What is the treatment for a popliteal cyst?

Treatment of Popliteal Cysts

Conservative management is the first-line treatment for popliteal cysts, with surgical intervention reserved for symptomatic cases that fail conservative measures and have associated intra-articular pathology. 1

Diagnostic Evaluation

• Ultrasound: First-line imaging modality due to excellent diagnostic accuracy, lack of radiation, and ability to perform dynamic evaluation 1
• MRI: Useful for evaluating associated intra-articular pathology, which is crucial as popliteal cysts in adults are almost invariably associated with other knee disorders 1, 2

Treatment Algorithm

Step 1: Conservative Management

• Rest, compression, elevation, and pain control for symptomatic relief 1
• Address underlying knee pathology (crucial to prevent recurrence) 1
• NSAIDs to reduce inflammation

Step 2: Minimally Invasive Interventions

For persistent symptomatic cysts despite conservative measures:

• Ultrasound-guided aspiration with corticosteroid injection 1
  • Note: High recurrence rate with aspiration alone if underlying knee pathology isn't addressed 3

Step 3: Surgical Management

For recalcitrant cases with persistent symptoms despite conservative measures:

• Arthroscopic treatment (preferred over open excision due to lower recurrence rates) 4:

  1. Treatment of associated intra-articular knee pathology
  2. Enlargement of the communication between joint and cyst
  3. Disruption of the one-way valve mechanism
  4. Intracystic debridement of fibrous membrane, nodules, and septa 3

• Open surgical excision may be necessary in specific cases:

  • When arthroscopic approach fails
  • In cases of septic arthritis with coexistent popliteal cyst 5
  • For complex cysts with solid components requiring histological examination 1

Special Considerations

• Ruptured cysts: Require rest, compression, elevation, pain control, and may need ultrasound-guided aspiration of fluid from the calf 1

• Differential diagnosis: Important to rule out popliteal artery aneurysm, which requires different management (surgical repair if ≥2.0 cm) 1

• Follow-up:

  • For complicated cysts: Short-term follow-up with ultrasound every 6-12 months for 1-2 years to assess stability 1
  • If cyst increases in size: Consider biopsy 1
  • Stable or confirmed complicated cysts with visible mobility of internal components can be managed with routine screening 1

Clinical Pearls

• Long-term success depends on addressing the underlying knee pathology, as isolated treatment of the cyst has high recurrence rates 4
• Chondral lesions (grade III or IV) are associated with higher risk of cyst persistence after treatment 1
• In cases of septic arthritis with coexistent popliteal cyst, consider open debridement or drainage of the cyst if arthroscopic irrigation and debridement fails 5

The treatment approach should focus on both the cyst and any associated intra-articular pathology to maximize outcomes and minimize recurrence.