Hip Structural Analysis and Multiple Fragility Fractures: Evidence from a Large Cross-Sectional Clinical Cohort.

Hip structural analysis parameters (HSAP) are associated with hip fracture risk, but associations with multiple fragility fracture phenotypes remain poorly characterised. We analysed 11 DXA-derived HSAP in patients referred between June 2004 and November 2019. Five mutually exclusive fracture phenotypes were defined: no fracture, single hip fracture, single non-hip fracture, multiple non-hip fractures, and multiple fractures including at least one hip fracture. Separate multinomial logistic regression models were fitted for each HSAP reported as odds ratio (OR) per standard deviation increase, adjusted for FRAX covariates and left femoral BMD. Benjamini-Hochberg false discovery rate correction was applied across all tests. A right-hip sensitivity analysis assessed bilateral consistency. 35,647 patients were included (mean age 64.5 years, 82% female). Of 13,777 (38.6%) with a fragility fracture, 1044 (2.9%) had a single hip fracture, 9723 (27.3%) a single non-hip fracture, 2268 (6.4%) multiple non-hip fractures, and 742 (2.1%) multiple fractures including at least one hip fracture. After multiple testing correction, no meaningful associations were observed for isolated hip or non-hip fracture phenotypes. Multiple fractures including at least one hip fracture were independently associated with greater hip axis length (OR 1.44, 95% CI 1.28 to 1.63), neck diameter (OR 1.24, 95% CI 1.11 to 1.38), and centre of mass to upper neck margin distance (OR 1.35, 95% CI 1.21 to 1.51). HSAP were significantly associated with multiple fractures including at least one hip fracture rather than isolated fracture phenotypes, potentially reflecting local structural vulnerability and broader biomechanical instability.