APPENDIX
Although there are a number of other relevant lower leg studies, the present study focused on
axial loading to the lower leg using PMHS as an experimental model and analyzed data for footankle injury risk using survival analysis.
All data were obtained based on tests applicable to
automotive environments, specifically frontal impacts. While axial loading to the human lower
leg occurs in other situations such as underbody blasts or improvised explosive devices, such
events may be associated with higher strain or loading rate than those encountered automotive
environments. The present methodology can be applied to such scenarios. This will be a future
study. Other bones/components of the lower leg can be injured in dynamic loading. For
example, fracture of the lateral process of the talus is unique to snowboarders and this particular
injury is difficult to detect on standard radiographic images (Boon et al., 2001). As another
example, malleolus or fibula fractures occurred in 38% of injured specimens in impact tests
simulating toe pan intrusion (Funk et al., 2000). The authors reported that axial loading may also
induce these fractures, which were “conventionally thought to be caused by excessive rotations.”
In addition, military events as briefly alluded to earlier also induce dynamic axial loading and
may have different tolerance levels due to impacting differences to the lower leg.
Some
laboratory studies in this area are available (McKay and Bir, 2009). Likewise, other modes such
as dorsi- or plantar flexion and inversion or eversion in association with axial loading to the
plantar surface of the foot can result in lower leg injuries. Studies in these modes are also
available (Begeman and Prasad, 1990; Funk et al., 2002b; Manning et al., 1997; Parenteau and
Viano, 1995; Petit et al., 1996; Portier et al., 1997; Rudd et al., 2004). Consequently, it would be
necessary to consider all injuries and injury mechanisms and derive risk curves for a
comprehensive understanding of lower leg injury tolerance (Boon et al., 2001; Carr et al., 1989;
Funk et al., 2002a; Funk et al., 2002b; Hirsch and Lewis, 1965; Kitagawa et al., 1998; Klopp et
al., 1997; McKay and Bir, 2009; McMaster et al., 2000; Schueler, 1995). These are considered
as future research topics.
Begeman, P. and Prasad, P., "Human Ankle Impact Response in Dorsiflexion," SAE Technical
Paper 902308, 1990, doi:10.4271/902308.
Boon AJ, Smith J, Zobitz ME, Amrami KM. Snowboarder's talus fracture. Mechanism of injury.
Am J Sports Med 2001.29:333-338.
Carr JB, Hamilton JJ, Bear LS. Experimental intra-articular calcaneal fractures: anatomic basis
for a new classification. Foot Ankle 1989.10:81-87.
Funk JR, Crandall JR, Tourret LJ, MacMahon CB, Bass CR, Patrie JT, Khaewpong N, Eppinger
RH. The axial injury tolerance of the human foot/ankle complex and the effect of Achilles
tension. J Biomech Eng 2002a.124:750-757.
Funk JR, Srinivasan SC, Crandall JR, Khaewpong N, Eppinger RH, Jaffredo AS, Potier P, Petit
PY. The effects of axial preload and dorsiflexion on the tolerance of the ankle/subtalar joint to
dynamic inversion and eversion. Stapp Car Crash J 2002b.46:245-265.
Funk, J., Tourret, L., George, S., and Crandall, J., "The Role of Axial Loading in Malleolar
Fractures," SAE Technical Paper 2000-01-0155, 2000, doi:10.4271/2000-01-0155.
Hirsch C, Lewis J. Experimental ankle-joint fractures. Acta Orthop Scand 1965.36:408-417.
Kitagawa, Y., Ichikawa, H., King, A., and Levine, R., "A Severe Ankle and Foot Injury in
Frontal Crashes and Its Mechanism," SAE Technical Paper 983145, 1998, doi:10.4271/983145.
Klopp GS, Crandall JR, Hall GW, Pilkey WD, Hurwitz SR, Kuppa SM. Mechanisms of injury
and injury criteria for the human foot and ankle in dynamic axial impacts to the foot.
Proceedings of the International Research Council on Biomechanics of Impact, 1997.
Manning, P., Wallace, W., Roberts, A., Owen, C. et al., "The Position and Movement of the Foot
in Emergency Manoeuvres and the Influence of Tension in the Achilles Tendon," SAE Technical
Paper 973329, 1997, doi:10.4271/973329.
McKay BJ, Bir CA. Lower extremity injury criteria for evaluating military vehicle occupant
injury in underbelly blast events. Stapp Car Crash J 2009.53:229-249.
McMaster J, Parry M, Wallace WA, Wheeler L, Owen C, Lowne R, Oakley C, Roberts AK.
Biomechanics of ankle and hindfoot injuries in dynamic axial loading. Stapp Car Crash J
2000.44:357-377.
Parenteau CS, Viano DC. A New Method to Determine the Biomechanical Properties of Human
and Dummy Joints. Proceedings of the International Research Council on Biomechanics of
Impact, 1995.
Petit P, Portier L, Foret-Bruno JY, Trosseille X, Parenteau C, Coltat J-C, Tarriere C, Lassau JP.
Quasistatic Characterization of the Human Foot-Ankle Joints in a Simulated Tensed State and
Updated Accidentological Data. Proceedings of the International Research Council on
Biomechanics of Impact, 1996.
Portier, L., Petit, P., Dômont, A., Trosseille, X. et al., "Dynamic Biomechanical Dorsiflexion
Responses and Tolerances of the Ankle Joint Complex," SAE Technical Paper 973330, 1997,
doi:10.4271/973330.
Rudd R, Crandall J, Millington S, Hurwitz S, Hoglund N. Injury tolerance and response of the
ankle joint in dynamic dorsiflexion. Stapp Car Crash J 2004.48:1-26.
Schueler R. Injuries of the lower legs -foot, ankle joint, tibia; mechanisms, tolerance limits,
injury -criteria evaluation of a recent biomechanic experiment series. Proceedings of the
International Research Council on Biomechanics of Impact, 1995.
Yoganandan N, Pintar, Gennarelli TA, Seipel R, Marks RM. Biomechanical tolerance of
calcaneal fractures, Annu Proc Assoc Adv Automot Med. 1999; 43: 345–356.
Table A: Data on a specimen-by-specimen basis