title: Development of injury criteria for pelvic fracture in frontal crashes.
abstract: OBJECTIVE
  This article assesses the position-dependent injury tolerance of the hip in the frontal direction based on testing of eight postmortem human subjects.
  
  
  METHODS
  For each subject, the left and right hemipelvis complex was axially loaded using a previously developed test configuration. Six positions were defined from a seated femur neutral condition, combining flexed, neutral, and extended femur positions with abducted, neutral, and adducted positions.
  
  
  RESULTS
  Axial injury tolerances based on peak force were found to be 6,850 +/- 840 N in the extended, neutral position and 4,080 +/- 830 N in the flexed, neutral position. From the flexed neutral orientation, the peak axial force increased 18% for 20 degrees abduction and decreased 6% for 20 degrees adduction. From the extended, neutral orientation, the peak axial force decreased 4% for 20 degrees abduction and decreased 3% for 20 degrees adduction. However, as there is evidence that increases in loading may occur after the initiation of fracture, the magnitude of the peak force is likely related to the extent of injury, not to the initial tolerance. Using the axial femur force at the initiation of fracture (assessed with acoustic crack sensors) as a potentially more relevant indicator of injury may lower the existing injury criteria. This fracture initiation force varied by position from 3,010 +/- 560 N in the flexed, neutral position to 5,470 N in the extended, abducted position. Further, there was a large position-dependent variation in the ratio of fracture initiation force to the peak axial force. The initiation of fracture was 83% of the peak axial force in the extended, abducted position, but the ratio was 34% in the extended, adducted position.
  
  
  CONCLUSIONS
  This may have significant implications for the development of pelvic injury criteria by automobile designers attempting to mitigate pelvis injuries.
authors.affiliation: University of Virginia Center for Applied Biomechanics, Charlottesville, Virginia, USA. salzar@virginia.edu
authors.forename: Robert S
authors.initials: RS
authors.lastname: Salzar
authors.forename: Cameron R Dale
authors.initials: CR
authors.lastname: Bass
authors.forename: Richard
authors.initials: R
authors.lastname: Kent
authors.forename: Steven
authors.initials: S
authors.lastname: Millington
authors.forename: Martin
authors.initials: M
authors.lastname: Davis
authors.forename: Scott
authors.initials: S
authors.lastname: Lucas
authors.forename: Rodney
authors.initials: R
authors.lastname: Rudd
authors.forename: Benny
authors.initials: B
authors.lastname: Folk
authors.forename: Lucy
authors.initials: L
authors.lastname: Donnellan
authors.forename: Daisuke
authors.initials: D
authors.lastname: Murakami
authors.forename: Seiichi
authors.initials: S
authors.lastname: Kobayashi
mesh_terms: D015998:Abbreviated Injury Scale; D000063:Accidents, Traffic; D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D002102:Cadaver; D005260:Female; D050723:Fractures, Bone / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010384:Pelvic Bones / Q000293:injuries* / Q000503:physiopathology