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Clothing increases the risk of indirect ballistic fractures.

Kieser DC, Carr DJ, Leclair SC, Horsfall I, Theis JC, Swain MV, Kieser JA - J Orthop Surg Res (2013)

Bottom Line: We compared the effect of two different gelatine depths and the effect of denim cloth laid onto the impact surface of the moulds.Bullet passage in thinner moulds failed to cause fracture because the bullet exited the mould before a large expanding temporary cavity was produced.Clothing increases the risk of indirect fracture and results in larger, more superficial temporary cavities, with greater lateral pressures than are seen in unclothed specimens, resulting in more comminuted fractures.

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Affiliation: Medical Corps, New Zealand Defence Force, Wellington 5045, New Zealand. kieserdavid@gmail.com.

ABSTRACT

Background: Current literature has shown the mechanism of how indirect fractures occur but has not determined what factors increase the risks of such fractures. The objective of this study is thus to determine the effect of clothing and soft tissue thickness on the risk of indirect fracture formation.

Methods: Twenty-five fresh red deer femora embedded in ballistic gelatine were shot with varying distances off their medial cortex with a 5.56 × 45 mm North Atlantic Treaty Organization (NATO) bullet while being filmed with a slow-motion video. We compared the effect of two different gelatine depths and the effect of denim cloth laid onto the impact surface of the moulds.

Results: Bullet passage in thinner moulds failed to cause fracture because the bullet exited the mould before a large expanding temporary cavity was produced. Clothing dramatically altered the size and depth of the expanding cavity, as well as increased lateral pressures, resulting in more severe fractures with greater bullet distances from the bone that can cause fracture.

Conclusions: Clothing increases the risk of indirect fracture and results in larger, more superficial temporary cavities, with greater lateral pressures than are seen in unclothed specimens, resulting in more comminuted fractures. Greater tissue depth affords the 5.56 × 45 mm NATO a chance to yaw and thus develop an enlarging temporary cavity that is sufficient to cause fracture.

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The average energy transferred to each mould and corresponding temporary cavity volume.
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Figure 1: The average energy transferred to each mould and corresponding temporary cavity volume.

Mentions: The average pre-impact velocity of the bullet was 970 m/s (range 959–980 m/s), with an average energy transfer to the sample of 1,560 J (1,307–1,874 J) for the thick unclothed mould, 1,578 J (1,453–1,784 J) for the single layer of clothing, 1,654 J (1,640–1,668 J) for the double layer and 533 J (527–539 J) for the thin rectangular mould (Figure 1).


Clothing increases the risk of indirect ballistic fractures.

Kieser DC, Carr DJ, Leclair SC, Horsfall I, Theis JC, Swain MV, Kieser JA - J Orthop Surg Res (2013)

The average energy transferred to each mould and corresponding temporary cavity volume.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4222043&req=5

Figure 1: The average energy transferred to each mould and corresponding temporary cavity volume.
Mentions: The average pre-impact velocity of the bullet was 970 m/s (range 959–980 m/s), with an average energy transfer to the sample of 1,560 J (1,307–1,874 J) for the thick unclothed mould, 1,578 J (1,453–1,784 J) for the single layer of clothing, 1,654 J (1,640–1,668 J) for the double layer and 533 J (527–539 J) for the thin rectangular mould (Figure 1).

Bottom Line: We compared the effect of two different gelatine depths and the effect of denim cloth laid onto the impact surface of the moulds.Bullet passage in thinner moulds failed to cause fracture because the bullet exited the mould before a large expanding temporary cavity was produced.Clothing increases the risk of indirect fracture and results in larger, more superficial temporary cavities, with greater lateral pressures than are seen in unclothed specimens, resulting in more comminuted fractures.

View Article: PubMed Central - HTML - PubMed

Affiliation: Medical Corps, New Zealand Defence Force, Wellington 5045, New Zealand. kieserdavid@gmail.com.

ABSTRACT

Background: Current literature has shown the mechanism of how indirect fractures occur but has not determined what factors increase the risks of such fractures. The objective of this study is thus to determine the effect of clothing and soft tissue thickness on the risk of indirect fracture formation.

Methods: Twenty-five fresh red deer femora embedded in ballistic gelatine were shot with varying distances off their medial cortex with a 5.56 × 45 mm North Atlantic Treaty Organization (NATO) bullet while being filmed with a slow-motion video. We compared the effect of two different gelatine depths and the effect of denim cloth laid onto the impact surface of the moulds.

Results: Bullet passage in thinner moulds failed to cause fracture because the bullet exited the mould before a large expanding temporary cavity was produced. Clothing dramatically altered the size and depth of the expanding cavity, as well as increased lateral pressures, resulting in more severe fractures with greater bullet distances from the bone that can cause fracture.

Conclusions: Clothing increases the risk of indirect fracture and results in larger, more superficial temporary cavities, with greater lateral pressures than are seen in unclothed specimens, resulting in more comminuted fractures. Greater tissue depth affords the 5.56 × 45 mm NATO a chance to yaw and thus develop an enlarging temporary cavity that is sufficient to cause fracture.

Show MeSH
Related in: MedlinePlus