Bone Abstracts

Background: The World Health Organisation (WHO) defines osteoporosis as a DXA T-score ≤ 2.5 at the lumbar spine, total hip or femoral neck, treating the diagnosis as binary. The anatomical pattern of osteoporosis across the lumbar spine and bilateral femoral necks may provide extra information about patient prognosis.

Objective: To determine whether the pattern of osteoporosis at different anatomical sites is associated with fragility fracture burden.

Methods: Analysis was performed on a DXA database in the northwest of England with data from June 2004 to February 2024. 36,740 patients with complete T-scores at the lumbar spine and both femoral necks were classified into eight osteoporosis site-pattern categories using the WHO ≤ 2.5 threshold. "No osteoporosis at any site" was the reference, and missing hip data were handled by complete-case analysis (4,240 excluded, predominantly prior arthroplasty). The outcome was distinct fragility fracture sites, sustained from a fall from standing height or less in individuals aged over 50, ascertained by technician verification at the time of DXA. Associations were examined using Poisson regression with robust standard errors, interpreted as prevalence rate ratios (PRR). Models were adjusted for 13 confounders based on the FRAX framework and prior analyses of this cohort.

Results: The cohort was 78.9% female, with mean (SD) age 67.58 (9.78) years and BMI 27.37 (5.60) kg/m². All osteoporotic site patterns were independently associated with higher fracture burden. Isolated spine PRR was 1.44 (95% CI 1.37-1.50). Isolated right-hip and left-hip osteoporosis 1.30 (1.20-1.42) and 1.43 (1.32-1.55) respectively; bilateral hip 1.33 (1.25-1.41). Combined spine-hip patterns showed the highest adjusted fracture burden: spine and right hip 1.62 (1.44-1.82), spine and left hip 1.58 (1.42-1.75), spine and both hips 1.60 (1.51-1.69); all P 0.001. A significant rank-order trend was observed across site-pattern categories (Spearman P 0.001), indicating a graded relationship between extent of involvement and fracture burden.

Conclusion: Fragility fracture burden significantly varies by osteoporosis site pattern, highest in combined spine and hip involvement. A graded relationship was observed between anatomical extent of osteoporosis and fracture burden. Spine involvement showed higher fracture burden than hip-only patterns of equivalent site count, suggesting site location carries prognostic relevance.