A new concept for the diagnostic of osteoporosis!

Thesis 1 Postnatally the strength of bones is just sufficient to prevent spontaneous fractures during voluntary muscle contractions no matter if the muscle forces are low, normal or supranormal. To supply sufficient (not maximal!) mechanical strength is the final criteria for the health of bones and the essential purpose of its biological mechanism. The maintenance of the mechanical stability is more important than other function of bone like homeostasis. According to thesis one bone health does not depend on absolute measures of strength or mass rather than the ratio of bone strength to the forces that act on bone.		Thesis 3 Postnatal bone strength definition is two fold: one part is defined prior to birth and the other one is added later. After birth in-utero the genes provided the bones with a basic anatomy and their biological function that allows the adaptation to later follow influences. At every time after birth bones post-natally paralyzed or normal limbs show typical differences in bone strength and other characteristics. These differences reflect the adaptations to mechanical forces that act on the starting conditions of a normal limb. This corresponds to the normal post natal phenotype. Bones in completely paralyzed limbs reflect the starting conditions under genetic and humoral conditions but not under the influence of normal mechanical forces and correspond to an abnormal postnatal phenotype. Even during a permanent immobilization bone is never completely lost and the remaining part might represent the starting conditions. Actual experimental data show a close correlation between muscle force and bone strength, also studies of paraplegic and immobilized subjects confirm these thesis.
Thesis 2 Strength of bone is reduced at all osteoporosis or osteopenias no matter how they are defined. It became obvious that single parameter of bone mass (BMC), bone d density (BMD), ultrasound parameters, and negative T and Z Scores are various unreliable measures of bone strength.

The determinant factor for the bone strength is muscle force. Peripheral fractures are caused by a fall, the risk of falling is mainly determined by muscle power, therefore any diagnosis of osteoporosis without estimation of the risk of falling or evaluation of muscle function is not comprehensive. Instead of statistical normal values, the measurement of the individual muscle function serves as a reference for the individual bone strength.
Comparison of muscle mass and bone mass	Comparison of muscle surface and bone surface