title: Comparison of Spinal Needle Deflection in a Ballistic Gel Model.
abstract: BACKGROUND
  Percutaneous diagnostic and therapeutic procedures are commonly used in the treatment of spinal pain. The success of these procedures depends on the accuracy of needle placement, which is influenced by needle size and shape.
  
  
  OBJECTIVE
  The purpose of this study is to examine and quantify the deviation of commonly used spinal needles based on needle tip design and gauge, using a ballistic gel tissue simulant.
  
  
  METHODS
  Six needles commonly used in spinal procedures (Quincke, Short Bevel, Chiba, Tuohy, Hustead, Whitacre) were selected for use in this study. Ballistic gel samples were made in molds of two depths, 40mm and 80 mm. Each needle was mounted in a drill press to ensure an accurate needle trajectory. Distance of deflection was recorded for each needle.
  
  
  RESULTS
  In comparing the mean deflection of 22 gauge needles of all types at 80 mm of depth, deflection was greatest among beveled needles [Short Bevel (9.96 ± 0.77 mm), Quincke (8.89 ± 0.17 mm), Chiba (7.71 ± 1.16 mm)], moderate among epidural needles [Tuohy (7.64 ± 0.16 mm) and least among the pencil-point needles [Whitacre (0.73 ± 0.34 mm)]. Increased gauge (25 g) led to a significant increase in deflection among beveled needles. The direction of deflection was away from the bevel with Quincke, Chiba and Short Beveled needles and toward the bevel of the Tuohy and Hustead needles. Deflection of the Whitacre pencil-point needle was minimal.
  
  
  CONCLUSIONS
  There is clinical utility in knowing the relative deflection of various needle tips. When a procedure requires a needle to be steered around obstacles, or along non-collinear targets, the predictable and large amount of deflection obtained through use of a beveled spinal needle may prove beneficial.
authors.affiliation: Department of Rehabilitation and Regenerative Medicine, Presbyterian Hospital, New York, The United States.
authors.forename: Ethan
authors.initials: E
authors.lastname: Rand
authors.affiliation: Department of Rehabilitation and Regenerative Medicine, Columbia University Medical Center, Presbyterian Hospital, New York, The United States.
authors.forename: George
authors.initials: G
authors.lastname: Christolias
authors.affiliation: Department of Rehabilitation and Regenerative Medicine, Columbia University Medical Center, Presbyterian Hospital, New York, The United States.
authors.forename: Christopher
authors.initials: C
authors.lastname: Visco
authors.affiliation: Department of Rehabilitation and Regenerative Medicine, Weill Cornell Medicine Spine Center, Presbyterian Hospital, New York, The United States.
authors.forename: Jaspal
authors.initials: J
authors.lastname: R Singh
keywords: Back Pain; Ballistic Gel; Interventional Pain; Needle Deflection; Spinal Needle