Inclusion Criteria:  Subjects over 21 years old, with inflammatory bowel disease (both ulcerative colitis and Crohn's disease), diagnosed by clinical, biochemical, endoscopic and anatomo-pathological criteria. Subjects over 21 years old, without IBD or known metabolic bone pathology, recruited voluntarily in the Endocrinology and Nutrition, Digestive System and Rheumatology departments of the Ruber Juan Bravo Hospital, during routine health control visits (control group). Subjects without language barriers, who expressed their willingness to cooperate in the follow-up and who gave their informed consent before entering the study.  Exclusion Criteria:  Other concomitant causes of metabolic bone disease: Paget's disease, severe chronic renal insufficiency (estimated glomerular filtration rate <30 ml/min/1.73m2), metastatic bone disease, multiple myeloma, Hypercalcemia > 11 mg/dl, period of immobilisation for more than 3 months in the previous year. Pregnant women or women planning pregnancy during the recruitment and testing process. Anatomical alteration of the right foot that may interfere with calcaneal ultrasound, including moderate-severe edema. Patients on active treatment with antiresorptive drugs, osteoformers, or pharmacological doses (>50,000 units/month) of vitamin D3 (cholecalciferol). Patients with a history of treatment with oral bisphosphonates, strontium ranelate or therapeutic doses of fluoride (>20 mg/day) for more than 3 months in the two years prior to the baseline visit, or for more than two years at any time in their life. Patients who have received an intravenous bisphosphonate in the three years prior to the baseline visit. Patients who have received denosumab within 6 months prior to the baseline visit. Patients who have received calcitonin or a selective oestrogen receptor modulator in the 3 months prior to the baseline visit.  Participation at the time of recruitment in a clinical trial with medicinal products for the prevention or treatment of osteoporosis and/or IBD.  Additional exclusion criteria for the control group:  Chronic diseases affecting bone metabolism, for example, active hyperthyroidism within the last 6 months, Cushing's syndrome, anorexia nervosa, early menopause, type 1 diabetes mellitus, poorly controlled type 2 diabetes mellitus of more than 5 years' duration or with microvascular complications, or primary hyperparathyroidism. Active treatment with drugs that affect bone quality such as corticoids, oral anticoagulants, anti-estrogens (aromatase inhibitors and/or GnRH analogues), anti-androgens and anti-retroviral