Parameniscal Cyst Aspiration and Injection

Other Names

Illustration of parameniscal cyst

Meniscal anatomy and relationship to important structures of the knee joint

• Parameniscal Cyst Aspiration and Injection
• Meniscal Cyst Aspiration and Injection

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Background

Key Points

• Needle: 20-25 gauge, 1.5 inch needle
• Transducer: High frequency, linear probe
• Approach varies widely depending on the location of the cyst
• Cysts are often loculated and gelatinous
• Typical procedure involves aspiration of cyst, injection of corticosteroids

Anatomy of the Menisci

• Pair of medial and lateral crescent shaped wedges of fibrocartilage oriented circumferentially
• Positioned between the tibial plateaus and the femoral condyles in the medial and lateral compartments
• Thick peripherally and thin centrally
• Primary function is to reduce compression stress at the tibiofemoral joint

Palpation Guidance vs Ultrasound Guidance

• Muddu et al: Using palpation guidance, successfully aspirated 12/19 cysts
• MacMahon et al: Using ultrasound guidance, successfully aspirated 18/18 cysts
• Studies comparing palpation guided vs ultrasound guided cysts have not been performed

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Indications

• Parameniscal Cyst

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Contraindications

• Absolute
  • Anaphylaxis to injectates
  • Overlying cellulitis, skin lesion or systemic infection
• Relative
  • Can be treated with less invasive means
  • Hyperglycemia or poorly controlled diabetes
  • Lack of symptom improvement with previous injection

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Procedure

(a) Diagram of lateral knee joint as seen with coronally placed ultrasound probe: demonstrating femoral condyle (F), tibial plateau (T), skin surface (S) and cross-section of triangular meniscus with mid-body tear (arrow). There is a small cyst (C) arising from the outer border of meniscus. (b) Diagram of the method of aspiration of larger meniscal cysts. Needle (N) inserted into cyst at oblique angle.

Short axis view of cyst with needle in plane. Post (posterior), medial knee TR (transverse).

Equipment

• Sterile prep (i.e. chloraprep, chlorhexidine, iodine, etc)
• Gloves
• Needle: typically 21-25 gauge, 1.5 inch
• Syringe: 5-10 mL
• Gauze
• Ethyl Chloride
• Bandage
• Injectate
  • Local anesthetic
  • Corticosteroid
• Sterile probe cover

Ultrasound Findings

• Transducer: High frequency, linear array
• Common ultrasound findings include:
  • Findings will depend on the position o the cyst
  • Unilobular or multilobular
  • Hypoechoic to anechoic
  • Clear communication of the cyst to the adjacent meniscus

Technique

• Patient Position
  • Depends on the location of cyst
  • Typically supine or lateral decubitus
• Transducer position
  • Depends on the location of the cyst
• Needle Approach/ Orientation
  • In plane, long axis to the cyst
  • Lateral to medial/ medial to lateral
• Target
  • Cyst
• Pearls and Pitfalls
  • Thorough pre-procedure scanning to confirm target, identify and avoid neurovascular structures
  • Use gentle pressure, too much compression can displace cyst
  • If loculated, must break up all loculations
  • If viscous, lavage with lidocaine or sterile water

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Aftercare

• No major restrictions in most cases
• Can augment with ice, NSAIDS
• Consider Knee Compression Sleeve to reduce re-accumulation

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Complications

• Infection
• Damage to surrounding tissue

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See Also

• Procedures Main
• Ultrasound Main
• Knee Pain Main

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