The main hypothesis is that muscle acts on bone tissue via the secretion of myokines (myostatin, follistatin, irisin). This is based on previous results showing that muscle mass in different patient populations with very different body mass indexes (anorexic or obese patients) is significantly and independently associated with bone mineral density.
Self-reported Caucasian ethnicity (Europe, Middle East, North Africa) only as there is a difference in BMD by ethnicity.
Person affiliated with or benefiting from a social security scheme.
Free, informed consent signed by the participant and the investigator (at the latest on the day of inclusion and before any examination required by the research).
Fragility fracture defined as a spontaneous or low-kinetic fracture (≤ one fall from height).
Early menopause (< 40 years), hysterectomy (complete < 40 years), primary amenorrhea (absence of menstruation before 15 years), current amenorrhea of more than 3 months without contraceptive if the patient is less than 40 years old.
Patients on treatments: prolonged corticosteroid therapy > 3 months or > 1 g (cumulative dose).
Immobilization of more than 3 months, less than 12 months old.