid arthritis.

Popliteal cysts occur commonly in both normal and arthritic knees. Most cysts are formed by distension of the medially situated semimembranosus bursa. Popliteus bursa distension occurs uncommonly as a lateral popliteal cyst. Two cases of rupture of lateral cysts which produced symptoms related to the anterolateral lower leg are reported. The difficulty of diagnosing the condition because of this unusual site of inflammation and subsequent management problems are discussed.     

Popliteal cyst rupture and the pseudothrombophlebitis syndrome

Fifteen patients presented during a four-year period with a pseudothrombophlebitis syndrome, subsequently confirmed arthrographically as being due to popliteal cyst rupture. Initially the majority of patients (73%) were erroneously diagnosed as having calf vein thrombosis, and were anticoagulated for periods of three to ten days. Clinical differentiation from venous thrombosis was usually impossible. Contrast arthrography was the definitive diagnostic investigation, revealing popliteal cysts in all patients, and an active synovial leak into the calf in 13 cases (87%). The mean delay in performing arthrography was 5.3 days, the procedure usually being performed after normal contrast venography. Doppler and isotope venography yielded misleading or equivocal results (42%) delaying diagnosis, and prolonging periods of potentially dangerous anticoagulation. We suggest that the marked overlap in the emergency presentation of popliteal cyst rupture and calf vein thrombosis mandates the aggressive use of arthrography combined with venography in all patients presenting with a painful swollen leg.     

Some historical notes on popliteal cysts

Popliteal cysts, more appropriately those involving the gastrocnemio-semimembranous bursa, are traditionally known as "Baker's cysts", since in 1877 the English surgeon William Morrant Baker published a paper on this topic ("On the formation of synovial cysts in the leg in connection with disease of the knee-joint"). As a matter of facts, some authors described popliteal cysts before Baker. In particular, in 1856 a French physician, E.Foucher, performed a clinical and experimental study on 18 patients, focusing on some important aspects on the semeiology and pathophysiology of popliteal cysts. In 1861, Pietro Antivari, a physician from Friuli, a northeastern region of Italy, graduated at the University of Padova by producing an interesting paper on the popliteal cysts ("Dell'idrope delle borse mucose poplitee con tre osservazioni"). In the present historical note we report in full one out of three cases described by Pietro Antivari.     

Anterior tibial compartment syndrome following rupture of a popliteal cyst

 A ruptured popliteal cyst usually results in calf pain and swelling. We report the case of a patient with rheumatoid arthritis who developed anterior compartment syndrome of the leg following rupture of a popliteal cyst. Since acute compartment syndrome requires prompt treatment, clinicians should be aware of this rare complication. Received: May 17, 2002 / Accepted: August 9, 2002     

The pathology and evaluation of surgical treatment in a ruptured giant popliteal/crural cyst associated with rheumatoid arthritis

Abstract

Popliteal cysts are often observed in patients with rheumatoid arthritis (RA), and giant cysts that extend from the popliteal to the crural region (popliteal/crural cysts) are occasionally encountered. We studied the background of popliteal/crural cysts and therapeutic results, and evaluated its etiologic factors and the effectiveness of surgical treatment. Nine knees of eight patients with popliteal/crural cyst secondary to RA, which was treated surgically because it resisted conservative treatment, and was followed up for 1 year or longer after surgery, were evaluated. The patients were five men and three women, with a mean age at surgery of 59.1 years and a mean duration of RA disease of 4.5 years. Only one male patient suffered pain in the bilateral joints. The mean level of erythrocyte sedimentation rate was 61.3?mm/h (range 3.9–100.2), the mean level of C-reactive protein was 3.6 (0.1–8.2) mg/dl, and the mean Lansbury index was 36.4 (12–61) at surgery. The cyst disappeared completely after surgery, and the postoperative course was uneventful in eight knees, but recurrence was observed in just one knee of the bilateral case. However, in this patient the cyst that recurred was not as large as the one before surgery, and it was eventually brought under control by subsequent outpatient medical management. Inflammatory reactions were suppressed, if temporarily, in all patients. The patients evaluated in this study showed the following characteristics: the male–female ratio of the patients was biased to males compared with that of RA patients in general; although knee joint damage was radiographically mild, marked symptoms of arthritis were observed in not only the knees but also other joints in all patients; and the disease could not be controlled effectively by medication. However, after surgical resection of the cysts, general as well as local signs of inflammation were mitigated, and surgery was considered to be very effective for the treatment of ruptured giant popliteal/crural cyst associated with RA.     

Non-invasive quantification of popliteal cyst volumes by three-dimensional ultrasonography

SIR, Popliteal cyst (Baker's cyst) arises in the medial aspectof the popliteal fossa and results from fluid distension ofthe gastrocnemius-semimebranosus (GS) bursa, which is locatedbetween the muscles bearing the corresponding names [1]. Thecommunication between the knee joint and the bursa, and thefluid dynamics of the cyst fluid contribute to the genesis ofthe popliteal cyst. Flexion of the knee causes the joint pressureto exceed bursal pressure and the valve-like connection betweenthe joint and the     

Intra-synovial 131I Human Serum Albumin (HSA) in the Investigation of Joint Disease

A procedure of radioisotope scanning using intra-synovial ¹³¹I HSA for the investigation of joint disease has been described. This has been shown to be useful in outlining cystic swellings related to joints. The most important application of the technique is the diagnosis of popliteal or calf cyst rupture which is difficult to distinguish from thrombophlebitis. Conventional radiography using phlebograms or arthro-grams has disadvantages which have not been encountered with this new technique. The radiation dose administered is not considered to be a hazard.     

Haemorrhage into a popliteal cyst: an unusual complication of haemophilia A.

A 7(1/2)-year-old boy with severe haemophilia A had increasing discomfort and pain in his left knee after sledding on ice and landing on his knees. Left knee pain persisted for days despite recombinant factor VIII replacement. Imaging studies showed that by day 10 a popliteal cyst had ruptured, with diffusion of blood into the calf muscles. This case illustrates another possible bleeding complication in patients with a bleeding disorder and a popliteal cyst.     

Evaluation of popliteal cysts and painful calves with ultrasonography: comparison with arthrography.

Grey-scale ultrasonography will detect reliably the presence of clinically significant popliteal cysts, fluid collections which do not fill by arthrography, and will frequently demonstrate ruptured cysts and the soft tissue changes resulting from a recent leak. Forty-eight knees, in 25 patients with popliteal and/or calf pain were examined by ultrasonography followed by arthrography. Popliteal cysts were demonstrated in 40% (19/48) by ultrasound and in 46% (22/48) by arthrogram. For comparison between arthrography and ultrasonography chi2 = 8.58 and contingency coefficient, phi = 0.42 (p less than 0.01). Acute cyst rupture was shown in 2 patients (8%) by both arthrography and ultrasound. In a further study ultrasonography demonstrated popliteal cysts with a prevalence of 31% (22/72) in 36 patients with definite or classical rheumatoid arthritis compared with 4% (3/72) in controls closely matched for age and sex. This difference in prevalence between the rheumatoid patients and controls was highly significant chi2 = 17.48, p less than 0.001. Ultrasonography, therefore, will demonstrate noninvasively the presence of popliteal cysts, may assist in the diagnosis of rupture, and furthermore will assist in quantitative, sequential assessment of patients with painful knees and calves.     

The pathology and evaluation of surgical treatment in a ruptured giant popliteal/crural cyst associated with rheumatoid arthritis

Popliteal cysts are often observed in patients with rheumatoid arthritis (RA), and giant cysts that extend from the popliteal to the crural region (popliteal/crural cysts) are occasionally encountered. We studied the background of popliteal/crural cysts and therapeutic results, and evaluated its etiologic factors and the effectiveness of surgical treatment. Nine knees of eight patients with popliteal/crural cyst secondary to RA, which was treated surgically because it resisted conservative treatment, and was followed up for 1 year or longer after surgery, were evaluated. The patients were five men and three women, with a mean age at surgery of 59.1 years and a mean duration of RA disease of 4.5 years. Only one male patient suffered pain in the bilateral joints. The mean level of erythrocyte sedimentation rate was 61.3 mm/h (range 3.9–100.2), the mean level of C-reactive protein was 3.6 (0.1–8.2) mg/dl, and the mean Lansbury index was 36.4 (12–61) at surgery. The cyst disappeared completely after surgery, and the postoperative course was uneventful in eight knees, but recurrence was observed in just one knee of the bilateral case. However, in this patient the cyst that recurred was not as large as the one before surgery, and it was eventually brought under control by subsequent outpatient medical management. Inflammatory reactions were suppressed, if temporarily, in all patients. The patients evaluated in this study showed the following characteristics: the male–female ratio of the patients was biased to males compared with that of RA patients in general; although knee joint damage was radiographically mild, marked symptoms of arthritis were observed in not only the knees but also other joints in all patients; and the disease could not be controlled effectively by medication. However, after surgical resection of the cysts, general as well as local signs of inflammation were mitigated, and surgery was considered to be very effective for the treatment of ruptured giant popliteal/crural cyst associated with RA.     

SYNOVIAL RUPTURE COMPLICATING BRUCELLA ARTHRITIS

A patient with Brucella arthritis presented as ‘pseudothrombophlebitissyndrome’, with rupture of knee synovial membrane intothe calf. Bacteriological identification of the same organismfrom the patient's blood, knee effusion and calf-swelling aspiratesuggested the diagnosis, and ultrasonography of the calf swellinggave supportive evidence. Synovial rupture into the calf in infective arthritis is a rareoccurrence and this has not been reported previously in Brucellaarthritis. KEY WORDS: Brucella arthritis, Baker's cyst rupture, Pseudothrombophlebitis syndrome     

Popliteal cysts in a pediatric patient

A 12-year-old boy with recurrent complaints of knee pain and swelling for six months, but without diagnosed rheumatological disease, presented with calf swelling and knee pain of several days duration. Examination revealed findings consistent with juvenile rheumatoid arthritis and a ruptured Baker's cyst. This is the sixth reported case of ruptured Baker's cyst reported in a child less than 14 years old and should alert emergency physicians that calf pain and swelling secondary to a ruptured popliteal (Baker's) cyst may be an early manifestation of juvenile rheumatoid arthritis.     

Pseudothrombophlebitis in neuropathic arthropathy

The pseudothrombophlebitis syndrome is a complication of large, ruptured, or dissecting popliteal cysts. We report a patient with neuropathic arthropathy of the knee and the pseudothrombophlebitis syndrome secondary to a dissecting popliteal cyst. This represents another form of arthritis associated with this syndrome.     

Treatment of popliteal cysts via arthroscopic enlargement of unidirectional valvular slits

Abstract

Objective. The aim of the present study was to investigate the efficacy of arthroscopic enlargement of unidirectional valvular slits for the treatment of popliteal cysts and to evaluate potential factors affecting the outcomes of our arthroscopic procedure.

Methods. Twenty-nine patients aged 43–77 years with popliteal cysts were treated with arthroscopic cyst decompression. Surgery was performed via two posterior portals after creating a transseptal portal. Rauschning and Lindgren clinical score, magnetic resonance images, and osteoarthritic grade were evaluated pre- and postoperatively, and cartilage degeneration class was confirmed via arthroscopy. The mean follow-up period was 22.9 ± 14.6 months (range, 9–60 months).

Results. Twelve cysts disappeared completely (group D), while 16 reduced and one enlarged (group R) in size by the final follow-up. Twenty-two (75.9%) of 29 popliteal cysts diminished to a volume that was less than 10% of the preoperative volume. Clinical scores improved in 93.1% of the patients, and more patients (68.8%) in group R had positive joint effusion at the final follow-up compared with group D (17.7%; p < 0.01).

Conclusions. Arthroscopic cyst decompression was effective in the treatment of symptomatic popliteal cysts. Intra-articular pathologies associated with joint effusion should be corrected simultaneously.     

Popliteal aneurysm simulating a Baker's cyst in a patient with rheumatoid arthritis: a case presentation

Baker's cyst is the most common mass located in the back side of the knee, the popliteal fossa, in patients with degenerative and inflamatory disease of the knee. Popliteal mass may also be due to proliferation of adipose tissue, popliteal artery aneurysm, thrombotic vein, or tumor. These lesions are rarer and may easily be misinterpreted as cysts. We show a man with rheumatoid arthritis who is presenting a palpable mass in the popliteal fossa. Ultrasonography examination demostrated a popliteal artery aneurysms.     

Rupture of Baker's cyst producing pseudothrombophlebitis in a patient with Reiter's syndrome

This is an unusual case of pseudothrombophlebitis resulting from rupture of Baker's cyst in a patient with Reiter's syndrome. The patient presented with a swollen, painful left calf and persistent itching on the skin of the calf. Ultrasonography showed a ruptured popliteal cyst with minimal hemorrhage and fluid collection within the fascial compartments and gastrocnemius muscle. Color Doppler ultrasound showed a patent popliteal vein and artery and duplex Doppler scans revealed a normal flow pattern. In conclusion, the clinical picture of deep vein thrombosis and that of pseudothrombophlebitis are difficult to distinguish by clinical examination and necessitate detailed examination by imaging techniques. Persistent pruritus on calf skin resulting from irritation of inflammatory synovial fluid may be an important clinical feature.     

Popliteal masses masquerading as popliteal cysts.

Two popliteal swellings, thought initially to be synovial cysts associated with arthritic knees, were found to be unrelated tumours of serious significance. In the presence of neurological signs or a large cyst in association with a noninflammed knee joint a disease other than a simple synovial cyst should be considered.     

POPLITEAL CYSTS AND SYNOVIAL RUPTURE IN OSTEOARTHROSIS

The range of symptomatology produced by synovial protrusionsin degenerative disease of the knee joint is demonstrated infive representative case histories. The most common mechanismis the formation of a popliteal cyst, which may be asymptomaticor painful. It may be in free communication with the knee jointor only fill after exercise. Rupture of the knee joint can occur,but the clinical picture is much less dramatic than with inflammatoryjoint disease. This is related to the less irritative characterof osteoarthritic synovial fluid. The diagnosis is proved byarthrography, which is an easy and relatively painless procedure,but it is important that a post-exercise film is taken. Healingof the rupture site may occur rapidly, as shown in one case. ^*Present address: Kantonssopital Zurich, Switzerland.     

Baker's cysts, pseudothrombophlebitis, pseudo-pseudothrombophlebitis: where do we stand?

The diagnostic approach and therapeutic attitudes to be assumed when facing the dilemma of deep vein thrombosis versus a complicated Baker's cyst remain unclear. We examined our own approach with 16 Baker's cysts [11 presenting with a "thrombophlebitis picture" (TP)] recently diagnosed in our services, and reviewed the literature. All of our patients had an underlying joint disorder and previous knee effusions. The diagnostic approach (i.e., the request or not for venography) was related to the specialty of the physician who saw the patient first. The results of the venography led to anticoagulation treatment in 5 of the 6 patients on whom it was performed, although these patients did not otherwise differ from those with a similar clinical picture in whom no venogram was obtained. Arthrograms performed early after onset of the TP were more likely to reveal cyst rupture. The recent literature does not mention serious venous complications (in particular, pulmonary embolism) in patients in whom only the cyst was treated, without knowledge of possible coexisting venous occlusions. The need to perform venography, the importance of the localisation of the occlusions and the therapeutic consequences are discussed and a proposal is made to study these patients in a systematic way in order to better understand the inter-relationship between complicated popliteal cysts and venous alterations, and to decide the best approach to assume in the future.