Background and objective: Resistance to hip fractures relies on adequate compressive strength, determined by femur alignment and geometry. Oestrogen is a crucial determinant of bone accrual, peak bone mass 1 and geometry 2; however, premature ovarian insufficiency (POI) is characterised by hypoestrogenism. We hypothesised that hypoestrogenism as seen in women with POI is associated with an impaired femur alignment and/or smaller femoral size.
Methods: We conducted a cross-sectional, case-control study including 89 women with spontaneous normal karyotype (s-POI) or iatrogenic (i-POI) POI, aged 20-40 years (cases) compared with 89 age and BMI-matched population-based controls, from 2005-2021. Hip geometrical features using Lunar Advanced Hip Analysis (AHA) software were measured and the axis of the femoral shaft with the vertical (α)- an indicator of its alignment with the upper body was also calculated (Figure 1).
Results:
Median age (range) of POI diagnosis occurred at 35 (18-40) years; mean POI duration at time of DXA was 2.07 (range 0-13) years. Oestrogen therapy was recorded in 82% of POI women. Cross-sectional area at the femoral neck (CSA mm2) was lower in POI women compared with controls (139.30 ± 29.08 vs 157.29 ± 22.26; p<0.001) (Table 1). The angle between the femur shaft axis and the upper body (α) was lower in POI women compared with controls (-2.34 ± 4.30 vs 1.24 ± 3.72; p<0.001). After adjustment for the differences in height and ethnicity among the controls and POI participants, cortical thicknesses and ratios, hip axis length, and buckling ratio were not significantly different between groups.
Conclusion and Inferences:
Women with POI exhibit a smaller femur that was poorly aligned with the upper body. Further research is needed to establish the role of this newly identified feature in fracture risk prediction in these patients and influence on therapeutic decisions.