Size, structure and gender: lessons about fracture risk

Area of Science:

• Bone biology
• Skeletal development
• Mechanobiology

Background:

• Age-related fracture risks differ between men and women due to gender-specific skeletal variables.
• Bone size and shape are influenced by periosteal modeling, driven by mechanical forces.
• Hormonal environments differentially affect bone cell responses to mechanical loading in males and females.

Purpose of the Study:

• To investigate gender differences in structural variables related to bone size and shape.
• To explore the role of hormonal environments and mechanical loading in skeletal development.
• To examine Frost's hypothesis regarding estrogen's effect on the bone mechanostat set point.

Main Methods:

• Comparative analysis of bone structure in males and females.
• Review of studies on periosteal and endosteal bone modeling.
• Examination of hormonal influences (estrogen) on bone mechanotransduction.

Main Results:

• Males exhibit greater bone strength due to periosteal bone apposition, while females undergo endosteal apposition post-puberty.
• Estrogen significantly influences the relationship between lean body mass and bone mineral content in females at puberty.
• Menopause is associated with endosteal resorption and periosteal apposition, weakening cortical structure.

Conclusions:

• Gender differences in bone structure and strength are established during skeletal development due to distinct hormonal and mechanical influences.
• Estrogen plays a critical role in modulating bone's response to mechanical loading, influencing fracture risk across the lifespan.
• Understanding these gender-specific mechanisms is crucial for addressing age-related fracture risks.