An in-vitro animal bone model study to predict spiral fracture strength of long bones in the young infant

Area of Science:

• Orthopedics
• Pediatric Traumatology
• Biomechanical Engineering

Background:

• Infant fractures from non-accidental injuries pose a significant clinical challenge.
• Distinguishing accidental from non-accidental causes of spiral long bone fractures in infants is difficult.
• This study investigates the relationship between bone geometry and torsional strength in immature long bones.

Purpose of the Study:

• To determine the correlation between geometric properties and torsional strength in immature long bones.
• To assist in differentiating accidental from non-accidental injuries in infants.
• To establish biomechanical parameters for assessing infant bone fracture risk.

Main Methods:

• Immature porcine metacarpals (n=21) were analyzed using dual-energy x-ray absorptiometry (DEXA) for bone mineral content (BMC_L), bone mineral density (BMD), and section modulus (Z).
• Specimens underwent torsional testing at 1°/second until failure.
• Correlation analysis was performed between failure strength and DEXA-derived parameters.

Main Results:

• The mean failure strength was 13.71 Nm (±2.42 Nm).
• Strong correlations were observed between failure strength and BMC_L (r²=0.81) and section modulus (Z) (r²=0.75).
• A weaker correlation was found with BMD (r²=0.283).

Conclusions:

• A novel approach using a size-matched animal model to estimate pediatric long bone torsional strength.
• Significant correlation exists between bone mineral content and fracture strength in immature long bones (BMC_L range: 0.59-0.77 g/cm).
• Findings support the use of biomechanical analysis in assessing fracture risk in infants.