Differential effects of romosozumab across central and peripheral skeletal sites: a prospective DXA and HR-pQCT study in high-risk postmenopausal osteoporosis.

INTRODUCTION

Romosozumab is known to markedly increase areal BMD (aBMD) at the LS and proximal femur assessed by DXA; however, its effects on peripheral volumetric BMD (vBMD) and bone microarchitecture measured by HR-pQCT remain incompletely characterized in postmenopausal women at very high fracture risk.

MATERIALS AND

METHODS

In this single-center, prospective longitudinal observational study, postmenopausal women with primary osteoporosis and a history of fragility fractures received romosozumab for 12 mo. DXA (LS, proximal femur, and radius) and HR-pQCT (distal radius and tibia) were performed at baseline and at 6 and 12 mo.

RESULTS

Twenty-five patients were enrolled; 22 completed 12 mo and were analyzed. LS (L1-L4) aBMD increased by 18.0% at 6 mo and 24.4% at 12 mo (both p < .001), whereas TH aBMD increased by 4.9% and 7.3%, respectively (p = .001 and p < .001). In contrast, radius aBMD did not change significantly at either the one-third distal or ultradistal sites. On HR-pQCT, cortical vBMD at distal radius decreased modestly (-1.0% at 6 mo, -1.2% at 12 mo, p = .001 and p = .002), while trabecular thickness increased at 12 mo (+2.0%, p = .001); no other parameters changed significantly at the distal radius. No significant changes in vBMD or bone microarchitecture were observed at the distal tibia.

DISCUSSION: These findings suggest that 12 mo of romosozumab treatment resulted in marked increases in central aBMD at the LS and proximal femur by DXA, while effects on peripheral aBMD, vBMD, and bone microarchitecture at the distal radius and tibia assessed by DXA and HR-pQCT were limited, suggesting site-specific skeletal responses.