title: Does the design of the Sprotte spinal needle reduce the force needed to deform the tip?
abstract: OBJECTIVE
  To determine whether the window design of pencil-point spinal needles leads to deformation under lateral or axial loading conditions.
  
  
  METHODS
  Independent-measure, multigroup study of the force required to deform needles.
  
  
  METHODS
  Independent testing laboratory.
  
  
  RESULTS
  The force necessary to bend 22- and 24-gauge Sprotte, 22- and 25-gauge Whitacre, and 22- and 25-gauge Quincke needles was measured using an Instron gauge (Instron Corp., Canton, MA) after microscopic verification of needle uniformity. Effects of lateral and axial forces were evaluated in separate experiments. The force needed to bend the Sprotte needles was less than that needed for the Whitacre and Quincke needles of similar size when lateral or axial pressure was applied. Microscopic inspection of the needles showed a marked variability in the window area placement in a single lot of Sprotte needles. Examination of the needle tips demonstrated that the Sprotte needles were most likely to bend at the needle window, while the Quincke and Whitacre needles deformed at the point of clamping.
  
  
  CONCLUSIONS
  The Sprotte needles have an inherent design weakness to lateral and axial pressure, which may result in a greater number of needle tip deformations upon needle insertion. The nature of this deformation may result in difficulty in needle withdrawal and possibly fracture of the needle tip.
authors.affiliation: Department of Anesthesiology, Rush-Presbyterian-St. Luke's Medical Center, Chicago, IL 60612.
authors.forename: E G
authors.initials: EG
authors.lastname: Lipov
authors.forename: M B
authors.initials: MB
authors.lastname: Sosis
authors.forename: R J
authors.initials: RJ
authors.lastname: McCarthy
authors.forename: A D
authors.initials: AD
authors.lastname: Ivankovich
mesh_terms: D000704:Analysis of Variance; D000775:Anesthesia, Spinal / Q000295:instrumentation*; D004867:Equipment Design; D004868:Equipment Failure; D009339:Needles; D013129:Spinal Puncture / Q000295:instrumentation; D013314:Stress, Mechanical; D013499:Surface Properties