Objective
It is commonly assumed that for given body size, Caucasian men have larger skeletal size and higher bone mass than women. We revisit this assumption by examining gender-related differences in bone size, geometry and density after controlling for body size.
Methods
The study involved 4196 women and men aged 20 years and older who were recruited from the general population of Ho Chi Minh City (Vietnam). Tibia and cortical bone volumetric BMD were measured at 4%, 38%, and 66% sites using a peripheral quantitative computed tomography XCT2000 (Stratec, Germany). Bone mineral density (BMD) was measured at the lumbar spine and femoral neck by DXA (Hologic Horizon). For each woman, we randomly matched with a man of similar age, height, and weight. The difference in bone parameters between both genders was tested by the paired t-test.
Results
The matching algorithm resulted in 325 pairs of men and women with identical age (48 years), height (160 cm), and weight (57 kg). Averagely, women had 12% more fat mass than men (P < 0.001). Men had higher lean mass (40.3±4.0 vs 33.5±3.8 kg, P < 0.001) but lower fat mass (17.2±4.1 vs 24.1±4.4 kg, P < 0.001) than women. Areal BMD at femoral neck and total hip was consistently higher in men than women (P < 0.001). Furthermore, men had greater bone area and volumetric BMD than women at either the radius or tibia regardless of at 4% or 66% sites. The force required to break the radius or tibia in men was about 1.5 times (P < 0.001) higher than in women.
Conclusion
These results show that for the same age, height and weight, men have greater bone size, volumetric BMD, and breaking force than women, and these differences may explain why men have a lower risk of fracture than women.