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Piriformis Injection

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Other Names

  • Piriformis Injection
  • Piriformis Bursa Injection
  • Piriformis Muscle Injection
  • Piriformis Muscle Sheath Injection

Background

Illustration of the piriformis anatomy
  • This page refers to injections in or around the piriformis muscle
    • This procedure should be performed with ultrasound guidance

Key Points

  • Transducer will be linear or curvilinear depending on patients body habitus
  • Best visualized in axial oblique plane from superomedial to inferolateral
  • Identify sciatic nerve prior to procedure

Anatomy

Palpation vs Ultrasound Guidance

  • A cadaveric study showed ultrasound is significantly more accurate than fluoroscopy[1]

Indications


Contraindications

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

Procedure

Demonstration of probe and needle position[2]
Demonstration of internal and external rotation position to help confirm identification of piriformis[2]
Needle tip is seen injecting into piriformis muscle a safe distance from the sciatic nerve[2]

Equipment

  • Sterile including chloraprep, chlorhexadine, iodine
  • Ultrasound with sterile probe cover
  • Gloves
  • Needle: typically 21-22 gauge, 3.5 inch
  • Syringe: 5-10 mL
  • Gauze
  • Bandage
  • Injectate
    • Local anesthetic
    • Corticosteroid/ injectate

Ultrasound Findings

  • Piriformis is best visualized in long axis[3]
    • Low frequency curvilinear probe is typically required
    • In patients with a smaller body habitus, a linear medium frequency probe may suffice
  • Identify piriformis
    • Identify the posterior superior iliac spine
    • Slide the probe caudally, the ilium will disappear and the probe will be over the great sciatic notch
    • Maintain the medial side of the probe while inferiorly rotating the lateral probe over the piriformis muscle
    • The piriformis can be seen originating from the sacrum extending inferolaterally to the greater trochanter
    • Flex the knee, internally/externally rotate hip to help identify piriformis
    • Final probe position: axial oblique from superomedial to inferolateral

Technique

  • Patient Position
    • The patient is prone
  • Transducer position
    • Axial oblique from superomedial to inferolateral
  • Needle orientation/ approach
    • In plane
    • Lateral to medial or medial to lateral
  • Target
    • Piriformis muscle sheath and/or muscle
  • Pearls and Pitfalls
    • Identify sciatic nerve during pre-procedural sonography
    • Sciatic nerve is typically deep but can run through or above piriformis
    • Passive internal/external rotation of hip is very useful to identify muscle

Aftercare

  • No major restrictions in most cases
  • Can augment with ice, NSAIDS

Complications

  • Sciatic Nerve Injury
    • May inadvertently regionally block the sciatic nerve which will resolve as anesthetic wears off
    • Can also fenestrate sciatic nerve if not careful during procedure

See Also

Internal

External


References

  1. Finnoff, Jonathan T., Mark Friedrich B. Hurdle, and Jay Smith. "Accuracy of ultrasound‐guided versus fluoroscopically guided contrast‐controlled piriformis injections: A cadaveric study." Journal of Ultrasound in Medicine 27.8 (2008): 1157-1163.
  2. 2.0 2.1 2.2 Bardowski, Elizabeth A., and JW Thomas Byrd. "Piriformis injection: an ultrasound-guided technique." Arthroscopy Techniques 8.12 (2019): e1457-e1461.
  3. Smith, Jay, et al. "Ultrasound-guided piriformis injection: technique description and verification." Archives of physical medicine and rehabilitation 87.12 (2006): 1664-1667.
Created by:
John Kiel on 15 May 2023 03:55:55
Authors:
Last edited:
28 May 2023 12:00:30
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