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Published on: October 20, 2023
Natural history of popliteal cysts in the pediatric population
Ryuichiro Akagi1, Takashi Saisu, Yuko Segawa
1Department of Orthopaedic Surgery, Chiba Children's Hospital, Chiba, Japan. ryu-a@nona.dti.ne.jp
Insights
Popliteal (Baker's) cysts in children often resolve naturally without surgery. Magnetic resonance imaging (MRI) confirmed complete resolution in most cases, indicating a favorable natural history for pediatric popliteal cysts.
Area of Science:
- Pediatric Orthopedics
- Radiology
- Musculoskeletal Imaging
Background:
- Popliteal cysts (Baker's cysts) are common in children but often asymptomatic.
- Previous studies suggest spontaneous resolution, but surgical intervention is sometimes considered.
- No prior studies utilized MRI to confirm the resolution of pediatric popliteal cysts.
Purpose of the Study:
- To investigate the natural history of popliteal cysts in pediatric patients.
- To evaluate the efficacy of conservative management and confirm resolution using MRI.
Main Methods:
- Retrospective review of medical records for pediatric patients with popliteal cysts followed for at least 12 months.
- Analysis of clinical data, symptoms, and imaging findings (including serial MRI for some patients).
- Classification of cysts based on MRI into Type I (gastrocnemio-semimembranosus or subgastrocnemius bursa) and Type II (both bursae).
Main Results:
- 85% of popliteal cysts showed natural size reduction or disappearance on clinical/ultrasound examination.
- MRI confirmed complete resolution in 5 out of 8 knees with serial imaging.
- All Type II cysts transformed into Type I, and all resolved cysts were initially Type I.
Conclusions:
- Popliteal cysts in children typically exhibit spontaneous resolution.
- MRI findings support complete resolution without the need for surgical intervention.
- The natural history of pediatric popliteal cysts is favorable, with most resolving over time.
Background:
Cystic mass lesions in the popliteal area, called popliteal cysts or Baker's cysts, are usually minimally symptomatic and not related to intra-articular morbidity in the pediatric population. Although multiple studies have described cases of spontaneous resolution over a period of several months to a few years, others still consider surgical treatment necessary. Furthermore, no previous studies have used magnetic resonance imaging (MRI) to confirm the disappearance of popliteal cysts. In this retrospective study, we reviewed records of patients with popliteal cysts to investigate the natural history of this disease.
Methods:
The medical records of patients with popliteal cysts followed for at least 12 months were retrospectively reviewed. The patient set comprised of 17 knees in 15 males and 3 knees in 2 females. Mean age was 5.6±2.0 years (range, 1.8 to 11.4 y) at their initial visit to the clinic, and mean follow-up period was 53.1±31.6 months (range, 12.6 to 147.8 mo). MRI findings were reviewed for the 16 knees in 13 patients who had undergone MRI. Symptoms and clinical course were extracted from the medical records of all the study subjects and analyzed.
Results:
Although 6 knees (30%) had histories of pain in the popliteal area, no patient complained of pain at their initial visit. Seventeen cysts (85%) naturally decreased in size or disappeared on clinical examination and/or ultrasound. Cysts confined to either the gastrocnemio-semimembranosus bursa or the subgastrocnemius bursa according to the MRI findings were classified as type I, and cysts which occupied both bursae were classified as type II. Eight knees received MRI examination more than once, and complete disappearance was confirmed in 5 of these knees. All type II cysts converted to type I, and all cysts which completely disappeared were type I before disappearance.
Conclusions:
The MRI findings in our study population confirmed that popliteal cysts in pediatric populations can be expected to completely resolve in due course without treatment.
Level Of Evidence:
Therapeutic study Level IV (Case series).
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