Biomechanics of Spiral Fractures: Investigating Periosteal Effects Using Digital Image Correlation

Area of Science:

• Biomechanics
• Pediatric Orthopedics
• Forensic Science

Background:

• Spiral fractures are common in abusive head trauma, especially in infants.
• Distinguishing accidental from non-accidental fractures is difficult.
• The periosteum's role in immature bone fracture is not well understood.

Purpose of the Study:

• Investigate spiral fracture biomechanics in immature long bones.
• Determine the periosteum's influence on fracture behavior under torsion.

Main Methods:

• Immature sheep metatarsals underwent torsional loading at varying speeds.
• High-speed digital image correlation (HS-DIC) analyzed strain.
• Bones were tested with and without periosteum.

Main Results:

• Spiral fractures were induced in over 85% of specimens.
• HS-DIC showed localized tensile strain at fracture sites.
• Intact periosteum constrained deformation, widening tensile stress regions.

Conclusions:

• Novel HS-DIC and biomechanical testing approach.
• Periosteum plays a biomechanical role in immature bone fracture.
• Periosteum may offer protection against torsional stress-induced fractures.