Citation

Quenneville CE, McLachlin SD, Greeley GS, Dunning CE. J. Trauma 2011; 70(1): E13-E18.

Affiliation

The Jack McBain Biomechanical Testing Laboratory (C.E.Q., S.D.M., G.S.G., C.E.D.), Thompson Engineering Building, The University of Western Ontario, London, Ontario, Canada; Departments of Mechanical and Materials Engineering (C.E.Q., S.D.M., C.E.D.), Surgery (C.E.D.), and The Biomedical Engineering Graduate Program (G.S.G., C.E.D.), The University of Western Ontario, London, Ontario, Canada; and Engineering Design and Development, General Dynamics Land Systems-Canada (G.S.G.), London, Ontario, Canada.

Copyright

(Copyright © 2011, Lippincott Williams and Wilkins)

DOI

10.1097/TA.0b013e3181f6bb0e

PMID

21217472

Abstract

BACKGROUND:: Impulse loading of the lower leg during events such as ejection seat landings or in-vehicle land mine blasts may result in devastating injuries. These impacts achieve higher forces over shorter durations than car crashes, from which experimental results have formed the current basis for protective measures of an axial force limit of 5.4 kN, as registered by an anthropomorphic test device (ATD). The hypotheses of this study were that the injury tolerance of the isolated tibia to short-duration axial loading is higher than that previously reported and that secondary parameters such as momentum or kinetic energy are significant for fracture tolerance, in addition to force. METHODS:: Seven pairs of cadaveric tibias were impacted using a pneumatic testing apparatus, replicating short-duration axial impulse events. One specimen from each pair was impacted with a light mass and the contralateral impacted with a heavy mass, to investigate the effects of momentum and kinetic energy, as well as force, on injury. Impacts were applied incrementally until failure. RESULTS:: Force, kinetic energy, age, and height were shown to be significant factors in the probability of fracture. A 10% risk of injury corresponded to an impact force of 7.9 kN, with an average kinetic energy of 240 J. In comparison, this same impact level applied to an ATD would register a force of 16.2 kN because of the higher stiffness of the ATD. CONCLUSIONS:: These results suggest that the current injury standard may be too conservative for the tibia during high-speed impacts such as in-vehicle land mine blasts and that factors in addition to force should be taken into consideration.

Language: en