title: Computed tomography analysis of third webspace injections for interdigital neuroma.
abstract: BACKGROUND
  Injection for interdigital neuroma (IDN) may not selectively target the common digital nerve. We investigated the anatomical localization and extent of extravasation with injection for IDN.
  
  
  METHODS
  Two fellowship-trained foot and ankle surgeons injected radiopaque contrast into the third webspace of 49 cadaveric specimens (29 with 2 mL and 20 with 1 mL). Computed tomography scan of each specimen was obtained. An independent blinded foot and ankle surgeon analyzed the scans.
  
  
  RESULTS
  All injections were accurate. Contrast was found in the second (greater than 70%) and fourth (greater than 30%) webspaces in both injection volume groups. No contrast was found within the third metatarsophalangeal joint. Extravasation extent was significantly greater with 2 mL versus 1 mL of solution in the medial to lateral (27.9 [7.8] mm vs 23.7 [6.0] mm; P = .05) and distal to proximal (52.1 [13.7] mm vs 40.4 [16.1] mm; P = .01) planes. No differences were observed in extravasation extent between surgeons.
  
  
  CONCLUSIONS
  Injection for IDN was accurate, and extravasation extended into adjacent webspaces in a large percentage of specimens with both solution volumes. Lower extent of extravasation with 1 mL of solution did not indicate better selectivity of injection.
  
  
  CONCLUSIONS
  Steroid injections for interdigital neuroma were accurate for therapeutic purposes but not diagnostic, except potentially for distinguishing webspace pain from joint pain.
authors.affiliation: Department of Orthopaedic Surgery, MedStar Union Memorial Hospital, Baltimore, MD 21218, USA.
authors.forename: W Chad
authors.initials: WC
authors.lastname: Hembree
authors.forename: Adam T
authors.initials: AT
authors.lastname: Groth
authors.forename: Lew C
authors.initials: LC
authors.lastname: Schon
authors.forename: Gregory P
authors.initials: GP
authors.lastname: Guyton
mesh_terms: D003287:Contrast Media / Q000008:administration & dosage*; D005119:Extravasation of Diagnostic and Therapeutic Materials / Q000453:epidemiology*; D005534:Foot Diseases / Q000601:surgery*; D006801:Humans; D015552:Injections, Intralesional; D009463:Neuroma / Q000601:surgery*; D014034:Toes / Q000294:innervation; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media