Osteopenia refers to bone mineral density that is reduced compared with that of young healthy adults but does not yet meet the densitometric criteria for osteoporosis. According to the WHO classification, osteopenia is present in postmenopausal women and men aged 50 years and older when the T-score measured by dual-energy X-ray absorptiometry is between −1.0 and −2.5 standard deviations. Osteopenia is not an independent fracture disease but a risk marker. Individual fracture and surgical risk is additionally determined by age, bone quality, propensity to fall, comorbidities, medications, and the planned biomechanical loading.

Neurosurgical relevance

In spinal neurosurgery, even osteopenia can impair the purchase of Pedicle screws and interbody implants during Spinal fusions[^1]. Possible consequences include:

Screw loosening or screw pullout
Cage subsidence and loss of segmental height
Pseudarthrosis
Adjacent-level fractures or adjacent-segment degeneration
Progressive malalignment after instrumented fusion
Revision surgery

This is particularly relevant in long-segment fusions, deformity corrections, revision procedures, older patients, and patients with preexisting vertebral body fractures.