Introduction

Baker’s cyst or Poplital cyst is a well delineated fluid filled herniated synovial bursa, which is usual located is between tendons of medial gastrocnemius and semimembranosus in the posterior aspect of the knee that communicate with the knee joint [1].It is also known as Morrent Baker cyst based on the name of British Surgeon Dr William Morrant Baker [2].

The cyst is commonly seen in the adult or older age groups with prevalence from 10% to 41% and is comparatively rare in the children with reported incidence from 2.4% to 6.3 % having male preponderance [3,4]. Most of the Baker’s cysts are asymptomatic in children because of having no secondary pathology involved, and hence the treatment of the Baker’s cyst in children is usually observation and about 70 % of cases resolve its own with the time in months or years [5].

But in few cases it increases in size to such extent that they become symptomatic and the child may have difficulty in squatting and cross leg sitting. For these symptomatic cyst, which do not resolve with the conservative treatment, surgical excision is recommended with ligature at the neck of bursa [6]. This surgical excision warrants hospitalization, loss of school days and morbidity. In view of this, we evaluated the simple technique of threading, a day care procedure as an alternative to surgical excision of Baker’s cyst in children.

Material and Method

We retrospectively evaluated the results of threading technique of Baker’s cyst done at our center. All children with less than 15 years age, with large cystic swelling in the popliteal fossa which was not responded to

Results

6 children were included in study after fulfilling inclusion criteria. All children were males. The mean age was 10 years (range 6 to 13 years). As per the patients all had uneasiness and for all the swelling was unacceptable cosmetically and socially. Swelling in all children was non reducible with positive trans-illumination test.

Children were followed for 1 year with no recurrence. In one patient, there was superficial infection which subsided with antibiotics for one more week.

Discussion

Pathophysiology involved in Baker’s cyst in adults is usually inflammatory or degenerative arthropathy like meniscal disorder (mostly medial meniscus), osteoarthritis, rheumatoid arthritis, villonodular synovitis or following infection [7,8].But in children, it is usually idiopathic in 95 % of cases affecting, mostly children of 2 to 14 years of age [9,10].

It is also seen in children with hyper laxity joint disorder or juvenile rheumatoid disorder [11,12]. In children, it is also presumed that cyst starts, after trivial trauma to posterior aspect of the knee. There is controversy regarding communication of the cyst with the knee joint [13].

Ultrasonography is the investigation of choice for the diagnosis of the most cases of Baker’s cyst although in few cases MRI may be recommended to rule out parameniscal cyst, cystic malignancies like fibrosarcoma, synovial sarcoma, malignant fibrous histiocytoma and popliteal vessel aneurysm which are rarely seen in children and are usually seen in adults [14-16].

Pathogenesis of Baker’s cyst depends upon the presence of the valve between the tendons of medial gastrocnemius and semimembranosus muscle which open during flexion of the knee and closes during extension of the knee. There is also pressure variation in the knee from -6 mm Hg during partial flexion to 16 mm Hg during extension [17].

Baker’s cyst protects knee joint from high effusion pressure by diverting fluid from knee to Bakers cyst with valve like mechanism that allow flow in only one direction [18]. Treatment of Baker’s cyst in adults needs addressing of the primary pathology for its successful treatment [19].

Excision is recommended when conservative therapy fails. But excision has high rate of recurrence ranging from 5 to 40% and in children it can result in loss of school days due to hospitalization and morbidity. Further, since in children the cyst is mostly of primitive origin only, when the cyst failed to respond to conservative therapy, threading technique can be used. We used this threading technique, in 6 children of baker’s cyst as an alternative to surgical excision.

In all the cases swelling of Baker’s cyst subsided in all cases in mean time to 6.4 weeks completely, without any recurrence when followed till one year. The thread technique along with aspiration, decompress the cyst and with the tract of the thread the cyst is decompressed continuously which needs regular dressing, and in the meantime, the thread causes inflammatory reaction and fibrosis to occurs to seal of the cyst, and hence preventing recurrence.

With success our results we can say that the procedure is easy, day care procedure without much morbidity, can be done minimal invasive, cost effective, reliable, without recurrence and with good results. Our study is limited by short sample size.