Disproportional geometry of the proximal femur in patients with Turner syndrome: A cross-sectional study

Objective: Patients with Turner syndrome (TS) have altered growth and increased risk of osteoporosis due to oestrogen deficiency and possibly a host of other factors. Thus, TS patients have a 4.9-fold increased risk of femoral neck fractures. Most patients are treated with oestrogen during puberty and adolescence to facilitate pubertal development and prevent secondary osteoporosis. The geometry of the hip is a predictor for hip fractures independent of bone mineral density (BMD). The purpose of the present study was to investigate the variation of the geometry of the hip in patients with TS in comparison with healthy controls. Patients: The study population comprised 58 patients with TS (aged 22-67 years) and 60 age-matched healthy women (aged 21-65 years). Measurements: Hip axis length (HAL), neck width (NW), neck shaft angle (NSA), and femoral head-radius (HR) on dual-energy X-ray absorptiometry (DXA) screen images. These parameters related to age of oestrogen supplementation, menarche, and duration of oestrogen exposure. Results: Height was 146.6 ± 6.9 cm and 167.1 ± 6.2 cm (P < 0.1) and weight 57.4 ± 13.9 kg and 62.3 ± 8.3 kg (P < 0.001) in patients and controls, respectively. After adjustment for differences in height, HAL was not significantly different (9.4 ± 0.5 vs. 9.5 ± 0.5 cm; NS) in TS compared with controls while NW was significantly increased (3.5 ± 0.4 cm vs. 3.3 ± 0.2 cm, P < 0.001), NSA was similar (129 ± 4° vs. 130 ± 4°, NS), and HR was significantly decreased (4.1 ± 0.4 vs. 4.5 ± 0.3 cm, P < 0.001). The duration of oestrogen exposure was significantly shorter among TS, but did not correlate significantly with the geometrical parameters in either TS or controls. Conclusion: Our data demonstrates that hip geometry is disproportionate in TS compared with normal controls. The altered hip geometry, however, cannot explain the increased risk of hip fracture in TS.