Wound Ballistics

[agalindo]

Found this on another forum thought it would make good reading. I couldn't post the article in it's entirety so here's a link.

http://rkba.org/research/fackler/wrong.html

Serious misunderstanding has been generated by looking upon "kinetic
energy transfer" from projectile to tissue as a mechanism of injury.
In spite of data to the contrary (1, 63), many assume that the
amount of "kinetic energy deposit" in the body by a projectile is
a measure of damage (2-5, 36, 37, 40). Such opinions ignore the
direct interaction of projectile and tissue that is the crux of
wound ballistics.

WHAT'S WRONG WITH THE WOUND BALLISTICS LITERATURE, AND WHY


by M.L. Fackler, M.D.

Letterman Army Institute of Research
Division of Military Trauma Research
Presidio of San Francisco, California 94219

Institute Report No. 239
July 1987

ABSTRACT

Attempts to explain wound ballistics (the study of effects on the body produced by penetrating projectiles) have succeeded in mystifying it. Fallacious research by those with little grasp of the fundamentals has been perpetuated by editors, reviewers, and other investigators with no better grasp of the subject. .................................................. ........

THE WOUND PROFILE - UNDERSTANDING THE PROJECTILE-TISSUE INTERACTION

A projectile crushes the tissue it strikes during penetration, and it may impel the surrounding tissue outward (centrifugally) away from the missile path.
............
MAJOR MISCONCEPTIONS

1. Idolatry of Velocity:

A widespread dogma claims that wounds caused by "high-velocity" projectiles must be treated by extensive excision of tissue around the missile path (34-40), whereas those caused by "low-velocity" missiles need little or no treatment (41, 42). Two half-truths nurture this error. The first of these, "Cavitation is a ballistic phenomenon associated with very high velocity missiles" (7), is easily disproved. ...............................................

2. Exaggeration of Temporary Cavity Size, Pressure, and Effect:

In 1971, Amato et al (53) wrote that the temporary cavity "can approximate 30 times the size of the missile." They showed the temporary cavity caused by a 0.25-in. (6.4-mm) steel sphere shot at 3,000 ft/s (914 m/s) through the hind leg of an anesthetized dog. Although no scale was included on the high-speed roentgenograms, the reader can use dividers to determine the sphere diameter and will find that the largest temporary cavity shown is 11 sphere diameters--not 30 diameters. ................................................


3. Assumption of Bullet "Tumbling" in Flight:

The notion that a common cause of increased wounding is the bullet's striking at large yaw angles (angle between the bullet's long axis and line of flight), or even sideways due to "tumbling" in flight (37, 40), is clearly fallacious. Anyone who has ever shot a rifle and observed the holes made by the bullet recognizes that they are round, not oblong, as would be the case if they yawed or tumbled in flight. ............................................

4. Presumption of "Kinetic Energy Deposit" to Be a Mechanism of Wounding:

Serious misunderstanding has been generated by looking upon "kinetic energy transfer" from projectile to tissue as a mechanism of injury. In spite of data to the contrary (1, 63), many assume that the amount of "kinetic energy deposit" in the body by a projectile is a measure of damage (2-5, 36, 37, 40). Such opinions ignore the direct interaction of projectile and tissue that is the crux of wound ballistics. Wounds that result in a given amount of "kinetic energy deposit" may differ widely. .........................................

5. Excision of the Wound as Not Only the Most Crucial but to Many the Sole Treatment for Gunshot Wounds:

"Debridement of missile injuries is essential to prevent clostridium myositis..." (7) is the often repeated military dogma. In many papers, administration of systemic antibiotics for the treatment of penetrating projectile wounds has been described as "only an ancillary measure" (40), "an issue of debate" (41), or not mentioned at all (7). However, this dogma apparently overlooks the historical fact that the most important cause of death from missile wounds on the battlefield in the preantibiotic era was streptococcal bacteremia (70). ...........................................

6. Spheres Assumed to Be a Valid Model for All Projectiles:

This misconception ignores the important variable of projectile shape. Comparing the wound profile produced by a sphere (Fig 4) with that produced by a military bullet (Fig 3) shows a basic difference in tissue disruption morphology. ..................................


7. Animals of 10 to 20 kg Falsely Assumed to Be a Valid Model for Human Wounds:

Temporary cavitation is no more than the pushing aside of tissue. The distance the tissue is displaced depends, among other things, on its weight. As might be expected, a given projectile will cause a temporary cavity of smaller diameter in a larger limb because of the increased weight of the mass being moved. .................................................

8. Use of Tissue Simulants with Unproved Equivalence to Living Animal Tissue:

Fundamental to the use of tissue simulants, in lieu of animals, in wound ballistics is the establishment of their equivalence to animal tissue. For validity the simulant must reproduce the physical effects of the projectile-tissue interaction on the projectile (deformation, fragmentation), and in the simulant the projectile must stop at the same penetration depth as it does in living animal tissue. .................................................. ...........

CONSEQUENCES OF THESE MISCONCEPTIONS

1. Inappropriate Treatment of Gunshot Wounds:

Sacrifice of viable tissue on the altar of high velocity--treatment more disruptive than the malady--is the most obvious consequence of the postulate that assumes that manifest tissue damage must accompany passage of a "high-velocity" missile.

2. Misguided Weapon Testing and Development:

A heavier bullet of lower initial velocity was recently adopted, by US military forces, to overcome deficiencies in the M-16 rifle's long-range performance. To stabilize this longer bullet the rifle's barrel had to be replaced by one with a faster rifling twist (causing the bullet to spin more rapidly)................................

An extensive body of misinformation has been promulgated (28,29), based on the assumption that the temporary cavity produced by a handgun bullet is the sole factor determining its "incapacitation" effect on the human target. .............


DISCUSSION

Violation of simple, fundamental scientific method appears to be the common thread that runs through the misconceptions dealt with in this review. The author has found verifiable validity in only a small percentage of the material in print. The field of wound ballistics is part physics and part biological science. ......................................


ACKNOWLEDGEMENTS

The author wishes to acknowledge the advice and assistance of John D. O'Benar, PhD, and Charles E. Wade, PhD, of the Military Trauma Research Division, and John P. Hannon, PhD, Scientific Advisor of the Letterman Army Institute of Research, in arranging the data and expressing the thoughts contained in this paper. He also wishes to express appreciation to Paul J. Dougherty, Senior Medical Student at the Uniformed Services University of the Health Sciences Medical School, for his contribution of valuable literature references previously unknown to the author.