Fragility fractures increase among elderly patients worldwide, representing a global burden in terms of disability and care expenditure.

Osteoporosis is asymptomatic up to the moment in which a first fracture occurs, reason why it is often underdiagnosed. Even after that, further fractures do occurr, as osteoporosis is often untreated. Several programs have been introduced worldwide to prevent secondary fractures among the population at risk (e.g., International Osteoporosis Foundation's Capture the Fracture), and several risk factors are being investigated to generate a predictive score. However, accurate validation is needed to make these scores reliable.

In this retrospective observational study, we aim to validate a predictive score trained on a population of elderly patients with a cohort of patients who underwent hip fracture surgery in a high-volume orthopedic center in the Region of Lombardy.

Inclusion Criteria:

• People who underwent total or partial hip replacement (ICD 9 CM 81.51, 81.52) in five years (2013-2017) at the hospital for a compound fracture of the hip (ICD 9 CM 820, 820.01-820.09).

Exclusion Criteria:

• People undergoing the same intervention for other reasons (e.g. pathological fracture, ICD 9 CM 733.14).

ICD 9 CM stands for International Classification of Disease, 9th Revision, Clinical Modification.

Patients aged 60 or more, of all sexes.