title: Optimal angle of needle insertion for fluoroscopy-guided transforaminal epidural injection of L5.
abstract: BACKGROUND
  Unlike other sites, there is difficulty in performing TFESI at the L5-S1 level because the iliac crest is an obstacle to needle placement.
  
  
  OBJECTIVE
  The objective of this study was to identify the optimal angle of fluoroscopy for insertion and advancement of a needle during L5 TEFSI.
  
  
  METHODS
  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.
  
  
  RESULTS
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Orthopedic Surgery, Kyungpook National University Hospital, Daegu, Korea.
authors.forename: In-Hoo
authors.initials: IH
authors.lastname: Ra
authors.affiliation: Department of Orthopedic Surgery, Kyungpook National University Hospital, Daegu, Korea.
authors.forename: Woo-Kie
authors.initials: WK
authors.lastname: Min
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005471:Fluoroscopy / Q000379:methods*; D006801:Humans; D007268:Injections, Epidural; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D009339:Needles / Q000592:standards; D010146:Pain / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D013256:Steroids / Q000008:administration & dosage
chemical_list: D013256:Steroids
keywords: fifth lumbar vertebra; fluoroscopy; iliac crest; optimal angle; safe triangle; technique; transforaminal epidural steroid injection