Changes in the mineral density distribution in human bone with age: image analysis using backscattered electrons in...

Area of Science:

• Biomaterials Science
• Orthopedic Research
• Microscopy Techniques

Background:

• Bone mineral density is crucial for skeletal health and changes throughout life.
• Assessing bone density typically involves complex imaging or destructive methods.
• Scanning electron microscopy (SEM) offers high-resolution imaging capabilities.

Purpose of the Study:

• To evaluate the feasibility of using backscattered electron (BSE) signals in SEM for bone mineral density analysis.
• To investigate age-related changes in bone mineral density distribution in human ribs.
• To determine if SEM-based BSE analysis can distinguish bone density across different age groups.

Main Methods:

• Human sixth rib samples (8 weeks to 59 years) were embedded in polymethylmethacrylate (PMMA).
• Samples were sectioned, polished, and carbon-coated for SEM analysis.
• A microcomputer-based image analysis system interfaced with SEM quantified BSE signal gray levels to assess mineral density distribution.

Main Results:

• Bone mineral density distribution in ribs changes significantly with age.
• High-density bone proportion increases, while low-density bone decreases, compressing the density range over time.
• Distinct age-related differences were observed between outer and inner rib cortices, with neonatal inner cortex influenced by growth zones and adult outer cortex showing higher turnover.

Conclusions:

• Backscattered electron signal analysis in SEM is a feasible method for studying bone mineral density distributions.
• This technique provides rapid and unbiased discrimination of bone density in neonates, children, and adults.
• SEM-BSE analysis reveals age-dependent structural and density variations in rib bone, potentially linked to mechanical loading and growth processes.