Bone mineral density differs by proximal femoral fracture location but not by fracture morphology

Abstract Whether the morphology of proximal femoral fractures reflects skeletal fragility remains unclear. Using a prospective multicenter registry of consecutive patients who underwent surgery for proximal femoral fracture at six Japanese hospitals between 2023 and 2026, we compared bone mineral density (BMD) and bone turnover markers across fracture locations and morphological subtypes. Femoral neck fractures were classified by the Garden classification and trochanteric fractures by the AO/OTA classification, with 31A2 fractures subdivided by fragment number on computed tomography. Of 1,724 patients analyzed (866 femoral neck and 858 trochanteric fractures), those with trochanteric fractures had lower BMD at the total hip (adjusted difference − 0.053 g/cm², 95% confidence interval − 0.067 to − 0.040), femoral neck, and lumbar spine (all P < 0.001). Within fracture types, total hip BMD did not differ between displaced and non-displaced femoral neck fractures (− 0.007, − 0.032 to 0.017), and more fragments were not associated with lower BMD in trochanteric fractures. Procollagen type I N-terminal propeptide was higher in trochanteric fractures, whereas tartrate-resistant acid phosphatase 5b and 25-hydroxyvitamin D did not differ. BMD was associated with fracture location but not with fracture morphology, suggesting that fracture type does not necessarily reflect the severity of osteoporosis.