Hydroxyapatite accounts for about what percentage of bone by mass?

Hydroxyapatite accounts for about what percentage of bone by mass?

• A. 65%
• B. 50%
• C. 75%
• D. 60%

Answer: (A)

Hydroxyapatite forms the main inorganic mineral portion of bone, and this mineral phase accounts for about 65% of bone by mass. Its crystalline calcium phosphate structure fills much of the space between collagen fibers, giving bone its hardness and ability to resist compression. The rest of bone mass comes from the organic matrix—primarily collagen—that provides tensile strength and some flexibility, along with small amounts of water. Because of this dominant mineral content, 65% is the standard figure students memorize for hydroxyapatite’s contribution to bone mass.

Hydroxyapatite forms the main inorganic mineral portion of bone, and this mineral phase accounts for about 65% of bone by mass. Its crystalline calcium phosphate structure fills much of the space between collagen fibers, giving bone its hardness and ability to resist compression. The rest of bone mass comes from the organic matrix—primarily collagen—that provides tensile strength and some flexibility, along with small amounts of water. Because of this dominant mineral content, 65% is the standard figure students memorize for hydroxyapatite’s contribution to bone mass.