Development of injury criteria for pelvic fracture in frontal crashes.
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.
Salzar
Robert S
RS
University of Virginia Center for Applied Biomechanics, Charlottesville, Virginia, USA. salzar@virginia.edu
Bass
Cameron R Dale
CR
Kent
Richard
R
Millington
Steven
S
Davis
Martin
M
Lucas
Scott
S
Rudd
Rodney
R
Folk
Benny
B
Donnellan
Lucy
L
Murakami
Daisuke
D
Kobayashi
Seiichi
S
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