Distribution of Prevalent and Incident Vertebral Fractures and Their Association with Bone Mineral Density in Postmenopausal Women in the Teriparatide Versus Risedronate VERO Clinical Trial

Vertebral fractures (VFx) occur most frequently in the mid-thoracic and thoraco-lumbar regions, which experience the highest mechanical loading along the spine. The prevalence and incidence of VFx by their location and severity, and their relationship with bone mineral density (BMD), are seldom reported in randomized clinical trial cohorts. The VERO trial randomized 1360 postmenopausal women with at least two moderate or one severe VFx to receive either teriparatide or risedronate for up to 24 months. In this post hoc analysis, we describe the centrally read distribution and severity of prevalent and incident VFx, and the association of their location with the baseline BMD. At baseline, 21.4% of all evaluable vertebral bodies had a prevalent VFx; most commonly at L-1, T-12, L-2 and T-11 (38.5%, 37.4%, 25.3% and 23.5% of patients, respectively). Patients with prevalent VFx only at T-12/L-1 showed a higher baseline BMD compared to patients with VFx at other levels. At month 24, 100 patients had 126 incident VFx (teriparatide: 35; risedronate: 91). The most frequent incident VFx occurred at T-12 (n = 17, 1.6% of patients), followed by L-1 and T-11 (n = 14, 1.3% both). The frequency of incident VFx was lower at all vertebral levels in patients given teriparatide. These results confirm prior reports that VFx occurs more frequently at mid-thoracic and thoraco-lumbar regions of the spine. Patients with these VFx locations have higher BMD than those who fracture at other sites, suggesting a role for mechanical stress in the etiology of VFx. Teriparatide is superior to risedronate in the prevention of VFx at these common fracture locations.