Ballistic fractures: indirect fracture to bone

Area of Science:

• Biomechanics
• Forensic Science
• Trauma Research

Background:

• Indirect fractures can result from projectile impacts via temporary cavity or sonic wave mechanisms.
• Understanding the primary mechanism is crucial for injury analysis and prevention.

Purpose of the Study:

• To investigate the temporal relationship between pressure waves and indirect fracture formation.
• To determine if sonic waves or temporary cavities are responsible for indirect fractures.

Main Methods:

• Utilized fresh frozen cadaveric long bones (tibia and femur) embedded in gelatin.
• Fired 9-mm and 5.56-mm bullets near bones to induce indirect fractures, capturing events with high-speed video (20,000 fps) and synchronized strain gauges (20,000 Hz).
• Analyzed strain data and video to pinpoint the exact time of fracture.

Main Results:

• Eight indirect fractures (simple oblique or wedge patterns) were produced.
• Fractured bones were closer to the projectile path (average 9.68 mm) than non-fractured bones (average 15.15 mm), with statistical significance (p=0.036).

Conclusions:

• The temporary cavity, not the sonic wave, was identified as the cause of indirect fractures in this study.
• Findings clarify projectile injury mechanisms and implications for forensic and trauma analysis.