The osteon is the fundamental functional unit of compact bone and it consists of concentric layers (lamellae), of compact bone tissue that surrounds a central canal. What gives a strength, hardness and rigidity to bone is the presence of mineral salt in the osteoid matrix, a complex of calcium and phosphate -hydroxyapatite. Calcified bone contains about 25% organic matrix (2-5% of which are cells), 5% water and 70% inorganic mineral (hydroxyapatite). So, changes in hydroxyapatite would cause the bones to bend under a person's body weight.
