ABSTRACT
Bone consists of the mineral calcium hydroxyapatite [Ca10(PO4)6(OH)2], collagen and glycosaminoglycans which bind collagen. Hydroxyapatite is strong in compression, whereas collagen gives bone flexibility and tensile strength. The weakest area is the cement line between osteons. Bone is 3× as light, 10× as flexible, but has approximately the same tensile strength as cast iron. Any material deforms under load, yet to act as a skeleton the deformations must be small. Bone tested in the laboratory is dead, but the data obtained are important and form the basis of the stress/strain curve-the formal expression of strength and stiffness.
