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Pain Pract. 2015 Jun;15(5):393-9. doi: 10.1111/papr.12187. Epub 2014 Apr 1.

Optimal angle of needle insertion for fluoroscopy-guided transforaminal epidural injection of L5.

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Department of Orthopedic Surgery, Kyungpook National University Hospital, Daegu, Korea.



Unlike other sites, there is difficulty in performing TFESI at the L5-S1 level because the iliac crest is an obstacle to needle placement.


The objective of this study was to identify the optimal angle of fluoroscopy for insertion and advancement of a needle during L5 TEFSI.


We conducted an observational study of patients undergoing fluoroscopy-guided L5 TFESI in the prone position. A total of 80 patients (40 men and 40 women) with radiating pain of lower limbs were enrolled. During TFESI, we measured the angle at which the L5 vertebral body forms a rectangular shape and compared men and women. Then, we measured area of safe triangle in tilting angle of fluoroscopy from 15° to 35° and compared men and women.


The mean cephalocaudal angle, where the vertebral body takes the shape of a rectangle, was 11.0° in men and 13.9° in women (P = 0.007). In men, the triangular area was maximal at 18.3 mm² with an oblique view angle of 25°. In women, the area was maximal at 23.6 mm² with an oblique view angle of 30°. At an oblique view angle of 30° and 35°, the area was significantly greater in women (P < 0.05).


When TFESI is performed at the L5 region in the prone position, placement of fluoroscopy at a cephalocaudal angle of 11.0° and an oblique angle of 25° in men and cephalocaudal angle of 13.9° and an oblique angle of 30° in women would be most reasonable.


fifth lumbar vertebra; fluoroscopy; iliac crest; optimal angle; safe triangle; technique; transforaminal epidural steroid injection

[Indexed for MEDLINE]

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