This monocentric observational study aims to evaluate the association between plasma vitamin C levels (ascorbemia) and the presence of osteoporotic vertebral fractures in patients with osteoporosis. Forty participants will be enrolled at the Rheumatology

1. . Patients in group A or B will be seen in consultation or admitted by one of the medical team members among the investigators.

2. . After signing the informed consent and checking the inclusion criteria, the blood sample will be taken by a member of the nursing team of the department.

3. . The collection tube will then be placed in an opaque cooler, refrigerated with ice, and transported to the university hospital's biochemistry lab (routine assay).

4. . Next, the collection of planned clinical and paraclinical data:

   • Diet and risk factors for vitamin C deficiency:
   • Demographic data - osteoporosis risk factors
   • Bone status

5. . Once all the data is collected, we will carry out the statistical analyses, then draft the article, and finally publish it.

Inclusion Criteria:

• Men aged 50 yars or older ;
• Postmenopausal women ;
• Afilliated with a health insurance and system ;
• Written informed consent obtained.
• Group 1 : Clincal osteoporotic vertebral fracture confirmed by imaging within the previous month ; Followed in the Rheumatology department for management of vertebral fracture.
• Group 2 : Densitometric osteoporosis (T-score ≤ -2.5) ; No history of severe osteoporotic fracture ; No history of clinical or morphometric vertebral fracture.

Exclusion Criteria:

• Legal protection measure (guardianship, curatorship);
• inability to provide informed consent ;
• refusal to participate ;
• Vertebral fracture related to tumor,
• infection, trauma or non osteoporotic causes ;
• asymptomatic vertebral fracture discovered incidentally ;
• Severe densitometric osteoporosis for group 2 ;
• Previous severe osteoporotic fracture for group B.