title: Injury risk function for the small female wrist in axial loading.
abstract: Previous experiments with human cadavers and side airbags revealed the potential for wrist injuries as a result of the hand becoming entrapped in the handgrip. The purpose of this paper was to develop an injury tolerance for the small female wrist that may be used in the design phase of side airbags in order to reduce the risk of wrist injuries resulting from side air bag deployment. Small female cadaver upper extremities were used to develop the wrist tolerance as a conservative estimate of the most vulnerable section of the driving population. The energy source was a pneumatic impactor that was configured to match the force onset rate, impulse, and peak force in order to simulate the load profile of a deploying side airbag. A total of 17 (n=17) axial impact experiments were performed on the wrists of small female cadavers. Post-test necropsy revealed that 9 of the 17 tests resulted in wrist injuries. The injury patterns were identical to those observed from cadaver tests with side airbags and included fractures of the scaphoid (AIS 2), lunate (AIS 1), distal radius (AIS 3), and distal ulna (AIS 2). Using the injury outcome as the binary variable, a logistic regression analysis was performed. When mass scaled to the fifth female, the analysis produced an injury risk function that predicts a 50% risk of injury at a wrist load of 1700 N (P=0.0037). Risk of injury was found not to be dependent of subject bone mineral density (P=0.49), age (P=0.99), mass (P=0.31), and stature (P=0.69). Based on the similarities in impact load profile and observed injury patterns between the impactor tests and the side airbag tests, it is suggested that the injury risk function will accurately predict the risk of wrist injuries in the automobile crash environment.
authors.affiliation: Virginia Tech, Impact Biomechanics Laboratory, Mechanical Engineering, 114 Randolph Hall, Blacksburg, VA 24061, USA. duma@vt.edu
authors.forename: Stefan M
authors.initials: SM
authors.lastname: Duma
authors.forename: Brian M
authors.initials: BM
authors.lastname: Boggess
authors.forename: Jeff R
authors.initials: JR
authors.lastname: Crandall
authors.forename: Conor B
authors.initials: CB
authors.lastname: MacMahon
mesh_terms: D000063:Accidents, Traffic; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017278:Air Bags / Q000009:adverse effects; D001696:Biomechanical Phenomena; D015519:Bone Density; D005260:Female; D006801:Humans; D016015:Logistic Models; D008875:Middle Aged; D018570:Risk Assessment; D012307:Risk Factors; D014954:Wrist Injuries / Q000453:epidemiology* / Q000503:physiopathology / Q000517:prevention & control