Abaloparatide effects on BMD in acetabular regions corresponding to DeLee and Charnley zones in women with postmenopausal osteoporosis.

BACKGROUND

Acetabular bone loss in patients with osteoporosis is associated with increased risk of acetabular fragility fractures, significant morbidity, and can increase risk of complications in patients undergoing total hip arthroplasty. The anabolic osteoporosis treatment abaloparatide increases total hip areal bone mineral density (BMD), but its effect on acetabular BMD is unknown.

METHODS

Anatomical landmarks were identified in DXA scans from a random subgroup of postmenopausal women with osteoporosis (PMO) treated with abaloparatide 80 μg/d or placebo (n = 250/group) from the phase 3 ACTIVE trial to virtually place a hemispherical shell model of an acetabular cup and define regions of interest corresponding to DeLee and Charnley zones 1 (R1), 2 (R2), and 3 (R3). Changes in BMD from baseline at 6 and 18 months were calculated. Statistical significance was tested using a mixed model with repeated measures. Local mean changes in BMD were depicted by alignment of DXA scans via intensity-based registration onto a reference scan.

RESULTS

Abaloparatide significantly increased acetabular areal BMD in all three DeLee and Charnley zones at 6 and 18 months versus placebo. Mean BMD increases with abaloparatide were 8.38 % (R1), 7.25 % (R2), and 9.73 % (R3) at 18 months. BMD increases were homogenously distributed throughout the regions. With placebo, localized losses in BMD were noted after 18 months.

CONCLUSIONS

Abaloparatide treatment rapidly and progressively increases BMD in acetabular zones in PMO.

CLINICAL TRIAL NUMBER

NCT01343004.