How is fluoroscopy-guided piriformis injection administered?

Updated: Nov 03, 2020
  • Author: Mary Louise Caire, MD; Chief Editor: Erik D Schraga, MD  more...
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For piriformis injection under fluoroscopic guidance, the patient is first placed in a comfortable prone position, with the C-arm positioned to provide an anteroposterior view of the affected side. [10] The sacrum and the greater trochanter are identified and used as medial and lateral bony landmarks, respectively (see the image below).

Fluoroscopy-guided piriformis injection. Greater t Fluoroscopy-guided piriformis injection. Greater trochanter and lateral border of sacrum are identified fluoroscopically and used as markers for needle insertion.

The skin is prepared with three consecutive povidone-iodine scrubs. A skin marker may be used to draw a line from the posterior inferior iliac spine to the greater trochanter. The estimated skin entry site is at the midpoint of this line.

Local anesthesia, both superficial and deep, is provided through local infiltration of 1% lidocaine buffered with sodium bicarbonate. The needle is advance to a bony end point and then withdrawn. Proper needle placement is confirmed by injecting a contrast solution, which should delineate the contour of the piriformis (see the image below).

Fluoroscopy-guided piriformis injection. Anteropos Fluoroscopy-guided piriformis injection. Anteroposterior fluoroscopic image of piriformis after contrast administration.

Once needle placement is confirmed, a diagnostic or therapeutic block may be carried out. Diagnostic blocks are performed with 1 mL of 1% lidocaine and 3 mL of 0.5% ropivacaine or bupivacaine. After a diagnostic block, the patient may be examined to evaluate for pain and hip function. Therapeutic blocks are performed with 3 mL of 0.5% ropivacaine or bupivacaine combined with 40 mg of triamcinolone.

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